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Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA UE Behaviors in Idle Mode
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Page1Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
ForewordUE behaviors in idle mode include :
PLMN selection
System information reception
Cell selection and reselection
Location registration
Paging procedure
Access procedure
PLMN selectionUsed to ensure that the PLMN selected by the UE properly provides services. Cell selection and reselectionUsed to ensure that the UE finds a suitable cell to camp on.Location registrationUsed for the network to trace the current status of the UE and to ensure that the UE is camped on the network when the UE does not perform any operation for a long period.System information receptionThe network broadcasts the network information to a UE which camps on the cell to control the behaviors of the UE.PagingUsed for the network to send paging messages to a UE which is in idle mode, CELL_PCH state, or URA_PCH state.AccessFrom the view of access stratum, access is the procedure UE shift from idle mode to connected mode.
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Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Page3Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Page4Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Cell SearchUE does not have UTRAN carrier information
In order to find a suitable cell to stay, UE will scan all the
frequencies in UTRAN. In each carrier, UE just need to find a
cell with best signal
UE has UTRAN carrier information
UE will try whether the original cell is suitable to stay. If not, UE
still need to scan all the frequencies about UTRAN in order to
find a suitable cell in PLMN
Typical scenario of first occasion is the first time a new UE is put into use.The second occasion is very common.
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Cell Search
Slot synchronization
Frame synchronization and code-group identification
Primary Scrambling code identification
Step 1: Slot synchronization During the first step of the cell search procedure the UE uses the primary synchronisation code (PSC) to acquire slot synchronisation to a cell.Step 2: Frame synchronization and code-group identificationDuring the second step of the cell search procedure, the UE uses the secondary synchronisation code (SSC) to find frame synchronisation and identify the code group of the cell found in the first step.Step 3: Primary Scrambling code identification: During the last step of the cell search procedure, the UE determines the exact primary scrambling code used by the found cell. The primary scrambling code is typically identified through symbol-by-symbol correlation over the CPICH with all codes within the code group identified in the second step.If the UE has received information about which scrambling codes to search for, steps 2 and 3 above can be simplified.
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PLMN SelectionUE shall maintain a list of allowed PLMN types. In the
PLMN list, the UE arranges available PLMNs by priorities.
When selecting a PLMN, it searches the PLMNs from the
high priority to the low.
The UE selects a PLMN from HPLMNs or VPLMNs.
UE can get the system information from PCCPCH, and the PLMN information is transmitted in MIB of PCCPCHAfter getting the MIB, UE can judge weather the current PLMN is the right one. If so, UE will get the SIB scheduling information from the MIB; if not, UE will search another carrier, do this procedure again
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PLMN Selection (Cont.)PLMN Selection in HPLMNs
Automatic PLMN Selection Mode
The UE selects an available and suitable PLMN from the whole
band according to the priority order
Manual PLMN Selection Mode
The order of manual selection is the same as that of automatic
selection.
The priority order for automatic PLMN selection mode
The PLMN selected by the UE before automatic PLMN selection
Previously selected PLMN6
The PLMNs are arranged in descending order of signal quality.
Other PLMN/access technology combinations excluding the previously selected PLMN5
The PLMNs are arranged in random order
Other PLMN/access technology combinations with the high quality of received signals excluding the previously selected PLMN
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The PLMNs are arranged in priority order
PLMNs contained in the "Operator Controlled PLMN Selector with Access Technology" data field in the SIM excluding the previously selected PLMN
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The PLMNs are arranged in priority order
PLMNs contained in the "User Controlled PLMN Selector with Access Technology" data field in the SIM excluding the previously selected PLMN
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Home PLMNsHPLMNs1
RemarkPLMN typeOrder
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PLMN Selection (Cont.)PLMN Selection in VPLMNs
If a UE is in a VPLMN, it scans the “user controlled PLMN
selector” field or the “operator controlled PLMN selector” field
in the PLMN list to find the HPLMN or the PLMN with higher
priority according to the requirement of the automatic PLMN
selection mode.
A value of T minutes may be stored in the SIM. T is either in the range from 6 minutes to 8 hours in 6-minute steps or it indicates that no periodic attempts shall be made. If no value is stored in the SIM, a default value of 60 minutes is used. After the UE is switched on, a period of at least 2 minutes and at most T minutes shall elapse before the first attempt is made. The UE shall make an attempt if the UE is on the VPLMN at time T after the last attempt.
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Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Structure of System Information System information is organized as a tree, including:
MIB (Master Information Block )
SB (Scheduling Block )
SIB (System Information Block )
System information is used for the network to broadcast network information to UEs camping on a cell so as to control the behavior of UEs. MIB
When selecting a new cell, the UE reads the MIB. The UE may locate the MIB by predefined scheduling information. The IEs in the MIB includes MIB value tag, PLMN type, PLMN identity, reference and scheduling information for a number of SIBs in a cell or one or two SBs in a cell.
SBScheduling Block (SB) gives reference and scheduling information to other SIBs. The scheduling information of a SIB may be included in only one of MIB and SB.
SIBSystem Information Block (SIB) contains actual system information. It consists of system information elements (IEs) with the same purpose.
Scheduling information for a system information block may only be included in either the master information block or one of the scheduling blocks.
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System Information SIB1: Contains the system information for NAS and the timer/counter for UE
SIB2: Contains the URA information
SIB3: Contains the parameters for cell selection and cell re-selection
SIB5: Contains parameters for the common physical channels of the cell
SIB7: Contains the uplink interference level and the refreshingtimer for SIB7
SIB11: Contains measurement controlling information
SIB4: Contains parameters for cell selection and cell re-selection while UE is in connected modeSIB6: Contains parameters for the common physical channels of the cell while UE is in connected modeSIB8: Contains the CPCH static informationSIB9: Contains the CPCH dynamic informationSIB10: Contains information to be used by UEs having their DCH controlled by a DRAC procedure. Used in FDD mode only. To be used in CELL_DCH state only. Changes so often, its decoding is controlled by a timerSIB12: Contains measurement controlling information in connecting modeSIB13: Contains ANSI-41 system informationSIB14: Contains the information in TDD modeSIB15: Contains the position service informationSIB16: Contains the needed pre-configuration information for handover from other RAT to UTRANSIB17: Contains the configuration information for TDDSIB18: Contains the PLMN identities of the neighboring cells
To be used in shared networks to help with the cell reselection process
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Page12Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Reception of System Information The UE shall read system information broadcast on a BCH
transport channel when the UE is in idle mode or in
connected mode, that is, in CELL_FACH, CELL_PCH, or
URA_PCH state.
The UE may use the scheduling information in MIB and SB to locate each SIB to be acquired. If the UE receives a SIB in a position according to the scheduling information and consider the content valid, it will read and store it.
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Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Page14Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Cell SelectionWhen the PLMN is selected and the UE is in idle mode, the
UE starts to select a cell to camp on and to obtain services.
There are four states involved in cell selection:
Camped normally
Any cell selection
Camped on any cell
Connected mode
Camped normally: The cell that UE camps on is called the suitable cell. In this state, the UE obtains normal service. Any cell selection: In this state, the UE shall attempt to find an acceptable cell of an any PLMN to camp on, trying all RATs that are supported by the UE and searching first for a high quality cellCamped on any cell: The cell that UE camps on is called the acceptable cell. In this state the UE obtains limited service. The UE shall regularly attempt to find a suitable cell of the selected PLMN, trying all RATs that are supported by the UE.Connected mode: When returning to idle mode, the UE shall use the procedure Cell selection when leaving connected mode in order to find a suitable cell to camp on and enter state Camped normally. If no suitable cell is found in cell reselection evaluation process, the UE enters the state Any cell selection.
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Cell Selection (Cont.)Two types of cell selection:
Initial cell selection
If no cell information is stored for the PLMN, the UE starts this
procedure.
Stored information cell selection
If cell information is stored for the PLMN, the UE starts this
procedure.
Initial cell selection: If no cell information is stored for the PLMN, the UE starts the initial cell selection. For this procedure, the UE need not know in advance which Radio Frequency (RF) channels are UTRA bearers. The UE scans all RF channels in the UTRA band according to its capabilities to find a suitable cell of the selected PLMN. On each carrier, the UE need only search for the strongest cell. Once a suitable cell is found, this cell shall be selected. Stored information cell selection: For this procedure, the UE need know the central frequency information and other optional cell parameters that are obtained from the measurement control information received before, such as scrambling codes. After this procedure is started, the UE selects a suitable cell if it finds one. Otherwise, the "Initial cell selection" procedure is triggered.
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Cell Selection Criteria
minqualqualmeasqual QQS −=
oncompensatirxlevrxlevmeasrxlev PQQS −−= min
Criterion S is used by the UE to judge whether the cell is
suitable to camped on.
Criterion S : Srxlev > 0 & Squal > 0, where:
If the pilot strength and quality of one cell meet S criteria, UE will stay in this cell and get other system information. Then, UE will initiate a location update registration process.If the cell doesn’t satisfy S criteria, UE will get adjacent cells information from SIB11. Then, UE will judge weather these cells satisfy S criteria. If the adjacent cell is suitable, UE will stay in the adjacent cell.If no cell satisfies S criteria, UE will take the area as dead zone and continue the PLMN selection and reselection procedure.
Max(UE_TXPWR_MAX_RACH-P_MAX,0), dBmPcompensation
Maximum TX power level an UE may use when accessing the cell on RACH (read in system information) (dBm)
UE_TXPWR_MAX_RACH
Maximum RF output power of the UE (dBm)P_MAX
Minimum required RX level in the cell (dBm)Qrxlevmin
Minimum required quality level in the cell (dB)Qqualmin
Measured cell RX level value. This is received signal, CPICH RSCP for current cells (dBm)
Qrxlevmeas
Measured cell quality value. The quality of the received signal expressed in CPICH Ec/N0 (dB) for current cell
Qqualmeas
Cell RX level value (dBm)Srxlev
Cell quality value (dB)Squal
ExplanationParameters
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Parameters of S CriterionQUALMEAS
Parameter name: Cell Se-reselection quality measure
Recommended value: CPICH_ECNO
QQUALMIN
Parameter name: Min quality level
Recommended value: -18, namely -18dB
QUALMEASParameter name: Cell Sel-reselection quality measure Value range: CPICH_ECNO(CPICH Ec/N0),CPICH_RSCP(CPICH RSCP)Physical unit: None.Content: Cell selection and reselection quality measure, may be set to CPICH Ec/N0 or CPICH RSCP.Recommended value: CPICH_ECNO.
QQUALMINParameter name: Min quality levelValue range: -24~0Physical value range: -24~0; step: 1Physical unit: dBContent: The minimum required quality level corresponding to CPICH Ec/No. The UE can camp on the cell only when the measured CPICH Ec/No is greater than the value of this parameter.Recommended value: -18Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of S CriterionQRXLEVMIN
Parameter name: Min Rx level
Recommended value: -58, namely -115dBm
MAXALLOWEDULTXPOWER
Parameter name: Max allowed UE UL TX power
Recommended value: 21, namely 21dBm
QRXLEVMINParameter name: Min Rx levelValue range: -58~-13.Physical value range: -115~-25; step: 2 (-58:-115; -57:-113; ..., -13:-25 ).Physical unit: dBm.Content: The minimum required RX level corresponding to CPICH RSCP. The UE can camp on the cell only when the measured CPICH RSCP is greater than the value of this parameter.Recommended value: -58. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
MAXALLOWEDULTXPOWERParameter name: Max allowed UE UL TX power Value range: -50~33 Physical value range: -50~33; step: 1Physical unit: dBmContent: The maximum allowed uplink transmit power of a UE in the cell, which is related to the network planning. Content: Allowed maximum power transmitted on RACH in the cell. It is related to network planning. Recommended value: -21Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Cell ReselectionAfter selecting a cell and camping on it, the UE periodically
searches for a better cell according to the cell reselection
criteria. If finding such a cell, the UE selects this cell to
camp on.
UE should monitor the quality of current cell and neighbor cells in order to camp on the better cell to initiate service. The better cell is the most suitable one for the UE to camp on and obtain services. The QoS of this cell is not necessarily more satisfying.
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Measurement Start Criteria (Cont.)Intra-frequency measurement
Squal ≤ Sintrasearch
↓
Qqualmeas − Qqualmin ≤ Sintrasearch
↓
Qqualmeas ≤ Qqualmin + Sintrasearch
Parameters of the measurement start criteria
Minimum required quality level in the cell (dB) .Qqualmin
Measurement threshold for UE to trigger inter-RAT cell reselection, compared with Squal.
SsearchRATm
Measurement threshold for UE to trigger inter-frequency cell reselection, compared with Squal.
Sintersearch
Measurement threshold for UE to trigger intra-frequency cell reselection, compared with Squal.
Sintrasearch
Cell quality value (dB)Squal
DescriptionName
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Measurement Start Criteria (Cont.)Inter-frequency measurement
Squal ≤ Sintersearch
↓
Qqualmeas − Qqualmin ≤ Sintersearch
↓
Qqualmeas ≤ Qqualmin + Sintersearch
Parameters of the measurement start criteria
Minimum required quality level in the cell (dB) .Qqualmin
Measurement threshold for UE to trigger inter-RAT cell reselection, compared with Squal.
SsearchRATm
Measurement threshold for UE to trigger inter-frequency cell reselection, compared with Squal.
Sintersearch
Measurement threshold for UE to trigger intra-frequency cell reselection, compared with Squal.
Sintrasearch
Cell quality value (dB)Squal
DescriptionName
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Measurement Start Criteria (Cont.)Inter-RAT measurement
Squal ≤ SsearchRATm
↓
Qqualmeas − Qqualmin ≤ SsearchRATm
↓
Qqualmeas ≤ Qqualmin + SsearchRATm
Parameters of the measurement start criteria
Minimum required quality level in the cell (dB) .Qqualmin
Measurement threshold for UE to trigger inter-RAT cell reselection, compared with Squal.
SsearchRATm
Measurement threshold for UE to trigger inter-frequency cell reselection, compared with Squal.
Sintersearch
Measurement threshold for UE to trigger intra-frequency cell reselection, compared with Squal.
Sintrasearch
Cell quality value (dB)Squal
DescriptionName
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Parameters of Measurement Start Criteria
IDLESINTRASEARCH
Parameter name: Intra-freq cell reselection threshold for idle
mode
Recommended value: None
CONNSINTRASEARCH
Parameter name: Intra-freq cell reselection threshold for
connected mode
Recommended value: None
IDLESINTRASEARCHParameter name: Intra-freq cell reselection threshold for idle mode Value range: {{-16~10},{127}} .Physical value range: -32~20; step: 2. Physical unit: dB.Content: A threshold for intra-frequency cell reselection in idle mode. When the quality (CPICH Ec/No measured by UE) of the serving cell is lower than this threshold plus the [Qqualmin] of the cell, the intra-frequency cell reselection procedure will be started. Recommended value: None. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
CONNSINTRASEARCHParameter name: Intra-freq cell reselection threshold for connected mode Value range: {{-16~10},{127}} .Physical value range: -32~20; step: 2. Physical unit: dBContent: A threshold for intra-frequency cell reselection in connect mode. When the quality (CPICH Ec/No measured by UE) of the serving cell is lower than this threshold plus the [Qqualmin] of the cell, the intra-frequency cell reselection procedure will be started. Recommended value: None.Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of Measurement Start Criteria
IDLESINTERSEARCH
Parameter name: Inter-freq cell reselection threshold for idle
mode
Recommended value: None
CONNSINTERSEARCH
Parameter name: Inter-freq cell reselection threshold for
connected mode
Recommended value: None
IDLESINTERSEARCHParameter name: Inter-freq cell reselection threshold for idle mode Value range: {{-16~10},{127}} .Physical value range: -32~20; step: 2. Physical unit: dB.Content: A threshold for inter-frequency cell reselection in idle mode. When the quality (CPICH Ec/No measured by UE) of the serving cell is lower than this threshold plus the [Qqualmin] of the cell, the inter-frequency cell reselection procedure will be started. Recommended value: None. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
CONNSINTERSEARCHParameter name: Inter-freq cell reselection threshold for connected mode Value range: {{-16~10},{127}} .Physical value range: -32~20; step: 2. Physical unit: dBContent: A threshold for inter-frequency cell reselection in connect mode. When the quality (CPICH Ec/No measured by UE) of the serving cell is lower than this threshold plus the [Qqualmin] of the cell, the inter-frequency cell reselection procedure will be started. Recommended value: None.Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of Measurement Start Criteria
SSEARCHRAT
Parameter name: Inter-RAT cell reselection threshold
Recommended value: None
SSEARCHRATParameter name: Inter-RAT cell reselection threshold Value range: {{-16~10},{127}} .Physical value range: -32~20; step: 2. Physical unit: dB.Content: A threshold for inter-RAT cell reselection. When the quality (CPICH Ec/No measured by UE) of the serving cell is lower than this threshold plus the [Qqualmin] of the cell, the inter-RAT cell reselection procedure will be started. Recommended value: None. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Measurement Start Criteria Description
The intra-frequency, inter-frequency, and inter-RAT measurement criteria are as shown in the figure.Usually, Sintrasearch > Sintersearch > SsearchRATm
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Cell Reselection CriteriaCriterion R is used for intra-frequency, inter-frequency cells
and inter-RAT cell reselection.
The cell-ranking criterion R is defined by :
nsoffsetnmeasn QQR,, −=
hystssmeass QQR += ,
The cells are ranked according to R criteria specified above ,deriving QQmeas,nmeas,n and QQmeas,smeas,s and calculating R value.In Rs, s means serving cell. In Rn, n means neighbor cell.The offset Qoffset1s,n is used for Qoffsets,n to calculate Rn. The hysteresis Qhyst1s is used for Qhysts to calculate Rs. If a TDD or GSM cell is ranked as the best cell, the UE shall reselect that TDD or GSM cell.If an FDD cell is ranked as the best cell and the quality measure for cell selection and reselection is set to CPICH RSCP, the UE shall reselect that FDD cell.If an FDD cell is ranked as the best cell and the quality measure for cell selection and reselection is set to CPICH Ec/N0, the UE shall perform a second ranking of the FDD cells according to the R criteria specified above. In this case, however, the UE uses the measurement quantity CPICH Ec/N0 for deriving the Qmeas,n and Qmeas,s and then calculating the R values of the FDD cells. The offset Qoffset2s,n is used for Qoffsets,n to calculate Rn, the hysteresis Qhyst2s is used for Qhysts to calculate Rs.
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Hysteresis and Time Interval
TimeTreselection
Quality
Rn
Rs
Qmeas,n
Qmeas,s
Qhyst,s
Qoffsets,n
In all the previous cases, the UE can reselect a new cell only when the following conditions are met:
The new cell is better ranked than the serving cell during a time interval Treselection.More than one second has elapsed since the UE camped on the current serving cell.
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Parameters of R CriteriaIDLEQHYST1S
Parameter name: Hysteresis 1 for idle mode
Recommended value: 2, namely 4dB
CONNQHYST1S
Parameter name: Hysteresis 1 for connect mode
Recommended value: 2, namely 4dB
IDLEQHYST1SParameter name: Hysteresis 1 for idle mode Value range: 0~20.Physical value range: 0~40; step: 2.Physical unit: dB.Content: The hysteresis value in idle mode for serving FDD cells in case the quality measurement for cell selection and reselection is set to CPICH RSCP. It is related to the slow fading feature of the area where the cell is located. The greater the slow fading variance is, the greater this parameter.Recommended value: 2. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
CONNQHYST1SParameter name: Hysteresis 1 for connected mode Value range: 0~20.Physical value range: 0~40; step: 2.Physical unit: dB.Content: The hysteresis value in connect mode for serving FDD cells in case the quality measurement for cell selection and reselection is set to CPICH RSCP. It is related to the slow fading feature of the area where the cell is located. The greater the slow fading variance is, the greater this parameter. Recommended value: 2. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of R Criteria (Cont.)IDLEQHYST2S
Parameter name: Hysteresis 2 for idle mode
Recommended value: Qhyst1s for idle mode
CONNQHYST2S
Parameter name: Hysteresis 2 for connected mode
Recommended value: Qhyst1s for connected mode.
IDLEQHYST2SParameter name: Hysteresis 2 for idle mode Value range: {{0~20},{255}} .Physical value range: 0~40; step: 2.Physical unit: dB.Content: The hysteresis value in idle mode for serving FDD cells in case the quality measurement for cell selection and reselection is set to CPICH Ec/No. It is related to the slow fading feature of the area where the cell is located. The greater the slow fading variance is, the greater this parameter. It is optional. If it is not configured, [Hysteresis 1] will be adopted as the value. Recommended value: Qhyst1s for idle mode . Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
CONNQHYST2SParameter name: Hysteresis 2 for connected mode Value range: {{0~20},{255}} .Physical value range: 0~40; step: 2.Physical unit: dB.Content: The hysteresis value in connect mode for serving FDD cells in case the quality measurement for cell selection and reselection is set to CPICH RSCP. It is related to the slow fading feature of the area where the cell is located. The greater the slow fading variance is, the greater this parameter. Recommended value: Qhyst1s for connected mode. . Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of R Criteria (Cont.)TRESELECTIONS
Parameter name: Reselection delay time
Recommended value: 1, namely 1s.
TRESELECTIONSParameter name: Reselection delay time Value range: 0~31 .Physical value range: 0~31; step: 1. Physical unit: s.Content: If the signal quality of a neighboring cell is better than the serving cell during the specified time of this parameter, the UE will reselect the neighboring cell. It is used to avoid ping-pong reselection between different cells. Note: The value 0 corresponds to the default value defined in the protocol. Recommended value: 1. Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL.
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Parameters of R Criteria (Cont.)IDLEQOFFSET1SN
Parameter name: IdleQoffset1sn
Recommended value: 0, namely 0dB.
CONNQOFFSET1SN
Parameter name: ConnQoffset1sn
Recommended value: 0, namely 0dB.
IDLEQOFFSET1SNParameter name: IdleQoffset1sn Offset of cell CPICH RSCP measurement value in cell selection or reselection when the UE is in idle mode Value range: -50 to +50 .Physical value range: -50 to +50; step: 1. Physical unit: dB.Content: This parameter is used for moving the border of a cell. The larger the value of this parameter, the lower the probability of neighboring cell selection. Recommended value: 0. Set this parameter through ADD INTRAFREQNCELL / ADD INTERFREQNCELL, query it through LST INTRAFREQNCELL / LST INTERFREQNCELL, and modify it through MOD INTRAFREQNCELL / MOD INTERFREQNCELL.
CONNQOFFSET1SNParameter name: ConnQoffset1sn Offset of cell CPICH RSCP measurement value in cell selection or reselection when the UE is in connected mode Value range: -50 to +50 .Physical value range: -50 to +50 ; step: 1. Physical unit: dB.Content: This parameter is used for moving the border of a cell. The larger the value of this parameter, the lower the probability of neighboring cell selection. Recommended value: 0. Set this parameter through ADD INTRAFREQNCELL / ADD INTERFREQNCELL, query it through LST INTRAFREQNCELL / LST INTERFREQNCELL, and modify it through MOD INTRAFREQNCELL / MOD INTERFREQNCELL.
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Parameters of R Criteria (Cont.)IDLEQOFFSET2SN
Parameter name: IdleQoffset2sn
Recommended value: 0, namely 0dB.
CONNQOFFSET2SN
Parameter name: ConnQoffset2sn
Recommended value: 0, namely 0dB.
IDLEQOFFSET2SNParameter name: IdleQoffset2sn Offset of cell CPICH Ec/No measurement value in cell selection or reselection when the UE is in idle mode Value range: -50 to +50 .Physical value range: -50 to +50; step: 1. Physical unit: dB.Content: This parameter is used for moving the border of a cell. The larger the value of this parameter, the lower the probability of neighboring cell selection. Recommended value: 0. Set this parameter through ADD INTRAFREQNCELL / ADD INTERFREQNCELL, query it through LST INTRAFREQNCELL / LST INTERFREQNCELL, and modify it through MOD INTRAFREQNCELL / MOD INTERFREQNCELL.
CONNQOFFSET2SNParameter name: ConnQoffset2sn Offset of cell CPICH RSCP measurement value in cell selection or reselection when the UE is in connected mode Value range: -50 to +50 .Physical value range: -50 to +50 ; step: 1. Physical unit: dB.Content: This parameter is used for moving the border of a cell. The larger the value of this parameter, the lower the probability of neighboring cell selection. Recommended value: 0. Set this parameter through ADD INTRAFREQNCELL / ADD INTERFREQNCELL, query it through LST INTRAFREQNCELL / LST INTERFREQNCELL, and modify it through MOD INTRAFREQNCELL / MOD INTERFREQNCELL.
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Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Location RegistrationThe location registration includes:
Location update (for non-GPRS)
Route update (for GPRS)
The location registration is used for the PLMN to trace the current status of the UE and to ensure that the UE is connected with the network when the UE does not perform any operation for a long period.
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Page36Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Periodic Location RegistrationPeriodic location registration is controlled by a Periodic
Location Update timer (T3212) or a Periodic Routing Area
Update timer (T3312)
Periodic location registration may be used to periodically notify the network of the availability of the UE.T3212 is for non-GPRS operationT3312 is for GPRS operation
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Page37Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Parameters of Location Registration
T3212
Parameter name: Periodical location update timer [6min]
Recommended value: 10, namely 60min
ATT
Parameter name: Attach/detach indication
Recommended value: ALLOWED
T3212Parameter name: Periodical location update timer [6min] Value range: 0~255. Physical unit: 6 min.Content: This parameter indicates the time length of the periodical location update. Periodical location update is implemented by MS through the location update procedure. 0: The periodical update procedure is not used. This parameter is valid only when [CN domain ID] is set as CS_DOMAIN. Recommended value: 10. Set this parameter through ADD CNDOMAIN, query it through LST CNDOMAIN, modify it through MOD CNDOMAIN.
ATTParameter name: Attach/detach indicationValue range: NOT_ALLOWED, ALLOWED . Content: NOT_ALLOWED indicates that MS cannot apply the IMSI attach/detach procedure. ALLOWED indicates that MS can apply the IMSI attach/detach procedure. This parameter is valid only when [CN domain ID] is set as CS_DOMAIN.Recommended value: ALLOWED. Set this parameter through ADD CNDOMAIN, query it through LST CNDOMAIN, modify it through MOD CNDOMAIN.
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Page38Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Page39Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Paging Initiation CN initiated paging
Establish a signaling connection
UTRAN initiated paging
Trigger the cell update procedure
Trigger reading of updated system information
For CN originated paging:In order to request UTRAN connect to UE, CN initiates the paging procedure, transmits paging message to the UTRAN through Iu interface, and UTRAN transmits the paging message from CN to UE through the paging procedure on Uu interface, which will make the UE initiate a signaling connection setup process with the CN.
For UTRAN originated paging:When the cell system message is updated: When system messages change, the UTRAN will trigger paging process in order to inform UE in the idle, CELL_PCH or URA_PCH state to carry out the system message update, so that the UE can read the updated system message.UE state transition: In order to trigger UE in the CELL_PCH or URA_PCH state to carry out state transition (for example, transition to the CELL_FACH state), the UTRAN will perform a paging process. Meanwhile, the UE will initiate a cell update or URA update process, as a reply to the paging.
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Page40Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Paging Type 1If UE is in CELL_PCH,URA_PCH or IDLE state,the paging message will be transmitted on PCCH with paging type 1
CN RNC1 RNC2 NODEB1.1 NODEB2.1 UE
RANAPRANAP
RANAP RANAP
PCCH: PAGING TYPE 1
PAGING
PAGING
PCCH: PAGING TYPE 1
Paging type 1:The message is transmitted in one LA or RA according to LAI or RAI.After calculating the paging time, the paging message will be transmitted at that timeIf UE is in CELL_PCH or URA_PCH state, the UTRAN transmits the paging information in PAGING TYPE 1 message to UE. After received paging message, UE performs a cell update procedure to transit state to CELL_FACH.
As shown in the above figure, the CN initiates paging in a location area (LA), which is covered by two RNCs. After receiving a paging message, the RNC searches all the cells corresponding to the LAI, and then calculates the paging time, at which it will send the PAGING TYPE 1 message to these cells through the PCCH.
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Page41Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Paging Type 2If UE is in CELL_DCH or CELL_FACH state,the paging message will be transmitted on DCCH with paging type 2
CN SRNC UE
RANAPRANAP
PAGING
RRCRRCDCCH: PAGING TYPE 2
Paging type 2:If UE is in CELL_DCH or CELL_FACH state,the paging message will be transmitted on DCCH with paging type 2The message will be only transmitted in a cell
As shown in the above figure, if the UE is in the CELL_-DCH or CELL_FACH state, the UTRAN will immediately transmit PAGING TYPE 2 message to the paged UE on DCCH channel.
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Page42Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Typical Call Flow of UE UE NAS UE AS NSS MSC
paging
AUTHENTICATION REQUEST
AUTHENTICATION RESPONSE
RR_SECURITY_CONTROL_REQ
(IK CK)
Security mode control
SETUP
CALL CONFIRM
ALERT
CONNECT
CONNECT ACKNOW LEDGE
RAB setup process
paging
RR_EST_REQ (PAGING RESPONSE)
RR_PAING_IND
INITIAL_DIRECT_TRANSFER
(PAGING RESPONSE)
RANAPRANAP
RRC setup process
Many problems will cause the target UE cannot receive the paging message properlyPower setting of paging channel is unreasonable.Unreasonable paging strategies will result in paging channel congestion, which can cause paging message loss.Paging parameter is unreasonableEquipment fault
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Page43Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
DRX ProcedureUE receives the paging indicator on PICH periodically, that
is the Discontinuous Reception (DRX)
The value for the DRX paging cycle length is determined as
follows: :
DRX Cycle Length = (2^K)×PBP frames
In idle mode, the UE can monitor the paging in two modes: one is to decode SCCPCH directly every 10ms, the other is to decode the PICH periodically. The second one is the DRX, which is Discontinuous Reception Mechanism.The paging period formula:
DRX Cycle Length = (2^K)*PBP framesK is the “CN domain specific DRX cycle length coefficient”, which is broadcasted in SIB1. The typical value is 6. PBP is paging block period, which is 1 for FDD modeThe paging period should be 640ms if K is 6
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DRX Procedure (Cont.)Through DRX, UE only listens to PICH at certain predefined
time. And UE will read the paging information on SCCPCH if
the paging indicator is 1.
The value of the Paging Occasion is determined as follows:
Paging Occasion (CELL SFN) =
{(IMSI mod M) mod (DRX cycle length div PBP)} * PBP
+ n * DRX cycle length + Frame Offset
Paging SFN formula:Paging Occasion (CELL SFN) = {(IMSI mod M) mod (DRX cycle length div PBP)} *PBP + n *DRX cycle length + Frame Offsetn =0, 1, 2……and the requirement is the calculated CELL SFN must be below itsmaximum value 4096 Frame Offset is 0 for FDD modeM is the number of SCCPCH which carries PCH, and the typical value is 1The formula cloud be simplified as: SFN = IMSI mod (2^K) + n * (2^K)
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Page45Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
DRX Procedure (Cont.)
⎣ ⎦ ⎣ ⎦ ⎣ ⎦( )( )( ) NpNpSFNSFNSFNSFNPIq mod144
144mod512/64/8/18 ⎟⎟⎠
⎞⎜⎜⎝
⎛⎥⎦⎥
⎢⎣⎢ ×+++×+=
UE must calculate q to know which PI to monitor in one
frame of PICH
The q value is achieved by the following formula :
Where, PI = (IMSI div 8192) mod NP
SFN is the paging occasion of the UEAs shown in the followed figure, the UE needs to monitor the frames (paging occasions) indicated by the red dots, and then decodes the qth PI of this frame.
¡ £¡ £¡ £
0
2^K-1
0 4095
¡ £¡ £¡ £
P I P I P I P I¡ £¡ £¡ £¡ £¡ £¡ £
0 1 q NP-1
One DRX cycle
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Page46Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
DRX Procedure (Cont.)
τPICH
Associated S-CCPCH frame
PICH frame containing paging indicator
Time offset between PICH and S-CCPCH
The timing relationship between PICH and S-CCPCH is defined by the above figure, and the interval is 3 slots duration (2ms, 7680 chips).
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Page47Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Parameters of DRXDRXCYCLELENCOEF
Parameter name: DRX cycle length coefficient
Recommended value: 6
PICHMODE
Parameter name: PICH mode
Recommended value: V36.
DRXCYCLELENCOEFParameter name: DRX cycle length coefficient Value range: 6~9 .Content: This parameter is broadcasted on SIB1. This parameter is used when a UE is in idle mode. Recommended value: 6. Set this parameter through ADD CNDOMAIN, query it through LST CNDOMAIN, and modify it through MOD CNDOMAIN.
PICHMODEParameter name: PICH mode Value range: V18, V36, V72, V144 .Physical value range: 18, 36, 72, 144 . Content: Indicating the number of PIs contained in each frame on the PICH. Recommended value: V36 . Set this parameter through ADD PICH, query it through LST PICH.
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Page48Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Parameters of DRXMACCPAGEREPEAT
Parameter name: Number of page re-TX
Recommended value: 1
MACCPAGEREPEATParameter name: Number of page re-TX Number of retransmissions of paging message Value range: 0~2 .Content: If the number of retransmissions of paging message exceeds this parameter value, retransmissions stop. Recommended value: 1. Set this parameter through SET WFMRCFGDATA, query it through LST WFMRCFGDATA.
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Page49Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. PLMN Selection
2. System Information Reception
3. Cell Selection and Reselection
4. Location Registration
5. Paging Procedure
6. Access Procedure
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Page50Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Two Working Mode of UEIdle mode
After turning on, UE will stay in idle mode
Connected mode
UE will switch to connected mode which could be CELL_FACH
state or CELL_DCH state from the idle mode
After releasing RRC connection, UE will switch to the idle
mode from the connected mode
The most important difference between idle mode and connected mode is whether UE has RRC connection with UTRAN or not.In idle mode, UE will be identified by IMSI, TMSI or PTMSI and so on.In connected mode, UE will be identified by URNTI (UTRAN Radio Network Temporary Identity), which is the ID of one RRC connection.
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Page51Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Random Access ProcedureDefinition
Random access procedure is initiated by UE in order to get
service from the system. Meanwhile, the access channels are
allocated to the UE by system
This process may happen in the following scenarios:Attach and detachLA update and RA updateSignaling connection for services
52
Page52Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Random Access Channel
AICH accessslots
10 ms
#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4τp-a
#0 #1 #2 #3 #14#13#12#11#10#9#8#7#6#5#4
PRACHaccess slots
SFN mod 2 = 0 SFN mod 2 = 1
10 ms
Access slot set 1 Access slot set 2
Definition
UE will transmit the preamble at the access time slotEach 20ms access frame is composed of two 10ms radio frames, which is divided into 15 access time slot, and 5120 chips for each slotThe PRACH access slots, AICH access slots and their time offset are showed in the above figure
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Page53Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
RACH Sub-Channels
1413121110987210765436
14131211109855432107648141312111093
7654321021110981413121
765432100
11109876543210Random access sub-channels numberSFN
mod 8
The access slots of different RACH sub-channels are illustrated by the following table
A RACH sub-channel defines a sub-set of the total set of uplink access slots. There are a total of 12 RACH sub-channels.
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Page54Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Access Service ClassThe PRACH resources can be classified into several ASCs,
so as to provide RACH applications with different priorities.
For Frequency Division Duplex (FDD) mode, the PRACH resources include access timeslots and preamble signatures, which can be classified into several ASCs, so as to provide RACH applications with different priorities.The ASCs range from 0 to 7, and the quantity of ASCs is 8. "0" indicates the highest priority and "7" indicates the lowest priority.The system will assign random access sub-channels and signatures according to the ASC (Access Service Class ) of UE.Set ASC of PRACH through ADD PRACHASC, modify it through MOD PRACHASC, and remove it through RMV PRACHASC.
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Access Control “Access Control” is used by network operators to prevent
overload of radio access channels under critical conditions.
Access class 0~Access Class 9
Access class 11~Access Class 15
Access class 10
The access class number is stored in the SIM/USIM.Access class 0~9 are allocated to all the users. And the 10 classes show the same priority.Access class 11~15 are allocated to specific high priority users as follows. (The enumeration is not meant as a priority sequence):
Access class 15: PLMN staff Access class 14: users subscribing to emergency services Access class 13: public organizations Access class 12: users subscribing to security services Access class 11: users responsible for PLMN management
Access Class 10 indicates whether or not network access for Emergency Calls is allowed for UEs with access classes 0 to 9 or without an IMSI. For UEs with access classes 11 to 15, Emergency Calls are not allowed if both "Access class 10" and the relevant Access Class (11 to 15) are barred. Otherwise, Emergency Calls are allowed.
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Page56Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Mapping between AC and ASCThe AC-ASC mapping information is optional and used for
the System Information Block 5 (SIB5) only.
Set the mapping between AC and ASC through ADD PRACHACTOASCMAP, modify it through MOD PRACHACTOASCMAP, and remove it through RMV PRACHACTOASCMAP.
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START
Choose a RACH sub channel fromavailable ones
Get available signatures
Set Preamble Retrans Max
Set Preamble_Initial_Power
Send a preamble
Check the corresponding AI
Increase message part power by p-m based on preamble power
Set physical status to be RACHmessage transmitted Set physical status to be Nack
on AICH received
Choose a access slot again
Counter> 0 & Preamblepower-maximum allowed power
<6 dB
Choose a signature and increase preamble transmit power
Set physical status to be Nackon AICH received
Get negative AI
No AI
Report the physical status to MAC
END
Get positive AI
The counter of preamble retransmit Subtract-1, Commanded preamble
power increased by Power Ramp Step
N
Y
Send the corresponding message part
Random Access Procedure
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Physical random access procedure1. Derive the available uplink access slots, in the next full access slot set, for the set of available RACH sub-channels within the given ASC. Randomly select one access slot among the ones previously determined. If there is no access slot available in the selected set, randomly select one uplink access slot corresponding to the set of available RACH sub-channels within the given ASC from the next access slot set. Therandom function shall be such that each of the allowed selections is chosen with equal probability2. Randomly select a signature from the set of available signatures within the given ASC3. Set the Preamble Retransmission Counter to Preamble_ Retrans_ Max4. Set the parameter Commanded Preamble Power to Preamble_Initial_Power5. Transmit a preamble using the selected uplink access slot, signature, and preamble transmission power6. If no positive or negative acquisition indicator (AI ≠ +1 nor –1) corresponding to the selected signature is detected in the downlink access slot corresponding to the selected uplink access slot:
A: Select the next available access slot in the set of available RACH sub-channels within the given ASCB: select a signatureC: Increase the Commanded Preamble PowerD: Decrease the Preamble Retransmission Counter by one. If the Preamble Retransmission Counter > 0 then repeat from step 6. Otherwise exit the physical random access procedure
7. If a negative acquisition indicator corresponding to the selected signature is detected in the downlink access slot corresponding to the selected uplink access slot, exit the physical random access procedure Signature8. If a positive acquisition indicator corresponding to the selected signature is detected , Transmit the random access message three or four uplink access slots after the uplink access slot of the last transmitted preamble9. Exit the physical random access procedure
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RRC Connection Message
Typical RRC connection messagesRRC_CONNECTION_REQUEST
RRC_CONNECTION_SETUP
RRC_CONNECTION_SETUP_COMPLETE
RRC_CONNECTION_RELEASE
When a UE needs network service, it first sets up RRC connection as follows:The UE sends a RRC CONNECTION REQUEST message from the cell where it camps to the RNC.The RNC allocates related resources for the UE and sends an RRC CONNECTIONSETUP message to the UE.The UE sends a RRC CONNECTION SETUP COMPLETE message to the RNC. The RRC connection setup ends.
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Page60Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
UE Timers and Constants in Idle Mode
T300
Parameter name: Timer 300 [ms]
Recommended value: D2000, namely 2000ms
N300
Parameter name: Constant 300
Recommended value: 3
T300Parameter name: Timer 300[ms] Value range: D100, D200, D400, D600, D800, D1000, D1200, D1400, D1600, D1800, D2000, D3000, D4000, D6000, D8000 . Physical value range: 100, 200, 400, 600, 800, 1000, 1200, 1400, 1600, 1800, 2000, 3000, 4000, 6000, 8000Physical unit: msContent: T300 is started after the UE transmits the RRC CONNECTION REQUEST message and stopped after the UE receives the RRC CONNECTION SETUP message. RRC CONNECTION REQUEST resents upon the expiry of the timer if V300 less than or equal to N300. Otherwise, the UE enters idle mode. Recommended value: D2000. Set this parameter through SET IDLEMODETIMER, query it through SET IDLEMODETIMER.
N300Parameter name: Constant 300 Value range: 0~7 .Content: Maximum number of retransmission of RRC CONNECTION REQUEST . Recommended value: 3. Set this parameter through SET IDLEMODETIMER, query it through SET IDLEMODETIMER.
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UE Timers and Constants in Idle Mode
T312
Parameter name: Timer 312 [s]
Recommended value: 6, namely 6s
N312
Parameter name: Constant 312
Recommended value: D1, namely 1
T312Parameter name: Timer 312[s] Value range: 1~15 . Physical value range: 1~15sPhysical unit: sContent: T312 is started after the UE starts to establish a DCH and stopped when the UE detects N312 consecutive "in sync" indications from L1. It indicates physical channel setup failure upon the expiry of the timer. Recommended value: 6. Set this parameter through SET IDLEMODETIMER, query it through SET IDLEMODETIMER.
N312Parameter name: Constant 312 Value range: D1, D2, D4, D10, D20, D50, D100, D200, D400, D600, D800, D1000 .Physical value range: 1, 2, 4, 10, 20, 50, 100, 200, 400, 600, 800, 1000Content: Maximum number of consecutive "in sync" indications received from L1. . Recommended value: D1. Set this parameter through SET IDLEMODETIMER, query it through SET IDLEMODETIMER.
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RRC Connection Establish Channel Type and Bit Rate
RRCCAUSE
Parameter name: Cause of RRC connection establishment
Recommended value: none
SIGCHTYPE
Parameter name: Channel type for RRC establishment
Recommended value: none
RRCCAUSEParameter name: Cause of RRC connection establishment Value range: ORIGCONVCALLEST, ORIGSTREAMCALLEST, ORIGINTERCALLEST, ORIGBKGCALLEST, ORIGSUBSTRAFFCALLEST, TERMCONVCALLEST, TERMSTREAMCALLEST, TERMINTERCALLEST, TERMBKGCALLEST, EMERGCALLEST, INTERRATCELLRESELEST, INTERRATCELLCHGORDEREST, REGISTEST, DETACHEST, ORIGHIGHPRIORSIGEST, ORIGLOWPRIORSIGEST, CALLREEST, TERMHIGHPRIORSIGEST, TERMLOWPRIORSIGEST, TERMCAUSEUNKNOWN, DEFAULTEST. Content: The cause of Rrc connection establishment. . Recommended value: none. Set this parameter through SET RRCESTCAUSE, query it through LST RRCESTCAUSE.
SIGCHTYPEParameter name: Channel type for RRC establishment Value range: FACH, DCH_3.4K_SIGNALLING, DCH_13.6K_SIGNALLING. Content: FACH indicates that the RRC is established on the common channel. DCH_3.4K_SIGNALLING indicates that the RRC is established on the dedicated channel of 3.4 kbit/s. DCH_13.6K_SIGNALLING indicates that the RRC is established on the dedicated channel of 13.6 kbit/s. . Recommended value: none. Set this parameter through SET RRCESTCAUSE, query it through LST RRCESTCAUSE.
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RRC Connection Establish Channel Type and Bit Rate
INTRAMEASCTRL
Parameter name: IntraMeas Ctrl Ind for RRC establishment
Recommended value: SUPPORT
INTRAMEASCTRLParameter name: IntraMeas Ctrl Ind for RRC establishment Value range: NOT_SUPPORT, SUPPORT. Content: NOT_SUPPORT indicates that the Intrafreq measurement control message will be send in RRC Connection Establishment. SUPPORT indicates that the Intrafreqmeasurement control will not be send in RRC Connection Establishment. Recommended value: SUPPORT . Set this parameter through SET RRCESTCAUSE, query it through LST RRCESTCAUSE.
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA Power Control and Relevant Parameters
263
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Objectives
Upon completion of this course, you will be able to:
Describe the purpose and function of power control
Explain open loop power control and parameters
Explain inner loop power control and relevant parameters
Explain outer loop power control and relevant parameters
264
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Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
265
Page3Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
266
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Purpose of Uplink Power Control
Uplink Transmission CharacterSelf-interference system
Uplink capacity is limited by interference level
Near-far effect
Fading
Uplink Power Control FunctionEnsure uplink quality with minimum transmission power
Decrease interference to other UE, and increase capacity
Solve the near-far effect
Save UE transmission power
CDMA system have the embedded characteristics of self-interference, for uplink one user’s transmission power become interference to others.
The more connected users, the higher interference. Generally the capacity is limited by interference level.
WCDMA suffer from Near-far effect, which means if all UE use the same transmission power, the one close to the NodeB may block the entire cell.
Uplink power control can guarantee the service quality and minimize the required transmission power. It will resolve the near-far effect and resist fading of signal propagation. By lowering the uplink interference level, the system capacity will be increased.
