07_HandoverControl_2004

1 NOKIA 30/11/2003 RANPAR Version 1.1

Course Content

Radio Resource Management Overview

Parameter Configuration

Common Channels & Power Control

Load Control

Admission Control

Packet Scheduling

Handover Control

Resource Manager


Course Objectives

At the end of the course you will be able to:

Name and describe the different handover types

Describe and list the steps of the handover procedure for each handover type

Name and describe the main RAN parameters related to handover reporting triggering

Describe the main difference between inter system handover and other handover types

Name and describe the main RAN parameters related to inter system handover


Handover Control Handover Types Intra-Frequency handover:

Parameters Mapping SHO Events and Measurements Hard handover RRC Connection Release

Compressed-Mode Inter-Frequency & Inter-System handover:

Measurement triggering Inter-Frequency & Inter-System Measurements Inter-Frequency HO decision Inter-System HO decision

GSM ISHO Load Based Handover to WCDMA Cell Reselection to WCDMA


Intra-Frequency Handovers Softer handover

Handover between sectors of the same Node B (handled by BTS) No extra transmissions across Iub interface Maximum Ratio Combining (MRC) is occurring in both the UL and DL

Soft handover MS simultaneously connected to multiple cells (from different Node Bs) Extra transmission across Iub, more channel cards are needed (compared to non-SHO) Mobile Evaluated HandOver (MEHO) DL/UE: MRC & UL/RNC: Frame selection combining

Hard handover Arises when inter-RNC SHO is not possible (Iur not supported or Iur congestion) Decision procedure is the same as SHO (MEHO and RNC controlled) Causes temporary disconnection of the (RT) user

Inter-Frequency Handover Can be intra-BS, intra-RNC, inter-RNC Network Evaluated HandOver (NEHO) Decision algorithm located in RNC

Inter-RAT Handover Handovers between GSM and WCDMA (NEHO)

Handover Types


Soft Handover

Main method is soft/softer handover MS connected to two or more cells Up to 3 branches can be used (MaxActiveSetSize parameter) Seamless handover without any disconnection of UE-RAN connection softer handover probability about 5-15 % : soft handover probability about 20-50 %

Same power levels in use for all soft handover branches Optimum power levels for link quality and cell capacity Macro Diversity Combining (MDC) gain to reduce power levels

Mobile Evaluated HandOver (MEHO) Enables different cell sizes due to Common Pilot Channel Ec/No measurement Optimum fast close loop power control in use Outer loop PC after MDC controls the BLER according to set target and thus maintains the quality

WCDMA F1 WCDMA F1 WCDMA F1


HC Parameter Database Structure

RNC = Radio Network Controller level parameters

WBTS = Node B level parameters

WCELL = Cell level parameters

FMCx = Frequency Measurement Control parameters (S=intra-frequency set; I=inter-frequency; G=inter-RAT)

ADJx = Adjacent Cell parameters (S=intra-frequency set; I=inter-frequency; G=inter-RAT)

HOPx = Handover Path parameters (S=intra- frequency set; I=inter-frequency; G=inter-RAT)

S:Intra-FrequencyS:Intra-

Frequency

I:Inter-FrequencyI:Inter-

Frequency

G:Inter-System

G:Inter-System

WCELL

ADJG

ADJI

ADJS

WBTS

RNC

FMCS

FMCI

FMCG

100

100

100

HOPS 100

HOPI 100

HOPG 100

32

48

32


SHO: Neighbour Cell Definition

ADJS

ADJS

ADJS

FMCS(NRT)

FMCS(RT)

HOPS(RT)

HOPS(NRT)

HOPS(NRT)

HOPS(NRT)

HOPS(RT)

HOPS(RT)

HOPSid = 5

HOPSid = 10

FMCSid = 3

FMCSid = 40

ADJSid = 1

ADJSid = 2

ADJSid = 3

WCELWCELWCEL

WCEL

WCELWCELWCELWBTS

Each WCEL has 1 FMCS for NRT & 1 for RT which is used for all Ncells. FMCS parameters could be defined on a serving cell type basis (urban, rural, macro/micro/pico)