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Purpose of Downlink Power Control
Downlink Transmission CharacterInterference among different subscribers
Interference from other adjacent cells
Downlink capacity is limited by NodeB transmission power
Fading
Downlink Power Control FunctionEnsure downlink quality with minimum transmission power
Decrease interference to other cells, and increase capacity
Save NodeB transmission power
The downlink has different characteristics from the uplink, for downlink interference is caused by multi-path, part of one user’s power also become interference to others.
Downlink power from adjacent cells also is one part of interference to the own cell.
Transmission power of NodeB is shared by all users channels, so downlink capacity usually is considered to be limited by transmission power.
Downlink power control also can guarantee the service quality and minimize the required transmission power, so the capacity is maximized in case that interference is lowered.
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Effect of Power Control
Time (ms)0 200 400 600 800
-20
-15
-10
-5
0
5
10
15
20
Rel
ativ
e po
wer
(dB
)
Channel FadingTransmitting powerReceiving power
Because of channel fading in mobile communication system, the radio signal is deteriorated and fluctuated, the fast power control become one key technology to resist this phenomenon.
In this figure, the channel fading is compensated by the transmitting power, which is adjusted by the fast power control, so the receiving power is almost constant and the radio propagation condition is improved.
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Power Control Classification
Open Loop Power Control
Uplink / Downlink Open Loop Power Control
Closed Loop Power Control
Uplink / Downlink Inner Loop Power Control
Uplink / Downlink Outer Loop Power Control
In WCDMA system, power control includes open loop and closed loop power control.
Open loop power control is used to determine the initial transmission power, and the closed loop power control adjusts the transmission power dynamically and continuously during the connection.
For uplink, the UE’s transmission power is adjusted; and for downlink, the NodeB’s transmission power is adjusted.
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Power Control For Physical Channels
Power control methods are adopted for these physical channels:
“√" – can be applied, “×" – not applied
√×××SCH
√×××PICH√×××AICH×××√PRACH√×××SCCPCH√×××PCCPCH
×√√√DPCCH×√√√DPDCH
Outer Loop Power Control
Inner Loop Power Control
No Power Control
Closed Loop Power ControlOpen Loop Power Control
Physical Channel
Open loop power control is used in two cases:
1. to decide the initial transmission power of PRACH preamble.
2. to decide the initial transmission power of DPCCH / DPDCH.
Closed loop power control is only applied on DPCCH and DPDCH
For other common channels, power control is not applied, they will use fixed transmission power:
The PCPICH power is defined by the PCPICH TRANSMIT POWER parameter as an absolute value in dBm.
All other common channels power is defined in relation with the PCPICH TRANSMIT POWER parameter, and measured in dB.
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Common Physical Channel Power Parameters
MAXTXPOWER
Parameter name: Max transmit power of cell
The recommended value is 430, namely 43dBm
PCPICHPOWER
Parameter name: PCPICH transmit power
The recommended value is 330, namely 33dBm
MAXTXPOWER
Parameter name: Max transmit power of cell
Value Range: 0 to 500
Physical Value Range: 0dBm to 50 dBm, step 0.1dB
The recommended value is 430, namely 43dBm
Content: The sum of the maximum transmit power of all DL channels in a cell.
Set this parameter through ADD CELLSETUP, query it through LST CELL and modify it through MOD CELL
PCPICHPOWER
Parameter name: PCPICH transmit power
Value Range: -100 to 500
Physical Value Range: -10dBm to 50 dBm, step 0.1dB
The recommended value is 330, namely 33dBm
Content: This parameter should be set based on the actual environment and the downlink coverage should be guaranteed firstly. If PCPICH transmit power is configured too great, the cell capacity will be decreased, for power resources is occupied by common channel and the interference to traffic channels is also increased.
Set this parameter through ADD PCPICH, query it through LST PCPICH and modify it through MOD CELL
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Common Physical Channel Power Parameters
PSCHPOWER or SSCHPOWER
Parameter name: PSCH / SCCH transmit power
The recommended value is -50, namely -5dB
BCHPOWER
Parameter name: BCH transmit power
The recommended value is -20, namely -2dB
PSCHPOWER or SSCHPOWER
Parameter name: PSCH / SCCH transmit power
Value range: -350 to 150.
Physical value range: -35 to 15, step 0.1dB
The recommended value is -50, namely -5dB
Content: The offset between the PSCH / SSCH transmit power and PCPICH transmit power.
For PSCH Power, set it through ADD PSCH, and query it through LST PSCH; for SSCH Power, set it through ADD SSCH, and query it through LST SSCH. And modify it through MOD CELL
BCHPOWER
Parameter name: BCH transmit power
Value Range:-350 to 150
Physical Value Range:-35 to 15 dB, step 0.1dB
The recommended value is -20, namely -2dB
Content: The offset between the BCH transmit power and PCPICH transmit power.
Set this parameter through ADD BCH, query it through LST BCH, and modify it through MOD CELL
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Common Physical Channel Power Parameters
MAXFACHPOWER
Parameter name: Max transmit power of FACH
The recommended value is 10, namely 1dB
PCHPOWER
Parameter name: PCH transmit power
The recommended value is -20, namely -2dB
MAXFACHPOWER
Parameter name: Max transmit power of FACH
Value range : -350 to 150
Physical Value Range:-35 to 15 dB, step 0.1dB
The recommended value is 10, namely 1dB
Content: The offset between the FACH transmit power and PCPICH transmit power.
Set this parameter through ADD FACH, query it through LST FACH, and modify it through MOD SCCPCH
PCHPOWER
Parameter name: PCH transmit power
Value Range:-350 to 150
Physical Value Range:-35 to 15 dB, step 0.1dB
The recommended value is -20, namely -2dB
Content: The offset between the PCH transmit power and PCPICH transmit power.
Set this parameter through ADD PCH, query it through LST PCH, and modify it through MOD SCCPCH
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Common Physical Channel Power Parameters
AICHPOWEROFFSET
Parameter name: AICH power offset
The default value of this parameter is -6, namely -6dB
PICHPOWEROFFSET
Parameter name: PICH power offset
The default value of this parameter is -7, namely -7dB
AICHPOWEROFFSET
Parameter name: AICH power offset
Value Range: -22 to 5
Physical Value Range: -22 to 5 dB, step 1dB
The default value of this parameter is -6, namely -6dB
Content: The offset between the AICH transmit power and PCPICH transmit power.
Set this parameter through ADD CHPWROFFSET, query it through LST CHPWROFFSET, and modify it through MOD AICHPWROFFSET
PICHPOWEROFFSET
Parameter name: PICH power offset
Value Range:-10 to 5
Physical Value Range:-10 to 5 dB , step 1dB
The default value of this parameter is -7, namely -7dB
Content: The offset between the PICH transmit power and PCPICH transmit power.
Set this parameter through ADD CHPWROFFSET, query it through LST CHPWROFFSET, and modify it through MOD PICHPWROFFSET
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Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
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Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power Control
2.4 Uplink Dedicated Channel Open Loop Power Control
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Open Loop Power Control Overview
Purpose
Calculate the initial transmission power of uplink / downlink channels
Principle
Estimates the downlink signal power loss on propagation path
Path loss of the uplink channel is related to the downlink channel
Application
Open loop power control is applied only at the beginning of connection
setup to set the initial power value.
In downlink open loop power control, the initial transmission power is calculated according to the downlink path loss between NodeB and UE.
In uplink, since the uplink and downlink frequencies of WCDMA are in the same frequency band, a significant correlation exists between the average path loss of the two links. This make it possible for each UE to calculate the initial transmission power required in the uplink based on the downlink path loss.
However, there is 90MHz frequency interval between uplink and downlink frequencies, the fading between the uplink and downlink is uncorrelated, so the open loop power control is not absolutely accurate.
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Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power Control
2.4 Uplink Dedicated Channel Open Loop Power Control
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PRACH Open Loop Power Control
5. Downlink Synchronization
UE Node BServing
RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
Open loop powercontrol of PRACH
1. CCCH: RRC Connection Request
In access procedure, the first signaling “RRC CONNECTION REQUEST” is transmitted in message part on PRACH.
Before PRACH message part transmission, UE will transmit PRACH preamble, and the transmission power of first preamble is calculated by this PRACH open loop power control.
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PRACH Open Loop Power Control
Initial Power Calculation for the First Preamble
When UE needs to set up a RRC connection, the initial power
of uplink PRACH can be calculated according to the following
formula:
Power Tx Initial gCalculatin For Value Constant+ceInterferen UL+CPICH_RSCP-Power Transmit PCPICH=ernitial_PowPreamble_I
In this formula, where
PCPICH TRANSMIT POWER defines the PCPICH transmit power in a cell. It is broadcast in SIB5.
CPICH_RSCP means received signal code power, the received power measured on the PCPICH. The measurement is performed by the UE.
UL interference is the UL RTWP measured by the NodeB. It is broadcast in SIB7.
CONSTANT VALUE compensates for the RACH processing gain. It is broadcast in SIB5.
The initial value of PRACH power is set through open loop power control. UE operation steps are as follows:
1. Read “Primary CPICH DL TX power”, “UL interference” and “Constant value”from system information.
2. Measure the value of CPICH_RSCP;
3. Calculate the Preamble_Initial_Power of PRACH.
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PRACH Open Loop Power Control Parameters
CONSTANTVALUE
Parameter name: Constant value for calculating initial TX
power
The recommended value is -20, namely -20dB
CONSTANTVALUE
Parameter name: Constant value for calculating initial TX power
Value range : -35 ~ -10
Physical Value Range:-35 to -10 dB
Content: It is used to calculate the transmit power of the first preamble in the random access process.
Recommended value: -20
Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and modify it through MOD PRACHUUPARAS
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PRACH Open Loop Power Control
Timing relationship of PRACH and AICH
AICH
PRACH
1 access slot
τ p-a
τ p-mτ p-p
Pre-amble
Pre-amble
Message part
Acq. Ind.
After UE transmit the first Preamble on PRACH, it will wait for the corresponding AI (Acquisition Indicator) on the AICH. The timing relationship of PRACH and AICH is shown in above figure.
There will be 3 parameters used to define the timing relationship:
τp-p: time interval between two PRACH preambles. τp-p is not a fixed value, it is decided by selecting access slot of PRACH preambles,
Here τp-p has one restriction, it must be longer than a minimum value τp-p min , namely τp-p ≥ τp-p min.
τp-a: time interval between PRACH preamble and AICH Acquisition Indicator. If UE sends the PRACH preamble, it will detect the responding AI after τp-a time.
τp-m: time interval between PRACH preamble and PRACH message part. If UE sends the PRACH preamble and receives positive AI from the AICH, it will send the message part after τp-m time.
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PRACH Open Loop Power Control Parameters
AICHTXTIMING
Parameter name: AICH transmission timing
Content:
When AICHTXTIMING = 0,
τp-p,min = 15360 chips, τp-a = 7680 chips, τp-m = 15360 chips
When AICHTXTIMING = 1,
τp-p,min = 20480 chips, τp-a = 12800 chips, τp-m = 20480 chips
The recommended value is 1
Parameter AICHTXTIMING is used to define the set of τp-p min, τp-a, τp-m.
AICHTXTIMING
Parameter name: AICH transmission timing
Value range:0,1
Content:
When AICHTXTIMING = 0,
τp-p,min = 15360 chips, τp-a = 7680 chips, τp-m = 15360 chips
When AICHTXTIMING = 1,
τp-p,min = 20480 chips, τp-a = 12800 chips, τp-m = 20480 chips
Recommended value: 1
Set this parameter through ADD AICH, query it through LST AICH, and modify it needs de-activated the cell through DEA CELL. After the old configuration of AICH is deleted through RMV AICH , a new AICH can be established through ADD AICH
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PRACH Open Loop Power Control
Power Ramping for Preamble Retransmission
Power Ramp Step
Power Offset Pp-m
Preamble_Initial_Power
Message part
Pre-amblePre-
amble……
Pre-amblePre-
amble
#1 #3 #N#2
After UE transmit the first Preamble,
If no positive or negative AI on AICH is received after τp-a time,
UE shall increase the preamble power by POWER RAMP STEP, and retransmit the preamble.
This ramping process stops until the number of transmitted preambles has reached the MAX PREAMBLE RETRANSMISSION within an access cycle, or when the maximum number of access cycles has reached MAX PREAMBLE LOOP.
If a negative AI on AICH is received by the UE after τp-a time,
which indicates rejection of the preamble, the UE shall wait for a certain “Back-off Delay” and re-initiate a new random access process.
When a positive AI on AICH is received by UE after τp-a time,
it will transmit the random access message after the uplink access slot of the last preamble.
The transmit power of the random access message control part should be POWER OFFSET higher than the power of the last transmitted preamble.
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PRACH Open Loop Power Control Parameters
POWERRAMPSTEP
Parameter name: Power increase step
The recommended value is 2, namely 2dB
PREAMBLERETRANSMAX
Parameter name: Max preamble retransmission
The Recommended value is 20
POWERRAMPSTEP
Parameter name: Power increase step
Value range : 1 to 8
Physical Value Range: 1 to 8 dB
Content: The power increase step of the random access preambles transmitted before the UE receives the acquisition indicator in the random access process.
Recommended value: 2
Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and modify it through MOD PRACHUUPARAS
PREAMBLERETRANSMAX
Parameter name: Max preamble retransmission
Value range : 1 to 64
Content: The maximum number of preambles transmitted in a preamble ramping cycle.
Recommended value: 20
Set this parameter through ADD PRACHBASIC, query it through LST PRACH, and modify it through MOD PRACHUUPARAS
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PRACH Open Loop Power Control Parameters
MMAX
Parameter name: Max preamble loop
The recommended value is 8
NB01MIN / NB01MAX
Parameter name: Random back-off lower / upper limit
The recommended value: 0 for both NB01MIN / NB01MAX
MMAX
Parameter name: Max preamble loop
Value range: 1 to 32
Content: The maximum number of random access preamble loops.
Recommended value: 8
Set this parameter through ADD RACH, query it through LST RACH, and modify it first de-activated the cell through DEA CELL, then MOD RACH.
NB01MIN / NB01MAX
Parameter name: Random back-off lower / upper limit
Value range: 0 to 50
Content: The lower / upper limit of random access back-off delay.
The recommended value: 0 for both NB01MIN / NB01MAX
Set this parameter through ADD RACH, query it through LST RACH, and modify it first de-activated the cell through DEA CELL, then MOD RACH.
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PRACH Open Loop Power Control Parameters
POWEROFFSETPPM
Parameter name: Power offset
The default value:
-3dB for signalling transmission;
-2dB for service transmission.
POWEROFFSETPPM
Parameter name: Power offset
Value range: -5 to 10dB
Content: The power offset between the last access preamble and the message control part. The power of the message control part can be obtained by adding the offset to the access preamble power.
The recommended value of this parameter is -3dB for signalling transmission , and that -2dB for service transmission
Set this parameter through ADD PRACHTFC, query it through LST PRACH, and modify it de-activated the cell through DEA CELL . After the old configuration of PRACH is deleted through RMV PRACHTFC , a new parameters can be established through ADD PRACHTFC
The PRACH message also consists of control part and data part, here the POWER OFFSET is the difference between the PRACH preamble and the message control part.
The PRACH message uses GAIN FACTOR to set the power of control / data part:
GAIN FACTOR BETAC ( βc ) is the gain factor for the control part.
GAIN FACTOR BETAD ( βd ) is the gain factor for the data part.
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Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power Control
2.4 Uplink Dedicated Channel Open Loop Power Control
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DL DPDCH Open Loop Power Control
5. Downlink Synchronization
UE Node B Serving RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
1. CCCH: RRC Connection Request
DL DPDCH Open Loop Power Control
According to the RRC connection establishment procedure, after RNC received the “RRC CONNECTION REQUEST” message, and NodeB set up the radio link for UE, then Iub interface resources is established between NodeB and RNC.
When DCH-FP of Iub interface finished downlink and uplink synchronization, the downlink DPCH starts to transmit, and DPDCH initial transmission power is calculated through open loop power control.
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DL DPDCH Open Loop Power Control
When a dedicated channel is set up, the initial power of
downlink DPDCH can be calculated according to the
following formula:
⎟⎟⎠
⎞⎜⎜⎝
⎛−××= Total
CPICH
CPICHDLInitial P
)No/Ec(P)
NoEb(
WRP α
In this formula, where
R is the requested data bitrate by the user
W is the chip rate
(Eb/No)DL is the Eb/No target to ensure the service quality. RNC searches for the (Eb/No)DL dynamically in a set of pre-defined values according to specific cell environment type, coding type, bitrate, BLER target and etc.
(Ec/Io)CPICH is the CPICH signal quality measured by UE, then it is sent to RNC through RACH.
α is the orthogonality factor in the downlink. In Huawei implementation, α is set to 0.
Ptotal is the total carrier transmit power measured at the NodeB
The initial transmission power of downlink DPDCH could be calculated through this formula, then, initial transmission power of downlink DPCCH can be obtained according to the power offset: PO1, PO2 and PO3.
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DL DPDCH Open Loop Power Control
Data1 TPC TFCI Data2 Pilot
DownlinkTransmit
Power
DPCCHDPDCH DPDCH DPCCH
PO2 PO1PO3
1 timeslot
This figure shows the power offset of downlink DPCH :
PO1 is the power offset of DPCCH TFCI bits to DPDCH data bits.
PO2 is the power offset of DPCCH TPC bits to DPDCH data bits.
PO3 is the power offset of DPCCH Pilot bits to DPDCH data bits.
The values of PO1, PO2 and PO3 are configured on RNC.
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DL DPDCH Open Loop Power Control Parameter
TFCIPO
Parameter name: TFCI power offset
The recommended value is 0, namely 0dB
TPCPO
Parameter name: TPC power offset
The recommended value is 12, namely 3dB
TFCIPO
Parameter name: TFCI power offset
Value range : 0 to 24
Physical value range: 0 to 6 dB, step: 0.25
Content: The offset of TFCI bit transmit power from data bit transmit power in each time slot of radio frames on DL DPCH
Recommended value: 0
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
TPCPO
Parameter name: TPC power offset
Value range : 0 to 24
Physical value range: 0 to 6 dB, step: 0.25
Content: The offset of TPC bit transmit power from data bit transmit power in each time slot of radio frames on DL DPCH
Recommended value: 12
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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DL DPDCH Open Loop Power Control Parameter
PILOTPO
Parameter name: Pilot power offset
The recommended value is 12, namely 3dB
PILOTPO
Parameter name: Pilot power offset
Value range : 0 to 24
Physical value range: 0 to 6 dB, step: 0.25
Content: The offset of pilot bit transmit power from data bit transmit power in each time slot of radio frames on DL DPCH
The recommended value is 12, namely 3dB
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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Downlink Power Control Restriction
The power of downlink dedicated channel is limited by an
upper and lower limit for each radio link.
The DL DPDCH power could not exceed Maximum_DL_Power,
nor could it be below Minimum_DL_Power.
RLMAXDLPWR / RLMINDLPWR
Parameter name: RL Max / Min DL TX power
The recommended value is shown in the following table.
Note: Both downlink open loop and close loop power control will be limited by this parameter.
RLMAXDLPWR
Parameter name: RL Max DL TX power
Value range : -350 to 150
Physical Value Range:-35 to 15 dB, step 0.1dB
Content: The maximum downlink transmit power of radio link. This parameter should fulfill the coverage requirement of the network planning, and the value is relative to [PCPICH transmit power]
Set this parameter through ADD CELLRLPWR , query it through LST CELLRLPWR, and modify it through MOD CELLRLPWR
RLMINDLPWR
Parameter name: RL Min DL TX power
Value range : -350 to 150
Physical Value Range:-35 to 15 dB, step 0.1dB
Content: The minimum downlink transmit power of radio link. This parameter should consider the maximum downlink transmit power and the dynamic range of power control, and the value is relative to [PCPICH transmit power].
Since the dynamic range of power control is set as 15dB, this parameter is recommended as [RL Max DL TX power] – 15 dB.
Set this parameter through ADD CELLRLPWR, query it through LST CELLRLPWR, and modify it through MOD CELLRLPWR
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Downlink Power Restriction Parameters
Referential configurations for typical services:
8-114384 kbps
8-132256 kbps
16-150144 kbps
32-17-264 kbps
64-19-432 kbps
128-23-88 kbps
PS Domain
32-15064 kbps
32-15056 kbps
64-17-232 kbps
64-17-228 kbps
128-18-312.2 kbps AMR
CS Domain
Downlink SFRL Min Downlink Transmit Power
RL Max Downlink Transmit PowerService
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Contents
2. Open Loop Power Control
2.1 Open Loop Power Control Overview
2.2 PRACH Open Loop Power Control
2.3 Downlink Dedicated Channel Open Loop Power Control
2.4 Uplink Dedicated Channel Open Loop Power Control
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UL DPCCH Open Loop Power Control
5. Downlink Synchronization
UE Node B Serving RNC
DCH - FP
Allocate RNTISelect L1 and L2parameters
RRCRRC
NBAPNBAP3. Radio Link Setup Response
NBAPNBAP2. Radio Link Setup Request
RRCRRC7. CCCH: RRC Connection Set up
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRCRRC9. DCCH: RRC Connection Setup Complete
6. Uplink Synchronization
NBAPNBAP8. Radio Link Restore Indication
DCH - FP
DCH - FP
DCH - FP
1. CCCH: RRC Connection Request
Open Loop PowerControl of UL DPCCH
According to the RRC connection establishment procedure, after RNC sent the “RRC CONNECTION SETUP” message, UE will try to synchronize with NodeB, and the uplink DPCCH starts to transmit, here DPCCH initial transmission power is calculated through open loop power control
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UL DPCCH Open Loop Power Control
The initial power of the uplink DPCCH can be calculated according to the following formula:
WhereCPICH_RSCP means the received signal code power, the received power measured on the CPICH.
DPCCH_Power_Offset is provided by RNC to the UE via RRC signaling.
RSCP_CPICHOffset_Power_DPCCHPower_Initial_DPCCH −=
For Huawei, DPCCH_Power_Offset is calculated with the following formula:
Where
PCPICH Transmit Power defines the PCPICH transmit power in a cell.
UL Interference is the UL RTWP measured by the NodeB.
Default Constant Value reflects the target Ec/No of the uplink DPCCH preamble.
Value ttanCons DefaultceInterferen ULPower Transmit PCPICHOffset_Power_DPCCH
++=
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UL DPCCH Open Loop Power Control Parameter
DEFAULTCONSTANTVALUE
Parameter name: Constant value configured by default
The recommended value is -27, namely -27dB.
DEFAULTCONSTANTVALUE
Parameter name: Constant value configured by default
Value range : -35 to -10 , unit :dB
Content: This parameter is used to obtain DPCCH_Power_Offset, which is used by UE to calculate the initial transmit power of UL DPCCH during the open loop power control process.
Recommended value: -27
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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Uplink Power Control Restriction
During the operation of uplink power control, the UE
transmit power shall not exceed the Maximum Allowed
Uplink Transmit Power.
MAXALLOWEDULTXPOWER
Parameter name: Max allowed UE UL TX power
The recommended value is 21, namely 21 dBm.
MAXALLOWEDULTXPOWER
Parameter name: Max allowed UE UL TX power
Value range: -50 to 33
Physical value range: -50 to 33 dBm. Step: 1
Content: The maximum allowed uplink transmit power of a UE in the cell, which is related to the network planning.
Recommended value: 21
Set this parameter through ADD CELLSELRESEL, query it through LST CELLSELRESEL, and modify it through MOD CELLSELRESEL
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Uplink Power Control Restriction
In addition, there are four parameters which correspond to the maximum allowed transmit power of four classes of services respectively:
MAXULTXPOWERFORCONV
Parameter name: Max UL TX power of Conversational service
MAXULTXPOWERFORSTR
Parameter name: Max UL TX power of Streaming service
MAXULTXPOWERFORINT
Parameter name: Max UL TX power of Interactive service
MAXULTXPOWERFORBAC
Parameter name: Max UL TX power of Background service
The recommended value is 24, namely 24 dBm.
MAXULTXPOWERFORCONV
Parameter name: Max UL TX power of Conversational service
MAXULTXPOWERFORSTR
Parameter name: Max UL TX power of Streaming service
MAXULTXPOWERFORINT
Parameter name: Max UL TX power of Interactive service
MAXULTXPOWERFORBAC
Parameter name: Max UL TX power of Background service
Value range: -50 to 33
Physical value range: -50 to 33 dBm. Step: 1
Content: The maximum UL transmit power for specific service in the cell, which is related to the network planning.
Recommended value: 24
Set this parameter through ADD CELLCAC, query it through LST CELLCAC, and modify it through MOD CELLCAC
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Contents
1. Power Control Overview
2. Open Loop Power Control
3. Closed Loop Power Control
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Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
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Closed Loop Power Control Overview
Why closed loop power control is needed?Open loop power control is not accurate enough, it can only estimate the initial transmission power.
Closed loop power control can guarantee the QoS with minimum power. By decreasing the interference, the system capacity will be increased.
Inner LoopOuter Loop
SIRtar
SIRmea>SIRtar→ TPC=0
SIRmea<SIRtar→ TPC=1
UntilSIRmea=SIRtar
TPCBLERtar
BLERmea>BLERtar→SIRtar
BLERmea<BLERtar→SIRtar
Until BLERmea=BLERtar
TPC=1 PowerTPC=0 Power
Inner Loop Power Control
The receiver compares SIRmea (measured SIR) with SIRtar (target SIR), and decide the TPC to send.
If SIRmea is greater than SIRtar, the TPC is set as “0” to increase transmission power
If SIRmea is less than SIRtar, the TPC is set as “1” to decrease transmission power
TPC is sent to the transmitter in DPCCH, the transmitter will adjust the power according to the value of received TPC.
Through inner loop power control, the SIRmea can be ensured to approach SIRtar.
Outer Loop Power Control
The receiver compares BLERmea (measured BLER) with BLERtar (target BLER), and decide how to set the SIRtar.
If BLERmea is greater than BLERtar, the SIRtar is increased
If BLERmea is less than BLERtar, the SIRtar is decreased
The adjusted SIRtar is sent for the inner loop power control, then it will be used in previous process to guide the transmitter power adjustment.
Through outer loop power control, the BLERmea can be ensured to approach BLERtar.
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Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
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Uplink Inner Loop Power Control
NodeB compares the measured SIR to the preset target SIR, then derives TPC and sends the TPC Decision to UE.
TPC Decision( 0, 1 )
Generate TPC_cmd( -1, 0, 1 )
Adjust DPCCH Tx△DPCCH =△TPC×TPC_cmd
Single RL / Soft HOPCA1 / PCA2
Adjust DPDCH Tx( βc , βd )
NodeB UETransmit TPC
Inner Loop
Set SIRtar
Compare SIRmea with SIRtarSIRmea > SIRtar → TPC = 0SIRmea ≤ SIRtar → TPC = 1
RNC sends SIRtar (target SIR) to NodeB and then NodeB compares SIRmea (measured SIR) with SIRtar once every timeslot.
If the estimated SIR is greater than the target SIR, NodeB sends TPC “0” to UE on downlink DPCCH TPC field.
Otherwise, NodeB sends TPC “1” to UE.
After reception of one or more TPC in a slot, UE shall derive a single TPC_cmd (TPC command, with value among -1,0,1):
For UE is in soft handover state, more than one TPC is received in a slot, so firstly multiple TPC_cmd is combined.
Two algorithms could be used by the UE for deriving the TPC_cmd, those are PCA1 and PCA2 (PCA means Power Control Algorithm).
When deriving the combined TPC_cmd, UE shall adjust the transmit power of uplink DPCCH with a step “UL Closed Loop Power Control Step Size“, as following:
△DPCCH =△TPC×TPC_cmd
This adjustment is executed on the DPCCH, then associated DPDCH transmit power is calculated according to DPDCH / DPCCH power ratio βd / βc.
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Uplink Inner Loop PCA1 with Single Radio Link
For single radio link and PCA1, UE derives one TPC_cmd in each
time slot as follows:
0110110110…… ……
…… ……TPC_cmd
TPC
-111-111-111-1
This control is performed in each time slot, so the power control frequency is 1500Hz
When UE has single radio link, only one TPC will be received in each slot. In this case, the value of TPC_cmd shall be derived by PCA1 as follows:
If the received TPC is equal to 0, then TPC_cmd for that slot is –1.
If the received TPC is equal to 1, then TPC_cmd for that slot is 1.
According to DPCCH channel structure, there are 15 time slots in a 10ms radio frame, and the control is performed once in each time slot, so the frequency of uplink inner loop PCA1 is 1500Hz.
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Uplink Inner Loop PCA2 with Single Radio Link
For single radio link and PCA2, UE derives one TPC_cmd in each
5-slot group as follows:
This control is performed in each 5-slot group, so the power control frequency is 300Hz
110111111100000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
10ms radio frame
Group 2Group 1 Group 3
…… ……
0000010000-10000
TPC
TPC_cmd
…… ……
When UE has single radio link, only one TPC will be received in each slot. In this case, the value of TPC_cmd shall be derived by PCA2 as follows:
For the first 4 slots of a set, TPC_cmd = 0.
For the fifth slot of a set, UE make the decisions on as follows:
If all 5 TPC within a group are 1, then TPC_cmd = 1 in the 5th slot.
If all 5 TPC within a group are 0, then TPC_cmd = -1 in the 5th slot.
Otherwise, TPC_cmd = 0 in the 5th slot.
According to DPCCH channel structure, there are 15 time slots in a 10ms radio frame, and the control is performed once in each 5-slot group, so the frequency of uplink inner loop PCA2 is 500Hz.
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Uplink Inner Loop with Soft Handover
When UE enters soft handover state, on the NodeB side,
there are two phases :
Uplink synchronization phase
Multi-radio link phase
On UE side, UE will receive different TPCs from different
RLS in one time slot. Therefore, the UE should combine all
the TPCs to get a unique TPC_CMD.
On the NodeB side, there are two phases during the soft handover state:
Uplink synchronization phase
The NodeB should send durative “TPC = 1” to the newly-added RL before successful synchronization.
Multi-radio link phase
Each NodeB and each cell will estimate the SIR individually and the general TPC individually. Therefore, the UE may receive different TPC from different RLS.
Especially, when UE is in softer handover state, it means UE has radio links to the same NodeB, in this case, these RLs (Radio Link) belong to the same RLS (Radio Link Set), and the all TPCs are the same from each RL.
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Uplink Inner Loop PCA1 with Soft Handover
For each slot, combine TPC from the same RLS, then get Wi
CELL1 CELL2
CELL4CELL3
RL1-1 RL1-2
RLS1
RLS2 RLS3Get TPC_cmd based onTPC_cmd = γ (W1, W2, … WN)
0110110110…… ……RLS1-TPC (W1)
…… ……RLS2-TPC (W2) 1010101101
…… ……
…… ……TPC_cmd
1101100100
-1-1-1-11-1-11-1-1
RLS3-TPC (W3)
When UE is in soft handover state, multiple TPC will be received in each slot from different cells in the active set. UE will generate the TPC_cmd by PCA1 as follows:
1. Combine the TPC from the same RLS and derive the Wi
When the RLs (Radio Link) are in the same RLS (Radio Link Set), they will transmit the same TPC in a slot. In this case, the TPCs from the same RLS shall be combined into one.
After combination, UE will obtain a soft symbol decision Wi for each RLSi.
2. Combine the TPC from different RLSs and derive the TPC_cmd
UE derives TPC_cmd, it is based on a function γ and all the N soft symbol decisions Wi:
TPC_cmd = γ (W1, W2, … WN),
Where TPC_cmd can only take the values 1 or -1.
In Huawei implementation, the function γ shall fulfil the following criteria:
If the TPCs from all RLSs are “1”, the output of γ shall be equal to “1” ;
If one TPC from any RLS is “0”, the output of γ shall be equal to “-1”.
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Uplink Inner Loop PCA2 with Soft Handover
Combine TPC from same RLSin each time slot
Calculate TPC_cmdIf any TPC_tempi = -1, TPC_cmd = -1
If , TPC_cmd = 1
Otherwise, TPC_cmd = 0
Calculate TPC_tempi for each RLSi
5.0_11
>∑=
N
iitempTPC
N
CELL1 CELL2
CELL4CELL3
RL1-1 RL1-2RLS1
RLS2 RLS3
When UE is in soft handover state, multiple TPC will be received in each slot from different cells in the active set. UE will generate the TPC_cmd by PCA2 as follows:
1. Combine the TPC from the same RLS.
When the RLs are in the same RLS, they will transmit the same TPC in a slot. In this case, the TPCs from the same RLS shall be combined into one.
2. Calculate the TPC_tempi for each RLS
UE derives TPC_tempi through the same way in the last slide, as follows:
For the first 4 slots of a group, TPC_tempi = 0.
For the 5th slot of a group:
If all 5 TPCs within a group are 1, then TPC_tempi = 1 in the 5th slot.
If all 5 TPCs within a group are 0, then TPC_tempi = -1 in the 5th slot.
Otherwise, TPC_tempi = 0 in the 5th slot.
3. Calculate the TPC_cmd
UE derives TPC_cmd through the following criteria:
If any TPC_tempi is equal to -1, TPC_cmd is set to -1.
If , TPC_cmd = 1
Otherwise, TPC_cmd = 0
5.0temp_TPCN1 N
1ii >∑
=
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Uplink Inner Loop PCA2 with Soft Handover
RLS3
RLS2
RLS1 100100000000100
100110000011111
111110000011111
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
…… ……
10ms/frameGroup 1 Group 2 Group 3
RLS3
RLS2
RLS1 00000-1000000000
00000-1000010000
10000-1000010000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0
…… ……
TPC
TPC_tempi
00000-1000010000
TS14TS13TS12TS11TS10TS9TS8TS7TS6TS5TS4TS3TS2TS1TS0…… ……
TPC_cmd
The example of the uplink inner loop PCA2 in soft handover state.
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Uplink Inner Loop Power Control Parameters
PWRCTRLALG
Parameter name: Power control algorithm selection
The recommended value is ALGORITHM1
ULTPCSTEPSIZE
Parameter name: UL closed loop power control step size
The recommended value is 1, namely 1dB
PWRCTRLALG
Parameter name: Power control algorithm selection
Value range: ALGORITHM1, ALGORITHM2
Content: This parameter is used to inform the UE of the method for translating the received TPC commands.
Recommended value: ALGORITHM1
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
ULTPCSTEPSIZE
Parameter name: UL closed loop power control step size
Value range :1dB, 2dB
Content: The step size of the closed loop power control performed on UL DPDCH. This parameter is mandatory when the parameter “Power control algorithm selection” is set as "ALGORITHM1".
Recommended value: 1
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
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Downlink Inner Loop Power Control
UE L1 compares the measured SIR to the preset target SIR, then derives TPC and sends the TPC Decision to NodeB.
Derive TPCest(k)( 0, 1 )
Generate PTPC(k)
Calculate P(k)
Adjust DPCH Tx Power
DPC_MODE
NodeB
L3 Set SIRtar
Derive and transmit TPC based on DPC_MODE
Inner Loop
UE
L1 compare SIRmea with
SIRtar
Basically the downlink inner loop power control process is similar with uplink, UE L3 sends SIRtar to UE L1 and then UE L1 compares SIRmea with SIRtar :
If the SIRmea is greater than the SIRtar , UE sends TPC “0” to NodeB on uplink DPCCH TPC field.
Otherwise, UE sends TPC “1” to NodeB.
The UE shall check the downlink power control mode before generating the TPC, two algorithm DPC_MODE1 and DPC_MODE2 could be used by UE to derive the TPC. Upon receiving the TPC, NodeB shall estimate the transmitted TPC and adjust its downlink DPCCH/DPDCH power accordingly.
After reception of one or more TPC in a slot, NodeB shall derive the estimated TPC TPCest(k) and calculate a PTPC(k), the power adjustment of k:th slot.
Then NodeB shall adjust the current downlink power P(k-1) to a new power P(k), and adjust the power of the DPCCH and DPDCH with the same amount, since power difference between them is fixed.
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Downlink Inner Loop Power Control Mode
Two DPC_MODE (Downlink Power Control Mode) could be
used:
If DPC_MODE = 0, UE sends a unique TPC in each slot,
UTRAN shall derive TPCest to be 0 or 1, and update the power
every slot;
If DPC_MODE = 1, UE repeats the same TPC over 3 slots,
UTRAN shall derive TPCest over three slots to be 0 or 1, and
update the power every three slots.
The DPC_MODE parameter is a UE specific parameter and controlled by the UTRAN.
The UE shall check the DPC_MODE (Downlink Power Control Mode) before generating the TPC, and upon receiving the TPC, the UTRAN shall adjust its downlink power accordingly.
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Downlink Inner Loop Power Control Parameters
DPCMODE
Parameter name: Downlink power control mode
The recommended value is SINGLE_TPC, namely
DPC_MODE = 0
DPCMODE
Parameter name: Downlink power control mode
Value range: SINGLE_TPC (DPC_MODE=0), TPC_TRIPLET_IN_SOFT (DPC_MODE=1), TPC_AUTO_ADJUST
Content:
SIGNLE_TPC, a fast power control mode, indicates that a unique TPC command is sent in each time slot on DPCCH.
TPC_TRIPLET_IN_SOFT, a slow power control mode, indicates that the same TPC is sent in three time slots, it is applicable to soft handover and it can decrease the power deviation.
TPC_AUTO_ADJUST, an automatically adjusted mode, indicates that the value of DPC_MODE can be modified by sending the message “ACTIVE SET UPDATE” to UE.
Recommended value: SINGLE_TPC
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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Downlink Inner Loop Power Control
After estimating the TPC, the UTRAN shall set the downlink power
to P(k) for k:th slot according to the following formula:
Where
P(k-1) is downlink transmission power in (k-1):th slot
PTPC(k) is the adjustment of downlink power in k:th slot
Pbal (k) is correction value according to the downlink power balance
procedure. For a single radio link, Pbal (k) equals 0.
)k(P)k(P)1k(P)k(P balTPC ++−=
If DOWNLINK_POWER_BALANCE_SWITCH is OFF, then Pbal(k) equals 0.
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Downlink Inner Loop Power Control
PTPC(k) is calculated according to the following:
If the value of “Limited Power Increase Used” parameter is “Not
Used” , then:
Where
TPCest (k) is uplink received TPC of the k:th slot
ΔTPC is downlink power adjustment step size
⎩⎨⎧
=−=+
=0)k(TPC if 1)k(TPC if
)k(PestTPC
estTPCTPC Δ
Δ
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Downlink Inner Loop Power Control
If the value of “Limited Power Increase Used” parameter is
“Used” , then:
Where ∑−
−=
=1k
Size_Window_Average_Power_DLkiTPCsum )i(P)k(Δ
⎪⎩
⎪⎨
⎧
=−≥+=<+=+
=0)k(TPC if
Limit_Raise_Power)k( and 1)k(TPC if 0Limit_Raise_Power)k( and 1)k(TPC if
)k(P
estTPC
TPCsumest
TPCsumestTPC
TPC
ΔΔΔΔΔΔ
Where,
Power_Raise_Limit : the restriction value of power increasing within a period
DL_Power_Average_Window_Size : the period of DL transmit power increasing.
From the definition above, Δsum(k) indicates the sum of downlink power adjustment in the latest DL_Power_Average_Window_Size time slots.
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Downlink Inner Loop Power Control Parameters
INNER_LOOP_DL_LMTED_PWR_INC_SWITCH
This is one switch in PCSWITCH (Power control algorithm
switch) parameter.
The default value is 0, namely OFF.
POWERRAISELIMIT
Parameter name: Power increase limit
The recommended value is 10dB
INNER_LOOP_DL_LMTED_PWR_INC_SWITCH
This is one switch in PcSwitch (Power control algorithm switch) parameter.
Value range:1 (ON) , 0 (OFF)
Content: When it is checked, limited power increase algorithm is applied in the inner loop power control. limited power increase algorithm means that when the DL transmit power is increased, there is a limit for the step, that is, each increase is limited.
Recommended value (default value): 0
Set this parameter through SET CORRMALGOSWITCH, query it through LST CORRMALGOSWITCH, and modify it through SET CORRMALGOSWITCH
POWERRAISELIMIT
Parameter name: Power increase limit
Value range: 0 to 10 dB
Content: The increase of DL transmit power within DL_Power_Average_Window_Size cannot exceed this parameter value.
Recommended value: 10
Set this parameter through ADD CELLSETUP, query it through LST CELL, and modify it through MOD CELLSETUP
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Downlink Inner Loop Power Control Parameters
DLPOWERAVERAGEWINDOWSIZE
Parameter name: DL power average window size
The recommended value is 20 time slots
FDDTPCDLSTEPSIZE
Parameter name: FDD DL power control step size
The recommended value is STEPSIZE_1DB, namely 1dB
DLPOWERAVERAGEWINDOWSIZE
Parameter name: DL power average window size
Value range: 1 to 60 time slots
Content: UTRAN calculates the increase of DL transmit power within the period defined via this parameter to determine whether the increase exceeds “Power Raise Limit”. If so, UTRAN will not increase the power even when it receives the command to raise the power
Recommended value: 20
Set this parameter through ADD CELLSETUP, query it through LST CELL ,and modify it through MOD CELLSETUP
FDDTPCDLSTEPSIZE
Parameter name: FDD DL power control step size
Value range: STEPSIZE_0.5DB, STEPSIZE_1DB, STEPSIZE_1.5DB, STEPSIZE_2DB
Physical value range: 0.5, 1, 1.5, 2 dB
Content: The step size of the closed loop power control performed on DL DPCH in Frequency Division Duplex (FDD) mode.
Recommended value: STEPSIZE_1DB
Set this parameter through SET FRC, query it through LST FRC, and modify it through SET FRC
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Downlink Power Balance
Purpose
The purpose of this procedure is to balance the DL transmission powers of more than one Radio Links.
The start and stop of DPB
The power offset of two RLs is greater than the DPB start threshold, the DPB process is started
The power offset of two RLs is less than the DPB stop threshold, the DPB process is stopped
NodeB NodeB
Monitor the Tx power of NodeBs and start the DPB
process
DPB process
During soft handover, the UL TPC is demodulated in each RLS, then due to demodulation errors, the DL transmit power of the each branch in soft handover will drift separately, which causes loss to the macro-diversity gain.
The DL Power Balance (DPB) algorithm is introduced to reduce the power drift between links during the soft handover.
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Downlink Power Balance Parameters
DOWNLINK_POWER_BALANCE_SWITCH
This is one switch in PCSWITCH (Power control algorithm switch)parameter.
The default value is 0, namely OFF.
DPBSTARTTHD / DPBSTOPTHD
Parameter name: DPB start threshold / DPB stop threshold
The recommended value:
DPB start threshold 8, namely 4dB;
DPB stop threshold 4, namely 2dB.
DOWNLINK_POWER_BALANCE_SWITCH
This is one switch in PcSwitch (Power control algorithm switch) parameter.
Value range:1 (ON) , 0 (OFF)
Content: When it is checked, Downlink Power Balance (DPB) algorithm is applied to RNC. Downlink power drift among different RLs, which is caused by TPC bit error or other reasons, could reduce the gain of soft handover. DPB is mainly used to balance the downlink power of different RLs for an UE in order to achieve the best gain of soft handover.
Recommended value (default value): 0
Set this parameter through SET CORRMALGOSWITCH, query it through LST CORRMALGOSWITCH, and modify it through SET CORRMALGOSWITCH
DPBSTARTTHD / DPBSTOPTHD
Parameter name: DPB start threshold / DPB stop threshold
Value range: 0~255
Physical value range: 0~127.5dB; step: 0.5
Content: The threshold of start / stop DL power balancing in soft handover. When the difference of the power values of every two paths is greater / smaller than or equal to this threshold in soft handover, the RNC shall start / stop DL power balancing; otherwise, shall not.
The recommended value is DPB start threshold 8, namely 4dB; DPB stop threshold 4, namely 2dB;
Set this parameter through SET DPB, query it through LST DPB and modify it through SET DPB
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Contents
3. Closed Loop Power Control
3.1 Closed Loop Power Control Overview
3.2 Uplink Inner Loop Power Control
3.3 Downlink Inner Loop Power Control
3.4 Outer Loop Power Control
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Outer Loop Power Control
Why we need outer loop power control?
SIR
BLER
Different curves correspond to different multi-path environment
The reason of outer loop power control
The QoS which NAS provides to CN is BLER, not SIR
The relationship between inner loop power control and outer loop power control
SIRtar should be satisfied with the requirement of decoding correctly. But different multi-path radio environments request different SIR
Therefore, the outer loop power control can adjust the SIR to get a stable BLER in the changeable radio environment
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Uplink Outer Loop Power Control
NodeB UETransmit TPC
Measure SIR and compare with SIRtar
Inner loop
Set SIRtar
Out loop
RNC
Measure BLER of received data and compare with the BLERtar
Set BLERtar
Uplink outer-loop power control is performed in the SRNC. The SRNC measures the received BLER and compares it with the BLERtar. If the BLERmea is greater than the BLERtar, the SRNC increases the SIRtar; otherwise, the SRNC decreases the SIRtar.
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Uplink Outer Loop Power Control
SIRtar Adjustment
Where
i is the i:th transmission channel.
n is the n:th adjustment period.