Each ADJS has 1 HOPS for NRT & 1 for RT which is used for all Ncells. HOPS parameters could be defined on a target cell type basis (urban, rural, macro/micro/pico)

NrtFmcsIdentifier = 3

RtFmcsIdentifier = 40

NrtHopsIdentifier = 5RtHopsIdentifier = 10


ADJS, HOPS & FMCSHO Parameter Categories

Intra-Frequency

Inter-Frequency

Inter-System

Handover Control ParametersRNC parametersWCEL parametersHOPS parameters FMCS parametersADJS parameters HOPI parameters FMCI parametersADJI parameters HOPG parameters FMCG parameters ADJG parameters

100HOPS parametersCell Re-selection HCS PriorityCell Re-selection HCS ThresholdCell Re-selection Minimum QualityCell Re-selection Minimum RX LevelCell Re-selection Penalty TimeCell Re-selection Quality Offset 1Cell Re-selection Quality Offset 2Cell Re-selection Temporary Offset 1Cell Re-selection Temporary Offset 2CPICH Ec/No Averaging WindowEnable Inter-RNC Soft HandoverEnable RRC Connection ReleaseHHO Margin for Average Ec/NoHHO Margin for Peak Ec/NoRelease Margin for Average Ec/NoRelease Margin for Peak Ec/No

Define Target Cell Selection

1100

FMCS parametersActive Set Weighting CoefficientAddition Reporting IntervalAddition TimeAddition WindowCPICH Ec/No Filter CoefficientCPICH Ec/No HHO CancellationCPICH Ec/No HHO Cancellation TimeCPICH Ec/No HHO ThresholdCPICH Ec/No HHO Time HysteresisCPICH RSCP HHO CancellationCPICH RSCP HHO Cancellation TimeCPICH RSCP HHO Filter CoefficientCPICH RSCP HHO ThresholdCPICH RSCP HHO Time HysteresisDrop TimeDrop WindowMaximum Active Set SizeReplacement Reporting IntervalReplacement TimeReplacement Window

Define Adjacent Cell Measurement Control

132

In GSM: Define HO TriggerHoThresholdsLevDL Rx (LDR): -92 dBm Px (LDP): 3 Nx (LDN): 4

Define Target Cell SelectionRx Lev Min Cell: -95 dBm

Define Adj Cell

ADJS parameters Cell Identifier CPICH Ec/No Offset Disable Effect on Reporting Range Location Area Code Maximum UE TX Power on RACH Mobile Country Code Mobile Network Code Mobile Network Code LenPrimary CPICH power NRT HOPS Identifier Primary Scrambling Code RNC Identifier Routing Area Code RT HOPS Identifier Tx Diversity Indicator

Define Adj Cell

1


Separate HandOver Parameter Set (HOPS) identifiers for real time(RT) & non-real time(NRT) traffic

RtHopsIdentifier - real time

NrtHopsIdentifier - non-real time

Each HOPS object is identified by a unique HOPSid (HOPS) in the RNC - on to which the RtHopsIdentifier and/or NrtHopsIdentifier parameters are mapped to identify the appropriate HOPS parameter set for that particular neighbour cell

Primary scrambling code for neighbour cell specified using AdjsScrCode

AdjsTxDiv specifies whether the neighbour cell is using Tx diversity

AdjsTxPwrRACH determines the maximum power the UE can use on the PRACH when accessing the neighbour cell

Neighbour Cell Definition



Each intra-frequency neighbour (ADJS) is identified using ADJSid (ADJS)

The ADJS parameters provide information on the identity of each neighbour cell together with its properties (i.e. handover parameter set identifier, scrambling code etc.)

AdjsName is the cell name provided by the network planner

Each neighbour cell is defined using the UTRAN cell identifier which comprises;

UTRAN Cell Identifier = MCC + MNC + RNC identifier + Cell identifier

MCC (Mobile Country Code) = AdjsMCCMNC (Mobile Network Code) = AdjsMNCRNC Identifier = AdjsRNCidCell Identifier = AdjsCI

The LAC (AdjsLAC) & RAC (AdjsRAC) are also in ADJS parameter set

ADJS Parameters



AdjsMCCAdjsMNCAdjsRNCidAdjsCI

UTRAN Cell ID

ADJSid

MaxActiveSetSizeRNCAdjsScrCodeAdjsTxDivAdjsTxPwrRACH

RT HO Control Parameter: RtHopsIdentifier NRT HO Control Parameter: NrtHopsIdentifier


Soft Handover

HC supports the following measurement reporting events: Event 1A: A primary CPICH enters the reporting range (Ncell addition) Event 1B: A primary CPICH leaves the reporting range (Ncell deletion) Event 1C: A non-active CPICH becomes better than an active primary CPICH (Ncell

replacement)

Cell individual offsets for modifying measurement reporting behaviour Mechanism for forbidding a neighbouring cell to affect the reporting range

Handover decision performed by RNC based on measurements and available resources

Admission Control can reject the branch addition in case the maximum load is achieved in DL (threshold + offset), valid both for RT and NRT bitrates.

Hard blocking may prevent branch addition


The handover measurement is based on CPICH Ec/Io

The accuracy of pilot Ec/Io measurements is important for handover performance

Measurement accuracy depends on the filtering length and mobile speed. When a MS moves slowly or is stationary, filtering length (in ms) has to be just long enough to

avoid fast fades leading to errors and causing unnecessary handovers within a short period.

Long filtering length will cause handover delays to fast moving MS

UE can perform averaging on EC/IO measurement prior to the event reporting process

EcNoFilterCoefficient (FMCS) defines the measurement period for intra-frequency CPICH EC/IO measurements used by UE (default = 200ms)

RNC averages CPICH Ec/Io measurements using EcNoAveragingWindow (HOPS) - defines the number of event triggered or periodic intra-frequency measurement reports used by RNC to calculate averaged CPICH EC/IO (default = 8 Measurements)

SHO: Measurement Control


SHO: Measurement Control

Node B

UTRAN

RNCUE

Measurement Control [ ]

I am in the CELL_DCH sub-state

Measurement Type: Intra-frequency measurements Reporting events:

1A: A primary CPICH enters the reporting range 1B: A primary CPICH leaves the reporting range 1C: A non-active CPICH becomes better than an active primary CPICH

Periodical reporting / event triggered Measurement quantity: CPICH Ec/No etc.

System Information [ ]

SIB 11/12 EcNoFilterCoefficient

Measurement accuracy depends on speed & Filter Coefficient

EcNoAveragingWindow


1A: A Primary CPICH Enters the Reporting Range Reporting range defined by offset (point 1 on next slide) from either

(i) best CPICH Ec/Io in the AS, or(ii) sum of the AS measurement resultsset using ActiveSetWeightingCoefficient (FMCS) (0 = use best CPICH : 0 = use sum)

Offset defined using AdditionWindow (FMCS) Event 1A triggered when CPCIH3 Ec/Io enters UE reporting range (point 2)

If CPICH3 Ec/Io remains within reporting range for a time period defined by AdditionTime(FMCS) , and the AS is not full, UE sends measurement report to RNC which adds Ncell3 to AS if possible (point 3)

AdditionTime defines the 'time-to-trigger' interval between the Ncell first entering the reporting range and the UE sending the measurement report to the RNC

If RNC is unable to add Ncell to AS, UE will wait for a period of time, defined by AdditionReportingInterval (FMCS) (point 4) after the first measurement report, before sending further reports periodically, with interval AdditionReportingInterval, until (a) Ncell moves out of reporting range, or (b) RNC adds Ncell to AS.


4

1A: A Primary CPICH Enters the Reporting Range

Strongest CPICH in AS

time

Ec/Io

P CPICH 3

P CPICH 1

P CPICH 2

1

2

3

AdditionWindow

AdditionTime

AdditionReportingInterval

RNC

MeasurementReport

Add tothe AS?

no

ActiveSetWeightingCoefficient


Reporting criteria of event 1A in 25.331/RRC Measurement Control :

Reporting Cell Status: All active cells + 2 monitored cells.