⎥⎥⎦
⎤
⎢⎢⎣
⎡××
−−+−= FactorStep
BLERBLER)1n(BLER
)1n(SIRMAX)n(SIR ii,tar
i,tari,meastartar
According to the formula above,
SIRtar(n) is the target SIR used for the n:th adjustment period.
MAX means the maximum value among the total i transmission channels.
BLERmeas,i (n) is measured for the i:th transmission channel in the n:thadjustment period.
BLERtar,i is the target BLER of the i:th transmission channel.
Stepi is the adjustment step of the i:th transmission channel.
Factor is the adjustment factor.
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Uplink Outer Loop Power Control Parameters
OPLC_SWITCH
This is one switch in PCSWITCH (Power control algorithm
switch) parameter.
The default value is 1, namely ON
INITSIRTARGET
Parameter name: Initial SIR target value
The recommended value is shown in following table.
OPLC_SWITCH
This is one switch in PCSWITCH (Power control algorithm switch) parameter.
Value range:1 (ON) , 0 (OFF)
Comments: When it is checked, RNC updates the uplink SIR TARGET of RLs on the NodeB side by Iub DCH FP signals
Default value: 1
Set this parameter through SET CORRMALGOSWITCH, query it through LST CORRMALGOSWITCH, and modify it through SET CORRMALGOSWITCH
INITSIRTARGET
Parameter name: Initial SIR target value
Value range: 0 to 255
Physical value range: -8.2 to +17.3 dB, step 0.1
Content: Defining the initial SIR target value of outer loop power control.
Recommended value: refer to the following table.
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB, and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
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Uplink Outer Loop Power Control Parameters
SIRADJUSTPERIOD
Parameter name: OLPC adjustment period
The recommended value is shown in following table.
SIRADJUSTFACTOR
Parameter name: SIR adjustment coefficient
The recommended value is 10, namely 1
SIRADJUSTPERIOD
Parameter name: OLPC adjustment period.
Value range: 1 to 100
Physical value range: 10 to 1000 ms, step 10
Comments: Outer loop power control varies with radio environment. A fast changing radio environment leads to a shorter outer loop power control adjustment period, while a slower changing one makes the period longer.
Default value: 40
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB, and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
SIRADJUSTFACTOR
Parameter name: SIR adjustment coefficient
Value range: 0 to 10
Physical value range: 0.1 to 1 , step: 0.1
Content: It is used to adjust the best OLPC step for different cells when the OLPC algorithm is given.
Recommended value: 10, namely 1
Set this parameter through SET OPLC / ADD CELLOLPC, query it through LST OPLC, and modify it through SET OPLC / MOD CELLOLPC
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Uplink Outer Loop Power Control Parameters
BLERQUALITY
Parameter name: Service DCH_BLER target value
The recommended value is shown in following table.
SIRADJUSTSTEP
Parameter name: SIR adjustment step
The recommended value is shown in the following table.
SIRADJUSTSTEP
Parameter name: SIR adjustment step
Value range: 0 to 10000
Physical value range: 0 to 10 , step: 0.001dB
Content: Step of target SIR adjustment in outer loop power control algorithm.
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB ,and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
BLERQUALITY
Parameter name: Service DCH_BLER target value
Value range: -63 to 0
Physical value range: 5×10-7 to 1
Content: This QoS-related parameter is used by CRNC to decide the target SIR value that influences access and power control. Use the formula below to get the integer value of the parameter: 10×Log 10(BLER).
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB, and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
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Uplink Outer Loop Power Control Parameters
Referential configurations for typical services:
-20-20-20-20-20-20-20-20-27-20-20-20Service
DCH_BLER target value
142122107102102102102102122102122102SIR init target value
4444444425104SIR
adjustment step
222222242224OLPC
adjustment period
PS I/B 384k
PS I/B 256k
PS I/B 144k
PS I/B 128k
PS I/B 64k
PS I/B 32k
PS I/B 16k
PS I/B 8k
CSD 64k
AMR 12.2k
SRB 13.6k
SRB 3.4kService
Where,
CSD: CS domain Data service
I/B: Interactive and Background.
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Uplink Outer Loop Power Control
The parameters MaxSirStepUp and MaxSirStepDown limit the adjustment range of the SIRtar , and the algorithm is:
If ΔSIRtar > 0 and ΔSIRtar > “MaxSirStepUp” ,
then SIRtar (n+1) = SIRtar (n) + MaxSirStepUp
If ΔSIRtar < 0 and ABS( ΔSIRtar ) > “MaxSirStepDown” ,
then SIRtar (n+1) = SIRtar (n) – MaxSirStepDown
The parameters MaxSirtarget and MinSirtarget limit the range of the SIRtar at any time.
Where,
ΔSIRtar is the adjustment of SIRtar, and ΔSIRtar = SIRtar (n+1) - SIRtar (n)
ABS( ΔSIRtar ) means absolute value of ΔSIRtar
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Uplink Outer Loop Power Control Parameters
MAXSIRSTEPUP / MAXSIRSTEPDN
Parameter name: Maximum SIR increase / decrease step
The recommended value is shown in following table.
MAXSIRTARGET / MINSIRTARGET
Parameter name: Maximum / Minimum SIR target
The recommended value is shown in following table.
MAXSIRSTEPUP / MAXSIRSTEPDN
Parameter name: Maximum SIR increase / decrease step
Value range: 0 to 10000
Physical value range: 0 to 10 dB, step: 0.001
Content: Maximum allowed SIR increase/ decrease step within an outer loop power control adjustment period.
The recommended value is shown in following table.
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB ,and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
MAXSIRTARGET / MINSIRTARGET
Parameter name: Maximum / Minimum SIR target
Value range: 0 to 255
Physical value range: -8.2 to17.3 dB, step: 0.1
Content: Define the maximum /minimum SIR target value of outer loop power control algorithm.
The recommended value is shown in following table.
Set this parameter through ADD TYPSRBOLPC / ADD TYPRABOLPC, query it through LST TYPSRB / LST TYPRAB ,and modify it through MOD TYPSRBOLPC / MOD TYPRABOLPC
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Uplink Outer Loop Power Control Parameters
Referential configurations for typical services:
4004004004004004004004001000500500400Maximum
SIR increase step
200200200200200200200200100200200200Maximum
SIR decrease step
626262626262626262626262Minimum SIR target
172152137132132132132132152132132132Maximum SIR target
PS I/B 384k
PS I/B 256k
PS I/B 144k
PS I/B 128k
PS I/B 64k
PS I/B 32k
PS I/B 16k
PS I/B 8k
CSD 64k
AMR 12.2k
SRB 13.6k
SRB 3.4kService
Where,
CSD: CS domain Data service
I/B: Interactive and Background.
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Downlink Outer Loop Power Control
NodeB
set SIRtar
Transmit TPC
Measure SIR and compare with SIRtar
Measure BLER of received data and compare with the
BLERtar
Outer loop
Inner loop
L1
L3
UE
The downlink outer loop power control is implemented inside the UE. Therefore, this algorithm is specified by UE manufacturer.
Generally, the UE L3 measures the received BLER and compares it with the BLERtar. If the BLERmea is greater than the BLERtar, the L3 increases the SIRtar and send it to UE L1; otherwise, the L3 decreases the SIRtar.
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Summary
In this course, we have discussed function, principle and
common parameters of the following power control
algorithm:
Open loop power control
Inner loop power control
Outer loop power control
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA Handover Principle and Relevant Parameters
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ForewordWhy mobile system need handover?
The mobility of UE
Load Balance
Any others ?
Handover is a basic function of a cellular mobile network. The purpose of handover is to ensure that a UE in CELL_DCH state is served continuously when it moves.
HCS: hierarchical cell structure
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Handover types supported by UMTS
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ObjectivesUpon completion of this course, you will be able to:
Know the features of each handover
Know the algorithms of handover
Know the handover procedure
Know the parameters of handover
Handover types supported by UMTS can be classified as:
Intra-frequency handover
Inter-frequency handover
Inter-RAT handover
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The Basic Concepts of HandoverActive Set
Monitored Set
Detected Set
Radio Link (RL)
Radio Link Set (RLS)
Maximum Ratio Combination
Selective Combination
Soft Handover Gain
P-CPICH
Active set : Cells, which belong to the active set. User information is sent from all these cells. In FDD, the cells in the active set are involved in soft handover. The UE shall only consider active set cells included in the variable CELL_INFO_LIST for measurement; i.e. active set cells not included in the CELL_INFO_LIST shall not be considered in any event evaluation and measurement reporting.
Monitored set :Cells, which are not included in the active set, but are included in the CELL_INFO_LIST belong to the monitored set.
Detected set : Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the active set belong to the detected set. Reporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCH state.
RL: Radio link between NodeB and UE.
RLS: Radio link set. The RLs from same NodeB.
Combination way: For soft handover, the uplink signals are combined in RNC. The RNC will select one best signal to process. We call this selective combination. For softer handover, the uplink signals are combined in the RAKE receiver of NodeB. It is maximum ratio combination.
Soft handover gain: We have introduced in Coverage Planning.
CPICH: Common Pilot Channel. UE measure the signal strength of CPICH for handover decision.
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Contents1. Intra-Frequency Handover
2. Inter-Frequency Handover
3. Inter-RAT Handover
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Contents1. Intra-Frequency Handover
1. Intra-Frequency Handover Overview
2. Intra-Frequency Handover Procedure
3. Signaling Procedures for Intra-Frequency Handover
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Intra-Frequency Handover Overview
Characters of Intra-Frequency Handover:
The carrier frequencies of the current cell and target cell are the same
Intra-frequency soft handover
Intra-frequency hard handover.
Intra-frequency handover consists of two types,
Intra-frequency soft handover: more than one radio link are set up for the UE.
Intra-frequency hard handover: only one radio link is set up for the UE.
Intra-frequency soft handover is more commonly used than intra-frequency hard handover. Intra-frequency hard handover is used only in some special scenarios, for example, when there is no Iur interface between two RNCs.
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Intra-Frequency Handover Overview
Comparison between soft handover and hard handover:
Can be happened in Intra-
frequency cells or Inter-frequency
cells
Only happened
between Intra-
frequency cells
The frequencies of cells
YesNoInterruption during
handover
OneSeveral The number of RLs in
active set after handover
Hard HandoverHard HandoverSoft HandoverSoft HandoverItemItem
The maximum number of RL is 3. This value can be changed. But this function need the UE to support. Normally, the active set supported by UE is fixed 3 and can not be changed.
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Intra-Frequency Handover Overview
Intra-Frequency Soft Handover :
Soft Handover
Softer Handover
Intra-Frequency soft handover is a function in which the UE is connected to several cells at the same time. Addition or release of radio links are controlled by the ACTIVE SET UPDATE procedure.
During soft handover, a UE is in the overlapping cell coverage area of two sectors belonging to different base stations. The communications between UE and base station take place concurrently via two air interface channels from each base station separately.
During softer handover, a UE is in the overlapping cell coverage area of two adjacent sectors of a base station. The communications between UE and base station take place concurrently via two air interface channels, one for each sector separately.
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Page10Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Intra-Frequency Handover Overview
Using selection combination Using maximum-ratio combination Uplink
signal
Using maximum-ratio combination Using maximum-ratio combination Downlink
signal
Occupying more Iub bandwidth Occupying less Iub bandwidthResource
use
When the UE is in the overlapped
coverage area of two neighboring
cells of different NodeBs
When the UE is in the overlapped
coverage area of two neighboring
cells of a NodeB with combined RLs
Scenario
Soft HandoverSoft HandoverSofter HandoverSofter HandoverItemItem
Comparison between soft handover and softer handover :
During softer handover, the uplink signaling are combined in NodeB by maximum ratio combination, but during soft handover they are combined in RNC by selective combinationCompare to later one, the maximum ratio combination can get more gain. So the performance of maximum ratio combination is betterSince softer handover is completed in NodeB, it do not consume transport resource of Iub
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Intra-Frequency Handover OverviewIntra-Frequency Hard Handover :
No Iur interface
Iur interface is congested
High-speed Best Effort (BE) service Handover
Soft handover fails
Intra-frequency hard handover refers to a handover where all the old radio links are released before the new radio links are established. Compared with soft handover, intra-frequency hard handover uses fewer resources.
The scenarios of intra-frequency hard handover are as follows:
The UE needs to perform the intra-frequency handover between two cells configured in different RNCs. No Iur interface is present between RNCs.The UE needs to perform the intra-frequency handover between two cells configured in different RNCs. The Iur interface is congested between RNCs.There is a high-speed Best Effort (BE) service.
Compared with soft handover, intra-frequency hard handover is used to save downlink bandwidth for a high-speed BE service.The intra-frequency soft handover fails and intra-frequency hard handover is allowed.
When intra-frequency soft handover fails because of a congestion problem of the target cell, the RNC tries an intra-frequency hard handover with a lower service bit rate.
The INTRA_FREQUENCY_HARD_HANDOVER_SWITCH parameter in the SET CORRMALGOSWITCH command is used to determine whether to enable intra-frequency hard handover. By default, this switch is ON.
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Contents1. Intra-Frequency Handover
1. Intra-Frequency Handover Overview
2. Intra-Frequency Handover Procedure
3. Signaling Procedures for Intra-Frequency Handover
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Intra-Frequency Handover Procedure
Decision
Execution
Measurement
The following figure shows handover procedure
Decision phase
Execution phase
Measurement phase
Yes
NoAre handover criteria satisfied?
Perform a handover and update relative parameters
Measure the CPICH Ec/N0 of the serving cell andits neighboring cells as well as the relative timedifference between the cells
Intra-frequency handover procedure is divided into three phases: handover measurement, handover decision, and handover execution.
After the UE transits to CELL_DCH state in connected mode during a call, the RNC sends a measurement control message to instruct the UE to take measurements and report the measurement event results.
Upon receiving an event report from the UE, the RNC makes a handover decision and performs the corresponding handover
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Contents1. Intra-Frequency Handover
1. Intra-Frequency Handover Overview
2. Intra-Frequency Handover Procedure
1. Intra-Frequency Handover Measurement
2. Intra-Frequency Handover Decision and Execution
3. Neighboring Cell Combination Algorithm
3. Signaling Procedures for Intra-Frequency Handover
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UE UTRAN
MEASUREMENT CONTROL
Intra-Frequency Handover MeasurementMEASUREMENT CONTROL
The measurement control message carries the following information:
Event trigger threshold
Hysteresis value
Event trigger delay time
Neighboring cell list
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UE UTRAN
MEASUREMENT REPORT
MEASUREMENT REPORT
Intra-Frequency Handover Measurement
The purpose of the measurement reporting procedure is to transfer measurement results from the UE to UTRAN.
Based on the algorithm in measurement control, the UE will measure the signal strength or quality and check if it meet the requirement of all event. If it meet the requirement of any event, UE will send the measurement report to UTRAN to trigger the handover. The most important information in the measurement are the PSC , the CPICH Ec/No of the target cell, and the triggered event.
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Intra-Frequency Handover Measurement
L3 Filtering for Intra-Frequency Handover
The value after L3 filtering procedure is calculated according to following formula:
Fn = (1 - α) x Fn-1 + α x Mn
where
Fn is the new measurement value obtained after L3 filtering.
Fn-1 is the last measurement value obtained after L3 filtering.
Mn is the latest measurement value obtained from the physical layer.
α = 1/2(k/2) (k is set to Intra-freq meas L3 filter coeff)
When α is set to 1, that is, k = 0, no L3 filtering is performed.
A is measurement value at the physical layer
B is the measurement value after layer 1 filtering at physical layer. The value goes from the physical layer to high layer
C is measurement after processing in the layer3 filter
C’ is another measurement value
D is measurement report information sent on the radio interface or Iub interface
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Key parameters of Intra-frequency Measurement
Intra-freq Measure Quantity
Parameter ID: IntraFreqMeasQuantity
The default value of this parameter is CPICH_Ec/No
Intra-freq meas L3 filter coeff
Parameter ID: FilterCoef
The default value of this parameter is 3
The measurement quantity of intra-frequency handover can be Common Pilot Channel (CPICH) Ec/No or CPICH Received Signal Code Power (RSCP). It can be used in all the measurement events of intra-frequency handover Intra-freq Measure Quantity
Parameter ID: IntraFreqMeasQuantityValue range: CPICH_Ec/No, CPICH_RSCP Content: This parameter specifies the measurement quantity used in intra-
frequency measurement. The default value of this parameter is CPICH_Ec/NoSet this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .Before judging a measurement event and sending the measurement report, the UE performs L3 filtering for the measurement value.
Intra-freq meas L3 filter coeffParameter ID: FilterCoefValue range: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 13, 15, 17, 19 Content: This parameter specifies the intra-frequency measurement L3 filter
coefficient. The greater this value is set, the greater the smoothing effect and the higher the anti-fast fading capability are, but the lower the signal change tracing capability is. The default value of this parameter is 3 Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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A non-active PCPICH becomes better than an active PCPICH. This
indicates that the quality or strength of a cell is close to the best cell.
In addition ,the number of cells in the active set has reached the
maximum value. The cell replaces the worst cell in the active set ;
thus achieving a higher combined gain
1C
RAN10.0 provides the solution to the issue of how to add an
HSUPA cell in a DCH active set to an E-DCH active set. Event 1J
is added to the 3GPP protocol. This event is triggered when a non-
active E-DCH but active DCH primary CPICH becomes better than
an active E-DCH primary CPICH.
1J
Event of the change of the best cell1D
The PCPICH quality or strength of the cells in the active set leaves
the reporting range. This indicates that a cell is much worse than
the quality of the best cell. The cell should not stay in the active set
1B
The PCPICH quality or strength of the cells in the monitored set
enters the reporting range . This indicates that the cell is close to
the best cell . A relative high combined gain can be achieved when
the cell is added to the active set
1A
DescriptionEvent
Intra-Frequency Handover Measurement Events
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Event 1A is triggered on the basis of the following formula
1A EVENT
Intra-Frequency Handover Measurement
)2/()1( 111
aaBest
N
iiNewNew HRMWMWCIOM
A
−−−+⎟⎟⎠
⎞⎜⎜⎝
⎛≥+ ∑
=
MNew is the measurement value of the cell in the reporting range.
CIONew is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.
W represents Weighted factor, used to weight the quality of the active set.
Mi is the measurement value of a cell in the active set.
NA is the number of cells not forbidden to affect the reporting range in the active set.
MBest is the measurement value of the best cell in the active set.
R1a is the reporting range or the relative threshold of soft handover. The threshold parameters of the CS non-VP service, VP service, and PS service are as follows:
CS non VP service 1A event relative THDVP service 1A event relative THDPS service 1A event relative threshold
H1a represents 1A hysteresis, the hysteresis value of event 1A.
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A: signal curve of the best cell in the active set
B: signal curve of a cell in the monitoring set
C: Th1A curve
1A EVENT
Intra-Frequency Handover Measurement
If the signal quality of a cell that is not in the active set is higher than Th1A for a period of time specified by 1A event trigger delay time (that is, Time to trigger in the figure), the UE reports event 1A
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Parameters of Intra-Frequency Handover
CS non VP service 1A event relative THD
Parameter ID: IntraRelThdFor1ACSNVP
The default value of this parameter is 6 ( 3dB )
VP service 1A event relative THD
Parameter ID: IntraRelThdFor1ACSVP
The default value of this parameter is 6 ( 3dB )
PS service 1A event relative threshold
Parameter ID: IntraRelThdFor1APS
The default value of this parameter is 6 ( 3dB )
CS non VP service 1A event relative THDParameter ID: IntraRelThdFor1ACSNVPValue range: 0~14.5; step: 0.5 Content: This parameter specifies the relative threshold of event 1A for the CS non-VP
service. The larger the parameter value is, the more easily event 1A is triggered.. The default value of this parameter is 6 (3dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .VP service 1A event relative THD
Parameter ID: IntraRelThdFor1ACSVPValue range: 0~14.5; step: 0.5 Content: This parameter specifies the relative threshold of event 1A for the VP service.
The larger the parameter value is, the more easily event 1A is triggered.. The default value of this parameter is 6 (3dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .PS service 1A event relative THD
Parameter ID: IntraRelThdFor1APSValue range: 0~14.5; step: 0.5 Content: This parameter specifies the PS service relative threshold of event 1A. The
smaller the parameter value is, the more easily event 1A is triggered. The default value of this parameter is 6 (3dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .
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Cell oriented Cell Individual Offset
Parameter ID: CIO
The default value of this parameter is 0 (0dB )
Neighboring cell oriented CIO
Parameter ID: CIOOffset
The default value of this parameter is 0 (0dB )
Parameters of Intra-Frequency Handover
Cell oriented Cell Individual Offset
Parameter ID: CIO
Value range: -10 to +10
Content: This parameter is used together with Neighboring cell oriented CIO. The sum of the two parameter values is added to the measurement quantity before the UE evaluates whether an event occurred. In handover algorithms, this parameter is used for moving the border of a cell.
The default value of this parameter is 0 ( 0dB )
Set this parameter through ADD CELLSETUP/MOD CELLSETUP
Neighboring cell oriented CIO
Parameter ID: CIOOffset
Value range: -10 to +10
Content: This parameter is used together with Cell oriented Cell Individual Offset. The sum of the two parameter values is added to the measurement quantity before the UE evaluates whether an event has occurred. In handover algorithms, this parameter is used for moving the border of 2 neighbors.
The default value of this parameter is 0 ( 0dB )
Set this parameter through ADD INTRAFREQNCELL/MOD INTRAFREQNCELL
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1A hysteresis
Parameter ID: Hystfor1A
The default value of this parameter is 0 (0dB )
1A event trigger delay time
Parameter ID: TrigTime1A
The default value of this parameter is D320 ( 320ms )
Weighted factor
Parameter ID: Weight
The default value of this parameter is 0
Parameters of Intra-Frequency Handover
1A hysteresisParameter ID: Hystfor1AValue range: 0~7.5; step: 0.5 Content: This parameter specifies the hysteresis value of event 1A. It is related to the
slow fading characteristic. The default value of this parameter is 0 (0dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .1A event trigger delay time
Parameter ID: TrigTime1A Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000
msContent: This parameter specifies the trigger delay time of event 1A. It is related to the
slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes. The recommended value of this parameter is D320 ( 320ms ) Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .Weighted factor
Parameter ID: WeightValue range: 0~20,step:0.1Content: This parameter is used to define the soft handover relative threshold based on
the measured value of each cell in the active set. The greater the parameter value, the higher the soft handover relative threshold. When this value is set to 0, the soft handover relative threshold is determined only by the best cell in the active set. . The Default Value of this parameter is 0Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO . 90
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Intra-Frequency Handover Measurement
Event Trigger Report
Event to Periodical Report
1A Event Report Mode:
The report mode of 1A is Event Trigger Report .
Generally the event 1A is reported only once. However, to avoid measurement report loss, the event 1A reporting can be turned to periodical reporting.
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1A event to periodical rpt period
Parameter ID: ReportIntervalfor1A
The default value of this parameter is D4000 (4000 ms )
1A event to periodical rpt number
Parameter ID: PeriodMRReportNumfor1A
The default value of this parameter is D16
Parameters of Intra-Frequency Handover
1A event to periodical rpt period
Parameter ID: ReportIntervalfor1A
Value range: NON_PERIODIC_REPORT, D250, D500, D1000, D2000, D4000, D8000, D16000
Content: The reporting period for the event 1A. Generally the event 1A isreported only once. However, to avoid measurement report loss, the event 1A reporting can be turned to periodical reporting.
The default value of this parameter is D4000 (4000 ms)
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1A event to periodical rpt number
Parameter ID: PeriodMRReportNumfor1A
Value range: D1, D2, D4, D8, D16, D32, D64, infinity
Content: The periodical reporting times for the event 1A. When the actualtimes exceed this parameter, the periodical reporting comes to an end.
The recommended value of this parameter is D16
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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Event 1B is triggered on the basis of the following formula
1B EVENT
),2/()1( 111
bbBest
N
iiOldOld HRMWMWCIOM
A
+−−+⎟⎟⎠
⎞⎜⎜⎝
⎛≤+ ∑
=
Intra-Frequency Handover Measurement
MOld is the measurement value of the cell that becomes worse.
CIOOld is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.
W represents Weighted factor, used to weight the quality of the active set.
Mi is the measurement value of the cell in the active set.
NA is the number of cells not forbidden to affect the reporting range in the active set. MBest is the measurement value of the best cell in the active set.
R1b is the reporting range or the relative threshold of soft handover. The threshold parameters of the CS non-VP service, VP service, and PS services are as follows:
CS non VP service 1B event relative THDVP service 1B event relative THDPS service 1B event relative threshold
H1b represents 1B hysteresis, the hysteresis value of event 1B.
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1B EVENT
A: signal curve of the best cell in the active set
B: signal curve of a cell in the monitoring set
C: Th1B curve
Intra-Frequency Handover Measurement
If the signal quality of a cell in the active set is lower than Th1B curve for a period of time specified by 1B event trigger delay time (Time to trigger in the figure), the UE reports event 1B
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Parameters of Intra-Frequency Handover
CS non VP service 1B event relative THD
Parameter ID: IntraRelThdFor1BCSNVP
The default value of this parameter is 12 ( 6dB )
VP service 1B event relative THD
Parameter ID: IntraRelThdFor1BCSVP
The default value of this parameter is 12 ( 6dB )
PS service 1B event relative threshold
Parameter ID: IntraRelThdFor1BPS
The default value of this parameter is 12 ( 6dB )
CS non VP service 1B event relative THDParameter ID: IntraRelThdFor1BCSNVPValue range: 0~14.5; step: 0.5 Content: This parameter specifies the relative threshold of event 1B for the CS non-
VP service. The smaller the parameter value is, the more easily event 1B is triggered .The default value of this parameter is 12 (6dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .
VP service 1B event relative THDParameter ID: IntraRelThdFor1BCSVPValue range: 0~14.5; step: 0.5 Content: This parameter specifies the relative threshold of event 1A for the VP
service. The smaller the parameter value is, the more easily event 1B is triggered .The default value of this parameter is 12 (6dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .
PS service 1A event relative THDParameter ID: IntraRelThdFor1APSValue range: 0~14.5; step: 0.5 Content: This parameter specifies the PS service relative threshold of event 1A. The
smaller the parameter value is, the more easily event 1B is triggered .The default value of this parameter is 12 (6dB)Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD
CELLINTRAFREQHO .
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1B hysteresis
Parameter ID: Hystfor1B
The default value of this parameter is 0 (0dB )
1B event trigger delay time
Parameter ID: TrigTime1B
The default value of this parameter is D640 ( 640ms )
Parameters of Intra-Frequency Handover
1B hysteresis
Parameter ID: Hystfor1B
Value range: 0~7.5; step: 0.5
Content: This parameter specifies the hysteresis value of event 1B. It is related to the slow fading characteristic.
The default value of this parameter is 0 (0dB)
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1B event trigger delay time
Parameter ID: TrigTime1B
Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640, 1280, 2560, 5000 ms
Content: This parameter specifies the trigger delay time of event 1B. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes.
The recommended value of this parameter is D640 ( 640ms )
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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Event 1C is triggered on the basis of the following formula
1C EVENT
,2/1cInASInASNewNew HCIOMCIOM ++≥+
Intra-Frequency Handover Measurement
MNew is the measurement value of the cell in the reporting range.
CIONew is the cell individual offset value of the cell in the reporting range. It is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO, which is the offset between the cell in the reporting range and the best cell in the active set.
MInAS is the measurement value of the worst cell in the active set.
CIOInAS is the cell individual offset value of the worst cell in the active set. It is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO.
H1c represents 1C hysteresis, the hysteresis value of event 1C.
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A: signal curve of the best cell in the active set
B: signal curve of a cell in the active set
C: signal curve of the worst cell in the active set
D: signal curve of a cell in the monitoring set
E: Th1C curve
1C EVENT
Intra-Frequency Handover Measurement
If the signal quality of a cell not in the active set is higher than Th1C for a period of time specified by 1C event trigger delay time (Time to trigger in the figure), the UE reports event 1C
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1C hysteresis
Parameter ID: Hystfor1C
The default value of this parameter is 8 (4dB )
1C event trigger delay time
Parameter ID: TrigTime1C
The default value of this parameter is D640 ( 640ms )
Parameters of Intra-Frequency Handover
1C hysteresisParameter ID: Hystfor1CValue range: 0~7.5; step: 0.5 Content: This parameter specifies the hysteresis value of event
1C. It is related to the slow fading characteristic. The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1C event trigger delay timeParameter ID: TrigTime1C Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320,
640, 1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of
event 1C. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes. The recommended value of this parameter is D640 ( 640ms ) Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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Intra-Frequency Handover Measurement
Event Trigger Report
Event to Periodical Report
1C Event Report Mode:
The report mode of 1C is Event Trigger Report .
Generally the event 1C is reported only once. However, to avoid measurement report loss, the event 1C reporting can be turned to periodical reporting.
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1C event to periodical rpt period
Parameter ID: ReportIntervalfor1C
The default value of this parameter is D4000 (4000 ms )
1C event to periodical rpt number
Parameter ID: PeriodMRReportNumfor1C
The default value of this parameter is D16
Parameters of Intra-Frequency Handover
1C event to periodical rpt period
Parameter ID: ReportIntervalfor1C
Value range: NON_PERIODIC_REPORT, D250, D500, D1000, D2000, D4000, D8000, D16000
Content: The reporting period for the event 1C. Generally the event 1C isreported only once. However, to avoid measurement report loss, the event 1C reporting can be turned to periodical reporting.
The default value of this parameter is D4000 (4000 ms)
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1C event to periodical rpt number
Parameter ID: PeriodMRReportNumfor1C
Value range: D1, D2, D4, D8, D16, D32, D64, infinity
Content: The periodical reporting times for the event 1C. When the actualtimes exceed this parameter, the periodical reporting comes to an end.
The recommended value of this parameter is D16
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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Event 1D is triggered on the basis of the following formula
1D EVENT
,2/10 1dBestNotbest HMM +≥
Intra-Frequency Handover Measurement
MNotBest is the measurement value of a cell that is not in the list of the best cells.
MBest is the measurement value of the best cell in the active set.
H1d represents 1D hysteresis, the hysteresis value of event 1D.
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1D Event
A: signal curve of the best cell in the active set
B: signal curve of a cell in the active set or monitoring set
C: Th1D curve
Intra-Frequency Handover Measurement
If the signal quality of a cell not in the active set is higher than Th1D for a period of time specified by 1D event trigger delay time (Time to trigger in the figure), the UE reports event 1D
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1D hysteresis
Parameter ID: Hystfor1D
The default value of this parameter is 8 (4dB )
1D event trigger delay time
Parameter ID: TrigTime1D
The default value of this parameter is D640 ( 640ms )
Parameters of Intra-Frequency Handover
1D hysteresisParameter ID: Hystfor1DValue range: 0~7.5; step: 0.5 Content: This parameter specifies the hysteresis value of event
1D. It is related to the slow fading characteristic. The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1D event trigger delay timeParameter ID: TrigTime1D Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320,
640, 1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of
event 1D. It is related to the slow fading characteristic. The greater the parameter value, the smaller the probability of misjudgment, but the slower the response of event reporting, triggered by measured signal changes. The recommended value of this parameter is D640 ( 640ms ) Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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Event 1J is triggered on the basis of the following formula
1J EVENT
Intra-Frequency Handover Measurement
,2/1JInASInASNewNew HCIOMCIOM ++≥+
Reporting event 1J: A non-active E-DCH but active DCH primary CPICH becomes better than an active E-DCH primary CPICH
MNew is the measurement result of the cell not included in the E-DCH active set but included in DCH active set.
CIONew is the individual cell offset for the cell not included in the E-DCH active set but included in DCH active set becoming better than the cell in the E-DCH active set if an individual cell offset is stored for that cell. Otherwise, it equals 0.
MInAS is the measurement result of the cell in the E-DCH active set with the lowest measurement result.
CIOInAS is the individual cell offset for the cell in the E-DCH active set that is becoming worse than the new cell.
H1J is the hysteresis parameter for event 1J.
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1J Event
Intra-Frequency Handover Measurement
A: signal quality curve of a cell in the E-DCH active setB: signal quality curve of the worst cell in the E-DCH active setC: signal quality curve of a cell not in the E-DCH active set but included in DCH active setD: signal quality curve of a cell not in the E-DCH active set but included in DCH active setIn the figure, the hysteresis and the cell individual offsets for all cells equal 0
The first measurement report is sent when primary CPICH D becomes better than primary CPICH B. The "cell measurement event result" of the measurement report contains the information of primary CPICH D and CPICH B.
On the assumption that the E-DCH active set has been updated after the first measurement report (E-DCH active set is now primary CPICH A and primary CPICH D), the second report is sent when primary CPICH C becomes better than primary CPICH A. The "cell measurement event result" of the second measurement report contains the information of primary CPICH C and primary CPICH A.
The parameters described in the following need to be set on the RNC LMT:
1J hysteresis
1J event trigger delay time
1J event to periodical rpt number
1J event to periodical rpt period
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Parameters of Intra-Frequency Handover
1J Event function
3GPP define the maximum DCH active set size is 6 and the maximumE-DCH active set size is 4
The DCH active set covers the E-DCH active set or they are the same
The best cell in E-DCH active set should be the same as that in DCH active set
Uplink channel type of UE is decided by the best cell in DCH active set
Uplink channel is E-DCH if the best cell in DCH active set supports HSUPA
Uplink channel is DCH if the best cell in DCH active set can NOT support HSUPA
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Parameters of Intra-Frequency Handover
Processing procedure for 1J Event
The UE reports 1J Event if it find a non-active E-DCH but active DCH cell PCICH becomes better than an active E-DCH PCIPCH
RNC will add the target cell into E-DCH active set if the E-DCH active set is NOT full
RNC will perform replace procedure if the E-DCH active set is full
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1J hysteresis
Parameter ID: Hystfor1J
The default value of this parameter is 8 (4dB )
1J event trigger delay time
Parameter ID: TrigTime1J
The default value of this parameter is D640 ( 640ms )
Max number of cell in edch active cell
Parameter ID: MAXEDCHCELLINACTIVESET
The default value of this parameter is 3
Parameters of Intra-Frequency Handover
1J hysteresis
Parameter ID: Hystfor1JValue range: 0~7.5; step: 0.5 Content: This parameter specifies the hysteresis value of event 1J. It
is related to the slow fading characteristic. The default value of this parameter is 8 (4dB)Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
1J event trigger delay timeParameter ID: TrigTime1J Value range: 0, 10, 20, 40, 60, 80, 100, 120, 160, 200, 240, 320, 640,
1280, 2560, 5000 msContent: This parameter specifies the trigger delay time of event 1D.
It is related to the slow fading characteristic. The recommended value of this parameter is D640 ( 640ms ) Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
Max number of cell in edch active cellParameter ID: MAXEDCHCELLINACTIVESETValue range: 1 to 4 Content: This parameter specifies the maximum number of cells in
the E-DCH active set. The recommended value of this parameter is 3 Set this parameter through SET HOCOMM .
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1A Event Report Mode:Event Trigger Report
Event to Periodical Report
Parameters1J event to periodical rpt period
Parameter ID: ReportIntervalfor1J
The default value of this parameter is D1000 (1000 ms )
1J event to periodical rpt number
Parameter ID: PeriodMRReportNumfor1J
The default value of this parameter is D64
Parameters of Intra-Frequency Handover
The report mode of 1J is Event Trigger Report .
Generally the event 1J is reported only once. However, to avoid measurement report loss, the event 1J reporting can be turned to periodical reporting.
1J event to periodical rpt period
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO
1J event to periodical rpt number
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO
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Contents1. Intra-Frequency Handover
1. Intra-Frequency Handover Overview
2. Intra-Frequency Handover Procedure
1. Intra-Frequency Handover Measurement
2. Intra-Frequency Handover Decision and Execution
3. Neighboring Cell Combination Algorithm
3. Signaling Procedures for Intra-Frequency Handover
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Intra-Frequency Handover Decision and Execution
RNC will make decision and execute handover depends on theEvents the RNC receives.
1A Event
1B Event
1C Event
1D Event
1J Event
When receiving an event 1C report, the RNC decides whether to change the worst cell.For event 1C, the UE reports a list that contains good cells and the cells to be replaced, and sequences the cells in descending order by measurement quantity.After receiving the list from the UE, the RNC replaces the bad cells in the active set with the good cells in the list.
1C
When receiving an event 1B report, the RNC determines whether todelete a cell.1B
When receiving an event 1A report, the RNC decides whether to add a cell.For event 1A, the UE can report more than one cell in the event list in one measurement report. These cells are in the list of the Measurement Control message, and they are sequenced in descending order by measurement quantity.For the cells in the list, the RNC adds the radio link to the active set only if the number of cells in the active set does not reach the maximum value.
1A
Decision and ExecutionEvent
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When receiving an event 1J report with information about the good cells and the cells to be replaced, the RNC proceeds as follows:•If the current number of cells in the E-DCH active set is less than the value of Max number of cell in edch active set, the uplink of the cell where event 1J is triggered is reconfigured to E-DCH.•If the current number of cells in the E-DCH active set is equal to the value of Max number of cell in edch active set, the RNC searches the measurement report for the non-serving Cell_EDCH with the lowest measured quality in the E-DCH active set. Then, the uplink of the cell where event 1J is triggered is reconfigured from DCH to E-DCH, and the uplink of CELL-EDCH is reconfigured from E-DCH to DCH.
1J
When receiving an event 1D report, which includes information about only one cell, the RNC learns that the quality of this cell is better than that of the serving cell and takes one of the following actions:•If the reported cell is in the active set, the RNC decides whether to change the best cell or reconfigure measurement control.•If the reported cell is in the monitored set,
•If the number of cells in the active set has not reached the maximum value, the RNC decides a soft handover and adds the cell to the active set.•If the number of cells in the active set has reached the maximumvalue, the RNC decides a soft handover and replaces the worst cell in the active set with the reported cell.
•The RNC determines whether the intra-frequency hard handover scenarios are applicable. For detailed information, see 3.1 Intra-Frequency Handover Types. If any scenario is applicable, the RNC performs an intra-frequency hard handover.
1D
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Max number of cell in active set
Parameter ID: MaxCellInActiveSet
The default value of this parameter is 3
Minimum Quality Threshold for SHO
Parameter ID: SHOQualmin
The default value of this parameter is -24 ( -24dB)
Parameters of Intra-Frequency Handover
When make decision, RNC must follow these restrictions
Max number of cell in active setParameter ID: MaxCellInActiveSetValue range: 1~6; Content: This parameter specifies the Max number of cell in
active set. The default value of this parameter is 3 Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
Minimum Quality Threshold for SHOParameter ID: SHOQualminValue range: -24~0,step:1dBContent: This parameter specifies the minimum quality
threshold for soft handover.. The recommended value of this parameter is -24 (-24dB) Set this parameter through SET INTRAFREQHO/ADD
CELLINTRAFREQHO/MOD CELLINTRAFREQHO .
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For R99 NRT services to increase the probability of a successful soft
handover, the rate reduction is triggered after a admission failure
Rate Reduction After an SHO Failure
1A,1C,1D is received by RNC
Execute admission control in target cell
Admission succeed?
Execute Handover
Rate Reduction
If the RNC receives a 1A, 1C, or 1D measurement report, the corresponding cell tries to admit the UE. If the cell fails to admit the UE, the RNC performs the estimation procedure for rate reduction.
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procedure for rate reduction
Estimation
Execution
Rate Reduction After an SHO Failure
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Estimation Procedure for Rate Reduction
117
The estimation procedure after the cell fails to admit the UE is described as follows:
Step 1 : The RNC evaluates whether the measurement quantity of the cell failing to be admitted meets the condition of rate reduction.
If the condition is met, the RNC performs a rate reduction process for the handover service immediately.
If the condition is not met, the RNC performs Step2.
The condition of rate reduction is as follows:
Mnew > Mbest_cell - RelThdForDwnGrd
where
Mnew is the CPICH Ec/No measurement value of the cell failing to be admitted.
Mbest_cell is the CPICH Ec/No measurement value of the best cell in the active set.
RelThdForDwnGrd is configured through the parameter Relative threshold of SHO failure.
Step 2 :The RNC evaluates whether the number of SHO failures in the cell exceeds the Threshold number of SHO failure.
If the number of SHO failures in the cell is smaller than the Threshold number of SHO failure, the RNC determines whether the SHO failure evaluation timer has been started:
If the timer has not been started, the RNC starts it.If the timer has been started, the RNC increments the SHO failure counter by one.Before the SHO failure evaluation timer expires, no action is taken and the RNC waits for the next measurement report period.
When the SHO failure evaluation timer expires, the RNC sets the SHO failure counter of the corresponding cell to 0 and ends the evaluation.
If the number of SHO failures in the cell is larger than or equal to the Threshold number of SHO failure, the RNC performs a rate reduction process for the access service and sets the SHO failure counter of the corresponding cell to 0.
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Relative threshold of SHO failure
Parameter ID: RelThdForDwnGrd
The default value of this parameter is 2 ( 1dB )
Max evaluation period of SHO failure
Parameter ID: ShoFailPeriod
The default value of this parameter is 60 ( 60s )
Threshold number of SHO failure
Parameter ID: ShoFailNumForDwnGrd
The default value of this parameter is 3
Parameters of Intra-Frequency Handover
Relative threshold of SHO failureParameter ID: RelThdForDwnGrdValue range: -29 to +29 ; step: 0.5 dBContent: This parameter specifies the relative threshold for direct rate reduction after an SHO
failure. If the difference between the signal quality of the target cell to which an SHO fails and that of the best cell is lower than this relative threshold, the RNC directly initiates a rate reduction process in the active set, regardless of the limitation on the number of SHO failures.The default value of this parameter is 2 (1dB)Set this parameter through SET INTRAFREQHO.
Max evaluation period of SHO failureParameter ID: ShoFailPeriodValue range: 0~120sContent: This parameter specifies the maximum evaluation period of SHO failures for rate
reduction. During the evaluation period, the RNC records the number of SHO failures in at most three cells for each UE. After the evaluation period, the RNC clears this record. The recommended value of this parameter is 60 ( 60s ) Set this parameter through SET INTRAFREQHO
Threshold number of SHO failureParameter ID: ShoFailNumForDwnGrdValue range: 0~63Content: This parameter specifies the threshold number of SHO failures for rate reduction. If the
number of SHO failures in a cell reaches or exceeds this threshold during the period specified by Max evaluation period of SHO failure, the RNC performs a rate reduction process in the active set. After the rate reduction succeeds, the RNC initiates an SHO in the cell. The recommended value of this parameter is 3 Set this parameter through SET INTRAFREQHO
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The rate reduction execution procedure is :
Step1:The RNC performs a rate reduction process for the access service.
Step2:After the rate reduction succeeds, the RNC immediately attempts to add this cell to the active set without measurement:
If the cell succeeds in admitting the UE, the RNC adds the radio link and sets the SHO failure counter of the cell to 0 and ends the execution.If the cell fails to admit the UE, the RNC starts the Period of penalty timer for SHO failure after down rate to avoid an increase in the rate triggered by DCCC within the period. Also in this period, the RNC sets the SHO failure counter of the cell to 0 and ends the execution.
If fails to perform a soft handover again, RNC performs the estimation procedure and the execution procedure, as previously described.
Execution Procedure of Rate Reduction
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Period of penalty timer for SHO failure after down rate
Parameter ID: DcccShoPenaltyTime
The default value of this parameter is 30 ( 30s )
Parameters of Rate Reduction Execution
Period of penalty timer for SHO failure after down rateParameter ID: DcccShoPenaltyTimeValue range: 0 to 255 ; step: 1 sContent: If an SHO fails again after the rate reduction, the RNC is forbidden to increase the rate
during the period specified by this parameter. The default value of this parameter is 30 ( 30s)Set this parameter through SET INTRAFREQHO.
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Contents1. Intra-Frequency Handover
1. Intra-Frequency handover Overview
2. Intra-Frequency Handover Procedure
1. Intra-Frequency Handover Measurement
2. Intra-Frequency Handover Decision and Execution
3. Neighboring Cell Combination Algorithm
3. Signaling Procedures for Intra-Frequency Handover
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Neighboring Cell Combination AlgorithmWhen the UE is in soft handover state
Intra-frequency neighboring cells
Inter-frequency neighboring cells
Inter-RAT neighboring cells
The combined neighboring cell list is affect by :
Repeat times
Serving cell signal quality (Ec/No) order
Neighboring cell priority
After obtaining the intra-frequency neighboring cells of each cell in the active set, the RNC calculates the union neighboring cell set of the intra-frequency cells, which is also referred as Sall, by using the following method. This method can also be used to generate the Sall of inter-frequency or inter-RAT cells.
1,The intra-frequency, inter-frequency and inter-RAT neighboring cells of each cell in the current active set are obtained.
2,The RNC sequences the cells in the active set in descending order of CPICH Ec/No according to the latest measurement report (event 1A, 1B, 1C, or 1D) from the UE. The best cell is based on event 1D, whereas other cells are based on the latest measurement report.
3,The cells in the active set are added to Sall.
4,The neighboring cells of the best cell in the active set are added to Sall. The priority of neighbor cell, which are set for each neighboring cell, are used to change the order of adding the neighboring cells to Sall.
5,The neighboring cells of other cells in the active set are added to Sall in descending order by CPICH Ec/No values of these cells in the active set. The neighboring cells of the same cell in the active set are added according to The priority of neighbor cell and repeated number of repeated neighboring cell is recorded.
6,If there are more than 32 neighboring cells in Sall, delete the neighboring cells whose repeat number in Sall is less. The top 32 neighboring cells are grouped into the final Sall.
If The flag of the priority is switched to FALSE, The priority of neighbor cell is cleared.
If The flag of the priority is switched to TRUE, The priority of neighbor cell is set simultaneously.
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Parameters of Neighboring Cell Combination Algorithm
Neighboring Cell Combination Switch
Parameter ID: NCELL_COMBINE_SWITCH
The default value of this parameter is OFF
The flag of the priority
Parameter ID: NPrioFlag
The default value of this parameter is FALSE
The priority of neighbor cell
Parameter ID: NPrio
The default value of this parameter is None
The NCELL_COMBINE_SWITCH of Handover Algorithm Switch parameter decides the measurement range of neighboring cells
If the switch is set to ON, measurement objects are chosen from the neighboring cells of all the cells in the active set.
If the switch is set to OFF, measurement objects are chosen from the neighboring cells of the best cell.
But, limited by the 3GPP, the maximum number of neighboring cells is 32. So if the NCELL_COMBINE_SWITCH is ON, it very possible that the neighboring cell of all the cells in the active set may exceed 32.
By the Neighboring Cell Combination Algorithm , RNC will choose 32 neighboring cell for measurement.
Neighboring Cell Combination SwitchParameter ID: NCELL_COMBINE_SWITCHValue range: OFF, ONContent: If the switch is set to ON, measurement objects are chosen from the neighboring cells of all the cells in the active set.If the switch is set to OFF, measurement objects are chosen from the neighboring cells of the best cell.The default value of this parameter is OFFSet this parameter through SET CORRMALGOSWITCH
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The flag of the priorityParameter ID: NPrioFlagValue range: FALSE, TRUE Content:
FALSE: The priority of the neighboring cell is invalid. The neighboring cells whose priority flag is FALSE are the last ones to be considered as the measurement objects in the neighboring cell combination algorithm.TRUE: The priority of the neighboring cell is valid in the neighboring cell combination algorithm. .
The default value of this parameter is FALSE Set this parameter through ADD INTRAFREQNCELL/MOD INTRAFREQNCELL / ADD INTERFREQNCELL/MOD INTERFREQNCELL / ADD GSMNCELL/MOD GSMNCELL
The priority of neighbor cellParameter ID: NPrioValue range: 0 to 30 The default value of this parameter is NoneContent:
When The flag of the priority is TRUE, The priority of neighbor cell specifies the priority of neighboring cells. The smaller the parameter value is, the higher the priority is and the more easily the neighboring cell is chosen as a measurement object in the neighboring cell combination algorithm. For example, the neighboring cells with priority 1 are more easily chosen as the measurement objects than the cells with priority 2 in the neighboring cell combination algorithm.
Set this parameter through ADD INTRAFREQNCELL/MOD INTRAFREQNCELL / ADD INTERFREQNCELL/MOD INTERFREQNCELL / ADD GSMNCELL/MOD GSMNCELL
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Contents1. Intra-Frequency Handover
1. Intra-Frequency Handover Overview
2. Intra-Frequency Handover Procedure
3. Signaling Procedures for Intra-Frequency Handover
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There are five types of signaling procedures for intra-frequency handover:
• Intra-NodeB Intra-Frequency Soft Handover
• Intra-RNC Inter-NodeB Intra-Frequency Soft Handover
• Inter-RNC Intra-Frequency Soft Handover
• Intra-RNC Inter-NodeB Intra-Frequency Hard Handover
• Inter-RNC Intra-Frequency Hard Handover
Signaling Procedures for Intra-Frequency Handover
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Intra-NodeB Intra-Frequency Soft Handover
Signaling Procedures for Intra-Frequency Handover
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Intra-RNC Inter-NodeB Intra-Frequency Soft Handover
Signaling Procedures for Intra-Frequency Handover
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Inter-RNC Intra-Frequency Soft Handover
Signaling Procedures for Intra-Frequency Handover
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Intra-RNC Inter-NodeB Intra-Frequency Hard Handover
Signaling Procedures for Intra-Frequency Handover
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Contents1. Intra-Frequency Handover
2. Inter-Frequency Handover
3. Inter-RAT Handover
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Contents2. Inter-Frequency Handover
Inter-Frequency Handover Overview
Inter-Frequency Handover Procedure
Signaling Procedures for Inter-Frequency Handover
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Inter-Frequency Overview
Characters of Inter-Frequency Handover:
The carrier frequency of the current cell and target cell are different
Based on the triggering causes of handover, inter-frequency handover
can be categorized into four types .
Coverage-based
QoS-based
Load-based
Speed-based
Coverage-based inter-frequency handover
If a moving UE leaves the coverage of the current frequency, the RNC needs to trigger the coverage-based inter-frequency handover to avoid call drops
QoS-based inter-frequency handover
According to the Link Stability Control Algorithm, the RNC needs to trigger the QoS-based inter-frequency handover to avoid call drops.
Load-based inter-frequency blind handover
To balance the load between inter-frequency con-coverage cells, the RNC chooses some UEs and performs the inter-frequency blind handover according to user priorities and service priorities.
Speed-based inter-frequency handover
When the Hierarchical Cell Structure (HCS) applies, the cells are divided into different layers according to coverage. The macro cell has a larger coverage and a lower priority, whereas the micro cell has a smaller coverage and a higher priority. Inter-frequency handover can be triggered by the UE speed estimation algorithm of the HCS. To reduce the frequencies of handover, the UE at a higher speed is handed over to a cell under a larger coverage, whereas the UE at a lower speed is handed over to a cell under a smaller coverage.
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
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The handover procedure is divided into four phases: handover triggering, handover measurement, handover decision, and handover execution.
In the triggering phase
The RNC notifies the UE to measure through an inter-frequency measurement control message. If the quality of the pilot signal in the current cell deteriorates, the CPICH Ec/No or CPICH RSCP of the UMTS cell that the UE accesses is lower than the corresponding threshold, and the UE reports event 2D.
In the measurement phase
If the RNC receives a report of event 2D, the RNC requests the NodeB and UE to start the compressed mode to measure the qualities of inter-frequency neighboring cells, and the RNC sends an inter-frequency measurement control message.
In the measurement phase, the method of either periodical measurement report or event-triggered measurement report can be used.
In the decision phase
After the UE reports event 2B, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, and the RNC makes a decision after evaluation.
In the execution phase
The RNC executes the handover procedure.
Procedure of Coverage-based inter-frequency handover
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The estimated quality or strength of the currently used frequency is above a
certain threshold.
2F
The estimated quality or strength of the currently used frequency is below a
certain threshold.
2D
DescriptionDescriptionEventEvent
MEASUREMENT EVENTS
Coverage-based inter-frequency handover
When the estimated quality or strength of the currently used frequency is below a certain threshold,2D Event will be triggered, Then RNC will initiate the compress Mode to start inter-frequency or inter-RAT handover measurement.
During compress mode, if the the estimated quality of the currently used frequency is above a certain
threshold, 2F Event will be triggered, Then RNC will stop the compress Mode.
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Compressed ModePurpose
Measure the inter-frequency cell or Inter-RAT cell under FDD mode
Categories
Downlink compressed mode
Uplink compressed mode
Realization Methods
SF/2
Higher layer scheduling
Coverage-based inter-frequency handover
Compressed Mode control is a mechanism whereby certain idle periods are created in radio frames during which the UE can perform measurements on other frequencies. The UE can carry out measurements in the neighbouring cell, such as GSM cell and FDD cell on other frequency. If the UE needs to measure the pilot signal strength of an inter-frequency WCDMA or GSM cell and has one frequency receiver only, the UE must use the compressed mode.
Each physical frame can provide 3 to 7 timeslots for the inter-frequency or inter-RAT cell measurement, which enhances the transmit capability of physical channels but reduces the volume of data traffic.
In DL, during compressed mode ,UE receiver can test signal from other frequency. In order to avoid the effect cause by UE transmitter, compress mode is also used in UL.
The compressed mode includes two types, spreading factor reduction (SF/2) and high layer approaches. The usage of type of compressed mode is decided by the RNC, according to spreading factor used in uplink or downlink.
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Event 2D is triggered on the basis of the following formula
2D EVENT
Coverage-based inter-frequency handover
QUsed <= TUsed2d - H2d/2
QUsed is the measured quality of the used frequency.
TUsed2d is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service, or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through one of the following parameters:
Inter-freq CS measure start Ec/No THDInter-freq R99 PS measure start Ec/No THDInter-freq H measure start Ec/No THDInter-freq CS measure start RSCP THDInter-freq R99 PS measure start RSCP THDInter-freq H measure start RSCP THD
H2d is the event 2D hysteresis value 2D hysteresis.
After the conditions of event 2D are fulfilled and maintained until the parameter 2D event trigger delay time is reached, the UE reports the event 2D measurement report message.
Note:
Any of the Ec/No and RSCP measurement result can trigger the 2D event.
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Parameters of inter-frequency handover
Inter-freq CS measure start Ec/No THD
Parameter ID: InterFreqCSThd2DEcNo
The default value of this parameter is -14dB
Inter-freq R99 PS measure start Ec/No THD
Parameter ID : InterFreqR99PsThd2DEcNo
The default value of this parameter is -14dB
Inter-freq H measure start Ec/No THD
Parameter ID : InterFreqHThd2DEcN0
The default value of this parameter is -14dB
Inter-freq CS measure start Ec/No THD
Parameter ID: InterFreqCSThd2DEcNo
Value range: –24 to 0 ,step :1dB.
The default value of this parameter is -14dB
Content: If the CS service uses Ec/No as a measurement quantity, the UE reports event 2D when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV .
Inter-freq R99 PS measure start Ec/No THD
Parameter ID : InterFreqR99PsThd2DEcNo
Value range: –24 to 0 ,step :1dB.The default value of this parameter is -14dB Content: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE reports event 2D
when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement. Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET
INTERFREQHOCOV
Inter-freq H measure start Ec/No THD
Parameter ID : InterFreqHThd2DEcN0
Value range: –24 to 0 ,step :1dB.The default value of this parameter is -14dB Content: For PS domain HSPA services, when Ec/No is used as the measurement quantity for inter-
frequency measurement, the RNC sends the signaling to activate compressed mode and start inter-frequency measurement, if the UE reports the event 2D when the measured value is smaller than the value of this parameter. Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET
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Parameters of inter-frequency handover
Inter-freq CS measure start RSCP THD
Parameter ID: InterFreqCSThd2DEcNo
The default value of this parameter is -95dBm
Inter-freq R99 PS measure start RSCP THD
Parameter ID : InterFreqCSThd2DRSCP
The default value of this parameter is -95dBm
Inter-freq H measure start RSCP THD
Parameter ID : InterFreqHThd2DRSCP
The default value of this parameter is -95dBm
Inter-freq CS measure start RSCP THDParameter ID: InterFreqCSThd2DEcNo Value range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -95dBmContent: If the CS service uses RSCP as a measurement quantity, the UE reports event 2D
when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement.. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV .Inter-freq R99 PS measure start RSCP THD
Parameter ID : InterFreqR99PsThd2DEcNoValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -95dBmContent: If the PS domain R99 service uses RSCP as a measurement quantity, the UE
reports event 2D when the measurement value is lower than the threshold. The RNC sends a message to enable the compressed mode and to start the inter-frequency measurement. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-freq H measure start RSCP THD
Parameter ID : InterFreqHThd2DRSCPValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -95dBmContent: For PS domain HSPA services, when RSCP is used as the measurement quantity
for inter-frequency measurement, the RNC sends the signaling to activate compressed mode and start inter-frequency measurement, if the UE reports the event 2D when the measured value is smaller than the value of this parameter . Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Parameters of inter-frequency handover
2D hysteresis
Parameter ID: Hystfor2D
The default value of this parameter is 4 (2dB)
2D event trigger delay time
Parameter ID : TimeToTrig2D
The default value of this parameter is D320 (320 ms)
2D hysteresis
Parameter ID: Hystfor2D
Value range: 0 to 29 step :0.5dB.
The default value of this parameter is 4 (2dB)
Content: This parameter specifies the event 2D trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV .
2D event trigger delay time
Parameter ID : TimeToTrig2D
Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000 The default value of this parameter is D320 (320 ms)
Content: This parameter specifies the time of event 2D trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Coverage-based inter-frequency handover
2F EVENT
Event 2F is triggered on the basis of the following formula
QUsed >= TUsed2d - H2d/2
QUsed is the measured quality of the used frequency.
TUsed2f is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:
Inter-freq CS measure stop Ec/No THDInter-freq R99 PS measure stop Ec/No THDInter-freq H measure stop Ec/No THDInter-freq CS measure stop RSCP THDInter-freq R99 PS measure stop RSCP THDInter-freq H measure stop RSCP THD
H2f is the event 2F hysteresis value 2F hysteresis.
After the conditions of event 2F are fulfilled and maintained until the parameter 2F event trigger delay time is reached, the UE reports the event 2F measurement report message.
Note:
Any of Ec/No and RSCP measurement result can trigger the 2F event.
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Parameters of inter-frequency handover
Inter-freq CS measure stop Ec/No THD
Parameter ID: InterFreqCSThd2FEcNo
The default value of this parameter is -12dB
Inter-freq R99 PS measure stop Ec/No THD
Parameter ID : InterFreqR99PsThd2FEcNo
The default value of this parameter is -12dB
Inter-freq H measure stop Ec/No THD
Parameter ID : InterFreqHThd2FEcN0
The default value of this parameter is -12dB
Inter-freq CS measure stop Ec/No THD
Parameter ID: InterFreqCSThd2FEcNoValue range: –24 to 0 ,step :1dB.The default value of this parameter is -12dBContent: If the CS service uses Ec/No as a measurement quantity, the UE reports event 2F
when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-freq R99 PS measure stop Ec/No THD
Parameter ID : InterFreqR99PsThd2FEcNo
Value range: –24 to 0 ,step :1dB.The default value of this parameter is -12dB
Content: If the PS domain R99 service uses Ec/No as a measurement quantity, the UE reports event 2F when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement.Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-freq H measure stop Ec/No THD
Parameter ID : InterFreqHThd2FEcN0
Value range: –24 to 0 ,step :1dB.The default value of this parameter is -12dB
Content: For PS domain HSPA services, when Ec/No is used as the measurement quantity for inter-frequency measurement, the RNC sends the signaling to deactivate compressed mode and stop inter-frequency measurement, if the UE reports the event 2F when the measured value is larger than the value of this parameter .Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV144
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Parameters of inter-frequency handover
Inter-freq CS measure stop RSCP THD
Parameter ID: InterFreqCSThd2FRSCP
The default value of this parameter is -92 dBm
Inter-freq R99 PS measure stop RSCP THD
Parameter ID : InterFreqR99PsThd2FRSCP
The default value of this parameter is -92dBm
Inter-freq H measure stop RSCP THD
Parameter ID : InterFreqHThd2FRSCP
The default value of this parameter is -92dBm
Inter-freq CS measure stop RSCP THDParameter ID: InterFreqCSThd2FRSCPValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -92 dBmContent: If the CS service uses RSCP as a measurement quantity, the UE reports event 2F
when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV .Inter-freq R99 PS measure stop RSCP THD
Parameter ID : InterFreqR99PsThd2FRSCP Value range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -92dBmContent: If the PS domain R99 service uses RSCP as a measurement quantity, the UE
reports event 2F when the measurement value is higher than the threshold. The RNC sends a message to disable the compressed mode and to stop the inter-frequency measurement. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-freq H measure stop RSCP THD
Parameter ID : InterFreqHThd2FRSCPValue range: –115 to -25 dBm ,step :1dB.The default value of this parameter is -92dBmContent: For PS domain HSPA services, when RSCP is used as the measurement quantity
for inter-frequency measurement, the RNC sends the signaling to deactivate compressed mode and stop inter-frequency measurement, if the UE reports the event 2F when the measured value is larger than the value of this parameter . Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Parameters of inter-frequency handover
2F hysteresis
Parameter ID: Hystfor2F
The default value of this parameter is 4 (2dB)
2F event trigger delay time
Parameter ID : TimeToTrig2D
The default value of this parameter is D1280 (1280 ms)
2F hysteresis
Parameter ID: Hystfor2F
Value range: 0 to 29 step :0.5dB.
The default value of this parameter is 4 (2dB)
Content: This parameter specifies the event 2F trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
2F event trigger delay time
Parameter ID : TimeToTrig2D
Value range: D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000
The default value of this parameter is D1280 (1280 ms)
Content: This parameter specifies the time of event 2F trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOV146
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Handover Measurement
Coverage-based inter-frequency handover
UE RNC
Measurement report
Physical Channel Recfg (CM)
Measurement control (RSCP)
2D
Physical Channel Recfg Complet(CM)
Measurement control (Ec/No)
When the UE enters the compress mode, RNC will trigger the inter-frequency handover measurement by two additional measurement control signaling , so as to request UE test inter-frequency neighbor cell.
In this Measurement control message, RNC should inform the UE inter-frequency measurement parameter (Neighbor list, reporting mode…)
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Coverage-based inter-frequency handover
Handover Measurement
Report Mode
UE RNC
Measurement control (Periodical, RSCP&Ec/No)
Measurement report
Handover
Measurement report
Measurement report
UE RNC
Measurement control (Event triggering, RSCP)
Handover
Measurement report (2B RSCP or Ec/No)
Periodical_reporting Event_trigger
Measurement control (Event triggering ,Ec/No)
The measurement report mode of inter-frequency handover is configured through the parameter Inter-frequency measure report mode. By default ,periodically reporting is recommended.
The advantage of periodical measurement report is that if the handover fails, the RNC reattempts the handover to the same cell after receiving the periodical measurement report from the UE. This increases the probability of the success of inter-frequency handover.
Based on the measurement control message received from the RNC, the UE periodically reports the measurement quality of the target cell. Then, based on the measurement report, the RNC makes the handover decision and performs handover.
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Parameters of inter-frequency handover
Inter-frequency measure report mode
Parameter ID: InterFreqReportMode
The default value of this parameter is Periodical reporting
Inter-frequency measure periodical rpt period
Parameter ID: PeriodReportInterval
The default value of this parameter is D500 (500 ms)
Inter-freq measure timer length
Parameter ID: InterFreqMeasTime
The default value of this parameter is 60 (60 s)
Inter-frequency measure report modeParameter ID: InterFreqReportModeValue range :Periodical reporting, Event trigger The default value of this parameter is Periodical reportingContent: This parameter specifies the inter-frequency measurement report mode. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-frequency measure periodical rpt period
Parameter ID: PeriodReportIntervalValue range : NON_PERIODIC_REPORT, 250, 500, 1000, 2000, 3000, 4000, 6000, 8000,
12000, 16000, 20000, 24000, 28000, 32000, 64000The default value of this parameter is D500 (500ms)Content: This parameter specifies the interval of the inter-frequency measurement report. Set this parameter through ADD CELLINTERFREQHOCOV/MOD
CELLINTERFREQHOCOV/SET INTERFREQHOCOVInter-freq measure timer length
Parameter ID: PeriodReportIntervalValue range : 0 to 512 ,step 1sThe default value of this parameter is 60 ( 60s)Content: This parameter specifies the inter-frequency measurement timer length of the inter-
frequency handover based on coverage or speed. This parameter has no effect on the inter-frequency measurement based on QoS.
If no such type of inter-frequency handover occurs upon expiry of the inter-frequency measurement timer, the system stops the inter-frequency measurement and disables the compressed mode. If this parameter is set to 0, the RNC does not start the inter-frequency
measurement timer. .Set this parameter for handover based on coverage through ADD
CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Coverage-based inter-frequency handover
Handover Measurement
Event 2B is triggered on the basis of the following formula
QNoused >= TNoused2b + H2b/2
QUsed <= TUsed2b - H2b/2
QNoused is the measured quality of the cell that uses the other frequencies.
TNoused2b is the absolute quality threshold of the cell that uses the other frequencies. Based on the service type (CS , PS domain) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:
Inter-freq CS target frequency trigger Ec/No THDInter-freq R99 PS target frequency trigger Ec/No THD
Inter-freq CS target frequency trigger RSCP THDInter-freq R99 PS target frequency trigger RSCP THD
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QUsed is the measured quality of the cell that uses the current frequency.
TUsed2b is the absolute quality threshold of the cell that uses the current frequency.
Based on the service type (CS service, PS domain service) and the measurement quantity (CPICH Ec/No or RSCP) in the coverage-based handover, TUsed2b can be configured through the following parameters.
If the event 2D with the CPICH RSCP value is received by the RNC,
TUsed2b of event 2B with the CPICH RSCP value can be:Inter-freq CS Used frequency trigger RSCP THDInter-freq R99 PS Used frequency trigger RSCP THD
TUsed2b of event 2B with the CPICH Ec/No value is configured as the maximum value 0 dB according to 3GPP specification.
If the event 2D with the CPICH Ec/No value is received by the RNC,
TUsed2b of event 2B with the CPICH Ec/No value can be:Inter-freq CS Used frequency trigger Ec/No THDInter-freq R99 PS Used frequency trigger Ec/No THD
TUsed2b of event 2B with the CPICH RSCP value is configured as the maximum value -25 dB according to 3GPP specification.
H2b is the event 2B hysteresis value 2B hysteresis.
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Parameters of inter-frequency Handover
Inter-freq CS target frequency trigger Ec/No THD
Parameter ID: TargetFreqCsThdEcN0
The default value of this parameter is –12 dB
Inter-freq CS Used frequency trigger Ec/No THD
Parameter ID: UsedFreqCSThdEcN0
The default value of this parameter is –12 dB
Inter-freq CS target frequency trigger Ec/No THD
Parameter ID: TargetFreqCsThdEcN0
Value range :–24 to 0, step 1dB
The default value of this parameter is –12 dB
Content: If the CS service inter-frequency handover uses the event-triggered measurement report mode, event 2B may be triggered when the Ec/No value of the target frequency is higher than the threshold. In periodical measurement report mode, this parameter is used for handover evaluation on the RNC side.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
Inter-freq CS Used frequency trigger Ec/No THD
Parameter ID: UsedFreqCSThdEcN0
Value range :–24 to 0, step 1dB
The default value of this parameter is –12 dB
Content: If the CS service inter-frequency handover uses the event-triggered measurement report mode, event 2B may be triggered when the Ec/No value of the used frequency is lower than the threshold.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
Event 2B is triggered only when the two necessary conditions are met at the same time.
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Parameters of inter-frequency handover
2B Event default setting
-12dB-12dBCS Ec/No threshold
Used cellTarget cell
-92dBm-92dBmPS RSCP threshold
-92dBm-92dBmCS RSCP threshold
-12dB-12dBPS Ec/No threshold
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Parameters of inter-frequency handover
2B hysteresis
Parameter ID: Hystfor2B
The default value of this parameter is 4 (2dB)
2B event trigger delay time
Parameter ID: TimeToTrig2B
The default value of this parameter is D0 (0ms)
2B hysteresis
Parameter ID: Hystfor2B
Value range :0 to 29 , step 0.5dB
The default value of this parameter is 4 (2dB)
Content: This parameter specifies the event 2B trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
2B event trigger delay time
Parameter ID: TimeToTrig2B
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000
The default value of this parameter is D0 (0ms)
Content: This parameter specifies the time of event 2B trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed.
Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
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Coverage-based inter-frequency handover
Periodical Measurement Report Mode
Event-Triggered Measurement Report Mode
Handover Decision and Execution
The coverage-based handover decision is categorized into two types according to the following two measurement report modes: periodical measurement report mode and event-triggered measurement report mode. Each mode corresponds to a different decision and execution procedure.
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Coverage-based inter-frequency handoverHandover Decision and Execution
Event-Triggered Measurement Report Mode
Based on the event 2B measurement reports of CPICH RSCP and event 2B CPICH Ec/No of the inter-frequency cell
RNC process the report by following procedure:Add all the pilot cells that trigger event 2B to a cell set and arrange the cells according to the measurement quality of CPICH_Ec/No in descending order.Select the cells in turn from the cell set to perform inter-frequency handover.
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Coverage-based inter-frequency handoverHandover Decision and Execution
Periodical Measurement Report Mode
Mother_Freq + CIOother_Freq ≥ Tother_Freq + H/2
Both the CPICH Ec/No value and CPICH RSCP value of the pilot signal of the target cell must meet the requirement
NOTE: No consideration of the current cell
Mother_Freq is the CPICH Ec/No or CPICH RSCP measurement value of the target cell reported by the UE. Both of the two measurement values of the inter-frequency cell must satisfy the formula.CIOother_Freq is the cell individual offset value of the target cell. It is equal to the sum of Cell oriented Cell Individual Offset and Neigbhoring cell oriented CIO.Tother_Freq is the decision threshold of inter-frequency hard handover.
Based on the service type (CS or PS service) and measurement quantity (CPICH Ec/No or CPICH RSCP), this threshold can be configured through the following parameters:
Inter-freq CS target frequency trigger Ec/No THDInter-freq R99 PS target frequency trigger Ec/No THDInter-freq H target frequency trigger Ec/No THDInter-freq CS target frequency trigger RSCP THDInter-freq R99 PS target frequency trigger RSCP THDInter-freq H target frequency trigger RSCP THD
NOTE:
These thresholds are the same as the quality threshold of event 2B.
H is the inter-frequency hard handover hysteresis value HHO hysteresis.
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Coverage-based inter-frequency handoverHandover Decision and Execution
Periodical Measurement Report Mode
Decide whether both the CPICH Ec/No value and CPICH RSCP value of the pilot signal of the target cell meet the requirement of inter-frequency handover. Start the hard handover time-to-trigger timer, which is configured through the parameter HHO period trigger delay time. Select the cells in sequence, that is, from high quality cells to low quality ones, to initiate inter-frequency handover in the cells where the hard handover time-to-trigger timer expires.
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Parameters of inter-frequency handover
Cell oriented Cell Individual Offset
Parameter ID: CIO
The default value of this parameter is 0 (0dB)
Neigbhoring cell oriented CIO
Parameter ID: CIOOffset
The default value of this parameter is 0 (0dB)
HHO hysteresis
Parameter ID: HystForPrdInterFreq
The default value of this parameter is 0 (0dB)
Cell oriented Cell Individual Offset
Parameter ID: CIO
Value range: -10 to +10
Content: This parameter is used together with Neighboring cell oriented CIO. The sum of the two parameter values is added to the measurement quantity before the UE evaluates whether an event occurred. In handover algorithms, this parameter is used for moving the border of a cell.
The default value of this parameter is 0 ( 0dB )
Set this parameter through ADD CELLSETUP/MOD CELLSETUP
Neigbhoring cell oriented CIOParameter ID: CIOOffsetValue range :–20 to +20 , step:0.5dBThe default value of this parameter is 0 (0dB)Content: The sum of the value of this parameter and the Cell oriented Cell Individual Offset specifies
the offset of the cell CPICH measurement value. In handover algorithms, this parameter is used for moving the border of a cell. Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET
INTERFREQHOCOV
HHO hysteresisParameter ID: HystForPrdInterFreqValue range 0 to 29 , step:0.5dBThe default value of this parameter is 0 (0dB)Content: This parameter is used to evaluate the inter-frequency handover on the RNC side. The greater
the value of the parameter, the smaller the probability of the ping-pong effect and misjudgment. In this case, however, the speed of response to handover is lower. Set this parameter through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET
INTERFREQHOCOV
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
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The handover procedure is divided into four phases: handover triggering, handover measurement, handover decision, and handover execution.
Besides the triggering step, the rest 3 steps are the same with Coverage-based inter-frequency handoverIn the triggering phase
If the service quality of the current cell deteriorates, the Link Stability Control Algorithm makes a handover measurement decision.In the measurement phase
The RNC requests the NodeB and the UE to start the compressed mode to measure the qualities of inter-frequency neighboring cells. Then, the RNC sends inter-frequency measurement control messages.
In the measurement phase, the method of periodical measurement report or event-triggered measurement report can be used.In the decision phase
After receiving the event 2B measurement reports of CPICH RSCP and CPICH Ec/No of the inter-frequency cell, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, and the RNC makes a decision after evaluation.In the execution phase
The RNC executes the handover procedure.
Note : About “Link Stability Control Algorithm” :When the uplink transmit power of the UE or downlink transmitted code power of the NodeB exceeds the
associated threshold :For AMR, a fixed sequence of rate downsizing, inter-frequency handover, and then inter-RAT handover are performed,for VP ,Inter-handover handover are performed,For BE service, rate downsizing, inter-frequency handover, and then inter-RAT handover are performed according to the configured sequence
Procedure of QoS-based inter-frequency handover :
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Parameters of inter-frequency handover
InterFreq Handover Switch based on Uplink Traffic AMR
Parameter ID: UlQoSAmrInterFreqHoSwitch
The default value of this parameter is NO
InterFreq Handover Switch based on Downlink Traffic AMR
Parameter ID: DlQoSAmrInterFreqHoSwitch
The default value of this parameter is NO
InterFreq Handover Switch based on Uplink/Downlink Traffic AMR
Parameter ID : UlQoSAmrInterFreqHoSwitch/ DlQoSAmrInterFreqHoSwitch
Value range NO, YES
The default value of this parameter is NO
Content: If the value of this parameter is YES, inter-frequency handover can be executed on the basis of the downlink/uplink QoS of AMR services.
Set this parameter through SET QOSACT
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Parameters of inter-frequency handover
InterFreq Handover Switch based on Uplink Traffic VP
Parameter ID: UlQoSVPInterFreqHoSwitch
The default value of this parameter is NO
InterFreq Handover Switch based on Downlink Traffic VP
Parameter ID: DlQoSVPInterFreqHoSwitch
The default value of this parameter is NO
InterFreq Handover Switch based on Uplink/Downlink Traffic VP
Parameter ID : UlQoSVPInterFreqHoSwitch/ DlQoSVPInterFreqHoSwitch
Value range NO, YES
The default value of this parameter is NO
Content: If the value of this parameter is YES, inter-frequency handover can be executed on the basis of the downlink/uplink QoS of VP services.
Set this parameter through SET QOSACT
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Parameters of inter-frequency handover
First / Second / Third Uplink QOS Enhancement Action for Traffic BE
Parameter ID: BeUlAct1/ BeUlAct2/ BeUlAct3
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
First / Second / Third Downlink QOS Enhancement Action for Traffic BE
Parameter ID: BeDlAct1/ BeDlAct2/ BeDlAct3
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
First / Second / Third Uplink QOS Enhancement Action for Traffic BE
Parameter ID : BeUlAct1/ BeUlAct2/ BeUlAct3
Value range None, RateDegrade, InterFreqHO, InterRatHO
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
Content: This parameter defines the action sequence to enhance the Uplink QoS of BE services .
Set this parameter through SET QOSACT
First / Second / Third Downlink QOS Enhancement Action for Traffic BE
Parameter ID : BeDlAct1/ BeDlAct2/ BeDlAct3
Value range None, RateDegrade, InterFreqHO, InterRatHO
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
Content: This parameter defines the action sequence to enhance the downlink QoS of BE services .
Set this parameter through SET QOSACT
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Parameters of inter-frequency handover
Down Link QoS Measure timer length
Parameter ID: DLQoSMcTimerLen
The default value of this parameter is 20 (20s)
Up Link QoS Measure timer length
Parameter ID: UpQoSMcTimerLen
The default value of this parameter is 20 (20s)
Down Link QoS Measure timer length
Parameter ID : DLQoSMcTimerLen
Value range 0 to 512 ,step 1s
The default value of this parameter is 20 (20s)
Content: This parameter specifies the inter-frequency measurement timer length of the inter-frequency handover based on downlink QoS. This parameter has no effect on the inter-frequency measurement based on coverage.
If no QoS-based inter-frequency handover occurs upon expiry of the downlink inter-frequency measurement timer, the RNC stops the QoS-based inter-frequency measurement.If this parameter is set to 0, the RNC does not start the inter-frequency
QoS-based measurement timer. Set this parameter through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
Down Link QoS Measure timer length
Parameter ID : UpQoSMcTimerLen
Value range 0 to 512 ,step 1s
The default value of this parameter is 20 (20s)
Content: This parameter specifies the inter-frequency measurement timer length of the inter-frequency handover based on uplink QoS. This parameter has no effect on the inter-frequency measurement based on coverage.
If no QoS-based inter-frequency handover occurs upon expiry of the uplink inter-frequency measurement timer, the RNC stops the inter-frequency measurement and disables the compressed mode.If this parameter is set to 0, the RNC does not start the inter-frequency
QoS-based measurement timer. . Set this parameter through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
166
The handover procedure is divided into three phases: handover triggering, handover decision, and handover execution
There is no measurement of the target cell, so we call it blind handover.
In the triggering phase
The Load Reshuffling (LDR) module directly determines whether the current cell is overloaded and whether an inter-frequency handover needs to be performed. The LDR module provides the target cell information for the current cell, and the RNC performs the handover procedure.
In the decision phase
The RNC decides to trigger an inter-frequency blind handover if If the blind handover neighbors are configured :
After the inter-frequency handover is triggered, the RNC chooses a decision algorithm according to whether the conditions “Blind handover condition” of direct blind handover are met.
If the value of the parameter of a cell is -115, the RNC performs direct blind handover to this cell.If there is no such cell with the parameter value -115, the RNC initiates an intra-frequency measurement for conditional blind handover.
In the execution phase
The RNC performs the blind handover according to the decision result.
Procedure of Load-based inter-frequency
handover :
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Load-based inter-frequency handoverHandover triggering
Target user
User with lower integrated priority
Target cell
Blind handover neighbor
Based on the service ARP, Traffic class, Channel type(R99, HSDPA), RNC will choose the users with lower priority to execute handover .
The target cell of this inter-frequency handover are only the blind handover neighbors with light load.which is indicated by the “Blind handover flag”
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Parameters of inter-frequency handover
Blind handover flag
Parameter ID: BlindHOFlag
The default value of this parameter is False
Cell oriented Cell Individual Offset
Parameter ID : BlindHOFlag
Value range FALSE, TRUE
The default value of this parameter is FALSE
Content: This parameter indicates whether the neighboring cell is the target cell for blind handovers. If the value is TRUE, blind handovers can be performed to the neighboring cell.
Set this parameter through ADD INTERFREQNCELL/MOD INTERFREQNCELL
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Load-based inter-frequency handoverHandover Decision and Execution
The RNC determines to trigger an inter-frequency blind handover
RNC performs direct blind handover or conditional blind handover
After the RNC determines to trigger an inter-frequency blind handover ,according to the parameter Blind handover condition, the RNC executes:
If the value of the parameter of a cell is -115, the RNC performs direct blind handover to this cell.If there is no such cell with the parameter value -115, the RNC initiates an intra-frequency measurement for conditional blind handover.
Note:If the neighboring cells have the same Blind handover condition value, the RNC chooses any one of them.
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Load-based inter-frequency handoverHandover Decision and Execution
Conditional Blind Handover
The inter-frequency cells with the same coverage area have the same CPICH
RSCP values. By measuring the CPICH RSCP of the current cell, the quality
of the cells with the same coverage area can be determined, which increases
the probability of successful blind handover
The intra-frequency measurement for conditional blind handover is described as follows:
1.The RNC initializes the timer of intra-frequency measurement for blind handover. The timer is specified by internal algorithm and needn't to be configured.
2. The RNC modifies the measurement mode:
The measurement reporting mode is changed to periodic reporting by a new measurement control . The reporting period is Intrafrequency measurement report interval of blind handover. The measurement reporting number is Intrafrequency measurement report amount of blind handover.The intra-frequency measurement quantity is CPICH RSCP.
3. After receiving from the UE the intra-frequency measurement reports for conditional blind handover, the RNC checks whether the following condition is met:
CPICH RSCP of the cell in the measurement report >= Blind handover condition
If the condition is met, the RNC increments the counter of the number of intra-frequency measurement reports for blind handover by 1. If the condition is not met, the RNC does not perform a blind handover to the cell that triggers LDR and stops intra-frequency measurement for blind handover. When the counter reaches the value of Intrafrequency measurement report amount of blind handover, the RNC initiates a blind handover to the cell that triggers LDR. If the counter does not reach this value, the RNC waits for the next intra-frequency measurement report from the UE. If the timer of intra-frequency measurement for blind handover expires, the RNC does not perform a blind handover to the cell that triggers LDR and stops intra-frequency handover for blind handover.
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Parameters of inter-frequency handover
Blind handover condition
Parameter ID: BlindHOQualityCondition
The default value of this parameter is -92 (-92dBm)
Intrafrequency measurement report interval of blind handover
Parameter ID: BlindHOIntrafreqMRInterval
The default value of this parameter is D250 (250ms)
Intrafrequency measurement report amount of blind handover
Parameter ID: BlindHOIntrafreqMRAmount
The default value of this parameter is D2
Blind handover conditionParameter ID : BlindHOQualityCondition
Value range -115 to -25 , step:1dBThe default value of this parameter is -92 (-92dBm)
Content: This parameter specifies whether the cell supports a direct or conditional blind handover.
The value -115 indicates that the cell supports a direct blind handover. This value is usually used in configuration of inter-frequency cells with large coverage areas overlapped. The other values indicate that the cell supports a conditional blind handover.
This value is usually used in configuration of inter-frequency cells with some coverage areas overlapped.
Set this parameter through ADD INTERFREQNCELL/MOD INTERFREQNCELLIntrafrequency measurement report interval of blind handover
Parameter ID: BlindHOIntrafreqMRInterval
Value range D250, D500 The default value of this parameter is D250 (250ms)
Content: This parameter specifies the intra-frequency measurement period for blind handover.
Set this parameter through SET INTRAFREQHOIntrafrequency measurement report amount of blind handover
Parameter ID: BlindHOIntrafreqMRAmount
Value range D1, D2, D4, D8 The default value of this parameter is D2
Content: This parameter specifies the maximum number of intra-frequency measurement reports for blind handover
Set this parameter through SET INTRAFREQHO
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
173
The handover procedure is divided into four phases: handover triggering, handover measurement handover decision, and handover executionIn the triggering phase
The RNC receives the internal handover request according to the HCS speed estimation. The handover based on HCS speed estimation is of two types:
When the UE is in low-speed state, RNC will trigger handover from the macro cell to the micro cell.
When the UE is in high-speed state, RNC will trigger handover from the micro cell to the macro cell.
For different types of handover, the RNC acts differently.In the measurement phase
If the handover is performed from a macro cell to a micro cell, the RNC triggers compressed mode ,then sends an inter-frequency measurement control message for 2C event to start the inter-frequency measurement procedureIf the handover is performed from a micro cell to a macro cell, the RNC directly performs blind handover, without measurement procedure. only if the handover fails, the RNC triggers compressed mode ,then sends an inter-frequency measurement control message for 2C event to start the inter-frequency measurement procedure
In the decision phase
For handover from a macro cell to a micro cell, after the UE reports event 2C, the RNC performs the handover decision.In the execution phaseThe RNC initiates a handover procedure.
If the handover is performed from a micro cell to a macro cell and the target cell of blind handover is configured, the RNC performs blind handover to the target cell.
If the blind handover fails or the handover is performed from a macro cell to a micro cell, the RNC performs the inter-frequency handover procedure to the cell with the best quality after receiving event 2C from the UE.
Procedure of Speed-based inter-frequency handover :
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The estimated quality of a non-used frequency is above a certain
threshold.
2C
DescriptionDescriptionEventEvent
MEASUREMENT EVENTS
Speed-based inter-frequency handover
Event 2C is only used in Speed-based inter-frequency handover.
After RNC believe the UE is in low-speed state, RNC will start handover from the macro cell to the micro cell.
RNC triggers compressed mode firstly, then sends an inter-frequency measurement control message for 2C event to start the inter-frequency measurement procedure.
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Event 2C is triggered on the basis of the following formula
2C EVENT
Speed-based inter-frequency handover
QNoused >= TNoused2c + H2c/2
2C only takes the Ec/No as the measurement quantity
QNoused is the measured quality of the cell that uses the other frequencies.
TNoused2c is the absolute quality threshold of the cell that uses the other frequencies, namely, Inter-freq measure target frequency trigger Ec/No THD.
H2c is the event 2C hysteresis value 2C hysteresis.
2C event trigger delay time is reached, the UE reports the event 2C measurement report message.
2C Event only takes the Ec/No as the measurement quantity.
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Parameters of inter-frequency handover
Inter-freq measure target frequency trigger Ec/No THD
Parameter ID: InterFreqNCovHOThdEcN0
The default value of this parameter is -16 (-16dB)
2C hysteresis
Parameter ID: Hystfor2C
The default value of this parameter is 6 (3dB)
2C event trigger delay time
Parameter ID: TrigTime2C
The default value of this parameter is D640 (640ms)
Inter-freq measure target frequency trigger Ec/No THDParameter ID : InterFreqNCovHOThdEcN0
Value range -24 to 0, step:1dBThe default value of this parameter is -16 (-16dB),
Content: When the Ec/No value of the target frequency is higher than the threshold, event 2C can be triggered
Set this parameter through ADD CELLINTERFREQHONCOV/MOD CELLINTERFREQHONCOV/SET INTERFREQHONCOV
2C hysteresisParameter ID: Hystfor2C
Value range 0 to 29 The default value of this parameter is 6(3dB)
Content: This parameter specifies the event 2C trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.
Set this parameter through ADD CELLINTERFREQHONCOV/MOD CELLINTERFREQHONCOV/SET INTERFREQHONCOV
2C event trigger delay timeParameter ID: TrigTime2C
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000 The default value of this parameter is D640 (640ms)
Content: This parameter specifies the time of event 2C trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed.
Set this parameter through ADD CELLINTERFREQHONCOV/MOD CELLINTERFREQHONCOV/SET INTERFREQHONCOV
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
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Blind handover Based on Event 1FBlind Handover
Handover without measuring the neighboring cell
Load-based handover
Speed-based handover from micro cell to macro cell
1F event triggered inter-frequency handover
Blind handover is a special handover, means :before the handover, the UE needn’t report the target cell signal quality, RNC just select a target inter-frequency or inter-rat neighbor for the UE ,then force the UE handover to the target, the compressed mode and inter-frequency measurement can be overleaped
The precondition of blind handover is :the blind handover neighbors are configured to a cell (Blind handover flag ), which is discussed in the forenamed slides.
Blind handover may be triggered by load, UE speed and also the 1F event
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A Primary CPICH becomes worse than an absolute threshold. 1F
DescriptionDescriptionEventEvent
MEASUREMENT EVENTS
Blind handover Based on Event 1F
1F Event is a intra-frequency measurement event, like 1A,1B,1C,1D.
Events 1A,1B,1C,1D are used to trigger intra-frequency handover, Event 1F only trigger inter-frequency or inter-RAT blind handover.
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Event 1F is triggered on the basis of the following formula
1F EVENT
Blind handover Based on Event 1F
MOld <= T1f - H1f/2
MOld is the measurement value of the cell that becomes worse.
T1f is an absolute threshold. It is set to 1F event absolute EcNo threshold or 1F event absolute RSCP threshold respectively, depending on the measurement quantity.
H1f is the event 1F hysteresis value 1F hysteresis.
After the conditions of event 1F are fulfilled and maintained until the 1F event trigger delay time is reached, the UE reports the event 1F measurement report message.
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Parameters of inter-frequency handover
1F event absolute EcNo threshold
Parameter ID: IntraAblThdFor1FEcNo
The default value of this parameter is -24 (-24dB)
1F event absolute RSCP threshold
Parameter ID: IntraAblThdFor1FRSCP
The default value of this parameter is -115 (-115dBm)
1F event absolute EcNo threshold
Parameter ID : IntraAblThdFor1FEcNo
Value range -24 to 0, step:1dB
The default value of this parameter is -24 (-24dB),
Content: This parameter specifies the absolute EcNo threshold of event 1F. The greater the parameter value is, the more easily event 1F is triggered. The smaller the parameter value is, the harder event 1F is triggered.
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO
1F event absolute RSCP threshold
•Parameter ID: IntraAblThdFor1FRSCP
Value range -115 to -25 step:1dB
The default value of this parameter is -115(-115dBm)
Content: This parameter specifies the absolute RSCP threshold of event 1F. The greater the parameter value is, the more easily event 1F is triggered. The smaller the parameter value is, the harder event 1F is triggered.
Set this parameter through ADD CELLINTERFREQHONCOV/MOD CELLINTERFREQHONCOV/SET INTERFREQHONCOV
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Parameters of inter-frequency handover
1F hysteresis
Parameter ID: HystFor1F
The default value of this parameter is 8 (4dB)
1F event trigger delay time
Parameter ID: TrigTime1F
The default value of this parameter is D640 (640 ms)
1F hysteresis
Parameter ID : HystFor1F
Value range 0 to 15, step:0.5dB
The default value of this parameter is 8 (4dB),
Content: This parameter specifies the hysteresis value of event 1D. It is related to the slow fading characteristic. The greater the parameter value is, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time.