Triggering Condition: Monitored Set cells

Reporting Range Constant AdditionWindow / 4 dB

Cells forbidden to affect Reporting range: AdjsDERR / Enable

W: ActiveSetWeightingCoefficient / 0

Time to trigger: AdditionTime / 0 = 0 ms

Reporting deactivation threshold: MaxActiveSetSize = 3

Amount of reporting: infinity

Reporting interval: AdditionReportingInterval / O.5 s

1A: A Primary CPICH Enters the Reporting Range


1B: A Primary CPICH Leaves the Reporting Range

Event 1B triggered when CPICH3 EC/I0 drops out of the UE reporting range for a defined period of time (point 1 on next slide)

Reporting range = Strongest CPICH in AS - DropWindow (FMCS) (point 2) Time-to-trigger period set using DropTime (FMCS) (point 3) UE sends RNC measurement report on expiry of DropTime to remove Ncell (CPICH3) from AS. RNC drops the cell from the AS and UE drops the cell from the AS to the Neighbour Set


Strongest CPICH in AS

time

Ec/Io

P CPICH 3

P CPICH 1

P CPICH 2

1

2

3

DropWindow

DropTime

MeasurementReport


Remove the reported cell from the AS


Reporting criteria of event 1B in 25.331/RRC Measurement Control :

Reporting cell Status: 3 active cells

Triggering Condition: Active cells

Reporting Range Constant: DropWindow / 4 dB

Cells forbidden to affect Reporting range AdjsDERR / Enable

W : ActiveSetWeightingCoefficient / 0

Time to trigger: DropTime / 320 ms



1C: A non-active CPICH becomes better than an active primary CPICH

UE AS full (MaxActiveSetSize = 3) Event 1C triggered when CPICH4 EC/IO > CPICH3 in AS by a defined margin,

ReplacementWindow (FMCS). (point 1 in next slide) Sending of measurement report to RNC can be delayed by using 'time-to-trigger' period set

by ReplacementTime (FMCS) If 'time-to-trigger' is used difference between CPICH4 and CPICH3 must be

ReplacementWindow for the period of ReplacementTime (point 2) If the RNC is not able to replace the Ncells, the UE continues to send measurement reports

periodically, with interval ReplacementReportingInterval, to the RNC until (a) CPICH4 falls out of ReplacementWindow or (b) RNC replaces CPICH4 by CPICH3 (point 3)


time

weakest CPICH3 in AS

Ec/Io

P CPICH 3

P CPICH 1P CPICH 2P CPICH 4

AS has 3 cells

ReplacementReportingInterval3

1

2

ReplacementWindow

ReplacementTime

MeasurementReport

RNC

ASupdate?

no



Reporting criteria of event 1C in 25.331/RRC Measurement Control :

Reporting cell Status: All active cells + 2 monitored cells.

Hysteresis: ReplacementWindow / 2 dB

Time to trigger: ReplacementTime / 0 = 0 ms

Replacement activation threshold : MaxActiveSetSize / 3

Amount of reporting: infinity

Reporting interval: ReplacementReportingInterval / 0.5s



Individual Ncell Offset &Forbidding Neighbour Cell from Reporting Range

Individual Ncell Offset

cell individual offsets for modifying measurement reporting behaviour

effectively 'moves' cell border (shrinks or enlarges cell)

offset set using AdjsEcNoOffset (= CPICH Ec/No Offset) (ADJS) offset applied to Primary CPICH measurements before event evaluation by the UE

Forbidding Neighbour Cells from Reporting Range

the primary CPICH of certain cells can be forbidden from reporting range calculation in some instances

cells can be forbidden from reporting range using AdjsDERR (ADJS)


Individual Ncell Offset

time

P CPICH 1

P CPICH 2

P CPICH 3

Reporting Range

Reporting Event 1B

Reporting Event 1A

AdjsEcNoOffset

Enlarging Cell 3 by x dB

Ec/Io


Forbidding Neighbour Cell from Reporting Range

Time

P CPICH 1

P CPICH 2

P CPICH 3

PCPICH3 is forbidden to affect the reporting range as its quality is quite unstable.