Set this parameter through SET INTRAFREQHO/ADD CELLINTRAFREQHO/MOD CELLINTRAFREQHO
•1F event trigger delay time
•Parameter ID: TrigTime1F
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000
The default value of this parameter is D640 (640 ms)
Content: This parameter specifies the trigger delay time of event 1F. It is related to the slow fading characteristic. The greater the parameter value is, the smaller the misjudgment probability, but the slower the response of the event to the measured signal changes.
Set this parameter through ADD CELLINTERFREQHONCOV/MOD CELLINTERFREQHONCOV/SET INTERFREQHONCOV
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
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Inter-frequency Anti-PingPongThe inter-frequency anti-ping-pong algorithm is as follows:
Step1-When a coverage-based inter-frequency handover or an inter-frequency blind handover based on event 1F occurs, the RNC starts the timer specified by The timer length of anti ping-pong NCOV interfreq handover for the UE
Step2-When a non-coverage-based inter-frequency handover is triggered, first, the RNC determines whether the timer specified by The timer length of anti ping-pong NCOV interfreq handover expires
If the timer does not expire, the RNC cancels the handover
If the timer expires, the RNC performs the handover
Parameters
The timer length of anti pingpong NCOV interfreq handover
Parameter ID: 1FAntiPingPongtimerLength
The default value of this parameter is 30s
The timer length of anti pingpong NCOV interfreq handover
Parameter ID :IFAntiPingpangTimerLength
Value range:0~120
Physical unit:s
Content: the length of anti non-coverage based inter-frequency pingpong handover timer.
Recommended value:30 Set this parameter through SET HOCOMM
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
1. Coverage-based inter-frequency handover
2. QoS-based inter-frequency handover
3. Load-based inter-frequency handover
4. Speed-based inter-frequency handover
5. Blind handover Based on Event 1F
6. Inter-frequency anti-PingPong
7. Inter-frequency handover retry
3. Signaling Procedures for Inter-Frequency Handover
186
For the inter-frequency handover based on coverage or QoS, the following two parameters determine the retry period and the maximum number of retry times:
2B event retry period
2B event retry max times
For the inter-frequency handover based on speed, the following two parameters determine the retry period and the maximum number of retry times:
2C event retry period
2C event retry max times
If an inter-frequency handover based on event-triggered measurement report mode fails, the RNC initiates the inter-frequency handover attempt according to an inter-frequency retry algorithm
After the inter-frequency handover fails, the retry timer for the cell is started. After the retry timer expires, the UE makes a handover attempt to the cell again until the retry number exceeds the maximum allowed retry number. If the handover succeeds or two new event 2B reports are received, the periodical retry is stopped.
Handover is failed
Retry condition is satisfied?
2B event? Start timer
Trigger handover
2B measurement control is
re-transmitted
END Timer isexpired
implementation
Inter-frequency handover retry
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Inter-frequency handover retry Parameters
2B event retry period
Parameter ID: PeriodFor2B
The default value of this parameter is 500ms
2B event retry max times
Parameter ID: AmntOfRpt2B
The default value of this parameter is 63 (infinity)
2C event retry period
Parameter ID: PeriodFor2C
The default value of this parameter is 2s
2C event retry max times
Parameter ID: AmntOfRpt2C
The default value of this parameter is 5
2B event retry period
2B event retry max times
Set above parameters through SET INTRERFREQHOCOV / ADD CELLINTERFREQHOCOV / MOD CELLINTERFREQHOCOV
2C event retry period
2C event retry max times
Set above parameters through SET INTRERFREQHONCOV / ADD CELLINTERFREQHONCOV / MOD CELLINTERFREQHONCOV
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Contents2. Inter-Frequency Handover
1. Inter-Frequency Handover Overview
2. Inter-Frequency Handover Procedure
3. Signaling Procedures for Inter-Frequency Handover
189
Intra-RNC Inter-Frequency Handover
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Inter-RNC Inter-Frequency Handover
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Contents1. Intra-Frequency Handover
2. Inter-Frequency Handover
3. Inter-RAT Handover
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure
3. Signaling Procedures for Inter-RAT Handover
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Inter-RAT Handover Overview
Inter-RAT Handover Application Scenario
Inter-RAT handover provides coverage expansion, load sharing, and layered services. It saves cost by utilizing the existing GSM network resources.
Inter-RAT handover refers to the handover between UMTS and GSM. The reason for the handover can be coverage limitation, link stability control or load limitation of the 3G system.
Inter-RAT handover can be UMTS-to-GSM or GSM-to-UMTS handover.
Strategy of 2G and 3G cooperation is shown in the picture:
Based on coverage, QoS , Service, load and speed, RNC can trigger UE handover from 3G to 2G; When UE return back to Idle Mode, trigger UE Cell reselect to 3G.
In this handover, however, GSM and UMTS dual-mode UEs (MSs) are required, and both the GSM MSC and the GSM BSS must be upgraded.
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Inter-RAT Handover Overview
Classification of Inter-RAT Handover:Based on the triggering causes of handover, inter-frequency handover can be categorized into four types .
Coverage-based
QoS-based
Load-based
Service-based
Speed-based
Coverage-based inter-frequency handoverThe coverage of the UMTS is incontinuous at the initial stage of the 3G network. On the border of the coverage, the poor signal quality of UMTS triggers the UMTS-to-GSM measurement. If the signal quality of GSM is good enough and all the services of the UE are supported by the GSM, the coverage-based UMTS-to-GSM handover is triggered.
QoS-based inter-frequency handoverAccording to the Link Stability Control Algorithm, the RNC needs to trigger the QoS-based UMTS-to-GSM handover to avoid call drops.
Load-based inter-frequency blind handoverIf the load of the UMTS is heavy and all the RAB of a UE are supported by the GSM, the load-based UMTS-to-GSM handover is triggered.
Service-based UMTS-to-GSM handover Based on layered services, the traffic of different classes is handed over to different systems. For example, when an Adaptive Multi Rate (AMR) speech service is requested, this service can be handed over to the GSM.
Speed-based inter-frequency handoverWhen the Hierarchical Cell Structure (HCS) is used, the cells are divided into different layers on the basis of coverage. Typically, a marco cell has large coverage and low priority, whereas a micro cell has small coverage and high priority.UMTS-to-GSM handover can be triggered by the UE speed estimation algorithm of the HCS. A UE moving at high speed is handed over to a cell with larger coverage to reduce the times of handover, whereas a UE moving at low speed is handed over to a cell with smaller coverage.
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Inter-RAT Handover Overview
Preconditions for UMTS-to-GSM Handover :
Service Handover Indicator
Capabilities of Deciding UMTS-to-GSM Handover
GSM neighboring cell capability
service capability
UE capability
Before handover, the RNC checks whether the preconditions meet the triggering requirements of the UMTS-to-GSM handover. The preconditions include the service handover indicator, GSM cell capability, service capability, and UE capability.
The parameter Service handover indicator indicates the CN policy for the service handover to the GSM. This parameter is indicated in the Radio Access Bearer (RAB) assignment signaling assigned by the CN, or can be configured on the RNC side by ADD/MOD TYPRABBASIC .
Before deciding UMTS-to-GSM handover, the RNC considers GSM cell capability, service capability and UE capability.
GSM cell capability could be “GSM”,”GPRS”,”EDGE”, it should be the real capability of the GSM neighbor, and configured in RNC data base by LMT correctly
Service capability could be “GSM”,”GPRS”,”EDGE” also, it should be properly configured in RNC data base by LMT
UE capability is reported by the UE itself in “RRC Setup Complete” message.
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Inter-RAT Handover Overview
Service Handover Indicator HO_TO_GSM_SHOULD_BE_PERFORM
HO_TO_GSM_SHOULD_NOT_BE_PERFORM
HO_TO_GSM_SHALL_NOT_BE_PERFORM
Example of rules for indicator of UMTS-to-GSM handover based on load and service
Preconditions for UMTS-to-GSM Handover :
Before handover, the RNC checks service handover indicator, This parameter is indicated in the Radio Access Bearer (RAB) assignment signaling assigned by the CNThe service handover indicators are as follows:
HO_TO_GSM_SHOULD_BE_PERFORM: means that the handover to the 2G network is performed when 2G signals are available.
HO_TO_GSM_SHOULD_NOT_BE_PERFORM: means that the handover to the 2G network is performed when 3G signals are weak but 2G signals are strong.
HO_TO_GSM_SHALL_NOT_BE_PERFORM: means that the handover to the 2G network is not performed even when 3G signals are weak but 2G signals are strong.
197
For the UE accessing combined services (with CS services), the RNC sets the service handover indicator of the UE to that of the CS service, because the CS service has the highest QoS priority.
For the UE accessing combined services (with only PS services), the RNC sets the service handover indicator of the UE to that of the PS service, which has the highest QoS priority.
If service handover indicators are not configured by the CN, each indictor can be set to Service parameter index of a service on the RNC.
Based on different service handover indicators .RNC may initiate different action, for example, handover based on service are not not performed for the services whose handover indicator is “HO_TO_GSM_SHOULD_NOT_BE_PERFORM” or “HO_TO_GSM_SHALL_NOT_BE_PERFORM”
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Inter-RAT Handover Overview
Preconditions for UMTS-to-GSM Handover :
Capabilities of Deciding UMTS-to-GSM Handover
GSM neighboring cell capability NO_CAPABILITY, GSM, GPRS, EDGE
Service required capability
GSM, GPRS, EDGE
UE capability
GSM, GPRS, or EDGE
Note: For Service-Based UMTS-to-GSM Handover, there
is an additional switch on RNC
The rules for enabling UMTS-to-GSM handover are based on the parameter Service Handover Indicator and the three types of capability parameters. The rules vary with different types of inter-RAT handover , that is , the 4 factors will decide if the inter-RAT handover is allowed.
The rules are:
Coverage-based and QoS-based UMTS-to-GSM handover
when Service Handover Indicator is set as follows:
HO_TO_GSM_SHOULD_BE_PERFORM HO_TO_GSM_SHOULD_NOT_BE_PERFORM
In addition, the RNC initiates inter-RAT handover based on the following capabilities:
GSM cell capability (can be set on RNC)Service required capability (can be set on RNC)UE capability (reported from UE “RRC setup complete” message )
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GSM neighboring cell with EDGE capability
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedAllowedAllowedGPRS
AllowedAllowedAllowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)UE Capability
GSM neighboring cell with GPRS capability
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedAllowedAllowedGPRS
AllowedAllowedAllowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)UE Capability
GSM neighboring cell with GSM capability
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedNot allowedNot allowedGPRS
AllowedNot allowedNot allowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)UE Capability
If the capability of all the GSM neighboring cells is "No capability", the inter-RAT handover cannot be started.
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load-based UMTS-to-GSM handover
when Service Handover Indicator is set as follows:
HO_TO_GSM_SHOULD_BE_PERFORM HO_TO_GSM_SHOULD_NOT_BE_PERFORM
service-based UMTS-to-GSM handover
when Service Handover Indicator is set as follows:
HO_TO_GSM_SHOULD_BE_PERFORM The following switch are on:
Inter-RAT CS handover switch (service based)Inter-RAT PS handover switch (service based)
In addition, the RNC initiates inter-RAT handover based on the following capabilities:
GSM cell capability (can be set on RNC)
Service required capability (can be set on RNC)
UE capability (reported from UE “RRC setup complete” message )
GSM neighboring cell with EDGE capability
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedAllowedNot allowedGPRS
AllowedAllowedAllowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)UE Capability
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GSM neighboring cell with GPRS capability
GSM neighboring cell with GSM capability
If the capability of all the GSM neighboring cells is "No capability", the inter-RAT handover cannot be started.
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedAllowedNot allowedGPRS
AllowedAllowedNot allowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)
UE Capability
Not allowedNot allowedNot allowedNot supported by 2G
AllowedNot allowedNot allowedGSM
AllowedNot allowedNot allowedGPRS
AllowedNot allowedNot allowedEDGE
GSMGPRSEDGE
Service capability (required by 2G)UE Capability
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Inter-RAT Handover Overview
Inter-RAT Handover RNC Algorithm Switch
INTER_RAT_PS_OUT_SWITCH
Default value is ON
INTER_RAT_CS_OUT_SWITCH
Default value is ON
These switches are the parameter values of Handover algorithm switch in the command SET CORRMALGOSWITCH.
INTER_RAT_PS_OUT_SWITCH
The switch decides whether the RNC will initiate inter-RAT measurement to trigger inter-RAT handover of the PS domain from the UTRAN.
INTER_RAT_CS_OUT_SWITCH
The switch decides whether the RNC will initiate inter-RAT measurement to trigger inter-RAT handover of the CS domain from the UTRAN.
Set this parameter through SET CORRMALGOSWITCH
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
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Coverage-based inter-RAT handover
The handover procedure is divided into four phases: handover triggering, handover measurement, handover decision, and handover execution.
In the triggering phase
The RNC sends a MEASUREEMNT CONTROL message to the UE, notifying the UE to measure the current carrier quality. This message defines the reporting rules and thresholds of events 2D and 2F. If the quality of the pilot signal in the current cell deteriorates, the CPICH Ec/No or CPICH RSCP of the UMTS cell that the UE accesses is lower than the corresponding threshold and the UE reports event 2D.
In the measurement phase
If the RNC receives a report of event 2D, the RNC may request the NodeB and UE to start the compressed mode to measure the qualities of GSM cells. Then, the RNC may send an inter-RAT measurement control message that defines the neighboring cell information, reporting period, and reporting rule.
In the measurement phase, either periodical measurement report mode or event-triggered measurement report mode can be used.
In the decision phase
After the UE reports event 3A, the RNC makes a handover decision. Or, after the UE periodically sends the measurement reports, the RNC evaluates the reports first and then makes a handover decision.
In the execution phase
The RNC initiates a handover procedure.
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The estimated quality of the currently used frequency is above a certain
threshold.
2F
The estimated quality of the currently used frequency is below a certain
threshold.
2D
DescriptionDescriptionEventEvent
MEASUREMENT EVENTS
Coverage-based inter-RAT handover
When the estimated quality of the currently used frequency is below a certain threshold,2D Event will be triggered, Then RNC will initiate the compress Mode to start inter-frequency or inter-RAT handover measurement.
During compress mode, if the the estimated quality of the currently used frequency is above a certain threshold, 2F Event will be triggered, Then RNC will stop the compress Mode.
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Event 2D is triggered on the basis of the following formula
2D EVENT
QUsed <= TUsed2d - H2d/2
Coverage-based inter-RAT handover
QUsed is the measured quality of the used frequency.
TUsed2d is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service, or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through one of the following parameters:
Inter-freq CS measure start Ec/No THDInter-freq R99 PS measure start Ec/No THDInter-freq H measure start Ec/No THDInter-freq CS measure start RSCP THDInter-freq R99 PS measure start RSCP THDInter-freq H measure start RSCP THD
H2d is the event 2D hysteresis value 2D hysteresis.
After the conditions of event 2D are fulfilled and maintained until the parameter 2D event trigger delay time is reached, the UE reports the event 2D measurement report message.
Note:
Any of the Ec/No and RSCP measurement result can trigger the 2D event.
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Parameters of inter-RAT handover
Inter-RAT CS measure start Ec/No THD
The default value of this parameter is -14dB
Inter-RAT R99 PS measure start Ec/No THD
The default value of this parameter is -15dB
Inter-RAT H measure start Ec/No THD
The default value of this parameter is -15dB
Inter-RAT CS measure start RSCP THD
The default value of this parameter is -95dBm
Inter-RAT R99 PS measure start RSCP THD
The default value of this parameter is -110dBm
Inter-RAT H measure start RSCP THD
The default value of this parameter is -110dBm
2D hysteresis
The default value of this parameter is 4 (2dB)
2D event trigger delay time
The default value of this parameter is D320 (320 ms)
The parameters for inter-RAT handover 2D are similar with inter-frequency handover.
Set above parameters through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
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Event 2F is triggered on the basis of the following formula
2F EVENT
QUsed >= TUsed2d - H2d/2
Coverage-based inter-RAT handover
QUsed is the measured quality of the used frequency.
TUsed2f is the absolute quality threshold of the cell that uses the current frequency. Based on the service type (CS , PS domain R99 service or PS domain HSPA service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:
Inter-freq CS measure stop Ec/No THDInter-freq R99 PS measure stop Ec/No THDInter-freq H measure stop Ec/No THDInter-freq CS measure stop RSCP THDInter-freq R99 PS measure stop RSCP THDInter-freq H measure stop RSCP THD
H2f is the event 2F hysteresis value 2F hysteresis.
After the conditions of event 2F are fulfilled and maintained until the parameter 2F event trigger delay time is reached, the UE reports the event 2F measurement report message.
Note:
Any of the Ec/No and RSCP measurement result can trigger the 2F event.
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Parameters of inter-RAT handover
Inter-freq CS measure stop Ec/No THD
The default value of this parameter is -12dB
Inter-freq R99 PS measure stop Ec/No THD
The default value of this parameter is -13dB
Inter-RAT H measure stop Ec/No THD
The default value of this parameter is -13dB
Inter-freq CS measure stop RSCP THD
The default value of this parameter is -97 dBm
Inter-freq R99 PS measure stop RSCP THD
The default value of this parameter is -107dBm
Inter-RAT H measure stop RSCP THD
The default value of this parameter is -107dBm
2F hysteresis
The default value of this parameter is 4 (2dB)
2F event trigger delay time
The default value of this parameter is D1280 (1280 ms)
The parameters for inter-RAT handover 2D are similar with inter-frequency handover.
Set above parameters through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
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Interoperability Between Inter-RAT and Inter-Frequency Handover
Coverage-based inter-RAT handover
Inter-frequency measurement 2D, 2F Event
Inter-frequency neighbor
Inter-RAT measurement 2D, 2F Event
Inter-RAT neighbor
Measure inter-RAT neighbor?
Measureinter-frequency
neighbor?
During the coverage-based and QoS-based UMTS-to-GSM handover, the measurements on both inter-frequency and inter-RAT neighboring cells can be made, which enables the cells to provide continuous coverage and high quality.
The preconditions for the measurements are as follows:
Both inter-frequency and inter-RAT neighboring cells are available.
Inter-freq and Inter-RAT coexist switch is set to SIMINTERFREQRAT.
If Inter-freq and Inter-RAT coexist switch is set as follows:
Inter-frequency measurement, which means that the RNC allows the UE to perform only this type of measurement.
Inter-RAT measurement, which means that the RNC allows the UE to perform only this type of measurement.
Concurrent inter-frequency and inter-RAT measurement, which means that the RNC allows the UE to perform both types of measurement in compressed mode at the same time.
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Parameters of inter-RAT handover
Inter-freq and Inter-RAT coexist switch
Parameter ID: InterFreqRATSwitch
The default value of this parameter is SIMINTERFREQRAT
InterFreq & InterRat coexist measure threshold choice
Parameter ID: CoexistMeasThdChoice
The default value of this parameter is
COEXIST_MEAS_THD_CHOICE_INTERFREQ
Inter-freq and Inter-RAT coexist switchParameter ID : InterFreqRATSwitchValue range INTERFREQ, INTERRAT, SIMINTERFREQRAT The default value of this parameter is SIMINTERFREQRAT Content: This parameter specifies the type of cells to be measured when inter-frequency and inter-
RAT adjacent cells coexist:InterFreq: means that only the inter-frequency cells are measured and inter-frequency handover is performed.InterRAT: means that only the GSM cells are measured and inter-RAT handover is performed.SimInterFreqRAT: means that both inter-frequency and inter-RAT cells are measured and inter-frequency or inter-RAT handover is performed according to the type of the cell that first meets the condition for handover decision. If only the inter-frequency cells or inter-RAT cells exist, the value of this parameter is invalid Set this parameter through ADD CELLHOCOMM/MOD CELLHOCOMMDuring the concurrent inter-frequency and inter-RAT measurement, the values of the parameter
InterFreq & InterRat coexist measure threshold choice for events 2D and 2F are chosen as follows:When the value COEXIST_MEAS_THD_CHOICE_INTERFREQ is chosen, the inter-frequency
measurement threshold for event 2D is used.When the value COEXIST_MEAS_THD_CHOICE_INTERRAT is chosen, the inter-RAT measurement
threshold for event 2D is used. InterFreq & InterRat coexist measure threshold choice
•Parameter ID: CoexistMeasThdChoiceValue range COEXIST_MEAS_THD_CHOICE_INTERFREQ,
COEXIST_MEAS_THD_CHOICE_INTERRAT The default value of this parameter is COEXIST_MEAS_THD_CHOICE_INTERFREQ Content: This parameter specifies the type of event 2D/2F measurement thresholds when inter-
frequency and inter-RAT adjacent cells coexist. COEXIST_MEAS_THD_CHOICE_INTERFREQ: represents the event 2D/2F measurement threshold
for the inter-frequency measurement.COEXIST_MEAS_THD_CHOICE_INTERRAT: represents the event 2D/2F measurement threshold
for the inter-RAT measurement. Set this parameter through SET HOCOMM/ADD CELLHOCOMM/MOD CELLHOCOMM
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Handover Measurement
Coverage-based inter-RAT handover
UE RNC
Measurement report
Physical Channel Recfg (CM)
Measurement control
2D
Physical Channel Recfg Complet(CM)
When the UE enters the compress mode, RNC will trigger the inter-RAT handover measurement by one additional measurement control signaling , so as to request UE test inter-RAT neighbor cell.
In this Measurement control message, RNC should inform the UE inter-RAT measurement parameter (Neighbor list, reporting mode…)
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Coverage-based inter-RAT handover
UE RNC
Measurement report
Handover
Measurement report
Measurement report
UE RNC
Measurement control (Event triggering, GSM RSSI ,WCDMA RSCP or Ec/No)
Handover
Measurement report (3A)
Periodical_reporting Event_trigger
Measurement control (Periodical, RSSI)
Handover Measurement
•Report Mode
The measurement report mode of inter-RAT handover is configured through the parameter Inter-frequency measure report mode. By default ,periodically reporting is recommended.
Based on the measurement control message received from the RNC, the UE periodically reports the measurement quality of the target cell. Then, based on the measurement report, the RNC makes the handover decision and performs handover.
If the reporting mode is periodically reporting : UE only test the inter-RAT neighbor RSSI only.
If the reporting mode is event trigger reporting : UE test the inter-RAT neighbor RSSI and current cell Ec/No or RSCP ( depend on the 3A Measure Quantity ) .
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Parameters of inter-RAT handover
Inter-RAT report mode
Parameter ID: InterRATReportMode
The default value of this parameter is Periodical reporting
Inter-RAT period report interval
Parameter ID: InterRATPeriodReportInterval
The default value of this parameter is D1000 (1000 ms)
Inter-RAT report mode
Parameter ID: InterRATReportMode
Value range :Periodical reporting, Event trigger
The default value of this parameter is Periodical reporting
Content: This parameter specifies the inter-frequency measurement report mode.
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
Inter-RAT period report interval
Parameter ID: InterRATPeriodReportInterval
Value range : NON_PERIODIC_REPORT, 250, 500, 1000, 2000, 3000, 4000, 6000, 8000, 12000, 16000, 20000, 24000, 28000, 32000, 64000
The default value of this parameter is 1000 (500ms)
Content: This parameter specifies the interval of the inter-frequency measurement report.
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
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Parameters of inter-RAT handover
Inter-RAT measure timer length
Parameter ID: InterRATMeasTime
The default value of this parameter is 60 (60 s)
3A Measure Quantity
Parameter ID: MeasQuantityOf3A
The default value of this parameter is Auto (based on the 2D)
Inter-RAT measure timer length
Parameter ID: InterRATMeasTime
Value range : 0 to 512 ,step 1s
The default value of this parameter is 60 ( 60s)
Content: If no inter-RAT handover occurs upon expiry of the inter-RAT measurement timer, the system stops the inter-RAT measurement and disables the compressed mode. If this parameter is 0, the system does not start the inter-RAT measurement timer.
Set this parameter for handover based on coverage through ADD CELLINTERFREQHOCOV/MOD CELLINTERFREQHOCOV/SET INTERFREQHOCOV
3A Measure Quantity
Parameter ID: MeasQuantityOf3A
Value range : CPICH_Ec/No, CPICH_RSCP, Auto
The default value of this parameter is Auto (based on the 2D)
Content: This parameter indicates the measurement value of the coverage-based inter-RAT measurement in event-triggered measurement report mode.
When 3A Measure Quantity is set to Auto, the measure quantity of the used UTRAN frequency is chosen the same as the measure quantity of the reporting 2D event that triggered this inter-RAT measurement.
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERFREQHOCOV/SET INTERRATHOCOV
This parameter can be configured only when Inter-RAT report mode is set to EVENT_TRIGGER.
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Coverage-based inter-RAT handover
Handover measurement
Event-Triggered Measurement Report Mode
Event 3A is triggered on the basis of the following formula:
– QUsed <= TUsed - H3a/2
– MOtherRAT + CIOOtherRAT >= TOtherRAT + H3a/2
QUsed is the measurement value of the cell at the currently used frequency.
TUsed is the absolute quality threshold of the cell that uses the current frequency.
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Parameters of inter-RAT handover
Inter-RAT CS Used frequency trigger Ec/No THD
Parameter ID: UsedFreqCsThdEcN0
The default value of this parameter is –12 dB
Inter-RAT CS handover decision THD
Parameter ID: TargetRatCsThd
The default value of this parameter is 16 (-95 dBm)
Inter-RAT CS Used frequency trigger Ec/No THD
Parameter ID: UsedFreqCsThdEcN0
Value range :–24 to 0, step 1dB
The default value of this parameter is –12 dB
Content: If CS service inter-RAT handover uses the event-triggered measurement report mode, event 3A is triggered only when the Ec/No value of the used frequency is lower than this threshold.
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
Inter-RAT CS handover decision THD
Parameter ID: TargetRatCsThd
Value range :0 to 63, step 1dB
The default value of this parameter is 16 (-95 dBm)
Content: This parameter indicates the requirement of CS service inter-RAT handover for the quality of inter-RAT cells.
If the event-triggered measurement report mode is used, event 3A may be triggered when the quality of the target frequency is higher than this threshold. In periodical measurement report mode, this parameter is used to evaluate the coverage-based inter-RAT handover on the RNC side.
The value 0 means that the physical value is smaller than –110 dBm. .
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
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Parameters of inter-RAT handover
3A Event default setting
-95dBm
-13dBPS Ec/No threshold
-13dBH Ec/No threshold
-12dBCS Ec/No threshold
Target cellUsed cell
-107dBmH RSCP threshold
-95dBm
-107dBmPS RSCP threshold
-97dBmCS RSCP threshold
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Parameters of inter-RAT handover
3A hysteresis
Parameter ID: Hystfor3A
The default value of this parameter is 4(2 dB)
3A event trigger delay time
Parameter ID: TrigTime3A
The default value of this parameter is D0 (0ms)
3A hysteresis
Parameter ID: Hystfor3A
Value range 0 to 15 , step 0.5dB
The default value of this parameter is 4 (2 dB)
Content: This parameter specifies the event 3A trigger hysteresis, which is related to slow fading. The greater the value of this parameter, the smaller the probability of ping-pong effect and misjudgment. In this case, however, the event cannot be triggered in time .
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
3A event trigger delay time
Parameter ID: TrigTime3A
Value range :D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320,D640, D1280, D2560, D5000
The default value of this parameter is 0 ( 0ms )
Content: This parameter specifies the time of event 3A trigger delay, which is related to slow fading. The greater the value of this parameter, the smaller the probability of misjudgment. In this case, however, the event responds to the changes of measured signals at a lower speed.
Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET INTERRATHOCOV
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Parameters of inter-RAT handover
Cell Individual Offset
Parameter ID: CIO
The default value of this parameter is 0 dB
Neigbhoring cell oriented CIO
Parameter ID: CIOOffset
The default value of this parameter is 0 dB
Cell Individual Offset
Parameter ID: CIO
Value range –50 to 50 , step 1dB
The default value of this parameter is 0 dB
Content: This parameter cooperates with the Neighboring cell oriented CIOin inter-RAT handover decision. The larger the sum, the higher the handover priority of the GSM cell. The smaller the sum, the lower the handover priority of the GSM cell.
Set this parameter through ADD GSMCELL/MOD GSMCELL
Neigbhoring cell oriented CIO
Parameter ID: CIOOffset
Value range :–50 to 50 , step 1dB
The default value of this parameter is 0 (0 dB)
Content: This parameter is used in inter-RAT handover decision. The larger the parameter, the higher the handover priority of the GSM cell. The smaller the parameter, the lower the handover priority of the GSM cell .
Set this parameter through ADD GSMNCELL/MOD GSMNCELL
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Coverage-based Inter-RAT handover
Periodical Measurement Report Mode
Event-Triggered Measurement Report Mode
Handover Decision and Execution
The coverage-based handover decision is categorized into two types according to the following two measurement report modes: periodical measurement report mode and event-triggered measurement report mode. Each mode corresponds to a different decision and execution procedure.
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Coverage-based inter-RAT handover
Handover Decision and ExecutionPeriodical Measurement Report Mode
The target cell must meet the requirement
–– Mother_RAT + CIOother_RAT ≥ Tother_RAT + H/2
NOTE: No consideration of the current cell
Mother_RAT is the measurement result of inter-RAT handover received by the RNC.
CIOother_RAT is the cell individual offset value of the target cell. It is equal to the sum of Cell oriented Cell Individual Offset and Neigbhoring cell oriented CIO. Neigbhoring cell oriented CIO indicates the offset of the measurement cell relative to the best cell.
Tother_RAT is the decision threshold of inter-RAT hard handover.
Based on the service type (CS or PS service) and measurement quantity (CPICH Ec/No or RSCP), this threshold can be configured through the following parameters:
Inter-RAT CS handover decision THDInter-RAT R99 PS handover decision THDInter-RAT H handover decision THD
NOTE:
These thresholds are the same as the quality threshold of event 3A.
For H is the inter-RAT handover hysteresis value Inter-RAT hysteresis.
Select the cells in sequence, that is, from high quality cells to low quality ones, to initiate UMTS-to-GSM handover in the cells where the handover time-to-trigger timer expires.
The length of the time-to-trigger timer is configured through the parameter Time to trigger for verified GSM cell (with BSIC acknowledged) or the parameter Time to trigger for non-verified GSM cell (with BSIC unacknowledged).
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Parameters of inter-RAT handover
Time to trigger for verified GSM cell
Parameter ID: TimeToTrigForVerify
The default value of this parameter is 0 (0 ms)
Time to trigger for non-verified GSM cell
Parameter ID: TimeToTrigForNonVerify
The default value of this parameter is 65535 (never)
Inter-RAT hysteresis
Parameter ID: HystforInterRAT
The default value of this parameter is 0 (0dB)
Time to trigger for verified GSM cellParameter ID : TimeToTrigForVerifyValue range 0 to 64000, step:1msThe default value of this parameter is 0 (0 ms)Content: This parameter specifies the delay time for triggering a GSM cell with BSIC acknowledged.In the period specified by this parameter, if the signal quality of an adjacent GSM cell meets the
requirement of inter-RAT handover, and this cell is acknowledged, the network will start inter-RAT handover. Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET
INTERRATHOCOVTime to trigger for non-verified GSM cell
Parameter ID: TimeToTrigForNonVerifyValue range 0 to 64000 , 65535 , step:1msThe default value of this parameter is 65535 (never)Content: This parameter specifies the delay time for triggering a GSM cell with BSIC unacknowledged. In the period specified by this parameter, if the signal quality of an adjacent GSM cell meets the
requirement of inter-RAT handover, and this cell is unacknowledged, the network will start inter-RAT handover. The value 65535 means that the RNC does not perform handover to an unacknowledged GSM cell. . Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET
INTERRATHOCOVInter-RAT hysteresis
Parameter ID: HystforInterRATValue range 0 to 15 , step:0.5dBThe default value of this parameter is 0 (0dB)Content: This parameter determines whether to trigger inter-RAT handover decision together with the
quality threshold. The smaller the shadow fading, the smaller the value of this parameter. Set this parameter through ADD CELLINTERRATHOCOV/MOD CELLINTERRATHOCOV/SET
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Coverage-based inter-frequency handoverHandover Decision and Execution
Event-Triggered Measurement Report Mode
Based on the event 3A
After receiving the event 3A measurement report of GSM cells, the RNC performs the following decision and execution procedures:
Put all the GSM cells that trigger event 3A into a cell set and arrange the cells according to the measurement quality in descending order.
Select the cells in sequence from the cell set to perform inter-RAT handover.
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
226
The handover procedure is divided into four phases: handover triggering, handover measurement, handover decision, and handover execution.
Besides the triggering step, the rest 3 steps are the same with Coverage-based inter-RAT handover
In the triggering phase
If the service quality of the current cell deteriorates, the Link Stability Control Algorithm makes a handover measurement decision.
In the measurement phase
The RNC requests the NodeB and the UE to start the compressed mode to measure the qualities of inter-frequency and inter-RAT neighboring cells. Then, the RNC sends measurement control messages for inter-frequency measurement and inter-RAT measurement
In the measurement phase, the method of periodical measurement report or event-triggered measurement report can be used.
In the decision phase
After the UE reports event 3A, the RNC performs the handover. Otherwise, the UE periodically generates measurement reports, and the RNC makes a decision after evaluation.In the execution phase
The RNC executes the handover procedure.
Note :
About “Link Stability Control Algorithm” :
When the uplink transmit power of the UE or downlink transmitted code power of the NodeB exceeds the associated threshold :
For AMR, a fixed sequence of rate downsizing, inter-frequency handover, and then inter-RAT handover are performed,
for VP ,inter-frequency handover are performed,
For BE service, rate downsizing, inter-frequency handover, and then inter-RAT handover are performed according to the configured sequence
Procedure of QoS-based inter-RAT handover :
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Parameters of inRAT-frequency handover
InterRAT Handover Switch based on Uplink Traffic AMR
Parameter ID: UlQoSAmrInterRATHoSwitch
The default value of this parameter is NO
InterRAT Handover Switch based on Downlink Traffic AMR
Parameter ID: DlQoSAmrInterRATHoSwitch
The default value of this parameter is NO
InterRAT Handover Switch based on Uplink/Downlink Traffic AMR
Parameter ID : UlQoSAmrInterRATHoSwitch/ DlQoSAmrInterRATHoSwitch
Value range NO, YES
The default value of this parameter is NO
Content: If the value of this parameter is YES, inter-RAT handover can be executed on the basis of the downlink/uplink QoS of AMR services.
Set this parameter through SET QOSACT
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Parameters of inter-frequency handover
First / Second / Third Uplink QOS Enhancement Action for Traffic BE
Parameter ID: BeUlAct1/ BeUlAct2/ BeUlAct3
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
First / Second / Third Downlink QOS Enhancement Action for Traffic BE
Parameter ID: BeDlAct1/ BeDlAct2/ BeDlAct3
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
First / Second / Third Uplink QOS Enhancement Action for Traffic BE
Parameter ID : BeUlAct1/ BeUlAct2/ BeUlAct3
Value range None, RateDegrade, InterFreqHO, InterRatHO
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
Content: This parameter defines the action sequence to enhance the Uplink QoS of BE services .
Set this parameter through SET QOSACT
First / Second / Third Downlink QOS Enhancement Action for Traffic BE
Parameter ID : BeDlAct1/ BeDlAct2/ BeDlAct3
Value range None, RateDegrade, InterFreqHO, InterRatHO
The default value of this parameter is RateDegrade/ InterFreqHO/ InterRatHO
Content: This parameter defines the action sequence to enhance the downlink QoSof BE services .
Set this parameter through SET QOSACT
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Parameters of inter-RAT handover
Down Link QoS Measure timer length
Parameter ID: DLQoSMcTimerLen
The default value of this parameter is 20 (20s)
Up Link QoS Measure timer length
Parameter ID: UpQoSMcTimerLen
The default value of this parameter is 20 (20s)
3A Used-Freq Measure Quantity for QoS
Parameter ID: UsedFreqMeasQuantityForQoS3A
The default value of this parameter is CPICH_RSCP
These two parameters are shared by QoS based inter-frequency and QoS based inter-RAT handover:
Down Link QoS Measure timer length
Up Link QoS Measure timer length
Set these parameters through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
3A Used-Freq Measure Quantity for QoS
Parameter ID : UsedFreqMeasQuantityForQoS3A
Value range CPICH_Ec/No, CPICH_RSCP
The default value of this parameter is CPICH_RSCP
Content: This parameter indicates the measurement quantity used in QoS-based UMTS-to-GSM measurement in event-triggered reporting mode.
If the coverage and QoS-based UMTS-to-GSM handovers are triggered simultaneously, the RNC distributes QoS-based measurement parameters.
Set this parameter through ADD CELLQOSHO/MOD CELLQOSHO/SET QOSHO
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
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The handover procedure is divided into three phases: handover triggering, handover decision, and handover execution
In the triggering phase
When the load of the UMTS cell that the UE accesses is higher than the related threshold, the Load Reshuffling (LDR) algorithm makes a handover decision.
In the measurement phase
The RNC enables the compressed mode and starts the inter-RAT handover measurement.
In the decision phase
After the UE reports event 3C, the RNC makes a handover decision.
In the execution phase
The RNC initiates a handover procedure.
Based on the service ARP, Traffic class, Channel type(R99, HSDPA), RNC will choose the users with lower priority to execute handover .
Procedure of Load-based inter-RAT handover :
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Parameters of inter-RAT handover
Inter-RAT measure timer length
Parameter ID: InterRATMeasTime
The default value of this parameter is 60 s
Inter-RAT measure timer length
Parameter ID : InterRATMeasTime
Value range 0 to 512
The default value of this parameter is 60 s
Content: If no inter-RAT handover occurs upon expiry of the inter-RAT measurement timer, the system stops the inter-RAT measurement and disables the compressed mode. If this parameter is 0, the system does not start the inter-RAT measurement timer.
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHOCOV/SET INTERRATHONCOV
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Event 3C is triggered on the basis of the following formula
3C EVENT
MOtherRAT + CIOOtherRAT >= TOtherRAT + H3c/2
Load-based inter-RAT handover
MOtherRAT is the measurement value of the cell (in another RAT) in the reporting range.
CIOOtherRAT is the cell individual offset value of the cell (in another RAT) in the reporting range, which is equal to the sum of Cell oriented Cell Individual Offset and Neighboring cell oriented CIO.
TOtherRAT is the absolute inter-RAT handover threshold. Based on the service type (CS , PS domain R99 service, or PS domain HSPA service), this threshold can be configured through the following parameters:
Inter-RAT CS handover decision THDInter-RAT R99 PS handover decision THD
H3c is 3C hysteresis, the hysteresis value of event 3C.
For the PS and CS combined services, the threshold(s) for CS services is (are) used.
When the conditions for event 3C are met and the delay requirement specified by the 3C event trigger delay time parameter can be satisfied, the UE sends the measurement report of event 3C.
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Parameters of inter-RAT handover
Inter-RAT CS handover decision THD
Parameter ID: InterRATNCovHOCSTh
The default value of this parameter is 21 (-90dBm)
Inter-RAT PS handover decision THD
Parameter ID: InterRATNCovHOPSThd
The default value of this parameter is 21 (-90dBm)
Inter-RAT CS handover decision THD
Parameter ID : InterRATNCovHOCSTh
Value range 0 to 63 ,step:1dB
The default value of this parameter is 21 (-90dBm)
Content: This parameter is used to set measurement control on the event 3C. The event 3C is triggered when the quality of the target frequency is higher than this threshold. Note that the value 0 means the physical value is smaller than -110 dBm .
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHOCOV/SET INTERRATHONCOV
Inter-RAT PS handover decision THD
Parameter ID : InterRATNCovHOPSTh
Value range 0 to 63 ,step:1dB
The default value of this parameter is 21 (-90dBm)
Content: This parameter is used to set measurement control on the event 3C. The event 3C is triggered when the quality of the target frequency is higher than this threshold. Note that the value 0 means the physical value is smaller than -110 dBm .
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHOCOV/SET INTERRATHONCOV
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Parameters of inter-RAT handover
3C hysteresis
Parameter ID: Hystfor3C
The default value of this parameter is 0 dB
3C event trigger delay time
Parameter ID: TrigTime3C
The default value of this parameter is D640 (640 ms)
3C hysteresis
Parameter ID : Hystfor3C
Value range 0 to 15 ,step:0.5 dB
The default value of this parameter is 0 dB
Content: This parameter specifies the event 3C trigger hysteresis, which is related to slow fading . The larger the value of this parameter, the smaller the probability of ping-pong effect and decision mistakes. In this case, however, event 3C cannot be triggered in time .
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHOCOV/SET INTERRATHONCOV
3C event trigger delay time
Parameter ID : TrigTime3C
Value range D0, D10, D20, D40, D60, D80, D100, D120, D160, D200, D240, D320, D640, D1280, D2560, D5000
The default value of this parameter is D640 (640 ms)
Content: This parameter specifies the time of event 3C trigger delay, which is related to slow fading. The larger the value of this parameter, the smaller the probability of decision mistakes. In this case, however, event 3C responds to the changes of measured signals more slowly.
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHOCOV/SET INTERRATHONCOV
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Load-based inter-RAT handover
Decision and Execution Procedure
Decision
3C Event
load information interchanging between the 3G and 2G cell
Execution
After receiving the event 3C measurement report of GSM cells, the RNC performs the following handover decision and execution procedure:
Put all the GSM cells that trigger event 3C into a cell set and arrange the cells according to the measurement quality in descending order.
Select the cells in sequence from the cell set.
The load status between the source cell and the target cell can be acquired by interchanging load information between a UMTS cell and a GSM cell during the load-based and service-based UMTS-to-GSM handover. Thus, whether to further conduct the handover can be determined to avoid the 2G cell overload and possible handover to the congested cell.
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The procedure of load information interchanging between the 3G source cell and 2G target cell is described as follows:When the RNC sends a RELOCATION REQUIRED message to the 3G CN,
If the switch Send Load Info to GSM Ind is set to ON, the RELOCATION REQUIRED message includes the load information of the 3G source cell.If the switch Send Load Info to GSM Ind is set to OFF, then the RELOCATION REQUIRED message does not include the Information
When the RNC receives the RELOCATION COMMAND message from the 2G CN,If the switch NCOV Reloc Ind based on GSM cell load is set to ON, the RNC obtains the load information of the 2G target cell by reading the RELOCATION COMMAND message.
If the 2G load is lower than CS domain Reloc GSM load THD (for CS service), or if the 2G load is lower than PS domain Reloc GSM load THD(for PS service), the RNC continues the inter-RAT handover procedure; otherwise, the RNC returns the RELOCATION CANCEL message to the CN to cancel this inter-RAT handover and makes another handover attempt to the next candidate cell generated in the cell list based on inter-RAT measurement.
If the load information of the 2G target cell is not included in the RELOCATION COMMAND message, the load information of the 2G target cell is not considered and this inter-RAT handover is continued.
If the switch NCOV Reloc Ind based on GSM cell load is set to OFF, the RNC continues the inter-RAT handover procedure without considering the thresholds.
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Parameters of inter-RAT handover
Send Load Info to GSM Ind
Parameter ID: SndLdInfo2GsmInd
The default value of this parameter is ON
NCOV Reloc Ind based on GSM cell load
Parameter ID: NcovHoOn2GldInd
The default value of this parameter is ON
Send Load Info to GSM Ind
Parameter ID : SndLdInfo2GsmInd
Value range ON, OFF
The default value of this parameter is ON
Content:
When the parameter is set to ON, the RNC sends UMTS cell load information to the GSM CN during the non-coverage based system relocation in or out process. When the parameter is set to OFF, the RNC does not send UMTS cell load
information to the GSM during the system relocation in or out process. Set this parameter through SET INTERRATHONCOV
NCOV Reloc Ind based on GSM cell load
Parameter ID : NcovHoOn2GldInd
Value range ON, OFF
The default value of this parameter is ON
Content:
When the parameter is set to ON, the RNC stops the non-coverage based system relocation out process if the GSM cell load exceeds the CS dormain Reloc GSM load THD or PS dormain Reloc GSM load THD. When the parameter is set to OFF, the RNC continues the system relocation out process without considering the thresholds. This parameter specifies the time of event 3C trigger delay, which is related to slow fading. The larger the value of this parameter, the smaller the probability of decision mistakes. In this case, however, event 3C responds to the changes of measured signals more slowly.
Set this parameter through SET INTERRATHONCOV239
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Parameters of inter-RAT handover
CS domain Reloc GSM load THD
Parameter ID: CSHOOut2GLoadThd
The default value of this parameter is 80 (80%)
PS domain Reloc GSM load THD
Parameter ID: PSHOOut2GLoadThd
The default value of this parameter is 60 (60%)
CS domain Reloc GSM load THD
Parameter ID : CSHOOut2GLoadThd
Value range 0 to 100 ,step:1%
The default value of this parameter is 80 (80%)
Content:
When the parameter is set to ON, the RNC sends UMTS cell load information to the GSM CN during the non-coverage based system relocation in or out process. When the parameter is set to OFF, the RNC does not send UMTS cell load
information to the GSM during the system relocation in or out process. Set this parameter through SET INTERRATHONCOV
PS domain Reloc GSM load THD
Parameter ID : PSHOOut2GLoadThd
Value range 0 to 100 ,step:1%
The default value of this parameter is 80 (80%)
Content:
When the parameter is set to ON, the RNC sends UMTS cell load information to the GSM CN during the non-coverage based system relocation in or out process. When the parameter is set to OFF, the RNC does not send UMTS cell load
information to the GSM during the system relocation in or out process. Set this parameter through SET INTERRATHONCOV
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Parameters of inter-RAT handover
Inter-RAT handover max attempt times
Parameter ID: InterRATHOAttempts
The default value of this parameter is 16
Inter-RAT handover max attempt times
Parameter ID : InterRATHOAttempts
Value range 1 to 16
The default value of this parameter is 16
Content: This parameter specifies the maximum number of attempts of load-based and service-based inter-RAT handover.
Set this parameter through ADD CELLINTERRATHONCOV/MOD CELLINTERRATHONCOV/SET INTERRATHONCOV
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
242
The handover procedure is divided into four phases: handover triggering, handover measurement handover decision, and handover executionIn the triggering phase
When a service is established (RAB Assignment ), If the Service Handover Indicator is set toHO_TO_GSM_SHOULD_BE_PERFORM, the RNC requests the handover to the GSM In the measurement phase
The RNC enables the compressed mode and starts the inter-RAT handover measurement.In the decision phase
After the UE reports event 3C, the RNC makes a handover decision.In the execution phase
The RNC initiates a handover procedure.
service type is defined by parameters on cell level:Inter-RAT CS handover switch and Inter-RAT PS handover switch
When a single CS service is initially set up by the UE, the RNC allows the UMTS-to-GSM service-based handover if Inter-RAT CS handover switch is set to ON.When a single PS service is initially set up by the UE, the RNC allows the UMTS-to-GSM service-based handover if Inter-RAT PS handover switch is set to ON.
For the CS and PS combined services, no service-based handover is triggedservice handover indicator assigned by the Core Network. Only the services with the indicator “HO_TO_GSM_SHOULD_BE_PERFORM” can trigger Service-based inter-RAT handover
Procedure of Service-based inter-RAT handover :
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Parameters of inter-RAT handover
Inter-RAT CS handover switch
Inter-RAT PS handover switch
Parameter ID:
CSServiceHOSwitch
PSServiceHOSwitch
The default value of this parameter is OFF
Inter-RAT CS handover switch
Inter-RAT PS handover switch
Parameter ID :
CSServiceHOSwitchPSServiceHOSwitch
Value range ON, OFF
The default value of this parameter is OFF
Content:
This parameter indicates whether the cell allows the service-based inter-RAT handover for the CS or PS services
Set this parameter through ADD CELLHOCOMM/MOD CELLHOCOMM
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
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VP service:•speech •videos
UMTS-to-GSM Multimedia Fallback
AMR service:•speech
GSMWCDMA
VP AMR AMR
Compared with the traditional speech service of the GSM, the VP service of the UMTS can transmit not only speech services but also the images and videos captured by both parties
For the UMTS-to-GSM handover, network-initiated multimedia fallback on the following occasions:
The RNC decides to send an inter-RAT handover request after receiving periodical measurement reports or event 1F, 3A, or 3C.
The service is combined with a VP, and the "Alternative RAB Para" in the RAB ASSIGNMENT message is a valid AMR speech format.
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The procedure for the fallback service is described as follows:
In the service set up stage, the CN sends the SRNC a RANAP RAB ASSIGNMENT REQUIREMENT message to set up the VP service. The message includes the "Alternative RAB Para" that has QoS parameters required for setting up the speech service.
During UMTS-to-GSM handover, the SRNC sends a RANAP MODIFY REQUEST message to change the VP service to the AMR speech service. In the 3GPP R6 protocol, the Alternative RAB Configuration is also added to the RAB MODIFY REQUEST message, which enables the RNC to request the CN to change the VP service to the AMR speech service.
The MSC initiates the Bearer Capability (BC) negotiation with the UE.
After the negotiation is modified, the RNC is informed of performing service change. The multimedia fallback ends when the service change is completed.
When the multimedia fallback ends, the RNC decides whether to perform the UMTS-to-GSM handover according to the current measurements reported by the UE.
At the beginning of the service setup, the RNC saves the RAB Para and "Alternative RAB Para" in the RAB ASSIGNMENT or REQUEST RELOCATION REQUEST message. This makes preparations for notifying the CN of changing the VP service to the AMR speech service.
The CN initiates the RAB reconfiguration to inform the two calling parties of performing the multimedia fallback. The multimedia fallback of the calling party is consistent with that of the called party. The single VP service falls back to the single AMR speech service. The multi-RAB service combined with VP falls back to the multi-RAB service combined with AMR. If the multimedia fallback succeeds, that is, the video phone in the service falls back to speech successfully, the inter-RAT handover is initiated. Otherwise, the inter-RAT handover fails.
Procedure of Multimedia Fallback
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
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PS UMTS-to-GSM Handover with NACC
What is NACC?
Network Assisted Cell Change
What is the use of NACC
To reduce the delay of PS UMTS-to-GSM handover
Normal PS is realized by cell reselection, the time delay can not be guaranteed. But Some PS services have requirements for the delay. If the handover takes too long, TCP may start slowly or data transmission of the stream service may be interrupted due to the overflow of the UE buffer.
The introduction of NACC enables the system information exchange between BSS and RAN , Thus the inter-system delay in PS domains, can be reduced.
With NACC, the RNC sends the cell change order to the UE, which contains the GSM EDGE Radio Access Network (GERAN) system information, when the UMTS-to-GSM handover in the PS domain is triggered.
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After the SRNC receives a measurement report from the UE, the UE is reselected to the GERAN cell according to the decision.
The SRNC sends a RAN INFORMATION REQUEST message to the SGSN.
The SGSN forwards the message to the corresponding BSS.
The BSS sends a GERAN SI/PSI message to the SRNC via the SGSN. RAN INFORMATION message can either be On-demand (single report) or On-modification (multiple reports).
The SGSN forwards the report message to the SRNC through Iu interface.
If there are several report messages, the SRNC terminates reporting by the TERMINATION/END message.
To enable the NACC function, do as follows:
Run the SET CORRMALGOSWITCH command to set PS_3G2G_CELLCHG_NACC_SWITCH to ON.
Run the ADD GSMCELL/MOD GSMCELL command to set Inter-RAT cell support RIM indicator to TRUE.
Procedure of NACC
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Parameters of inter-RAT handover
PS 3G to 2G Cell change order NACC Switch
Parameter ID: PS_3G2G_CELLCHG_NACC_SWITCH
The default value of this parameter is OFF
Inter-RAT cell support RIM indicator
Parameter ID: SuppRIMFlag
The default value of this parameter is FALSE
PS 3G to 2G Cell change order NACC Switch
Parameter ID : PS_3G2G_CELLCHG_NACC_SWITCH
Value range OFF, ON
The default value of this parameter is OFF
Content: When it is checked, and inter-RAT handover of the PS domain from UTRAN use cell change order method, inter-RAT handover support NACC(Network Assisted Cell Change) function.
Set this parameter through SET CORRMALGOSWITCH
Inter-RAT cell support RIM indicator
Parameter ID: SuppRIMFlag
Value range FALSE, TRUE
The default value of this parameter FALSE
Content: The parameter indicates whether the inter-RAT cell supports RIM.
Set this parameter through ADD GSMCELL/MOD GSMCELL
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Contents3. Inter-RAT Handover
1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure1. Coverage-based inter-RAT handover
2. QoS-based inter-RAT handover
3. Load-based inter-RAT handover
4. Service-based inter-RAT handover
5. UMTS-to-GSM Multimedia Fallback
6. PS UMTS-to-GSM Handover with NACC
7. UMTS-to-GSM Handover retry
3. Signaling Procedures for Inter-RAT Handover
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UMTS to GSM Handover Retry
In case of event triggered inter-RAT handover failure, if the cause
of the failure is not a configuration failure and the retry timer
expires, the handover attempts to the cell again until the retry
number exceeds the maximum retry number
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UMTS to GSM Handover Retry
Parameters 3A event retry period
Parameter ID: PeriodFor3A
The default value of this parameter is 1 (500ms)
3A event retry max times
Parameter ID: AmntOfRpt3A
The default value of this parameter is 63 (infinity)
3C event retry period
Parameter ID: PeriodFor3C
The default value of this parameter is 4 (2000ms)
3C event retry max times
Parameter ID: AmntOfRpt3C
The default value of this parameter is 5
3A event retry period
3A event retry max times
Set this parameter through ADD CELLINTERRATHOCOV / MOD CELLINTERRATHOCOV / SET INTERRATHOCOV
3C event retry period
3C event retry max times
Set this parameter through ADD CELLINTERRATHONCOV / MOD CELLINTERRATHONCOV / SET INTERRATHONCOV
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Contents
3. Inter-RAT Handover1. Inter-RAT Handover Overview
2. Inter-RAT Handover Procedure
3. Signaling Procedures for Inter-RAT Handover
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The signaling procedures for PS and CS inter-RAT handover are different:
• UMTS-to-GSM Handover in CS Domain
• UMTS to GSM Handover in PS Domain
Signaling Procedures for Inter-RAT Handover
256
UMTS-to-GSM Handover in CS Domain
257
UMTS-to-GSM Handover in CS Domain
1. The SRNC sends the 3G MSC a RANAP message RELOCATION REQUIRED ifthe condition of inter-RAT outgoing handover is met.
2. As indicated in the received message, the 3G MSC forwards this request to the 2G MSC on the MAP/E interface through a MAP message PREPARE HANDOVER.
3. The 2G MSC forwards the request to the BSC. The message shown in the figure is for reference only and is subject to the actual condition of the GSM.
4. The BSC responds to this request. The message shown in the figure is for reference only and is subject to the actual condition of the GSM.
5. Once the initial procedures are completed in the 2G MSC/BSS, the 2G MSC returns a MAP/E message PREPARE HANDOVER RESPONSE.
6. The 3G MSC sends the SRNC a RANAP message RELOCATION COMMAND.
7. The SRNC sends the UE an RRC message HANDOVER FROM UTRAN throughthe existing RRC connection. This message may include information from one or several other systems.
8. The BSC performs handover detection. The figure does not show such procedures as GSM BSS synchronization. The message shown in the figure is for reference only and is subject to the actual condition of the GSM.
9. The UE sends the BSC a HANDOVER COMPLETE message.
10. The BSC sends the MSC a HANDOVER COMPLETE message. The message shown in the figure is for reference only and is subject to the actual condition of the GSM.
11. After detecting the UE in the coverage area of the GSM, the MSC sends the CN a MAP/E message SEND END SIGNAL REQUEST.
12. The CN sends the former SRNC an IU RELEASE COMMAND message, requesting the former SRNC to release the allocated resource.
13. After the bearer resource is released in the UMTS, the former SRNC sends the CN an IU RELEASE COMPLETE message.
14. After the call ends, the CN sends the MSC a MAP/E message SEND END SIGNAL RESPONSE.
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UMTS-to-GSM Handover in PS Domain
The signal quality of the WCDMA cell where the UE camps on is dissatisfactory or the load of
the serving cell is heavy.
When the UE is in CELL_DCH state, the UTRAN sends a CELL CHANGE ORDER message to the UE to perform a handover to GSM by cell reselection.
The NodeB sends a RADIO LINK FAILURE INDICATION message, because the UE shuts down transmission towards the WCDMA cell after cell reselection to a GSM cell.
After the UE accesses a GSM cell, the SGSN directly sends an IU RELEASE COMMAND message to the SRNC, if the Packet Data Protocol (PDP) context does not need to be transferred.
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UMTS-to-GSM Handover in CS Domain
1. The UE in CELL_DCH state or the UTRAN (when the UE is in CELL_FACH state) decides to initiate an inter-RAT handover in the PS domain to hand over the UE to a new GSM cell and stop the data transmission between the UE and the network.
2. The UE sends a ROUTING AREA UPDATE REQUEST message to the 2G SGSN. The Update Type in the message indicates RA update, combined RA/LA update, or combined RA/LA update with IMSI attach. The BSS adds the CGI including the RAC and LAC of the cell to the received message before forwarding the message to a new 2G SGSN.
3. The new 2G SGSN sends an SGSN CONTEXT REQUEST message to the old 3G SGSN to obtain the MM and PDP contexts. The old 3G SGSN validates the old P-TMSI Signature. If the old P-TMSI Signature is valid, the old 3G SGSN starts a timer. Otherwise, the old 3G SGSN responds with an error cause.
4. If the UE stays in connected mode before handover, the old 3G SGSN sends an SRNS CONTEXT REQUEST message. After receiving this message, the SRNS buffers the DPUs, stops sending the PDUs to the UE, and sends an SRNS CONTEXT RESPONSE message to the old 3G SGSN.
5. The old 3G SGSN sends an SGSN CONTEXT RESPONSE message to the 2GSGSN, including the MM and PDP contexts.
6. The security functions can be executed.
7. The new 2G SGSN sends an SGSN CONTEXT ACKNOWLEDGE message to theold 3G SGSN. This informs the old 3G SGSN that the new 2G SGSN is ready to receive the PDUs belonging to the activated PDP contexts.
8. The old 3G SGSN sends a DATA FORWARD COMMAND message to the SRNS. The SRNS starts a data-forwarding timer and sends the buffered PDUs to the old 3G SGSN.
9. The old 3G SGSN tunnels the GTP PDUs to the new 2G SGSN. In the PDUs, the sequence numbers in the GTP header remain unchanged.
10. The new 2G SGSN sends an UPDATE PDP CONTEXT REQUEST message to each related GGSN. Each GGSN sends an UPDATE PDP CONTEXT RESPONSE message after updating its PDP context fields.
11. The new 2G SGSN sends an UPDATE GPRS LOCATION message, requesting the HLR to modify the SGSN number.
12. The HLR sends a CANCEL LOCATION message to the old 3G SGSN. The old 3G SGSN responds with a CANCEL LOCATION ACK message. After the timer expires, the old 3G SGSN removes the MM and PDP contexts.
13. The old 3G SGSN sends an IU RELEASE COMMAND message to the SRNS. After the data-forwarding timer expires, the SRNS responds with an IU RELEASE COMPLETE message.
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UMTS-to-GSM Handover in CS Domain
14. The HLR sends an INSERT SUBSCRIBER DATA message to the new 2G SGSN. The 2G SGSN constructs an MM context and PDP contexts for the UE and returns an INSERT SUBSCRIBER DATA ACK message to the HLR.
15. The HLR sends an UPDATE GPRS LOCATION ACK message to the new 2G SGSN.
16. If the association has to be established, the new 2G SGSN sends a LOCATION UPDATE REQUEST message to the VLR. The VLR stores the SGSN number for creating or updating the association.
17. If the subscriber data in the VLR is marked as not confirmed by the HLR, the new VLR informs the HLR. The HLR cancels the old VLR and inserts subscriber data in the new VLR.
1. The new VLR sends an UPDATE LOCATION message to the HLR.2. The HLR cancels the data in the old VLR by sending a CANCEL
LOCATION message to the old VLR.3. The old VLR acknowledges the message by responding with a
CANCEL LOCATION ACK message.4. The HLR sends an INSERT SUBSCRIBER DATA message to the
new VLR.5. The new VLR acknowledges the message by responding with an
INSERT SUBSCRIBER DATA ACK message.6. The HLR responds with a UPDATE LOCATION ACK message to the
new VLR.18. The new VLR allocates a new TMSI and responds with a LOCATION UPDATE
ACCEPT message to the 2G SGSN.
19. The new 2G SGSN checks the presence of the MS in the new RA. If all checks are successful, the new 2G SGSN constructs the MM and PDP contexts for the MS. A logical link is established between the new 2G SGSN and the UE. The 2G SGSN responds to the UE with a ROUTING AREA UPDATE ACCEPT message.
20. The UE acknowledges the new P-TMSI by returning a ROUTING AREA UPDATE COMPLETE message, including all PDUs successfully sent to the UE before the routing area update procedure.
21. The new 2G SGSN sends a TMSI REALLOCATION COMPLETE message to the new VLR if the UE confirms the VLR TMSI.
22. The 2G SGSN and the BSS perform the BSS PACKET FLOW CONTEXT procedure.
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Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
WCDMA Load Control
The WCDMA system is a self interference system. As the load of the WCDMA system increases, the interference rises. A relatively high interference may affect the coverage and Quality of Service (QoS) of established services. Therefore, capacity, coverage and QoS of the WCDMA system are mutually affected. The purpose of load control is to maximize the system capacity while ensuring coverage and QoS.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
ObjectivesUpon completion of this course, you will be able to:
Know load control principles
Know load control realization methods in WCDMA system
Know load control parameters in WCDMA system
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. Load Control Overview
2. Load Control Algorithms
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. Load Control Overview
1.1 Load Control Algorithms Overview
1.2 Load Measurement
1.3 Priorities Involved in Load Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load DefinitionLoad: the occupancy of capacity
Two kinds of capacity in WCDMA system
Hard capacity
Cell DL OVSF Code
NodeB Transport resource
NodeB processing capability (NodeB credit)
Soft capacity
Cell Power (UL and DL)
WCDMA network load can be defined by 4 factors:1,Power ,include DL transmitting power of cell and increased UL interference (RTWP).2,DL OVSF code of a cell3,DL and UL NodeB processing capability which is defined by NodeB credit.4,Iub transmission bandwidth of a NodeBThe power resource is related to the mobility, distribution of the UE and also effected by the radio conditions. Therefore, for a fixed power resource, the numbers of service can be supported is not a fix result. We believe the UL and DL power resources are soft.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
The Objectives of Load ControlKeeping system stable
Maximizing system capacity while ensuring coverage and
QoS
Realize different priorities for different service and different
user
WCDMA network load can be defined by 4 factors:1,Power ,include DL transmitting power of cell and increased UL interference (RTWP).2,DL OVSF code of a cell3,DL and UL NodeB processing capability which is defined by NodeB credit.4,Iub transmission bandwidth of a NodeBThe power resource is related to the mobility, distribution of the UE and also effected by the radio conditions. Therefore, for a fixed power resource, the numbers of service can be supported is not a fix result. We believe the UL and DL power resources are soft.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load Control Algorithms
The load control algorithms are applied to the different
UE access phases as follows:
PUC: Potential User Control CAC: Call Admission Control
IAC: Intelligent Admission Control LDB : Intra-frequency Load Balancing
LDR: Load Reshuffling OLC: Overload Control
The load control algorithms are applied to the different UE access phases as follows:Before UE access: Potential User Control (PUC)During UE access: Intelligent Access Control (IAC) and Call Admission Control (CAC)After UE access: intra-frequency Load Balancing (LDB), Load Reshuffling (LDR), and Overload Control (OLC)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load Control AlgorithmsLoad control algorithm in the WCDMA system
The load control algorithms are built into the RNC. The input of load control comes from the RNC and measurement information of the NodeB. RNC can calculate hard resource load, that is OVSF ,NodeB credit, Iub occupancy. The soft load need the NodeB reporting.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. Load Control Overview
1.1 Load Control Algorithms Overview
1.2 Load Measurement
1.3 Priorities Involved in Load Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Soft Load Measurement The major measurement objects of the load measurement
Received scheduled Enhanced Dedicated Channel (E-DCH) power share (RSEPS)
•Uplink Received Total Wideband Power (RTWP)
UL Load
HSDPA GBP
HSDPA PBR
Non-HSPA TCPDL Load
TCP
E-DCH Provided Bit Rate
The soft load control algorithms use load measurement values in the uplink and the downlink. A common Load Measurement (LDM) algorithm is required to control load measurement in the uplink and the downlink.The NodeB and the RNC perform measurements and filtering in accordance with the parameter settings. The statistics obtained after the measurements and filtering serve as the data input for the load control algorithms.The major measurement objects of the LDM are as follows:Uplink Received Total Wideband Power (RTWP)
•Received scheduled Enhanced Dedicated Channel (E-DCH) power share (RSEPS)•E-DCH Provided Bit Rate
Downlink Transmitted Carrier Power (TCP)TCP of all codes not used for High Speed Physical Downlink Shared Channel (HS-
PDSCH), High Speed Shared Control Channel , (Non-HSPA TCP)Provided Bit Rate on HS-DSCH (PBR) HS-DSCH required power ,also called Guaranteed Bit Rate (GBR) required power
(GBP)
Based on the measurement parameters set on the NodeB Local Maintenance Terminal (LMT), the NodeB measures the major measurement quantities and then obtains original measurement values. After layer 3 filtering on the NodeB side, the NodeB reports the cell measurement values to the RNC.Based on the measurement parameters set on the RNC LMT, the RNC performs smooth filtering on the measurement values reported from the NodeB and then obtains the measurement values, which further serve as data input for the load control algorithms.
Filtering on the NodeB Side
A is the sampling value of the measurement.B is the measurement value after layer 1 filtering.C is the measurement value after layer 3 filtering ,which is the reported measurement value
Layer 1 filtering is not standardized by protocols and it depends on vendor equipment. Layer 3 filtering is standardized. The filtering effect is controlled by a higher layer.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load Measurement procedure
Smooth Window Filtering on the RNC Side
N : the size of the smooth window
: the reported measurement value
1
0( )
N
n ii
PP n
N
−
−==∑
nP
The interval at which the NodeB reports each measurement quantity to the RNC is configured by the Time unit and Report cycle on RNC LMT: SET LDMThe report interval = Time unit * Report cycleBy default, Time unit for all measurement are set to 10ms ;Report cycle for RTWP is 100, that is 1s; Report cycle for TCP and Non HSPA TCP is 20 ,that is 200ms ;Report cycle for HSDPA GBP is 10, that is 100 ms; Report cycle for HSDPA PBR is 10, that is 100 ms
Smooth Window Filtering on the RNC SideAfter the RNC receives the measurement report, it filters the measurement value with the smooth window.Assuming that the reported measurement value is Qn and that the size of the smooth window is N, the filtered measurement value is :
Delay susceptibilities of PUC, CAC, LDB,LDR, and OLC to common measurement are different. The LDM algorithm must apply different smooth filter coefficients and measurement periods to those algorithms , on RNC LMT, we can set the smooth window length for different algorithms by SET LDM:The following table lists the parameters :
251 to 32DlOLCAvgFilterLenDL OLC moving average filter length
251 to 32UlOLCAvgFilterLenUL OLC moving average filter length
31 to 32DlCACAvgFilterLenDL CAC moving average filter length
31 to 32UlCACAvgFilterLenUL CAC moving average filter length
251 to 32DlLdrAvgFilterLenDL LDR moving average filter length
251 to 32UlLdrAvgFilterLenUL LDR moving average filter length
321 to 32LdbAvgFilterLenLDB moving average filter length
321 to 32PucAvgFilterLenPUC moving average filter length
default Value
Value RangeParameter IDParameter Name
Smooth window for GBP for all related algorithms are the same and the default setting is 1
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents1. Load Control Overview
1.1 Load Control Algorithms Overview
1.2 Load Measurement
1.3 Priorities Involved in Load Control
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
PriorityThe service of user with low priority will be affected by the
load control algorithms first
Three kinds of priorities
User Priority
RAB Integrate Priority
User Integrate Priority
User Priority: mainly applying to provide different QoS for different users. Eg., setting different GBR according to the user priority for BE service. No consideration about the service.RAB Integrate Priority: Priority of a service, related to the service type, and the user priority of the user.User Integrate Priority: Only used for multi-RAB user ,it is a temporary priority of an ongoing-service user.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
User PriorityThere are three levels of user priority
gold (high), silver (middle) and copper (low) user
32kbps64kbps128kbpsUplink
CopperSilverGoldUser priority
32kbps64kbps128kbpsDownlink
gold user
Pay $100 for 3G
services
In CN HLR, we can set ARP (Allocation Retention Priority ), during service setup, CN sends ARP to RNC .Based on the mapping relation( configured in RNC), RNC can identify the user is a gold, silver or copper one.The user priority affect GBR of BE service in RAN, Iub transmission management and so on.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
User PriorityThe mapping relation between user priority and ARP
(Allocation/Retention Priority) is configured in RNC by SET USERPRIORITY
The default relation is:
CopperSilverGoldUser Priority
151413121110987654321ARP
The user priority mapping can be configured in RNC by SET USERPRIORITYARP 15 is always the lowest priority and it cannot be configured. It corresponds to copper. If ARP is not received in messages from the Iu interface, the user priority is regarded as copper.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
RAB Integrate PriorityRAB Integrate Priority is mainly used in load control
algorithms
RAB Integrate Priority are set according to :
ARP
Traffic Class
THP(for interactive service only)
HSPA or DCH
RAB Integrate Priority is mainly used in load control algorithms.The values of RAB Integrate Priority are set according to the Integrate Priority Configured Reference parameter as follows:If Integrate Priority Configured Reference is set to Traffic Class, the integrate priority abides by the following rules:
Traffic classes: conversational -> streaming -> interactive -> background =>Services of the same class: Priority based on Allocation/Retention Priority (ARP) values, that is, ARP1 -> ARP2 -> ARP3 -> ... -> ARP14 =>Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP, defined in CN , sent to RNC during service setup), that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>Services of the same ARP, class and THP (only for interactive services): High Speed Packet Access (HSPA) or Dedicated Channel (DCH) service preferred depending on the value of the Indicator of Carrier Type Priority parameter.
If Integrate Priority Configured Reference is set to ARP, the integrate priority abides by the following rules:
ARP1 -> ARP2 -> ARP3 -> ... -> ARP14 =>Traffic classes: conversational -> streaming -> interactive -> background =>Only for the interactive service of the same ARP value: priority based on Traffic Handling Priority (THP), that is, THP1 -> THP2 -> THP3 -> ... -> THP14 =>Services of the same ARP, class and THP (only for interactive services): HSPA or DCH service preferred depending on the value of the Indicator of Carrier Type Priority parameter.Integrate Priority Configured Reference and Indicator of Carrier Type Priority are set by SET USERPRIORITY .By default Integrate Priority Configured Reference is set to ARPIndicator of Carrier Type Priority is set to NONE, that means HSDPA and DCH services have the same priority.
ARP and THP are carried in the RAB ASSIGNMENT REQUEST message, and they are not configurable on the RNC LMT.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Example for RAB Integrate Priority
DCHBackground2D
DCHConversational2C
HSDPAInteractive1B
DCHInteractive1A
Bear type
Traffic ClassARPService ID
Services attribution in the cell
Based on ARP, HSDPA priority is higher
Based on Traffic Class, HSDPA priority is higher
DCHBackground2D
DCHConversational2C
DCHInteractive1A
HSDPAInteractive1B
Bear type
Traffic ClassARPService ID
BackgroundInteractiveInteractiveConversational
Traffic Class
DCH2D
DCH1A
HSDPA1B
DCH2C
Bear type
ARPService ID
This example shows the RAB Integrate Priority calculation in 2 different conditions
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
User Integrate PriorityWhen the user has one RAB, User integrate priority is the
same as the RAB integrate priority
For multiple RAB users, the integrate priority of the user is
based on the service of the highest priority
When the user has one RAB, User integrate priority is the same as the service of the RAB integrate priority;For multiple RAB users, the integrate priority of the user is based on the service of the highest priority.User integrate priority is used in user-specific load control. For example, the selection of R99 users during preemption, the selection of users during inter-frequency load handover for LDR, and the selection of users during switching BE services to CCH are performed according to the user integrate priority.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Integrate Priority Configured Reference
Parameter ID: PRIORITYREFERENCE
The default value of this parameter is ARP
Indicator of Carrier Type Priority
Parameter ID: CARRIERTYPEPRIORIND
The default value of this parameter is NONE
Key parameters of Priority
Integrate Priority Configured ReferenceParameter ID: PRIORITYREFERENCE Value range: ARP, Traffic Class Content: This parameter is used to set the criterion by which the priority is first sorted. The default value of this parameter is ARPSet this parameter through SET USERPRIORITY
Indicator of Carrier Type PriorityParameter ID: CARRIERTYPEPRIORIND Value range: NONE, DCH, HSPA Content: This parameter is used to decide which carrier (DCH or HSPA) takes precedence when ARP and Traffic Class are identical. When this parameter is set to NONE, the bearing priority of services on the DCH is the same as that of HSPA services. The default value of this parameter is NONE,Set this parameter through SET USERPRIORITY
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
PUC PrinciplesThe Potential User Control (PUC) algorithm controls the
Inter-frequency cell reselection of the potential UE, and
prevents UE from camping on a heavily loaded cell.
Potential UE :
IDLE Mode UE
CELL-FACH UE,CELL-PCH UE,URA-PCH UE
The function of PUC is to balance traffic load among inter-frequency cells. By modifying cell selection and reselection parameters and broadcasting them through system information, PUC leads UEs to cell with light load. The UE may be in idle mode, Cell_FACH state, Cell _PCH state, URA_PCH state
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
PUC Load Judgment
Cell load for PUC is of three states: heavy, normal, and lightThe RNC periodically monitors the downlink load of the cell and compares the measurement results with the configured thresholds Load level division threshold 1 and Load level division threshold 2, that is, load level division upper and lower thresholds. If the cell load is higher than the load level division upper threshold plus the Load level division hysteresis, the cell load is considered heavy.If the cell load is lower than the load level division lower threshold minus the Load level division hysteresis, the cell load is considered light.Otherwise the cell load is considered normal
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
PUC Procedure
NodeB UE
Heavy?
Light?
Normal?
Cell TCP
RNC
Threshold
cell reselection parameters
Every 200ms
Every 30 minutes
System information
The parameters related to cell selection and cell reselection are Qoffset1(s,n) (load level offset), Qoffset2(s,n) (load level offset), and Sintersearch (start threshold for inter-frequency cell reselection).The NodeB periodically reports the total TCP of the cell, and the PUC periodically triggers the following activities:Assessing the cell load level based on the total TCPConfiguring Sintersearch, Qoffset1(s,n), and Qoffset2(s,n) based on the cell load levelPUC can Modify inter-frequency cell reselection parameters based on the load:1. Sintersearch :
when the load of a cell is “Heavy”, PUC will increase Sintersearch
when the load of a cell is “Light”, PUC will decrease Sintersearch
2. QOffset:when the load of current cell is “Heavy” and neighbor is “Non heavy”, PUC will decrease
QOffset
when the load of current cell is “Non heavy” and neighbor is “Heavy”, PUC will increase QOffset
Updating the parameters of system information SIB3 and SIB11
→: indicates that the parameter value remains unchanged.↗: indicates that the parameter value increases.↘: indicates that the parameter value decreases.
↗S'intersearch = Sintersearch + Sintersearch offset 2Heavy
→S'intersearch = SintersearchNormal
↘S'intersearch = Sintersearch + Sintersearch offset 1Light
Change of Sintersearch
SintersearchLoad of Current Cell
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
PUC Principles
Freq1
Freq2
System InfoSIB3,11
System InfoSIB3,11
System InfoSIB3,11
Heavy load
Light load Normal load
Idle state CCH state
Modify
1.Easy to trigger reselection2.Easy to select light loadInter-freq neighbor Cell
Decrease the POTENTIAL load
Modify
1.Hard to trigger reselection2.Easy to camp on the cell
Increase the POTENTIAL load
Stay
Based on the characteristics of inter-frequency cell selection and reselection.Sintersearch
When this value is increased by the serving cell, the UE starts inter-frequency cell reselection ahead of schedule.
When this value is decreased by the serving cell, the UE delays inter-frequency cell reselection.
Qoffset1(s,n): applies to R (reselection) rule with CPICH RSCPWhen this value is increased by the serving cell, the UE has a lower probability of
selecting a neighboring cell.When this value is decreased by the serving cell, the UE has a higher probability
of selecting a neighboring cell.
Qoffset2(s,n): applies to R (reselection) rule with CPICH Ec/I0When this value is increased by the serving cell, the UE has a lower probability of
selecting a neighboring cell.When this value is decreased by the serving cell, the UE has a higher probability
of selecting a neighboring cell.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell LDC algorithm switch
Parameter ID: NBMLDCALGOSWITCH PUC
The default value of this parameter is Off
Load level division threshold 1 (Heavy)
Parameter ID: SPUCHEAVY
The default value of this parameter is 70(70%)
Load level division threshold 2 (Light)
Parameter ID: SPUCLIGHT
The default value of this parameter is 45(45%)
Key parameters PUC
Cell LDC algorithm switchParameter ID: NBMLDCALGOSWITCH PUCValue range: OFF, ON Content: This parameter is used to enable or disable the PUC algorithm.. The default value of this parameter is OFFSet this parameter through ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
Load level division threshold 1 (Heavy)Parameter ID: SPUCHEAVY Value range: 0 to 100 Content: This parameter is one of the thresholds used to assess cell load level and to decide whether the cell load level is heavy or not. The default value of this parameter is 70%,Set this parameter through ADD CELLPUC / MOD CELLPUC
Load level division threshold 2 (Light)Parameter ID: SPUCLIGHT Value range: 0 to 100 Content: This parameter is one of the thresholds used to assess cell load level and to decide whether the cell load level is heavy or not. The default value of this parameter is 45%,Set this parameter through ADD CELLPUC / MOD CELLPUC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load level division hysteresis
Parameter ID: SPUCHYST
The default value of this parameter is 5 (5%)
PUC period timer length
Parameter ID: PUCPERIODTIMERLEN
The default value of this parameter is 1800(s)
Key parameters PUC
Load level division hysteresisParameter ID: SPUCHYST Value range: OFF, ON Content: This parameter specifies the hysteresis used during cell load level assessment to avoid unnecessary ping-pong effect of a cell between two load levels due to a little load change. The default value of this parameter is 5 (5%)Set this parameter through ADD CELLPUC / MOD CELLPUC
PUC period timer lengthParameter ID: PUCPERIODTIMERLEN Value range: 6 to 86400 sContent: This parameter specifies the period of potential user control. The higher the parameter is set, the longer the period to trigger the PUC is. The default value of this parameter is 1800(s) Set this parameter through SET LDCPERIOD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Sintersearch offset 1
Parameter ID: OFFSINTERLIGHT
The default value of this parameter is –2 (-4dB)
Sintersearch offset 2
Parameter ID: OFFSINTERHEAVY
The default value of this parameter is 2 (4dB)
Key parameters PUC
Sintersearch offset 1Parameter ID: OFFSINTERLIGHT Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Sintersearch when the center cell load level is "Light". It is strongly recommended that this parameter be set to a value not higher than 0. The default value of this parameter is –2 (-4dB)Set this parameter through ADD CELLPUC / MOD CELLPUC
Sintersearch offset 2Parameter ID: OFFSINTERHEAVY Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Sintersearch when the center cell load level is "Heavy". It is strongly recommended that this parameter be set to a value not lower than 0. The default value of this parameter is 2 (4dB)Set this parameter through ADD CELLPUC / MOD CELLPUC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Qoffset1 offset 1
Parameter ID: OFFQOFFSET1LIGHT
The default value of this parameter is –4 (-8dB)
Qoffset1 offset 2
Parameter ID: OFFQOFFSET1HEAVY
The default value of this parameter is 4 (8dB)
Key parameters PUC
Qoffset1 offset 1Parameter ID: OFFQOFFSET1LIGHT Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset1(RSCP) when the current cell has heavy load and the neighboring cell has light or normal load. To enable the UE to select a neighboring cell with relatively light load, it is strongly recommended that this parameter be set to a value not higher than 0. The default value of this parameter is -4 (-8dB)Set this parameter through ADD CELLPUC/MOD CELLPUC
Qoffset1 offset 2Parameter ID: OFFQOFFSET1HEAVY Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset1(RSCP) when the load of a neighboring cell is heavier than that of the center cell. To enable the UE to select a neighboring cell with relatively light load, it is strongly recommended that this parameter be set to a value not lower than 0. The default value of this parameter is 4 (8dB)Set this parameter through ADD CELLPUC/MOD CELLPUC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Qoffset2 offset 1
Parameter ID: OFFQOFFSET2LIGHT
The default value of this parameter is –4 (-8dB)
Qoffset2 offset 2
Parameter ID: OFFQOFFSET2HEAVY
The default value of this parameter is 4 (8dB)
Key parameters PUC
Qoffset1 offset 1Parameter ID: OFFQOFFSET1LIGHT Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset1(RSCP) when the current cell has heavy load and the neighboring cell has light or normal load. To enable the UE to select a neighboring cell with relatively light load, it is strongly recommended that this parameter be set to a value not higher than 0. The default value of this parameter is -4 (-8dB)Set this parameter through ADD CELLPUC/MOD CELLPUC
Qoffset1 offset 2Parameter ID: OFFQOFFSET2HEAVY Value range: –10 to 10 ,step:2dBContent: This parameter defines the offset of Qoffset2(EcNo) when the load of a neighboring cell is heavier than that of the center cell. To enable the UE to select a neighboring cell with relatively light load, it is strongly recommended that this parameter be set to a value not lower than 0. The default value of this parameter is 4 (8dB)Set this parameter through ADD CELLPUC / MOD CELLPUC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Intra-Frequency Load BalancingIntra-frequency Load Balancing (LDB) is performed to adjust
the coverage areas of cells by modifying PCPICH power
LDB affect UEs in all states
Intra-frequency Load Balancing (LDB) is performed to adjust the coverage areas of cells according to the measured values of cell downlink power load. RNC checks the load of cells periodically and adjusts the transmit power of the P-CPICH in the associated cells based on the cell load.When the load of a cell increases, the cell reduces its coverage to lighten its load. When the load of a cell decreases, the cell extends its coverage so that some traffic is off-loaded from its neighboring cells to it. Reduction of the pilot power will make the UEs at the edge of the cell handed over to neighboring cells, especially to those with a relatively light load and with relatively high pilot power. After that, the downlink load of the cell is lightened accordingly.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDB Procedure
NodeB UE
Heavy?
Light?
Normal?
Cell TCP
RNC
Threshold
Modify cell PCPICH power
Updated PCPICH POWER
Handover or
Cell Reselection
The NodeB periodically reports the total TCP of the cell, and the LDB periodically triggers the following activities:Assessing the cell load level based on the total TCPIf the downlink load of a cell is higher than the value of the Cell overload threshold, it is an indication that the cell is heavily loaded. In this case, the transmit power of the P-CPICH needs to be reduced by a step, which is defined by the Pilot power adjustment step parameter. However, if the current transmit power is equal to the value of the Min transmit power of PCPICH parameter, no adjustment is performed.If the downlink load of a cell is lower than the value of the Cell underload threshold, it is an indication that the cell has sufficient remaining capacity for more load. In this case, the transmit power of the P-CPICH increases by a step, which is defined by the Pilot power adjustment step parameter, to help to lighten the load of neighboring cells. However, if the current transmit power is equal to the value of the Max transmit power of PCPICHparameter, no adjustment is performed.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell LDC algorithm switch
Parameter ID: NBMLdcAlgoSwitch LDB
The default value of this parameter is Off
Intra-frequency LDB period timer length
Parameter ID: IntraFreqLdbPeriodTimerLen
The default value of this parameter is 1800 (s)
Key parameters LDB
Cell LDC algorithm switchParameter ID: NBMLdcAlgoSwitch LDB Value range: OFF, ON Content: This parameter is used to enable or disable the LDB algorithm.. The default value of this parameter is OFFSet this parameter through ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
Intra-frequency LDB period timer lengthParameter ID: IntraFreqLdbPeriodTimerLenValue range: 0 to 86400 Content: This parameter specifies the length of the intra-frequency LDB period. The default value of this parameter is 1800 (s)Set this parameter through SET LDCPERIOD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell overload threshold (Heavy)
Parameter ID: CellOverrunThd
The default value of this parameter is 90(90%)
Cell underload threshold (Light)
Parameter ID: CellUnderrunThd
The default value of this parameter is 30(30%)
Key parameters LDB
Cell overload thresholdParameter ID: CellOverrunThd
Value range: 0 to 100 Content: If the downlink load of a cell exceeds this threshold, the algorithm can decrease the pilot transmit power of the cell so as to extend the capacity of the whole system. The default value of this parameter is 90%,Set this parameter through ADD CELLLDB / MOD CELLLDB
Cell underload threshold Parameter ID: CellUnderrunThdValue range: 0 to 100 Content: If the downlink load of a cell is lower than this threshold, the algorithm can increase the pilot transmit power of the cell so as to share the load of other cells. The default value of this parameter is 30%,Set this parameter through ADD CELLLDB / MOD CELLLDB
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Pilot power adjustment step
Parameter ID: PCPICHPowerPace
The default value of this parameter is 2 (0.2dB)
Max transmit power of PCPICH
Parameter ID: MaxPCPICHPower
The default value of this parameter is 346 (34.6dBm)
Key parameters LDB
Pilot power adjustment step Parameter ID: PCPICHPowerPaceValue range: 0 to 10 , Step 0.1dBContent: This parameter defines the step for the adjustment to the pilot power. The default value of this parameter is 2, 0.2dBSet this parameter through ADD CELLLDB / MOD CELLLDB
Max transmit power of PCPICHParameter ID: MaxPCPICHPower
Value range: –100 to 500 ,Step 0.1dBContent: This parameter defines the maximum transmit power of the P-CPICH in a cell.This parameter has to be set according to the actual system environment, that is, for example, cell coverage (radius) and geographical environment. If the maximum transmit power of the P-CPICH is set too low, the cell coverage decreases. When a certain proportion of soft handover area is ensured, any more increase in the pilot power achieves no improvement on the performance of the downlink coverage. The default value of this parameter is 346 (34.6dBm) Set this parameter through ADD PCPICH / MOD PCPICHPWR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Min transmit power of PCPICH
Parameter ID: MinPCPICHPower
The default value of this parameter is 313 (31.3dBm)
Key parameters LDB
Min transmit power of PCPICHParameter ID: MinPCPICHPowerValue range: -100 to 500 Content: This parameter defines the minimum transmit power of the P-CPICH in a cell.This parameter has to be set according to the actual system environment, that is, for example, (radius) and geographical environment. If the minimum transmit power of the P-CPICH is set too low, the cell coverage will be affected. The parameter has to be set under the condition that a certain proportion of soft handover area is ensured or the occurrence of coverage hole can be prevented. The default value of this parameter is 313 (31.3dBm)Set this parameter through ADD PCPICH / MOD PCPICHPWR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Why we need CAC?WCDMA is an interference limited system, after a new call is
admitted, the system load will be increased
If a cell is high loaded, a new call will cause ongoing user
dropped
We must keep the coverage planned by the Radio Network
Planning
CAC is needed under such scenarios:1. RRC connection setup request 2. RAB setup and Bandwidth increasing 3. Handover4. RB reconfiguration
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Flow chart of CAC
The admission decision is based on:• Cell available code resource: managed in RNC• Cell available power resource, that is DL/UL load : measured in NodeB• NodeB resource state, that is, NodeB credits : managed in RNC• Available Iub transport layer resource, that is, Iub transmission bandwidth:
managed in RNC
• HSPA user number (only for HSPA service)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Admission control Switches can be set on RNC LMT:Power CAC
Uplink CAC algorithm switch
Downlink CAC algorithm switch
NodeB Credit CACCAC algorithm switch : CacSwitch
Cell CAC algorithm switch: CRD_ADCTRL
HSDPA user number CACCAC algorithm switch :HSDPA_UU_ADCTRL
HSUPA user number CAC
CAC algorithm switch: HSUPA_UU_ADCTRL
Algorithm Switch of CAC
Except the mandatory code and Iub resource admission control, the admission control based on power and NodeB credit ,HSDPA User Number can be disabled through the LMT command:
Power CAC can be switched off by ADD CELLALGOSWITCH / MOD CELLALGOSWITCHUplink CAC algorithm switch (NBMULCACALGOSELSWITCH ) specifies the algorithm used
for power admission in the uplink. Downlink CAC algorithm switch (NBMDLCACALGOSELSWITCH) specifies the algorithm
used for power admission in the downlink.
NodeB Credit CAC can be switched off by SET CACALGOSWITCH or ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
CAC algorithm switch (CacSwitch) specifies the NodeB level credit CAC algorithmCell CAC algorithm switch (CRD_ADCTRL) specifies the Cell level credit CAC algorithm
HSDPA user number CAC switched off by ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
HSDPA_UU_ADCTRL specifies whether to enable or disable the HSDPA admission control algorithm.
HSUPA user number CAC switched off by ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
HSUPA_UU_ADCTRL specifies whether to enable or disable the HSUPA admission control algorithm
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Code Resource Code Resource CAC functions in:
RRC connection setup
Handover
R99 services RAB setup
Note: RRC connection setup and Handover have higher priority
When a new service attempts to access the network, code resource admission is mandatory.
1. For RRC connection setup requests, the code resource admission is successful if the current remaining code resource is enough for the RRC connection.
2. For handover services, the code resource admission is successful if the current remaining code resource is enough for the service.
3. For other R99 services, the RNC has to ensure that the remaining code does not exceed the configurable threshold after admission of the new service.
4. For HSDPA services, the reserved codes are shared by all HSDPA services. Therefore, the code resource admission is not needed.