Reporting Range

AdjsDERR

Ec/Io


Event 1A(Add)

Event 1B(Drop)

Event 1C(Replace)

Active set cells +2 monitored set

cells

Monitored set cells

Addition Window/4 dB

Active set cells Active set cellsDrop Window/

6 dB

Active set cells +2 monitored set

cells- Replacement Window/4 dB

Addition Time/0 ms

AdditionReportingInterval/0.5 s

Drop time/320 ms -

Replacementtime/0 ms

ReplacementReportingInterval/

1s

Event Reporting cell statusTriggering Condition

Reporting Range/Hysteresis Time to Trigger

Reporting Interval

Cells forbidden to affect Reporting range (for 1A and 1B) : AdjsDERR / default Enable

For 1A and 1B: ActiveSetWeightingCoefficient / default 0

For 1A: Reporting deactivation threshold: MaxActiveSetSize 1 / default 2

For 1C: Replacement activation threshold : MaxActiveSetSize / default 3

SHO Summary


SHO for synchronisation reason: Event 6F: The UE Rx-Tx time difference for a Radio Link (RL) included in

the active set becomes larger than an absolute threshold Reporting Reporting event 6G: The UE Rx-Tx time difference for a RL included in

the active set becomes smaller than an absolute threshold Estimation of these events:

Based on UE Rx-Tx time difference Measurement configuration:

Time-to-trigger: not used. 6F: UE Rx-Tx time difference threshold: UpperRxTxTimeDiffdefault: 1174 chips, range:1152 ... 1280 chips, step 1 chip

6G: UE Rx-Tx time difference threshold: LowerRxTxTimeDiffdefault: 874 chips range: 768 ... 896 chips, step 1 chip

NOTE: Some UE does not support these events

UE Internal Measurements


Node B

UTRAN

RNCUE

Measurement Control [ ] I am in the

CELL_DCH sub-state

Measurement Type: UE Internal measurements Reporting events:

6F: The UE Rx-Tx time difference for a RL included in the active set becomes larger than an absolute threshold Reporting 6G: The UE Rx-Tx time difference for a RL included in the active set becomes smaller than an absolute threshold

DLnom

time

T0

UL DPCH

time

time

6F 6G

UE Internal Measurements


Measurement reporting criteria are cell specific

Neighbouring cells (ADJS and HOPS parameters) are defined on a controlling cell (cell from which the call has been started or best cell in case the original cell has been deleted from the active set)

During SHO the measurement reporting criteria are taken from the cell where the UE has started the connection

The measurement reporting criteria are updated only when the original cell leaves the Active Set (Nokia Implementation), according to the strongest cell in the Active Set, by sending the MEASUREMENT CONTROL message, transmitted on the downlink DCCH. Standard would allow to update reporting criteria, according the current best server.

When the UE receives a MEASUREMENT CONTROL message, the UE shall stop monitoring and measurement reporting and shall replace the measurement reporting criteria with the new information received in the MEASUREMENT CONTROL message.

Measurement Report Updating


Measurements Reporting Criteria Updating during Soft handover

Cell 1 Cell 2

Neighbour ListCell1 Addition WindowCell1Drop WindowCell1Drop TimeCell1

1. Idle Mode

System Information

(BCCH)

BEST Server: Cell 1BEST Server: Cell 1

2. Connected Mode: Cell_DCH

The UE shall continue monitoring the list of

neighbouring cells assigned in System Information during Idle

Mode

The UE shall continue monitoring the list of

neighbouring cells assigned in System Information during Idle

Mode

Measurement Reporting Criteria according to Cell 1


The UE shall send the MEASUREMENT REPORT message when reporting

criteria are fulfilled.

The UE shall send the MEASUREMENT REPORT message when reporting

criteria are fulfilled.

Connected Mode: Cell_DCH

3. MEASUREMENT REPORT (DCCH)



Intra-frequency MeasurementIntra-frequency Measurement

The measurement reporting criteria are updated as soon as the original cell drops out from the Active Set (Nokia

Implementation).

The measurement reporting criteria are updated as soon as the original cell drops out from the Active Set (Nokia

Implementation).