So the RRC connection setup and Handover has higher priority to access a cell
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Power Resource UL and DL Power Resource CAC functions in:
R99 cellRRC connection setup
R99 RAB setup
Handover
HSPA cell RRC connection
R99 RAB setup
HSPA RAB setup
Handover
Note: RRC connection setup and Handover have higher priority
The UL CAC and DL CAC are independent .The basic principle of Power CAC is: RNC predict the cell power load after the access. If the load will be higher than a threshold, the admission is failed.So, by setting different threshold for different access, we can realize different priorities.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Power CAC AlgorithmsAlgorithm 1: based on UL/DL load measurement and load
prediction (RTWP and TCP)
Algorithm 2: based on Equivalent Number of User (ENU)
Algorithm 3: loose call admission control algorithm
Huawei provide 3 Power CAC AlgorithmsAlgorithm 1: power resource admission decision based on power or interference.Depending on the current cell load (uplink load factor and downlink transmitted carrier power) and the access request, the RNC determines whether the cell load will exceed the threshold upon admitting a new call. If yes, the RNC rejects the request. If not, the RNC accepts the request.Algorithm 2: power resource admission decision based on the number of equivalent users.Based on Huawei testing and experience, The 12.2 kbit/s AMR traffic is used to calculate the Equivalent Number of Users (ENU) of all other services in UL and DL. The 12.2 kbit/s AMR traffic's ENU is assumed to be 1. Depending on the current number of equivalent users and the access request in UL and DL, the RNC determines whether the number of equivalent users will exceed the threshold upon admitting a new call. If yes, the RNC rejects the request. If not, the RNC accepts the request.Algorithm 3: power resource admission decision based on power or interference, but with the estimated load increment always set to 0.Depending on the current cell load (uplink load factor and downlink TCP) and the access request, the RNC determines whether the cell load will exceed the threshold, with the estimated load increment set to 0. If yes, the RNC rejects the request. If not, the RNC accepts the request.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Basic principle of Uplink CAC Algorithm 1
Get current RTWP, and calculate the current load factor
Admission request
Get the traffic characteristic, and estimate the increment of load factor
Calculate the predicted load factor
admitted rejected
End of UL CAC
Y NSmaller than the threshold?
RTWPPN
UL −= 1η
ηΔ
CCHULpredictedUL ηηηη +Δ+=_
Pn is uplink receive background noise.The procedure for uplink power resource decision is as follows:1. The RNC obtains the uplink RTWP of the cell, and calculate the current uplink load
factor.2. The RNC calculates the uplink load increment ΔηUL based on the service request. 3. The RNC uses the formula ηUL,predicted=ηUL + ΔηUL to forecast the uplink load
factor. 4. By comparing the forecasted uplink load factor ηUL,predicted with the corresponding
threshold ,the RNC decides whether to accept the access request or not.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Basic principle of Downlink CAC Algorithm1
The procedure for downlink power resource decision is as follows:1. The RNC obtains the cell downlink TCP, and calculates the downlink load factor by
multiplying the maximum downlink transmit power by this TCP. 2. The RNC calculates the downlink load increment ΔP based on the service request and
the current load.3. The RNC forecasts the downlink load factor.4. By comparing the downlink load factor with the corresponding threshold (DL threshold
of Conv AMR service, DL threshold of Conv non_AMR service, DL threshold of other services, DL Handover access threshold), the RNC decides whether to accept the access request or not.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Basic principle of CAC Algorithm 2
Get current total ENU
Admission request
Get the traffic characteristic, and estimate the increment of ENU
Calculate the predicted ENU
admitted rejected
End of UL/DL CAC
Y NSmaller than the threshold?
∑=
=N
iitotal ENUNENU
1)(
newENU
newtotaltotal ENUNENUNENU +=+ )()1(
max/)1( ENUNENUENULoad total +=
The procedure for ENU resource decision is as follows:1. The RNC obtains the total ENU of all exist users ENUtotal.2. The RNC get the ENU of the new incoming user ENUnew.3. The RNC forecast the ENU load.4. By comparing the forecasted ENU load with the corresponding threshold (the same
threshold as power resource), the RNC decides whether to accept the access request or not.
The ENUmax can be set by LMT, the ENUnew and ENUi is determined by Huawei algorithm, there is an example in next slide.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Power CAC for RRC connection Setup For the RRC connection request is, tolerance principles are
applied :
Emergency call, Detach , Registration
Direct Admission
RRC connection request for other reasons
UL/ DL OLC Trigger threshold Admission
To ensure that the RRC connection request is not denied by mistake, tolerance principles are applied.
The admission decision is made for the following reasons of the RRC connection request:1. For the RRC connection request for the reasons of emergency call, detach or
registration, direct admission is used ,that is no limitation.2. For the RRC connection request for other reasons, UL/DL OLC Trigger
threshold is used for admission. By default, the OLC trigger threshold isrelatively high (DL/UL 95%), which make the RRC connections are easily set up.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL Power CAC for R99 Cell (Algorithm1)
For R99 DCH RAB Setup, The RNC uses the following formula
to predict the uplink load factor :
Where the
By comparing the predicted uplink load factor ηUL,predicted with the
corresponding threshold ,the RNC decides whether to accept the
access request or not
CCHULULULpredictedUL −+Δ+= ηηηη _
RTWPPN
UL −=1η
The threshold for Conv AMR service , Conv non_AMR service , Other R99 services , Handover are set independently, which provide different priorities.
Normally, Other R99 services < Conv non_AMR service services < Conv AMR service < Handover
The uplink load increment ΔηUL is determined by :1. The Eb/No of the new incoming call2. The uplink load increment is proportional to the value of Eb/No.3. UL neighbor interference factor4. Active Factor of the new incoming call
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL Power CAC for R99 Cell (Algorithm1)
For R99 DCH RAB Setup, The RNC uses the following formula to
predict the downlink load factor :
Where the
By comparing the predicted downlink load factor ηDL,predicted with
the corresponding threshold ,the RNC decides whether to accept
the access request or not
CCHDLDLDLpredictedDL −+Δ+= ηηηη _
maxPTCP
DL =ηmaxP
DLDL
ηη Δ=Δ
The threshold for Conv AMR service , Conv non_AMR service , Other R99 services , Handover are set independently, which provide different priorities.
Normally, Other R99 services < Conv non_AMR service services < Conv AMR service < Handover
The downlink load increment ΔηDL is determined by :1. The Eb/No of the new incoming call 2. Non-orthogonality factor 3. Current transmission carrier power 4. Active Factor of the new incoming call
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL Power CAC for HSPA Cell (Algorithm1)
The power increment of an HSUPA service is related to Ec/No, GBR requirement, neighboring interference factor, active factor of the service. The formula of UL power CAC for HSUPA is similar tothat for R99
After RSEPS measurement is introduced, the UL RTWP is divided into two parts:
Controllable part
The UL interference generated by E-DCH scheduling services belong to the controllable part
Uncontrollable part
RSEPS: Received scheduled E-DCH power share
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL Power CAC for HSPA Cell (Algorithm1)E-DCH scheduling service consists of following two types:
TypeA: all UEs for which this cell is the serving E-DCH cellThe uplink load generated by TypeA E-DCH scheduling service is defined as follows:
TypeB: all UEs for which this cell is
NOT the serving EDCH-cellThe uplink load generated by
TypeB E-DCH scheduling service
is defined by ηUL,EDCH,f,
which is fixed to zero
The Uplink uncontrollable load
Is defined as follows:
RTWPRSEPS
SEDCHUL =− ,η
fEDCHULsEDCHULULctrlnonUL ,,,,, ηηηη −−=−
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL Power CAC for HSPA Cell (Algorithm1)UL Power CAC for HSUPA Scheduling Services and HSUPA Non-Scheduling Services
RNC admits HSUPA scheduling service in either of the following casesFormula 1,2 or 3 is fulfilled
Formula 4 is fulfilled
RNC admits HSUPA Non-scheduling service in either of the following casesFormula 1,2 or 3 is fulfilled
Formula 4 and 5 are fulfilled
ThdL is the Low priority HSUPA user PBR threshold of the current cellThdE is the Equal priority HSUPA user PBR threshold of the current cellThdGE is the High priority HSUPA user PBR threshold of the current cell
ηHS-DPCCH is the value of the UL HS-DPCCH reserve factor parameter, which defines the factor of UL HS-DPCCH resource reservedηthd is the cell UL admission threshold for specific type of service, that is UL threshold of ConvAMR service, UL threshold of Conv non_AMR service, UL threshold of other services or UL handover access service threshold
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL Power CAC for HSPA Cell (Algorithm1)
UL Power CAC for R99 service in HSPA cell
Uncontollable interference must be kept within a given range. The purpose is to ensure the stability of system and to prevent non-scheduling services and DCH services from seizing the resources of HSUPA services
RNC admits R99 services if formula 1 and 2 are fulfilled
thdDPCCHHScchULULctrlnonUL ηηηηη <++Δ+ −− ,,
totalthdDPCCHHScchULULUL −− <++Δ+ ηηηηη .,
ηthd-total is the UL total power threshold of the current cellηthd is the cell UL admission threshold for specific type of service, that is UL threshold of ConvAMR service, UL threshold of Conv non_AMR service, UL threshold of other services or UL handover access service threshold
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL Power CAC for HSPA Cell (Algorithm1)
DL Power incremental estimation for DCH RAB in HSPA
cell is similar to the DCH RAB in R99 cell
DL Power incremental estimation for HSDPA RAB ΔPDL is
made based on GBR, Ec/No, Non-orthogonality factor
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL Power CAC for HSPA Cell (Algorithm1)
DL power CAC for R99 service in HSPA cell
RNC admits R99 service (i.e. DCH RAB) in either of the following situations:
Formula 1 and 2 are fulfilled
Formula 1 and 3 are fulfilled
Pnon-hspa is the current non-HSDPA powerPcch-res is the power reserved for the common channelPmax is the cell maximum transmit powerThdnon-hspa-cac is the cell DL admission threshold for different types of service, that is DL threshold for Conv AMR service, DL threshold for Conv non-AMR service, DL threshold for other service or DL handover access thresholdPtotal is the current downlink transmitted carrier powerThdtotal-cac is the threshold of cell DL total power. It is defined by the DL total power thresholdparameter GBP is power requirement for GBRPhsupa-res is the power reserved for HSUPA downlink control channels (E-AGCH/E-RGCH/E-HICH)Pmax-hspa is the maximum available power for HSPA. Its value is associated with the HSDPA power allocation mode.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL Power CAC for HSPA Cell (Algorithm1)DL power CAC for HSDPA RAB in HSPA cell
RNC admits the HSDPA streaming service in any of the following situations:Formula 1 is fulfilled
Formulas 3 and 4 are fulfilled
Formulas 3 and 5 are fulfilled
RNC admits the HSDPA BE service in any of the following situations:Formula 2 is fulfilled
Formulas 3 and 4 are fulfilled
Formulas 3 and 5 are fulfilled
PBRstrm is the provided bit rate of all existing streaming servicesThdhsdap-str is the admission threshold for streaming PBR decision. It is defined by the Hsdpastreaming PBR threshold parameterPBRbe is the provided bit rate of all existing BE servicesThdhsdap-be is the admission threshold for BE PBR decision. It is defined by the Hsdpa best effort PBR threshold parameterGBR is the power requirement for GBRPhsupa-res is the power reserved for HSUPA downlink control channels (E-AGCH/E-RGCH/E-HICH)Pmax-hspa is the maximum available power for HSPA. Its value is associated with the HSDPA power allocation mode.Ptotal is the current downlink transmitted carrier powerPmax is the cell maximum transmitted powerThdtotal-cac is the threshold of cell DL total power, which is defined by the DL total power threshold parameterPcch-res is the power reserved for the common channelsPnon-hspa is the current non-HSDPA power
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL Power CAC for HSPA Cell (Algorithm1)
DL power CAC for HSUPA control channels in HSPA cell
The power of downlink control channels (E-AGCH/E-RGCH/E-
HICH) are reserved by DL HSUPA reserved factor. Therefore,
the power admission for these channels is NOT needed
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Power CAC for Algorithm2For R99 and HSDPA RAB, The RNC uses the following formula
to predict the uplink load factor :
(ENUtotal + ENUnew) / ENUmax
By comparing the forecasted ENU load with the corresponding
threshold ,the RNC decides whether to accept the access request
or not
ENUtotal is the total ENU of all existing users.ENUnew is ENU of the new incoming user .ENUmax is the configured maximum ENU (UL total equivalent user number or DL total nonhsdpa equivalent user number) .The threshold for Algorithm2 are the same with Algorithm1,for Conv AMR service , Conv non_AMR service , Other R99 services , Handover , HSDPA are set independently:
DL total power thresholdHSDPA
DL threshold of Conv AMR serviceDL threshold of Conv non_AMR serviceDL threshold of other servicesDL Handover access threshold
DL DCH
UL threshold of Conv AMR serviceUL threshold of Conv non_AMR serviceUL threshold of other servicesUL Handover access threshold
UL DCH/HSUPA
Admission ThresholdService Type
Typically ENU (equivalent number of users) for different services (with activity factor to be 100%)
DL total power thresholdHSDPA
DL threshold of Conv AMR serviceDL threshold of Conv non_AMR serviceDL threshold of other servicesDL Handover access threshold
DL DCH
UL threshold of Conv AMR serviceUL threshold of Conv non_AMR serviceUL threshold of other servicesUL Handover access threshold
UL DCH/HSUPA
Admission ThresholdService Type
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL threshold of Conv AMR service
Parameter ID: UlNonCtrlThdForAMR
The default value of this parameter is 75%
UL threshold of Conv non_AMR service
Parameter ID: UlNonCtrlThdForNonAMR
The default value of this parameter is 75%
Key parameters
UL threshold of Conv AMR serviceParameter ID: UlNonCtrlThdForAMRValue range: 0 to 100 %Content: The uplink threshold for the AMR conversational service is used for the uplink admission of AMR conversational service users. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3.The default value of this parameter is 75%Set this parameter through ADD CELLCAC / MOD CELLCAC
UL threshold of Conv non_AMR serviceParameter ID: UlNonCtrlThdForNonAMRValue range: 0 to 100 %Content: The downlink threshold for the AMR conversational service is used for the downlink admission of AMR conversational service users. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3.The default value of this parameter is 75%
Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL threshold of other services
Parameter ID: UlNonCtrlThdForOther
The default value of this parameter is 60%
UL Handover access threshold
Parameter ID: UlNonCtrlThdForHo
The default value of this parameter is 80%
Key parameters
UL threshold of other servicesParameter ID: UlNonCtrlThdForOtherValue range: 0 to 100 %Content: This parameter is the uplink threshold for services other than the conversational service. It is used for uplink admission of other services. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3. The default value of this parameter is 60%Set this parameter through ADD CELLCAC / MOD CELLCAC
UL Handover access thresholdParameter ID: UlNonCtrlThdForHoValue range: 0 to 100 %Content: The uplink handover threshold is used for uplink admission of handover users. The parameter is useful only to uplink inter-frequency handovers. Do not make the admission decision in the uplink soft handover. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3.The default value of this parameter is 80%Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL threshold of Conv AMR service
Parameter ID: DLCONVAMRTHD
The default value of this parameter is 80%
DL threshold of Conv non_AMR service
Parameter ID: DLCONVNAMRTHD
The default value of this parameter is 80%
Key parameters
DL threshold of Conv AMR serviceParameter ID: DLCONVAMRTHDValue range: 0 to 100 %Content: The downlink threshold for the AMR conversational service is used for the downlink admission of AMR conversational service users. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3. The default value of this parameter is 80%Set this parameter through ADD CELLCAC / MOD CELLCAC
DL threshold of Conv non_AMR serviceParameter ID: DLCONVNAMRTHDValue range: 0 to 100 %Content: The downlink threshold for the non-AMR conversational service is used for the downlink admission of non-AMR conversational service users. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3.The default value of this parameter is 80%Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL threshold of other services
Parameter ID: DLOTHERTHD
The default value of this parameter is 75%
DL Handover access threshold
Parameter ID: DLHOTHD
The default value of this parameter is 85%
Key parameters
DL threshold of other servicesParameter ID: DLOTHERTHD Value range: 0 to 100 %Content: This parameter is the downlink threshold for services other than the conversational service. It is used for downlink admission of users of other services. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3.The default value of this parameter is 75%Set this parameter through ADD CELLCAC/MOD CELLCAC
DL Handover access thresholdParameter ID: DLHOTHDValue range: 0 to 100 %Content: The downlink handover threshold is used for downlink admission of handover users. The threshold is shared by algorithm 1, algorithm 2 and algorithm 3. The default value of this parameter is 85%Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL total power threshold
Parameter ID: DLCELLTOTALTHD
The default value of this parameter is 90%
Hsdpa streaming PBR threshold
Parameter ID: HSDPASTRMPBRTHD
The default value of this parameter is 70%
Hsdpa best effort PBR threshold
Parameter ID: HSDPABEPBRTHD
The default value of this parameter is 70%
Key parameters
DL total power thresholdParameter ID: DLCELLTOTALTHD Value range: 0 to 100 %Content: This parameter specifies the total downlink power threshold of the cell. The default value of this parameter is 90%Set this parameter through ADD CELLCAC / MOD CELLCAC
Hsdpa streaming PBR thresholdParameter ID: HSDPASTRMPBRTHDValue range: 0 to 100 %Content: This parameter specifies the average throughput admission threshold of the HSDPA streaming traffic. The default value of this parameter is 70%Set this parameter through ADD CELLCAC / MOD CELLCAC
Hsdpa streaming PBR thresholdParameter ID: : HSDPABEPBRTHD Value range: 0 to 100 %Content: This parameter specifies the average throughput admission threshold of the HSDPA best effort traffic. The default value of this parameter is 70%Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL total equivalent user number
Parameter ID: ULTOTALEQUSERNUM
The default value of this parameter is 80
DL total equivalent user number
Parameter ID: DLTOTALEQUSERNUM
The default value of this parameter is 80
Key parameters
UL total equivalent user numberParameter ID: ULTOTALEQUSERNUM Value range: 1 to 200Content: When algorithm 2 is used, this parameter defines the total equivalent number of users corresponding to the 100% uplink load. The default value of this parameter is 80Set this parameter through ADD CELLCAC/MOD CELLCAC
DL total equivalent user numberParameter ID: DLTOTALEQUSERNUMValue range: 1 to 200Content: When algorithm 2 is used, this parameter defines the total equivalent number of users corresponding to the 100% downlink load. The default value of this parameter is 80Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on NodeB Credit Resource When a new service accesses the network, NodeB credit
resource admission is optional
The principles of NodeB credit admission control are similar
to those of power resource admission control, that is, to
check in the local cell whether the remaining credit can
support the requesting services
CE stands for NodeB credit on RNC side and for Channel Element on NodeB side. It is used to measure the channel demodulation capability of the NodeBsThe resource of one 12.2kbps voice service, including 3.4kbps signaling on the DCCH, consumed in baseband is defined as one CE. If there is 3.4kbps signaling on the DCCH, but no voice channel, one CE is consumed.The credit resource are divided into several resource pools. Each resource pool is shared by a local cell. According to the common and dedicated channels capacity consumption laws, as well as the addition, removal, and reconfiguration of the common and dedicated channels, the Controlling RNC (CRNC) debits the amount of the credit resource consumed from or credits the amount to the Capacity Credit of the local cell group (and local cell , if any) based on the spreading factor.the UL Capacity Credit and DL Capacity Credit are separate, so the CAC is performed in the UL and DL, respectively.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on NodeB Credit Resource For DCH service, MBR is used to calculate the NodeB
Credit based on spreading factor :
The total NodeB Credit Resource of a local cell is depend on
the configuration.
204UL 384 kbit/s PS
88DL
108UL 128 kbit/s PS
416DL
616UL 64 kbit/s PS
232DL
332UL 32 kbps PS
164DL
616UL 64 kbit/s VP
232DL
264UL 12.2 kbit/s AMR
1128DL
264UL 13.6 kbit/s SRB
1128DL
2256UL 3.4 kbit/s SRB
1256DL
Typical Traffic ClassCorresponding Credits ConsumedSpreading Factor
Direction
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on NodeB Credit Resource
For HSUPA service, the rate used to calculate the
spreading factor is MBR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on NodeB Credit Resource When a new service tries to access the network, the credit
resource admission CAC functions in :
RRC connection setup
Handover service
The other services
For an RRC connection setup request, the credit resource admission is successful if the current remaining credit resource is sufficient for the RRC connection.For a handover service, the credit resource admission is successful if the current remaining credit resource is sufficient for the service.For other services, the RNC has to ensure that the remaining credit does not exceed the configurable thresholds after admission of the new services.There is no capacity consumption law for HS-DSCH in 3GPP TS 25.433, so certain credits are reserved for HSDPA RAB, and credit admission for HSDPA is not needed.UL Capacity Credit and DL Capacity Credit are separate, the credit resource admission is implemented in the UL and DL, respectively.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Ul HandOver Credit Reserved SF
Parameter ID: UlHoCeResvSf
The default value of this parameter is SF16
Dl HandOver Credit and Code Reserved SF
Parameter ID: DlHoCeCodeResvSf
The default value of this parameter is SF32
Key parameters
Ul HandOver Credit Reserved SFParameter ID: UlHoCeResvSfValue range: SF4, SF8, SF16, SF32, SF64, SF128, SF256, SFOFF Content: The spreading factor specified by this parameter is used to define the uplink credit resource reserved for handover services.SFOFF means that none of resources are reserved for handover services. If the remaining uplink resource cannot fulfill the requirement for the reserved resource after the admission of a new service, the service is rejected. The default value of this parameter is SF16 Set this parameter through ADD CELLCAC / MOD CELLCAC
Dl HandOver Credit and Code Reserved SFParameter ID: DlHoCeCodeResvSfValue range: SF4, SF8, SF16, SF32, SF64, SF128, SF256, SFOFF Content: The spreading factor specified by this parameter is used to define the downlink credit and channelized code resources reserved for handover services.SFOFF means that none of the resources is reserved for handover. If the remaining downlink resource cannot fulfill the requirement for the reserved resource after the access of a new service, the service is rejected. The default value of this parameter is SF32Set this parameter through ADD CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Iub Interface Resource The CAC of the Iub transmission resources is similar
Admission Control is used to determine whether the Iub
resources are enough to accept a new access request
It functions in:
RRC connection setup and Services RAB setup
Handover
A user accessing the network from a path should go through the admission of the path, resource group, and physical port in turn. The user that passes all the admission can be successfully admitted by the transport layer. Path means AAL2 PATH, IP PATHThe physical ports correspond to IMA, UNI, FRAATM, NCOPT, ETHER, PPP, and MLPPP. The priority of the 2 types of access follows : Handover >RRC connection setup and Services RAB setup
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Iub Interface Resource
Iub OverbookingThe Iub overbooking feature considers the statistic multiplexing
of service activities and multiple users
Admit more users, increases the resource utilization on the Iub
interface.
The Iub overbooking feature considers the statistic multiplexing of service activities and multiple users. Through the admission of more users, Iub overbooking increases the resource utilization on the Iub interface.If the RNC allocates the maximum bandwidth to the subscriber when a service is established, a large proportion of the Iub transmission bandwidth is unused. For example, downloading a 50 KB page takes only about one second, but reading this page needs dozens of seconds. Thus, over 90% of the Iub transmission bandwidth is not used.To save the Iub transmission bandwidth for operator use, Huawei provides the Iub overbooking function, which applies an admission control mechanism to access the service.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Iub Interface Resource
Iub Overbooking CS voice services
Service rate:12.2 kbit/s
SID
PS interactive and background services
Download time
Reading time
The UMTS supports four traffic classes: conversational, streaming, interactive, and background. The transmission rate varies with the traffic class as follows:For Circuit Switched (CS) conversational services, the channel transmits voice signals at a certain rate (for example, 12.2 kbit/s) during a conversation and only transmits Silence Descriptors (SIDs) at intervals when there is no conversation.For Packet Switched (PS) interactive and background services, such as web browsing, there is data transmitted during data downloading. After a web page has been downloaded, and when the user is reading the page, however, there is very little data to transfer.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Iub Interface Resource
Iub OverbookingCS voice services
Activity Factor
PS interactive and background services
GBR
MML
SET DEFAULTFACTORTABLE
SET USERGBR
SET CORRMALGOSWITCH (IUB_OVERBOOKING_SWITCH)
ADD AAL2PATH
ADD IPPATH
Use SET DEFAULTFACTORTABLE to set a default of Activity Factor table for all the services. Use SET USERGBR to set GBR for BE servicesUse SET CORRMALGOSWITCH (IUB_OVERBOOKING_SWITCH) to define the switch of Iub overbooking
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
CAC Based on Number of HSPA Users
HSPA user number can be limited in:
Cell level
maximum number of HSPA users in a cell
NodeB level
Maximum number of HSPA users in all the cells configured in
one NodeB
When the HSDPA_UU_ADCTRL is on, the HSDPA services have to undergo HSDPA user number admission decision. When a new HSDPA service attempts to access the network, it is admitted if the number of HSDPA users in the cell and that in the NodeB do not exceed the associated thresholds
When the HSUPA_UU_ADCTRL is on, the HSUPA services have to undergo HSUPA user number admission decision. When a new HSUPA service attempts to access the network, it is admitted if the number of HSUPA users in the cell and that in the NodeB do not exceed the associated thresholds
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
HSDPA_UU_ADCTRLParameter ID: HSDPA_UU_ADCTRL
Maximum HSDPA user numberParameter ID: MaxHSDSCHUserNum
The default value of this parameter is 64
HSDPA_UU_ADCTRLParameter ID: HSUPA_UU_ADCTRL
Maximum HSUPA user numberParameter ID: MaxHsupaUserNum
The default value of this parameter is 20
Key parameters
Maximum HSDPA user numberParameter ID: MaxHSDSCHUserNumValue range: 0 to 100 Content: This parameter specifies the maximum number of HSDPA users in a cell. The default value of this parameter is 64 Set this parameter through ADD CELLCAC/MOD CELLCAC
HSDPA_UU_ADCTRLParameter ID: HSDPA_UU_ADCTRL Value range: 0 ,1 Content: This parameter specifies whether to enable or disable the HSDPA admission control algorithm. Set this parameter through ADD CELLALGOSWITCH / LST CELLALGOSWITCH/MOD CELLALGOSWITCH
HSUPA_UU_ADCTRLParameter ID: HSDPA_UU_ADCTRL Value range: 0 ,1 Content: This parameter specifies whether to enable or disable the HSDPA admission control algorithm. Set this parameter through ADD CELLALGOSWITCH / LST CELLALGOSWITCH/MOD CELLALGOSWITCH
Maximum HSUPA user numberParameter ID: MaxHsupaUserNumValue range: 0 to 100 Content: This parameter specifies the maximum number of HSDPA users in a cell. The default value of this parameter is 20Content: This parameter specifies the maximum number of HSUPA users in a cell.Set this parameter through ADD CELLCAC / LST CELLCAC / MOD CELLCAC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Why we need IAC?The disadvantage of CAC
For PS NRT (Non-Real Time) services, CAC is not flexible
No consideration about the priority of different users
No consideration about Directed Retry after CAC rejection
“Intelligent” means the algorithm can increase admission
successful rate
CAC limits the setup of RRC and RAB . When the cell is overloaded , the CAC will cause access failure.
In order to improve the access success rate the Intelligent Access Control (IAC) algorithm is used to improve the access success rate. The IAC procedure includes rate negotiation, Call Admission Control (CAC), preemption, queuing, and Directed Retry Decision (DRD).
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC Overview
The access procedure (include the IAC)
As shown in the Figure, the procedure for the UE access includes the procedures for RRC connection setup and RAB setup. The success in the RRC connection setup is one of the prerequisites for the RAB setup.During the RRC connection processing, if resource admission fails, DRD and redirection apply.During the RAB processing, the RNC performs the following steps:• Performs RAB DRD to select a suitable cell to access, for service steering or load balancing.• Performs rate negotiation according to the service requested by the UE.• Performs cell resource admission decision. If the admission is passed, UE access is granted. Otherwise, the RNC performs the next step.• Selects a suitable cell, according to the RAB DRD algorithm, from the cells where no admission attempt has been made, and then goes to rate negotiation and cell resource admission again. If all DRD admission attempts to the cells fail, go to the next step.• Makes a preemption attempt. If the preemption is successful, UE access is granted. If the preemption fails or is not supported, the RNC performs the next step, queuing.• Makes a queuing attempt. If the queuing is successful, UE access is granted. If the queuing fails or is not supported, the RNC Rejects UE access.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC - RRC Connection Processing
When a new service accesses the network, an RRC connection must be set up first. If the RRC connection request is denied, DRD is performed. If DRD also fails, RRC redirection is performed to direct the UE to an inter-frequency or inter-RAT cell through cell reselection.
After the RNC receives the RRC CONNECTION REQUEST message, the CAC algorithm decides whether an RRC connection can be set up between the UE and the current cell.
If the RRC connection can be set up between the UE and the current cell, the RNC sends an RRC CONNECTION SETUP message to the UE. If the RRC connection cannot be set up between the UE and the current cell, the RNC takes the following actions:
RRC DRD :If the DRD_SWITCH is set to 0, the RRC DRD fails, and RRC redirection is performed. Else, the RNC performs the following steps:
1. The RNC selects inter-frequency neighboring cells of the current cell. These neighboring cells are suitable for blind handovers.
2. The RNC generates a list of candidate DRD-supportive inter-frequency cells. The quality of the candidate cell meets the requirements of inter-frequency DRD:
(CPICH_Ec/No)RACH > DRD_Ec/No nbcell
where(CPICH_Ec/No)RACH is the cached CPICH Ec/N0 value included in the RACH
measurement report.DRD_Ec/No nbcell is the DRD Ec/N0 Threshold set for the inter-frequency
neighboring cell.
3. RNC selects a target cell from the candidate cells for UE access. If the candidate cell list contains more than one cell, the UE tries a cell randomly.
1. If the admission is successful, the RNC initiates an RRC DRD procedure.2. If the admission to a cell fails, the UE tries admission to another cell in the candidate cell
list. If all the admission attempts fail, the RNC makes an RRC redirection decision.4. If the candidate cell list does not contain any cell, the RRC DRD fails. The RNC performs the next
step, that is, RRC redirection.
5. RRC redirection, the RNC performs the following steps:1. The RNC selects all inter-frequency cells of the local cell.2. The RNC selects candidate cells. That is, exclude the cells to which inter-frequency RRC
DRD attempts have been made from the cells selected in the previous step.3. If more than one candidate cell is available, the RNC selects a cell randomly and redirects
the UE to the cell.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Key parametersRRC redirect switch
Parameter ID: RrcRedictSwitch
The default value of this parameter is
Only_To_Inter_Frequency
DRD Ec/N0 threshold
Parameter ID: DRDEcN0Threshhold
The default value of this parameter is -18(-9 dB)
RRC redirect switchParameter ID: RrcRedictSwitchValue range: OFF, Only_To_Inter_Frequency, Allowed_To_Inter_RATContent: This parameter specifies the RRC redirection strategy. The default value of this parameter is Only_To_Inter_FrequencySet this parameter through SET DRD
DRD Ec/N0 thresholdParameter ID: DRDEcN0ThreshholdValue range: –24 to 0 Content: If the measured Ec/N0 value of the neighbor cell is less than this parameter, this neighboring cell cannot be selected to be the candidate DRD cell. The default value of this parameter is -18(-9 dB)
Set this parameter through ADD INTERFREQNCELL
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – PS Rate Negotiation PS Service Rate Negotiation Includes:
Maximum expected rate negotiation
Initial rate negotiation
Target rate negotiation
Rate negotiation includes the maximum expected rate negotiation, initial rate negotiation, and target rate negotiation.When setting up, modifying, or admitting a PS service (conversational, streaming, interactive, or background service)
the RNC and the CN negotiate the rate according to the UE capability to obtain the maximum expected rate while ensuring a proper QoS.
For a non-real-time service in the PS domain, the RNC selects an initial rate to allocate bandwidth for the service when Setup or UE state transits from CELL_FACH to CELL_DCH based on cell code and credit resource
The Initial rate selection is affected by 2 algorithm switches: RAB Downsizing Switch, DCCC SwitchFor DCH For HSUPA
For a non-real-time service in the PS domain, if cell resource admission fails, the RNC chooses a target rate to allocate bandwidth for the service based on cell resource in Service setup or Soft handover
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Key parametersRAB_Downsizing_Switch
Parameter ID: RAB_DOWNSIZING_SWITCH
The default value of this parameter is 1 (on)
UL/DL BE traffic Initial bit rate
Parameter ID:
ULBETRAFFINITBITRATE / DLBETRAFFINITBITRATE
The default value of this parameter is D64 (64k)
RAB_Downsizing_SwitchParameter ID: RAB_DOWNSIZING_SWITCH Value range: (0,1) Content: This parameter specifies whether to support the RAB downsizing function.The default value of this parameter is 1 (on)When this parameter is set to 1, the RAB downsizing function is applied to determine the initial bit rate based on cell resources (code and credit). .Set this parameter through SET CORRMALGOSWITCH
UL/DL BE traffic Initial bit rateParameter ID: ULBETRAFFINITBITRATE / DLBETRAFFINITBITRATE Value range: D8, D16, D32, D64, D128, D144, D256, D384, D768, D1024, D1536, D1800, D2048 kContent: This parameter defines the uplink initial access rate of background and interactive services in the PS domain. The default value of this parameter is D64 (64k)Set this parameter through SET FRC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – RAB Directed Retry Decision RAB Directed Retry Decision (DRD) is used to select a
suitable cell for the UE to try an access
Inter-frequency DRD
Service Steering
Load Balancing
Inter-RAT DRD
Through the RAB DRD procedure, the RNC selects a suitable cell for RAB processing during access control. RAB DRD is of two types: inter-frequency DRD and inter-RAT DRD. For inter-frequency DRD, the service steering and load balancing algorithms are available.
After receiving a RANAP RAB ASSIGNMENT REQUEST, the RNC initiates an RAB DRD procedure to select a suitable cell for RAB processing during access control.
The RNC performs inter-frequency DRD firstly. If all admission attempts of inter-frequency DRD fail, the RNC performs an inter-RAT DRD. If all admission attempts of inter-RAT DRD fail, the RNC selects a suitable cell to perform preemption and queuing .
Relation Between Service Steering DRD and Load Balancing DRDWhen both service steering DRD and load balancing DRD are enabled, the general
principles of inter-frequency DRD are as follows:• Service steering DRD takes precedence over load balancing DRD. That is,
preferably take service priorities into consideration.• To services of the same service priority, load balancing applies.
IAC – RAB Directed Retry Decision RAB Directed Retry Switchs
DRD is applicable to RAB setup only when this switch is on.
RAB_SETUP_DRD_SWITCHRAB setup
DRD is applicable to traffic-volume-based DCCC procedure or UE state transition, only when this switch is on.
RAB_DCCC_DRD_SWITCHDCCC
DRD is applicable to RAB modification only when this switch is on.
RAB_MODIFY_DRD_SWITCHRAB modification
DRD is applicable to HSUPA services only when this switch is on.
HSUPA_DRD_SWITCHHSUPA service
DRD is applicable to HSDPA services only when this switch is on.
HSDPA_DRD_SWITCH HSDPA service
DRD is applicable to combined services only when this switch is on.
COMB_SERV_DRD_SWITCH Combined services
This is the primary DRD algorithm switch. The secondary DRD switches are valid only when this switch is on.
DRD_SWITCHDRD switch
DescriptionSwitch Scenario
DRD algorithm switchParameter ID: DRDSWITCH The default value of this parameter is offSet this parameter through SET CORRMALGOSWITCH
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRD Inter-Frequency DRD for Service Steering
DRD for Service Steering is based on Service priorities of
cells ,include:
– R99 RT services priority
– R99 NRT services priority
– HSPA services priority
– Other services priority
Called Service priority group
If the UE requests a service in an area covered by multiple frequencies, the RNC selects the cell with the highest service priority for UE access, based on the service type of RAB and the definitions of service priorities in the cells.
Cell service priorities help achieve traffic absorption in a hierarchical way. The priorities of specific service types in cells are configurable. If a cell does not support a
service type, the priority of this service type is set to 0 in this cell. The service priorities in each cell is called Service priority group , which is identified by
the Service priority group Identity parameter.Service priority groups are configured on the LMT. In each group, priorities of R99 RT
services, R99 NRT services, HSPA services, and other services are defined.When selecting a target cell for RAB processing, the RNC check the service type firstly ,
then, selects a cell with a high priority for the service, that is, a cell that has a small value of service priority.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRDInter-Frequency DRD for Service Steering
An example of service priority group
00212
01121
Service priority of
other service
Service priority of HSPA service
Service priority of R99 NRT
service
Service priority of R99 RT
service
Service priority group
Identity
Cell A and cell B are of different frequencies.Assume that the service priority groups given in the table are defined on an RNC, 2
groups of service priorities are defined. Then ,Cell A is configured with service priority group 1. Cell B is configured with service
priority group 2If UE requests a R99 RT service in cell A ,Cell B has a higher service priority of the R99
RT service than cell A. If the UE requests an RT service in cell A, preferably, the RNC selects cell B for the UE to access.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRDInter-Frequency DRD procedure for Service Steering
The procedure for the service steering DRD is as follows: 1、The RNC determines candidate cells to which blind handovers can be performed and sorts the
candidate cells into a descending order according to service priority.A candidate cell must meet the following conditions:
• The frequency of the candidate cell is within the band supported by the UE.• The quality of the candidate cell meets the Ec/No requirements of inter-frequency DRD (DRD
Ec/N0 Threshold )• The candidate cell supports the requested service.
2、The RNC selects a target cell from the candidate cells in order of service priority for UE access.3、The CAC algorithm makes an admission decision based on the status of the target cell.
• If the admission attempt is successful, the RNC accepts the service request.• If the admission attempt fails, the RNC removes the cell from the candidate cells and then
choose next candidate cell.4、If admission decisions have been made in all the candidate cells
• For HSPA access, the HSPA request falls back to a DCH one. Then, the algorithm goes back to Step 1 to make an admission decision based on R99 service priorities.
• For DCH access, the RNC initiates an inter-RAT DRD.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Key parametersService differential drd switch
Parameter ID: ServiceDiffDrdSwitch
The default value of this parameter is OFF
Service priority group Identity
Parameter ID: PriorityServiceForR99RT
Service differential drd switchParameter ID: ServiceDiffDrdSwitchValue range: ON, OFF Content: This parameter specifies whether to enable the service steering DRD algorithm The default value of this parameter is OFF.Set this parameter through ADD CELLDRD
Service priority of R99 RT serviceParameter ID: SpgIdValue range: 1 to 8 Content: This parameter uniquely identifies a group of service priorities that map to cells and indicate the support of each cell for the following service types: R99 RT service, R99 NRT service, HSPA service, and other services.
Set this parameter through ADD SPG
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Service priority of R99 RT service
Parameter ID: SpgId
Service priority of R99 NRT service
PriorityServiceForR99NRT
Service priority of HSPA service
PriorityServiceForHSPA
Service priority of Other service
PriorityServiceForExtRab
Key parameters
Service priority of R99 RT serviceParameter ID: PriorityServiceForR99RT Value range: 0 to 7 Content: This parameter specifies the support of the cells with a specific Service priority group Identity for R99 RT services.The value 0 means that these cells do not support R99 RT services.For the values 1 through 7, the service priority is inversely proportional to the value, that is, the value 7 indicates the lowest service priority, whereas the value 1 indicates the highest.
Set this parameter through ADD SPG
Service priority of R99 NRT serviceParameter ID: PriorityServiceForR99NRT Value range: 0 to 7 Content: This parameter specifies the support of the cells with a specific Service priority group Identity for R99 NRT services.The value 0 means that these cells do not support R99 NRT services.For the values 1 through 7, the service priority is inversely proportional to the value, that is, the value 7 indicates the lowest service priority, whereas the value 1 indicates the highest. Set this parameter through ADD SPG
Service priority of HSPA serviceParameter ID: PriorityServiceForHSPAValue range: 0 to 7 Content: This parameter specifies the support of the cells with a specific Service priority group Identity for HSPA services.The value 0 means that these cells do not support HSPA services.For the values 1 through 7, the service priority is inversely proportional to the value, that is, the value 7 indicates the lowest service priority, whereas the value 1 indicates the highest. Set this parameter through ADD SPG
Service priority of Other serviceParameter ID: PriorityServiceForExtRabValue range: 0 to 7 Content: This parameter specifies the support of the cells with a specific Service priority group Identity for Other services .The value 0 means that these cells do not support Other service .For the values 1 through 7, the service priority is inversely proportional to the value, that is, the value 7 indicates the lowest service priority, whereas the value 1 indicates the highest.
Set this parameter through ADD SPG
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRDInter-Frequency DRD for Load Balance
The resources triggering DRD for Load Balance include:
DL Power
OVSF code
Any of these 2 resources can trigger inter-frequency DRD for
Load Balance
Load balancing considers two resources: power, and code.If both are activated, power-based load balancing DRD takes precedence over code-based load balancing DRD.Code-based load balancing DRD is applicable to only R99 services because HSDPA services use reserved codes.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRDInter-Frequency DRD procedure for DL Power Load Balance
The procedure for the service steering DRD is as follows: 1、The RNC determines candidate cells to which blind handovers can be performed and sorts the candidate cells into a descending order according to service priority.A candidate cell must meet the following conditions:
• The frequency of the candidate cell is within the band supported by the UE.• The quality of the candidate cell meets the Ec/No requirements of inter-frequency
DRD (DRD Ec/N0 Threshold )• The candidate cell supports the requested service.
2、The RNC determines whether the DL radio load of the current cell is lower than the power threshold for load balancing DRD (condition 1 )power threshold for load balancing DRD is CAC parameter.
•If the DL load of the current cell is lower than the threshold, the service tries admission to the current cell. •If the DL load of the current cell is equal to or higher than the threshold, the RNC checks the candidate cells to try to find out a target cell for UE access.
RNC will check if there is a candidate cell will meet the following condition (condition 2 ) :
•Ptotal_thd,nbcell is DL total power threshold for the inter-frequency neighboring cell. •Pload,nbcell is total power load of the inter-frequency neighboring cell. For a R99 cell, it is the Downlink Transmitted Carrier Power of the cell, and for an HSPA cell, it is the non-HSDPA power and GBP. •Ptotal_thd,cutcell is DL total power threshold for the current cell. •Pload,cutcell is the total downlink load of the current cell. •Ploadoffset is the Power balancing drd offset of the current cell.
Then, the RNC selects the target cell as follows: • If there is only one inter-frequency neighboring cell that meets the load balancing DRD conditions, the RNC selects this cell as the target cell. • If there are multiple such cells, the RNC selects the cell with the lightest load as the target cell.• If there is no such cell, the RNC selects the current cell as the target cell.
3、The CAC algorithm makes an admission decision based on the status of the target cell.• If the admission attempt is successful, the RNC accepts the service request.• If the admission attempt fails, the RNC removes the cell from the candidate cells and then choose next candidate cell.
4、If admission decisions have been made in all the candidate cells•For HSPA access, the HSPA request falls back to a DCH one. Then, the algorithm goes back to Step 1 to make an admission decision based on R99 service priorities.•For DCH access, the RNC initiates an inter-RAT DRD.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Power balance DRD switch on DCHParameter ID: LdbDrdSwitchDCH
The default value of this parameter is OFF
Power balance DRD switch on HSDPAParameter ID: LdbDrdSwitchHSDPA
The default value of this parameter is OFF
Max transmit power of cell Parameter ID: MaxTxPower
The default value of this parameter is 430 (43dBm)
Dl power balancing drd power threshold for DCH
Parameter ID: LdbDRDOffsetDCH
The default value of this parameter is 10%
Dl power balancing drd power threshold for HSDPA
Parameter ID: LdbDRDOffsetHSDPA
The default value of this parameter is 10%
Key parameters
Power balancing drd switchParameter ID: PowerBalancingDrdSwitchValue range: ON, OFF Content: This parameter specifies whether to enable the power-based load balancing DRD algorithm .The default value of this parameter is OFF.Set this parameter through SET DRD / ADD CELLDRD
Max transmit power of cellParameter ID: MaxTxPowerValue range: 0 to 500 , step:0.1dBmContent: This parameter specifies the sum of the maximum transmit power of all the downlink channels in a cell. The default value of this parameter is 430 (43dBm).
Set this parameter through MOD CELLPower balancing drd offset
Parameter ID: LoadBalanceDRDOffsetValue range: 0% to 100% Content: This parameter specifies the load offset threshold of the current cell and the inter-frequency cell when power balancing drd algorithm is applied. Only when the cell load offset reaches this threshold, the inter-frequency cell can be selected to be the target drd cell.The default value of this parameter is 10%Set this parameter through SET DRD / ADD CELLDRD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-frequency DRDInter-Frequency DRD procedure for Code Load Balance
The procedure of load balancing DRD based on code resource is similar to that based on power resource.
1、The RNC determines whether the minimum remaining spreading factor of the current cell is smaller than Minimum SF threshold for code balancing drd.
• If the minimum SF is smaller than Minimum SF threshold for code balancing drd, the RNC tries the admission of the service request to the current cell.
• If the minimum SF is not smaller than Minimum SF threshold for code balancing drd, the RNC performs the next step .
2、The RNC determines whether the code load of the current cell is lower than Code occupied rate threshold for code balancing drd. .
• If the code load is lower than Code occupied rate threshold for code balancing drd, the service tries the admission to the current cell.
• If the code load is not lower than Code occupied rate threshold for code balancing drd, the RNC selects the cell with the lightest code load or the current cell as the target cell.
3、The RNC selects the cell as follows:• If the difference between the code resource occupancies of the cell and the current cell
is larger than the value of Delta code occupied rate , the RNC selects the cell with the lightest code load as the target cell. Otherwise, the RNC selects the current cell as the target cell.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Code balancing drd switch
Parameter ID: CodeBalancingDrdSwitch
The default value of this parameter is OFF
Minimum SF threshold for code balancing drd
Parameter ID: CodeBalancingDrdMinSFThd
The default value of this parameter is SF8
Key parameters
Code balancing drd switchParameter ID: CodeBalancingDrdSwitchValue range: ON, OFF Content: This parameter specifies whether to enable the code-based load balancing DRD algorithm.The default value of this parameter is OFF.Set this parameter through SET DRD / ADD CELLDRD
Minimum SF threshold for code balancing drdParameter ID: CodeBalancingDrdMinSFThdValue range: SF4, SF8, SF16, SF32, SF64, SF128, SF256 Content: If the downlink minimum SF of the best cell is below this threshold, the code-based load balancing DRD is not triggered. The default value of this parameter is SF8 .Set this parameter through SET DRD / ADD CELLDRD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Code occupied rate threshold for code balancing drd
Parameter ID: CodeBalancingDrdCodeRateThd
The default value of this parameter is 13%
Delta code occupied rate
Parameter ID: DeltaCodeOccupiedRate
The default value of this parameter is 7%
Key parameters
Code occupied rate threshold for code balancing drdParameter ID: CodeBalancingDrdCodeRateThdValue range: 0% to 100% Content: This parameter specifies the code occupancy threshold of the current cell for code-based load balancing DRD.Only when the code occupancy of the best cell reaches this threshold can code-based load balancing DRD be triggered. The default value of this parameter is 13%.Set this parameter through SET DRD / ADD CELLDRD
Delta code occupied rateParameter ID: DeltaCodeOccupiedRateValue range: 0% to 100% Content: This parameter specifies the code occupied rate offset threshold of the current cell and the inter-frequency cell when code balancing drd algorithm is applied. Only when the code occupied rate offset reaches this threshold, the inter-frequency cell can be selected to be the target drd cell. The default value of this parameter is 7% .Set this parameter through SET DRD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Inter-RAT DRD Inter-RAT DRD
Inter-RAT DRD is available for AMR service only in RAN 10:
The inter-RAT DRD procedure is as follows:1,If the current cell is configured with any neighboring GSM cell suitable for blind handover
and the Service Handover Indicator is set to HO_TO_GSM_SHOULD_BE_PERFORM, the RNC performs next step. Otherwise, the service request undergoes preemption and queuing.
2,The RNC generates a list of candidate DRD-supportive inter-RAT cells that fulfill the Ec/No threshold.
3,The service request then tries admission to a target GSM cell in order of blind handover priority.
4,If all admission attempts fail or the number of inter-RAT directed retries exceeds the value of Max inter-RAT direct retry number, the service request undergoes preemption and queuing.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Max inter-RAT direct retry number
Parameter ID: DRMaxGSMNum
The default value of this parameter is 2
Key parameters
Max inter-RAT direct retry numberParameter ID: DRMaxGSMNumValue range: 0 to 5 Content: This parameter defines the maximum number of inter-RAT directed retries for an RAB. The value 0 means that inter-RAT DRD is not allowed. The default value of this parameter is 2Set this parameter through ADD CELLDRD
Preemption and Queuing guarantees the success in the access of a higher-priority user by forcibly releasing the resources of a lower-priority user.
After cell resource admission fails, the RNC performs Preemption and Queuing if the following conditions are met:
The RNC receives an RAB ASSIGNMENT REQUEST message indicating that Preemption and Queuing is supported.
By default, Preemption and Queuing setting in CN may be:
Preemption and Queuing is applicable to the following cases:Setup or modification of a serviceHard handover or SRNS relocationUE state transits from CELL_FACH to CELL_DCH
The RNC selects a suitable cell according to the settings of the DRD algorithms.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
IAC – Preemption and Queuing
After cell admission fails, the RNC performs preemption
and Queuing
Precondition of Preemption and Queuing
– According to CN setting, Preemption and Queuing is supported
Target cell of Preemption and Queuing
– Based on DRD
Not allowedallowedNot able Low
allowedallowedAbleMedium
allowedNot allowed Able High
Queuing PreemptablePreemption capability
USER LEVEL
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IAC – PreemptionPreemption on different resources
√√-Number of users
√√√Iub bandwidth
---CE
√√√Power
---CodeHSDPA service
√√√Iub bandwidth
√-√CE
√√√Power
√-√CodeR99 service
R99 + HSPA Combined ServiceHSDPA ServiceR99 Service
Service That can Be PreemptedResourceService
The preemption procedure is as follows:1、The preemption algorithm determines which radio link sets can be preempted. The
algorithm proceeds as follows:Chooses SRNC users first. If no user under the SRNC is available, the algorithm chooses users under the DRNC.Sorts the pre-emptable users by user integrate priority, or sorts the pre-emptable RABs by RAB integrate priority.Determines candidate users or RABs.
Only the users or RABs with priorities lower than the RAB to be established are selected.
Selects as many users or RABs as necessary in order to match the resource needed by the RAB to be established. When the priorities of two users or RABs are the same, the algorithm chooses the user or RAB that can release the most resources.
2、The RNC releases the resources occupied by the candidate users or RABs.3、The requested service directly uses the released resources to access the network
without admission decision.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Preempt algorithm switch
Parameter ID: PREEMPTALGOSWITCH
The default value of this parameter is OFF
Key parameters
Preempt algorithm switchParameter ID: PREEMPTALGOSWITCH Value range: ON, OFF Content: This parameter specifies whether to support the preemption function. The default value of this parameter is OFF
Set this parameter through SET QUEUEPREEMPT
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IAC – Queuing
After Preemption rejection, UE can wait in queue, then
admission attempts for the service are made periodically till
Tmax expires.
Admission attempts are made based on Queuing priority:
Pqueue = Tmax – Telapsed
Tmax is the maximum time in the queue, default value is 5s
Telapsed is the time has queued
After the cell resource decision fails, the RNC performs queuing if the RNC receives an RAB ASSIGNMENT REQUEST message indicating the queuing function is supported
The queuing algorithm checks whether the queue is full, that is, whether the number of service requests in the queue exceeds the queue length that is defined by the Queue length
The queuing algorithm is triggered by the heartbeat timer, which is set through the Poll timer length .
If the queue is not full:• Stamps this request with the current time.• Puts this request into the queue.
If the queue is full:• Checks whether there are requests whose integrate priorities are lower than that of
the priority of the new request. If there is, delete the low priority request, put the new service in the queue. (Otherwise, the queuing algorithm rejects the new request directly.)
• Stamps the new request with the current time and then puts it into the queue.After the heartbeat timer (Poll timer length) expires, the queuing algorithm proceeds as follows:
• Selects the request with the highest integrate priority for an attempt of resource allocation .
• If the attempt fails, the queuing algorithm proceeds as follows:• Puts the service request back into the queue with the time stamp
unchanged for the next attempt.• Chooses the request with the greatest weight from the rest and makes
another attempt until a request is accepted or all requests are rejected.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Queue algorithm switch
Parameter ID: QUEUEALGOSWITCH
The default value of this parameter is OFF
Queue length
Parameter ID: QUEUELEN
The default value of this parameter is 5
Key parameters
Queue algorithm switchParameter ID: QUEUEALGOSWITCH Value range: ON, OFF Content: This parameter specifies whether to support the queuing function. The default value of this parameter is OFFSet this parameter through SET QUEUEPREEMPT
Queue lengthParameter ID: QUEUELEN Value range: 5 to 20 Content: This parameter defines the length of a queue. The default value of this parameter is 5
Set this parameter through SET QUEUEPREEMPT
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Poll timer length
Parameter ID: POLLTIMERLEN
The default value of this parameter is 50 (500ms)
Max queuing time length
Parameter ID: MAXQUEUETIMELEN
The default value of this parameter is 5
Key parameters
Poll timer lengthParameter ID: POLLTIMERLEN Value range: 1 to 6000 , step: 10msContent: This parameter defines the length of the heartbeat timer. Each time the timer expires, the RNC chooses the service that meets the requirement to make an admission attempt . The default value of this parameter is 50 (500ms)Set this parameter through SET QUEUEPREEMPT
Max queuing time lengthParameter ID: MAXQUEUETIMELENValue range: 1 to 60s Content: This parameter defines the maximum time that the service request can be in the queue. The default value of this parameter is 5sSet this parameter through SET QUEUEPREEMPT
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
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LCC (Load Congestion Control)
Overload state: OLC will be used
Load
%
THLDR
THOLC
100%section A
section B
section C
1 2
Normal state: Permit entry
Times
Basic congestion state: LDR
will be used
LCC (Load Congestion Control) consist of LDR (Load Reshuffling) and OLC (Over Load Control).In basic congestion state, LDR will be used to optimize resource distribution, the main
rules is not to affect the feeling of users as possible as we can.In overload state, OLC will be used to release overload state quickly, keep system stability and the service of high priority users.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load ReshufflingReasons
When the cell is in basic congestion state, new coming calls
could be easily rejected by system
Purpose
Optimizing cell resource distribution
Decreasing load level, increasing admission successful rate
When the usage of cell resource exceeds the basic congestion triggering threshold, the cell enters the basic congestion state. In this case, LDR is required to reduce the cell load and increase the access success rate.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load ReshufflingTriggering of LDR
Power resources
Code resource
Iub resources
NodeB Credit resource
For power resource, the RNC performs periodic measurement and checks whether the cells are congested. For code, Iub, and NodeB credit resources, event-triggered congestion applies, that is, the RNC checks whether the cells are congested when resource usage changes.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Load ReshufflingLDR Actions:
Inter-frequency load handover
Code reshuffling
BE service rate reduction
AMR rate reduction
Inter-RAT load handover in the CS domain
Inter-RAT load handover in the PS domain
Real time service Iu QoS renegotiation
MBMS power reduction
When the cell is in basic congestion state, the RNC takes one of the actions in each period until the congestion is resolved
Load Reshuffling Actions triggered by different resources
If the downlink power admission uses the equivalent user number algorithm, basic congestion can also be triggered by the equivalent number of users. In this situation, LDR actions do not involve AMR rate reduction or MBMS power reduction, as indicated by the symbol "*" in above table
Congestion of different resource may trigger different actions.For example, Credit congestion do not trigger “Inter-Frequency Load Handover”, “AMR Rate Reduction”, and “Code Reshuffling”When congestion of all resources is triggered, the action to be taken is based on the resource priorityconfiguration.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell LDC algorithm switch
Parameter ID: NBMLDCALGOSWITCH
UL_UU_LDR
DL_UU_LDR
CELL_CODE_LDR
NodeB LDC algorithm switch
Parameter ID: NodeBLdcAlgoSwitch
IUB_LDR
NODEB_CREDIT_LDR
Key parameters
Cell LDC algorithm switchParameter ID: NBMLDCALGOSWITCH Value range: ON, OFFContent: If ULLDR, DLLDR, CELL_CODE_LDR are selected, the corresponding algorithms are enabled. . Set this parameter through ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
NodeB LDC algorithm switchParameter ID: NodeBLdcAlgoSwitchValue range: ON, OFFContent: If IUB_LDR, NODEB_CREDIT_LDR, are selected, the corresponding algorithms will be enabled; otherwise, disabled. . Set this parameter through ADD NODEBALGOPARA / MOD NODEBALGOPARA / SET LDCALGOPARA
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL (RTWP) LDR trigger threshold
Parameter ID: ULLDRTRIGTHD
The default value of this parameter is 55%
UL (RTWP) LDR release threshold
Parameter ID: ULLDRRELTHD
The default value of this parameter is 45%
Key parameters
UL LDR trigger thresholdParameter ID: ULLDRTRIGTHD Value range: 0 to 100 , %Content: If the UL load of the cell is not lower than this threshold, the UL load reshuffling function of the cell is triggered. The default value of this parameter is 55%Set this parameter through ADD CELLLDM/MOD CELLLDM
UL LDR release thresholdParameter ID: ULLDRRELTHD Value range: 0 to 100 , %Content: If the UL load of the cell is lower than this threshold, the UL load reshuffling function of the cell is stopped. The default value of this parameter is 45%Set this parameter through ADD CELLLDM / MOD CELLLDM
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL (TX POWER) LDR trigger threshold
Parameter ID: DLLDRTRIGTHD
The default value of this parameter is 70%
DL (TX POWER) LDR release threshold
Parameter ID: DLLDRRELTHD
The default value of this parameter is 60%
Key parameters
DL LDR trigger thresholdParameter ID: DLLDRTRIGTHD Value range: 0 to 100 , %Content: If the DL load of the cell is not lower than this threshold, the DL load reshuffling function of the cell is triggered. The default value of this parameter is 70%Set this parameter through ADD CELLLDM / MOD CELLLDM
DL LDR release thresholdParameter ID: DLLDRRELTHD Value range: 0 to 100 , %Content: If the DL load of the cell is lower than this threshold, the DL load reshuffling function of the cell is stopped. The default value of this parameter is 60%Set this parameter through ADD CELLLDM / MOD CELLLDM
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell LDR SF reserved threshold
Parameter ID: CELLLDRSFRESTHD
The default value of this parameter is SF8
Ul LDR Credit SF reserved threshold
Parameter ID: ULLDRCREDITSFRESTHD
The default value of this parameter is SF8
Dl LDR Credit SF reserved threshold
Parameter ID: DLLDRCREDITSFRESTHD
The default value of this parameter is SF8
Key parameters
Cell LDR SF reserved thresholdParameter ID: CELLLDRSFRESTHD Value range: SF4, SF8, SF16, SF32, SF64, SF128, SF256 Content: If the SF corresponding to the current remaining code of the cell is higher than the threshold defined by this parameter, code congestion is triggered and the related handling actions are taken. The default value of this parameter is SF8Set this parameter through ADD CELLLDR / MOD CELLLDR
Ul LDR Credit SF reserved thresholdParameter ID: ULLDRCREDITSFRESTHD Value range: 0 to 100 , %Content: If the SF corresponding to the current UL remaining credit resource is higher than the threshold defined by this parameter, the UL credit LDR can be performed and the related handling actions are taken. The default value of this parameter is 60%Set this parameter through ADD NODEBLDR/MOD NODEBLDR
Dl LDR Credit SF reserved thresholdParameter ID: DLLDRCREDITSFRESTHD Value range: 0 to 100 , %Content: If the value of SF corresponding to the current DL remaining credit resource is higher than the threshold defined by this parameter, the DL credit LDR can be performed and the related handling actions are taken. The default value of this parameter is SF8
Set this parameter through ADD NODEBLDR/MOD NODEBLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
The First / Second/ Third/ Fourth priority for load reshuffling
Parameter ID:
LdrFirstPri
LdrSecondPri
LdrThirdPri
LdrFourthPri
The default configuration is :
IUBLDR > CREDITLDR > CODELDR > UULDR
Key parameters
The First / Second/ Third/ Fourth priority for load reshufflingParameter ID: LdrFirstPri / LdrSecondPri / LdrThirdPri / LdrFourthPriValue range: IUBLDR(Iub load reshuffling), CREDITLDR(Credit load reshuffling), CODELDR (Code load reshuffling), UULDR (Uu load reshuffling) Content: These parameters specify the triggering resource order when congestion of all resources are triggered. The default configuration is IUBLDR > CREDITLDR > CODELDR > UULDR Set this parameter through SET LDCALGOPARA
LDR procedure
Mark "current LDR state = uncongested"
Wait for congestion indication
Congestionstate indication
Turn on LDR algorithm switch
Current LDR state = congested?
Start LDM congestion indication report
Mark "current action = first LDR action"
Clear "selected" mark of all UE LDR actions
Sequence ofactions can be
configured(current actionis taken firstly)
Inter-systemhandover
in CS domain
AMR ratereduction
Inter-freqload handover
QoS renogiationon Iu interface
BE ratereduction
Succeed?
Mark"current action= successful
action"
Wait timefor LDR
action duration
Y
Y
Y
Y
Y
N
N
N
N
N
N
Mark "current action = first LDR action"No related action can be found
N
Inter-systemhandover
in PS domain
Succeed?
Succeed?
Succeed?
Succeed?
Succeed?
Codereshuffling
Succeed?Y
N
MBMS powerreduction
N
Succeed?
Y
Y
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR period timer length
Parameter ID: LDRPERIODTIMERLE
The default value of this parameter is 10 s
Gold User Load Control Switch
Parameter ID: GoldUserLoadControlSwitch
The default value of this parameter is OFF
Key parameters
LDR period timer lengthParameter ID: LDRPERIODTIMERLE Value range: 0 to 86400 sContent: This parameter specifies the period of load reshuffling . The default value of this parameter is 10 sSet this parameter through SET LDCPERIOD
Gold User Load Control SwitchParameter ID: GoldUserLoadControlSwitchValue range: ON, OFFContent: This parameter specifies whether LDR actions are applicable to users of gold priority. The default value of this parameter is OFFSet this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL LDR first / second / third / fourth / fifth / sixth / seventh /
eighth / ninth / tenth action
Parameter ID:
DlLdrFirstAction / DlLdrSecondAction / DlLdrThirdAction /
DlLdrFourthAction / DlLdrFifthAction / DlLdrSixthAction /
DlLdrSeventhAction / DlLdrEighthAction / DlLdrNinthAction /
DlLdrTenthAction
The default configuration is :
1st:CODEADJ , 2nd: INTERFREQLDHO , 3rd: BERATERED
Key parameters
DL LDR first / second / third / fourth / fifth / sixth / seventh / eighth / ninth / tenth actionParameter ID: DlLdrFirstAction / DlLdrSecondAction / DlLdrThirdAction / DlLdrFourthAction / DlLdrFifthAction / DlLdrSixthAction / DlLdrSeventhAction / DlLdrEighthAction / DlLdrNinthAction / DlLdrTenthActionValue range: NOACT (NO ACTION), INTERFREQLDHO (INTER-FREQ LOAD HANDOVER), BERATERED (BE TRAFF RATE REDUCTION), QOSRENEGO (UNCONTROLLED REAL-TIME TRAFF QOS RE-NEGOTIATION), CSINTERRATSHOULDBELDHO (CS DOMAIN INTER-RAT SHOULD BE LOAD HANDOVER), PSINTERRATSHOULDBELDHO (PS DOMAIN INTER-RAT SHOULD BE LOAD HANDOVER), AMRRATERED (AMR TRAFF RATE REDUCTION), MBMSDECPOWER(MBMS DESCEND POWER), CODEADJ(CODE ADJUST), CSINTERRATSHOULDNOTLDHO (CS DOMAIN INTER-RAT SHOULD NOT BE LOAD HANDOVER), PSINTERRATSHOULDNOTLDHO (PS DOMAIN INTER-RAT SHOULD NOT BE LOAD HANDOVER). Content: These parameters specify the LDR action order. The default configuration is 1st:CODEADJ , 2nd: INTERFREQLDHO , 3rd: BERATERED ,Set this parameter through ADD CELLLDR / MOD CELLLDR / ADD NODEBLDR / MOD NODEBLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR ActionsInter-frequency load handover
Target usersBased on user integrate priority
Current bandwidth for DCH or “GBR bandwidth for HSPA” has to be less than the UL/DL Inter-freq cell load handover maximum bandwidth parameter
Target cellsLoad difference between current load and the basic congestion trigger threshold of target cell is larger than “UL/DL Inter-freq cell load handover load space threshold”
It is implemented as follows:1. The LDR check whether the existing cell has a target cell of inter-frequency blind handover. If there is no
such a target cell, the action fails, and the LDR performs the next action. 2. The principles of selecting inter-freq handover target cell are different as a result of the different resources
which trigger the basic congestion.1. If the basic congestion is triggered by the power resource:
The LDR checks whether the load difference between the current load and the basic congestion triggering threshold of each target cell for blink handover is larger than the UL/DL Inter-freq cell load handover load space threshold (both the uplink and downlink conditions must be fulfilled). The other resources (code resource, Iub bandwidth, and NodeB credit resource) in the target cell do not trigger basic congestion. If the difference is not larger than the threshold, the action fails, and the LDR takes the next action.If there are more than one cell meeting the requirements, the first one is selected as the blind handover target cell.
2. If the basic congestion is triggered by the code resource:Weather there are blind handover target cells meeting the requirements is decided by the following conditions:The minimum SF of the target cell is not greater than that of current cell.The difference of code occupy rate between current cell and the target cell is greater than InterFreq HO code used ratio space threshold.The state of target cell is normal.If there is no such cell, this action fails and the LDR performs the next action. If there are more than one cell meeting the requirements, the first cell is selected as the blind handover target cell.
3. If the LDR finds out a target cell that meets the specified blind handover conditions, the LDR selects one UE to make an inter-frequency blind handover, depending on the UE’s ARP and occupied bandwidth. For the selected UE other than a gold user, its UL/DL current bandwidth for DCH, GBR bandwidth for HSPA, shall be less than and have the least difference from the UL/DL Inter-freq cell load handover maximum bandwidthparameter (Both the uplink and downlink condition must be fulfilled). If the LDR cannot find such a UE, the action fails. The LDR performs the next action.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL/DL Inter-freq cell load handover load space threshold
Parameter ID: UL/DLINTERFREQHOCELLLOADSPACETHD
The default value of this parameter is 20
InterFreq HO code used ratio space threshold
Parameter ID: LdrCodeUsedSpaceThd
The default value of this parameter is 13
UL/DL Inter-freq cell load handover maximum bandwidth
Parameter ID: UL/DLINTERFREQHOBWTHD
The default value of this parameter is 200000
Key parameters
UL/DL Inter-freq cell load handover load space thresholdParameter ID: UL/DLINTERFREQHOCELLLOADSPACETHD Value range: 0 to 11 %Content: The target cell can be a cell for inter-frequency blind handover only when the UL/DL load space is higher than the threshold.The UL/DL load space is the difference between the UL/DL basic congestion triggering threshold and the current UL/DL load of a target cell for blind handover. . The default value of this parameter is 20%Set this parameter through ADD CELLLDR / MOD CELLLDR
InterFreq HO code used ratio space thresholdParameter ID: LdrCodeUsedSpaceThdValue range: 0% to 100% (0~1) ,step:1%Content: The target cell can be used for inter-frequency blind handover only when the DL Code used ratio space is higher than the threshold. The DL Code used ratio space is the difference of code used ratio between the source cell and the target cell. The default value of this parameter is 13%Set this parameter through ADD CELLLDR / LST CELLLDR / MOD CELLLDR
UL/DL Inter-freq cell load handover maximum bandwidthParameter ID: UL/DLINTERFREQHOBWTHD Value range: 0 to 400000 bpsContent: During the inter-frequency load handover, the UE is selected as the target of inter-frequency load handover from the UE set where the bandwidth is less than this threshold. The default value of this parameter is 200000 Set this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR Actions BE Rate Reduction
Target RABs
Based on RAB integrate priority
The data rate of BE service is larger than GBR
Number of RABs to be selected is configurable
BE rate reduction is implemented by reconfiguring the bandwidth. Bandwidthreconfiguration requires signaling interaction on the Uu interface.
The LDR algorithm is implemented as follows:1. Based on the integrate priority, the LDR sorts the RABs into a descending order. The
top RABs related to the BE services (whose current rate is higher than its GBR configured by SET USERGBR command) are selected. If the integrate priorities of some RABs are identical, the RAB with the highest rate is selected. The number of RABs to select is determined by the UL/DL LDR-BE rate reduction RAB numberparameter.
2. The bandwidth of the selected services is reduced to the specified rate. 3. If services can be selected, the action is successful. If services cannot be selected, the
action fails. The LDR takes the next action. 4. The reconfiguration is completed as indicated by the RB RECONFIGURATION
message on the Uu interface and through the RL RECONFIGURATION message on the Iub interface.
5. The BE rate reduction algorithm is controlled by the DCCC algorithm switch. BE rate reduction can be performed only when the DCCC algorithm is enabled.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL /DL LDR-BE rate reduction RAB number
Parameter ID: UL/DLLDRBERATEREDUCTIONRABNUM
The default value of this parameter is 1
Key parameters
UL /DL LDR-BE rate reduction RAB numberParameter ID: UL/DLLDRBERATEREDUCTIONRABNUM Value range: 1 to 10 Content: These parameters specify the number of RABs to select in a UL/DL LDR BE rate reduction.If the number of RABs that fulfil the criteria for BE rate reduction is smaller than the value of this parameter, then all the RABs that fulfil the criteria are selected. The default value of this parameter is 1Set this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR Actions Uncontrolled Real-time service QoS Renegotiation
Target RABs
Based on RAB integrate priority
Real-time services in the PS domain
The load is reduced by adjusting the rate of the real-time services through uncontrolled real-time OoS renegotiation.
Upon receipt of the message, the CN sends the RAB ASSIGNMENT REQUEST message to the RNC for RAB parameter reconfiguration. Based on this function, the RNC can adjust the rate of real-time services to reduce the load.
The LDR algorithm is implemented as follows:1. Based on the integrate priority, the LDR sorts the real-time services in the PS domain in
descending order. The top services are selected for QoS renegotiation. 2. The LDR performs QoS renegotiation for the selected services. The GBR during
service setup is the rate of the service after QoS renegotiation. 3. The RNC initiates the RAB Modification Request message to the CN for QoS
renegotiation. 4. If the RNC cannot find a proper service for QoS renegotiation, the action fails. The LDR
performs the next action.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL / DL LDR un-ctrl RT Qos re-nego RAB num
Parameter ID: UL/DLLDRPSRTQOSRENEGRABNUM
The default value of this parameter is 1
Key parameters
UL / DL LDR un-ctrl RT Qos re-nego RAB numParameter ID: UL/DLLDRPSRTQOSRENEGRABNUM Value range: 1 to 10 Content: These parameters specify the number of RABs to select in a UL/DL LDR uncontrolled real-time QoS renegotiation.If the number of RABs that fulfil the criteria for uncontrolled real-time QoS renegotiation is smaller than the value of this parameter, then all the RABs that fulfil the criteria are selected. The default value of this parameter is 1Set this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR ActionsInter-system Handover In the CS/PS Domain
Target user
Based on the user integrate priority
Handover Indicator
– “Handover to GSM should be performed”
– "handover to GSM should not be performed"
WCDMA cell
GSM cell
The 2G and 3G systems have different cell sizes and coverage modes. Therefore, blind handover across systems is not taken into account.
The LDR is implemented in the downlink (e.g.) as follows:1. Based on the integrate priority, the LDR sorts the UEs in descending order. The top
CS/PS services are selected.2. For the selected UEs, the LDR sends the load handover command to the inter-system
handover module to ask the UEs to hand over to the 2G system. 3. The handover module decides to trigger inter-system handover, depending on the
capability of the UE and the capability of the algorithm switch to support the compression mode.
4. This action is successful if any load handover UE is found. Otherwise, this action fails.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL / DL CS should be ho user number
Parameter ID: UL/DLCSINTERRATSHOULDBEHOUENUM
The default value of this parameter is 3
UL / DL CS should not be ho user number
Parameter ID: UL/DLCSINTERRATSHOULDNOTBEHOUENUM
The default value of this parameter is 3
Key parameters
UL / DL CS should be ho user numberParameter ID: UL/DLCSINTERRATSHOULDBEHOUENUM Value range: 1 to 10 Content: These parameters specify the number of users to select in a UL/DL Inter-RAT Should Be Load Handover in the CS Domain.If the number of users that fulfil the criteria for Inter-RAT Should Be Load Handover in the CS Domain is smaller than the value of this parameter, then all the users that fulfil the criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLLDR / MOD CELLLDR
UL / DL CS should not be ho user numberParameter ID: UL/DLCSINTERRATSHOULDNOTBEHOUENUM Value range: 1 to 10 Content: These parameters specify the number of users to select in a UL/DL Inter-RAT Should Not Be Load Handover in the CS Domain.If the number of users that fulfil the criteria for Inter-RAT Should Not Be Load Handover in the CS Domain is smaller than the value of this parameter, then all the users that fulfilthe criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
UL / DL PS should be ho user number
Parameter ID: UL/DLPSINTERRATSHOULDBEHOUENUM
The default value of this parameter is 3
UL / DL PS should not be ho user number
Parameter ID: UL/DLPSINTERRATSHOULDNOTBEHOUENUM
The default value of this parameter is 3
Key parameters
UL / DL PS should be ho user numberParameter ID: UL/DLPSINTERRATSHOULDBEHOUENUM Value range: 1 to 10 Content: These parameters specify the number of users to select in a UL/DL Inter-RAT Should Be Load Handover in the PS Domain.If the number of users that fulfil the criteria for Inter-RAT Should Be Load Handover in the PS Domain is smaller than the value of this parameter, then all the users that fulfilthe criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLLDR / MOD CELLLDR
UL / DL PS should not be ho user numberParameter ID: UL/DLPSINTERRATSHOULDNOTBEHOUENUM Value range: 1 to 10 Content: These parameters specify the number of users to select in a UL/DL Inter-RAT Should Not Be Load Handover in the PS Domain.If the number of users that fulfil the criteria for Inter-RAT Should Not Be Load Handover in the PS Domain is smaller than the value of this parameter, then all the users that fulfilthe criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLLDR / MOD CELLLDR
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LDR ActionsAMR Rate Reduction
Target user
AMR services and with the bit rate higher than the GBR
Based on RAB integrate priority
In the WCDMA system, voice services work in eight AMR modes. Each mode has its own rate. Therefore, mode control is functionally equal to rate control.
The LDR algorithm is implemented as follows:1. Based on the integrate priority, the LDR sorts the RABs in the descending order. The top
UEs accessing the AMR services (conversational) and with the bit rate higher than the GBR are selected.
2. In uplink, the RNC sends the “Rate Control request” message through the Iu-UP to the CN to adjust the AMR rate to the GBR.
3. In downlink, The RNC sends the TFC CONTROL command to the UE to adjust the AMR rate to the assured rate.
4. If the RNC cannot find a proper service for AMR rate reduction, the action fails. The LDR performs the next action.
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UL/DL LDR-AMR rate reduction RAB number
Parameter ID: UL/DLLDRAMRRATEREDUCTIONRABNUM
The default value of this parameter is 3
Key parameters
UL/DL LDR-AMR rate reduction RAB numberParameter ID: UL/DLLDRAMRRATEREDUCTIONRABNUM Value range: 1 to 10 Content: These parameters specify the number of RABs to select in a UL/DL LDR AMR rate reduction.If the number of RABs that fulfil the criteria for AMR rate reduction is smaller than the value of this parameter, then all the RABs that fulfil the criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLLDR / MOD CELLLDR
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
LDR ActionsCode Reshuffling
Reallocate code resources for candidate user
Code Adjustment
The algorithm operates as follows:1,Initialize the SF_Cur of the root node of subtrees to Cell LDR SF reserved threshold.2,Traverse all the subtrees with this SF_Cur at the root node. Leaving the subtrees
occupied by common channels and HSDPA channels out of account, take the subtrees in which the number of users is not larger than the value of the Max user number of code adjust parameter as candidates for code reshuffling.
3,Select a subtree from the candidates according to the setting of the LDR code priority indicator parameter.
If this parameter is set to TRUE, select the subtree with the largest code number from the candidates.If this parameter is set to FALSE, select the subtree with the smallest number of users from the candidates. In the case that multiple subtrees have the same number of users, select the subtree with the largest code number.
4,Treat each user in the subtree as a new user and allocate code resources to each user.5,Initiate the reconfiguration procedure for each user in the subtree and reconfigure the
channel codes of the users to the newly allocated code resources.The reconfiguration procedure on the air interface is implemented through the PHYSICAL
CHANNEL RECONFIGURATION message and that on the Iub interface through the RL RECONFIGURATION message.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Max user number of code adjust
Parameter ID: MAXUSERNUMCODEADJ
The default value of this parameter is 1
LDR code priority indicator
Parameter ID: LdrCodePriUseInd
The default value of this parameter is TRUE
Key parameters
Max user number of code adjustParameter ID: MAXUSERNUMCODEADJ Value range: 1 to 3 Content: This parameter specifies the maximum number of users that can be selected whenever code reshuffling is performed. The default value of this parameter is 1Set this parameter through ADD CELLLDR / MOD CELLLDR
LDR code priority indicatorParameter ID: LdrCodePriUseIndValue range: True, False Content: This parameter specifies whether to select preferentially the subtree with a relatively large code number during subtree selection. Set this parameter through ADD CELLLDR / MOD CELLLDR
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LDR ActionsMBMS Power Reduction
Purpose
The downlink power load can be reduced by lowering power on
MBMS traffic channels
The LDR algorithm is implemented as follows:1. Select all RABs with low priorities. 2. The RNC initiates the reconfiguration procedure and resets the transmit power of
MTCH (FACH) to the minimum value. The transmit power corresponds to the MBMS service.
3. The reconfiguration procedure on the Iub interface is implemented through the COMMON TRANSPORT CHANNEL RECONFIGURATION REQUEST message.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Contents2. Load Control Algorithms
2.1 PUC (Potential User Control)
2.2 LDB (Intra-Frequency Load Balancing)
2.3 CAC (Call Admission Control)
2.4 IAC (Intelligent Admission Control)
2.5 LDR (Load Reshuffling)
2.6 OLC (Overload Control)
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Over Load ControlReasons
In overload state, system is not stable
Purpose
Ensuring the system stability and making the system back to
the normal state as soon as possible
Triggering of Over Load
Power resource
After the UE access is granted, the power consumed by a single link is adjusted by the single link power control algorithm. The power varies with the mobility of the UE and the changes in the environment and the source rate. In some situations, the total power load of the cell may be higher than the target load. To ensure system stability, overload congestion must be handled.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Over Load ControlOver Load triggering
If the current UL/DL load of an R99 cell is not lower than the UL/DL OLC Trigger threshold for some hysteresis (defined by the DL State Trans Hysteresis threshold in DL; not configurable in UL), the cell works in overload congestion state and the related overload handling action is taken. If the current UL/DL load of the R99 cell is lower than the UL/DL OLC Release threshold for some hysteresis (defined by the DL State Trans Hysteresis threshold in DL; not configurable in UL), the cell comes back to the normal state.The HSPA cell has the same uplink decision criterion as the R99 cell. The load in the downlink, however, is the sum of load of the non-HSPA power (transmitted carrier power of all codes not used for HS-PDSCH or HS-SCCH transmission) and the GBP..
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Cell LDC algorithm switch
Parameter ID: NBMLDCALGOSWITCH
UL_UU_OLC, DL_UU_OLC
UL/DL OLC trigger threshold
Parameter ID: UL/DLOLCTRIGTHD
The default value of this parameter is 95%
UL/DL OLC release threshold
Parameter ID: UL/DLOLCRELTHD
The default value of this parameter is 85%
Key parameters
Cell LDC algorithm switchParameter ID: NBMLDCALGOSWITCH Value range: OFF, ON Content: This parameter specifies the switch of UL/DL OLC. UL_UU_OLC: UL overload control algorithmDL_UU_OLC: DL overload control algorithmSet this parameter through ADD CELLALGOSWITCH / MOD CELLALGOSWITCH
UL/DL OLC trigger thresholdParameter ID: UL/DLOLCTRIGTHD Value range: 0 to 100 % Content: If the UL load of the cell is not lower than the value of the UL OLC trigger threshold, the UL overload congestion control of the cell is activated.If the DL load of the cell is not lower than the value of the DL OLC trigger threshold, the DL overload congestion control of the cell is activated. Set this parameter through ADD CELLLDR / MOD CELLLDR
UL/DL OLC release thresholdParameter ID: UL/DLOLCRELTHD Value range: 0 to 100 % Content: If the UL load of the cell is lower than the value of the UL OLC release threshold, the UL overload congestion control of the cell is deactivated.If the DL load of the cell is lower than the value of the DL OLC release threshold, the DL overload congestion control of the cell is deactivated. Set this parameter through ADD CELLLDR / MOD CELLLDR
The general OLC procedure covers the following actions: TF control of BE services, channel switching of BE services, and release of RABs. The RNC takes periodical actions if overload congestion is detected.
When the cell is overloaded, the RNC takes one of the following actions in each period (defined by the OLC period timer length parameter, e.g.3s) until the congestion is resolved:
1. TF control of BE service (only for DCH BE service)2. Switching BE services to common channel3. Choosing and releasing the RABs (for HSPA or DCH service)
If the first action fails or the first action is completed but the cell is still in congestion, then the second action is taken.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
OLC period timer length
Parameter ID: OLCPERIODTIMERLEN
The default value of this parameter is 3000 (ms)
Key parameters
OLC period timer lengthParameter ID: OLCPERIODTIMERLEN Value range: 100 to 86400000 Content: This parameter specifies the period of overload control. The default value of this parameter is 3000 (ms)Set this parameter through SET LDCPERIOD
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
OLC ActionTF Control
Target user
Based on RAB integrate priority
The RABs with the DCH BE services
Execution
The RNC sends the “TF control indication” message to the MAC.
MAC restricts the TFC selection :
TFmax(N+1) = TFmax(N) x Ratelimitcoeff
Based on the RAB integrate priority, the OLC sorts the RABs into a descending order.Thefollowing RABs are selected:
1. The RABs with the DCH BE services 2. The RABs with the lowest integrate priority.3. The number of RABs selected is DL/UL OLC fast TF restrict RAB number.
The RNC sends the TF control indication message to the MAC. Each MAC of selected RABs will receive one TF control indication message and will restrict the TFC selection of the BE services to reduce the data rate step by step.
MAC restricts the TFC selection in a way like that the maximum TB number is calculated with the formula:
TFmax(N+1) = TFmax(N) x RatelimitcoeffRatelimitcoeff is a configurable parameter (DL OLC fast TF restrict data rate restrict
coefficient).If the RNC cannot find an appropriate service for the TF control or the time for performing
the TF control exceed the DL OLC fast TF restrict times parameter, the action fails. The OLC performs the next action.
If the congestion is released, the RNC sends the congestion release indication to the MAC. At the same time, the rate recovery timer (whose length is defined by DL OLC fast TF restrict data rate recover timer length) is started. When this timer is expired, the MAC increases the data rate step by step.
MAC recovers the TFC selection by calculating the maximum TB number with the formula:TFmax(N+1) = TFmax(N) x RateRecoverCoeffRateRecoverCoeff is a configurable parameter (DL TF rate recover coefficient)
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OLC ActionTF Control example
Before point A, the cell is not in OLC state. The downlink data transfer rate is 384 kbit/s, the corresponding TF is 12 x 336, and TFS is {12 x 336, 8 x 336, 4 x 336, 2 x 336, 1 x 336, 0 x 336}.336 is the TB size, 320 payload + 16 MAC head
At point A, the cell enters OLC state. The RNC selects this RAB to do fast TF restriction. MAC restricts the TFC selection during time between point A and point B by calculating the maximum TB number as follows:TFmax(1) = TFmax(0) x Ratelimitcoeff = 12 x 0.68 = 8.16Match 8.16 and the TFS. Therefore, the maximum TB number is 8.
At point B, MAC performs further TFC restriction by calculating maximum TB number as follows:TFmax(2) = TFmax(1) x Ratelimitcoeff = 8 x 0.68 = 5.44Match 5.44 and the TFS. Then, the maximum TB number is 4.
At point C and point D, similar process is followed.
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UL/DL OLC fast TF restrict RAB number
Parameter ID: UL/DLOLCFTFRSTRCTRABNUM
The default value of this parameter is 3
UL/DL OLC fast TF restrict times
Parameter ID: UL/DLOLCFTFRSTRCTTIMES
The default value of this parameter is 3
Key parameters
UL/DL OLC fast TF restrict RAB numberParameter ID: UL/DLOLCFTFRSTRCTRABNUM Value range: 0 to 10 Content: These parameters specify the maximum number of RABs selected in a fast TF restriction of UL/DL OLC.If the number of RABs that fulfil the criteria for TF control is smaller than the value of this parameter, then all the RABs that fulfil the criteria are selected. The default value of this parameter is 3Set this parameter through ADD CELLOLC / MOD CELLOLC
UL/DL OLC fast TF restrict timesParameter ID: UL/DLOLCFTFRSTRCTTIMES Value range: 0 to 100Content: These parameters specify the times of UL/DL OLC fast TF restrictions that are executed. The default value of this parameter is 3
Set this parameter through ADD CELLOLC / MOD CELLOLC
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DL TF rate restrict coefficient
Parameter ID: RateRstrctCoef
The default value of this parameter is 68%
DL TF rate restrict timer length
Parameter ID: RateRstrctTimerLen
The default value of this parameter is 3000 (ms)
Key parameters
DL TF rate restrict coefficientParameter ID: RateRstrctCoefValue range: 1 to 99 % Content: This parameter specifies the data rate restriction coefficient in the fast TF restriction. The smaller the parameter is, the more effective the TF restriction is. After receiving the TF control indication, the MAC obtains the maximum TF format with the formula TFmax' = TFmax x Ratelimitcoeff . The default value of this parameter is 68 %Set this parameter through ADD CELLOLC / MOD CELLOLC
DL TF rate restrict timer lengthParameter ID: RateRstrctTimerLenValue range: 1 to 65535 msContent: This parameter specifies the length of the data rate restriction timer in the fast TF restriction. The smaller the value of this parameter is, the more effective the TF restriction is. The default value of this parameter is 3000 msSet this parameter through ADD CELLOLC / MOD CELLOLC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
DL TF rate recover timer length
Parameter ID: RateRecoverTimerLen
The default value of this parameter is 5000 (ms)
DL TF rate recover coefficient
Parameter ID: RecoverCoef
The default value of this parameter is 130 %
Key parameters
DL TF rate recover timer lengthParameter ID: RateRecoverTimerLenValue range: 1 to 65535 msContent: This parameter specifies the length of the data rate recovery timer. The smaller the value of this parameter is, the faster the BE traffic rate increases after the congestion is resolved. The default value of this parameter is 5000 msSet this parameter through ADD CELLOLC / MOD CELLOLC
DL TF rate recover coefficientParameter ID: RecoverCoefValue range: 100 to 200 %Content: This parameter specifies the data rate recovery coefficient in the fast TF restriction. The larger the parameter is, the larger the TF recover effect. After receiving congestion release indication, the MAC obtains the maximum TF format with the formula TFmax' = TFmax x RateRecovercoeff. The default value of this parameter is 130%Set this parameter through ADD CELLOLC / MOD CELLOLC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
OLC ActionSwitching BE Services to Common Channel
Target user
Based on the user integrate priority
The users with the DCH or HSDPA BE services in PS
Execution
The RNC sends “RB Reconfiguration” message to UE
UE make a response by “RB Reconfiguration Complete”
The OLC algorithm for switching BE services to common channel operates as follows:Based on the user integrate priority, the OLC sorts all UEs that only have PS services
including HSPA and DCH services (except UEs having also a streaming bearer) into a descending order.
The top N UEs are selected. The number of selected UEs is equal to Transfer Common Channel user number. If UEs cannot be selected, the action fails. The OLC performs the next action.
The selected UEs are switched to common channel.
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Transfer Common Channel User number
Parameter ID: TransCchUserNum
The default value of this parameter is 1
Key parameters
Transfer Common Channel User numberParameter ID: TransCchUserNumValue range: 1 to 10Content: This parameter specifies the transfer common channel user number The default value of this parameter is 1Set this parameter through ADD CELLOLC / LST CELLOLC / MOD CELLOLC
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OLC ActionRelease of Some RABs
Target user
Based on the RAB integrate priority
DCH services RAB
Execution
The RNC sends “IU Release Request” message to CN
The RNC sends “RRC Connection Release” message to UE
OLC Algorithm for the Release of Some RABs in the Uplink:The OLC algorithm for the release of some RABs in the uplink operates as follows:Based on the integrate priority, the OLC sorts all RABs including HSUPA and DCH services
into a descending order.The top RABs selected. If the integrate priorities of some RABs are identical, the RAB with
higher rate (current rate for DCH RAB and GBR for HSUPA RAB) in the uplink is selected. The number of selected RABs is equal to UL OLC traff release RAB number.
The selected RABs are released directly.OLC Algorithm for the Release of Some RABs in the DownlinkThe OLC algorithm for the release of some RABs in the downlink operates as follows:Based on the integrate priority, the OLC sorts all RABs into a descending order.The top-priority RABs are selected. If the integrate priorities of some RABs are identical,
the RAB with higher rate (current rate) The number of selected RABs is equal to DL OLC traff release RAB number.
The selected RABs are directly released.
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UL/DL OLC traff release RAB number
Parameter ID: UL/DLOLCTRAFFRELRABNUM
The default value of this parameter is 0
Key parameters
UL/DL OLC traff release RAB numberParameter ID: UL/DLOLCTRAFFRELRABNUMValue range: 0 to 10 Content: Either parameter specifies the number of RABs released in a UL or DL OLC release action.If the number of RABs that fulfil the criteria for release is smaller than the value of this parameter, then all the RABs that fulfil the criteria are selected. The default value of this parameter is 0Set this parameter through ADD CELLOLC / MOD CELLOLC
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
SummaryLoad Control Algorithms
PUC (Potential User Control)
LDB (Intra-Frequency Load Balancing)
CAC (Call Admission Control)
IAC (Intelligent Admission Control)
LDR (Load Reshuffling)
OLC (Overload Control)
Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.
Thank You
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