Connected Mode: Cell_DCH

4. MEASUREMENT

CONTROL (DCCH)

Neighbour ListCell2Addition WindowCell2Drop WindowCell2Drop TimeCell2




Reporting Criteria

Updating


Neighbour List Measurement during SHO

Cell 1 Cell 2

Intra-frequency MeasurementIntra-frequency Measurement

Addition WindowCell1Drop WindowCell1Drop TimeCell1

1. System Information (BCCH)


Neighbour List Cell 1Neighbour List Cell 1

Measurement Reporting Criteria according to

Cell 1


Cell 1

Active Set: Cell 1Active Set: Cell 1

2

3

5

2

3

5

3. MEASUREMENT REPORT (DCCH)

1A1B6. MEASUREMENT REPORT

(DCCH)

4. ACTIVE SET UPDATE

8. MEASUREMENT CONTROL (DCCH)

Addition WindowCell2Drop WindowCell2Drop TimeCell2


Measurement Reporting Criteria according to Cell 2Measurement Reporting

Criteria according to Cell 2

Neighbour List Update

1

3

4

1

3

4

Neighbour List Cell 2Neighbour List Cell 2

Active Set: Cell 2Active Set: Cell 2Meas. Rep.

Criteria Update


Cell 1


Cell 1

3

1

4

2

5

3

1

4

2

5

Neighbour List CombinationNeighbour List Combination

Neighbour List Update

5. MEASUREMENT CONTROL (DCCH)

Active Set: Cell1 - Cell2Active Set: Cell1 - Cell2

2. Setup Call

2. Setup Call

7. ACTIVE SET UPDATE


Inter-RNC soft handovers are performed if: RNC: IurUPSupport indicates the support of the user plane over Iur HOPS: EnableInterRNCsho indicates whether cell can participate in a SHO

Otherwise, HC checks whether Hard Handover is possible. HHO decision is made by the RNC if either;

AveEcNoDownlink + HHoMarginForAveEcNo(n) < AvEcNoNcell(n)

EcNoDownlink + HHoMarginPeakEcNo(n) < EcNoNcell(n)

AveEcNoDownlink and AvEcNoNcell(n) = measured values for the best AS cell and the nth NS cell, averaged over EcNoAveragingWindow measurements

EcNoDownlink and EcNoNcell(n) = instantaneous values

HHoMarginForAveEcNo (HOPS) = average Ec/N0 margin [-6 6]dB, default 1dB HHOMarginPeakEcNo (HOPS) = peak Ec/N0 margin [-6 6]dB, default 2dB

Inter-RNC Soft HO and Hard HO


Inter-RNC Soft HO

cell3 cell2

cell1

cell4cell6

cell5

RNC RNCIurUPSupport

EnableInterRNCsho

EnableInterRNCsho


If RNC is not able to add (Event 1A) to or replace (Event 1C) an Ncell from the AS, UE sends periodic measurement reports (AdditionReportingInterval / ReplacementReportingInterval) until; Ncell is added/replaced in to AS Ncell leaves reporting range HO no longer required (e.g. different Ncell enters AS)

RNC may not be able to add/replace Ncell due to (a) Iur congestion or (b) inter-RNC SHO is prevented due to setting of EnableInterRNCsho (HOPS) (point1 on next slide)

If CPICH EC/NO of non-active Ncell continues to increase it will cause additional interference due to a non-optimal connection (point 2)

To avoid excessive uplink interference, RNC will perform an intra-frequency hard handover to the Ncell (CPICH3) if either of the following criteria are met (point 3);

AveEcNoDownlink + HHOMarginAveEcNo < AveEcNoNcellEcNoDownlink + HHOMarginPeakEcNo < EcNONcell

(Both HOPS)

Hard Handover


Time

Ec/Io

P CPICH 3

P CPICH 1

P CPICH 2Reporting

range

AdditionReportingInterval

1

2

HHOMarginAverageEcNoHHOMarginPeakEcNo

1A (AdditionTime = 0)

AveEcNoDownlink + HHOMarginAveEcNo < AveEcNoNcellEcNoDownlink + HHOMarginPeakEcNo < EcNONcell

Hard Handover

3


If difference between the best AS cell and the NS cell is too high and SHO is not performed, the RRC connection is released to avoid excessive interference

Why might an AS update not be possible? Excessive load in the neighbouring cell Hard blocking in the target BTS Unavailability of DL spreading codes Iub transport resources unavailable

This function is activated by EnableRRCRelease (HOPS parameter)/0=no (def),1 =yes

The RRC connection is released if either:

AveEcNoDownlink + ReleaseMarginForAveEcNo(n) < AvEcNoNcell(n)EcNoDownlink + ReleaseMarginPeakEcNo(n) < EcNoNcell(n)

ReleaseMarginForAveEcNo (HOPS) = average Eb/N0 margin [-6 6] dB, default 2.5dB ReleaseMarginPeakEcNo (HOPS) = peak Eb/N0 margin [-6 6] dB, default 3.5dB

Emergency calls are exempt from RRC Connection Release process

RRC Connection Release


Compressed Mode in UplinkGSM BTS WCDMA BTS

DL

DL CM (this should be offwhen GSM is measured)

UL CM (needed to avoid interference)

During WCDMA transmissionsignal leakage will go to GSMRx also


Compressed Mode (CM) CM was introduced to WCDMA to allow inter-frequency (system) handovers CM is used to create idle periods (gaps) in the transmission during which ncell measurements on

another frequency can be made

Gaps can be created using single or double frame approach (Nokia supports both) Because same data amount is sent in a shorter time more power is needed during CM (both in

UE and BTS)=> affects WCDMA coverage

Fast Power control information might be lost during the gap => higher Eb/No=> affects WCDMA capacity

Compressed frames may be lost if power control is not set correctly=> affects WCDMA quality

CM methods are Puncturing, Spreading Factor Halving and Higher Layer Scheduling

Normal frame Normal frame

Measurement gapMeasurement gapPower / Data Rate

CompressedMode

Normal frame


AssumptionAssumption Effect to the capacityEffect to the capacity

Required Eb/No is 1.5 dB higher during compressed frames

Required Eb/No is 1.5 dB higher during compressed frames 1.5 dB = 41% more interference1.5 dB = 41% more interference

Every 3rd frame is compressedEvery 3rd frame is compressed 41% /3 = 14% more interference41% /3 = 14% more interference

10% of the users are measured at the same time

10% of the users are measured at the same time 14% /10 = 1.4% more interference

14% /10 = 1.4% more interference

Capacity degradation < 2%

Performance of Compressed Mode: Capacity

Exact increase in Eb/N0 depends on service, multipath diversity, antenna diversity, mobile speed, uplink or downlink, measurement gap length, compressed mode method (spreading factor or puncturing), and 1.5 dB represents a typical value.

Exact increase in Eb/N0 depends on service, multipath diversity, antenna diversity, mobile speed, uplink or downlink, measurement gap length, compressed mode method (spreading factor or puncturing), and 1.5 dB represents a typical value.


Performance of Compressed Mode: CoverageAssumptionAssumption Effect to the coverageof real time services

Effect to the coverageof real time services

Required Eb/No is 1.5 dB higher during compressed frames

Required Eb/No is 1.5 dB higher during compressed frames 1.5 dB reduced coverage1.5 dB reduced coverage

7-slot gap is used7-slot gap is used 10*log10(15/8) = 2.7 dB reduced coverage

10*log10(15/8) = 2.7 dB reduced coverage

Every 2nd frame is compressed with 20 ms interleaving (speech)

Every 2nd frame is compressed with 20 ms interleaving (speech) 4.2 dB / 2 = 2.1 dB reduced coverage

4.2 dB / 2 = 2.1 dB reduced coverage

Total coverage reduction 2.1 dB

Compressedmode

Mobile max. power

Frame error if mobile hitsits maximum power

2.7 dB + 1.5 dB more power is needed during compressed mode

Non-real time services can reduce the bit rate during compressed frames no effect to coverage

Speech connection can switch to a lower AMR mode


Measurement Gap

Min transmitted TSs per Frame: 8

radio frame radio frame

TGL

Length of gap:3, 4, 5, 7 timeslots

Single-frame method

radio frame radio frame

TGL

Double-frame method

Length of gap:3, 4, 5, 7, 10, or 14 timeslots


Compressed mode methods Puncturing for Speech in DL

Reducing the physical channel bit amount (Channel Coding Convolution Coding) More Tx power is needed if same QoS requirements have to be satisfied Only if all DCHs have enough free puncturing capacity

RNC: DLPuncturingLimit/0.68 =puncturing from coding rate 1/3 to coding rate 1/2.

Halving Spreading Factor, SF/2 for RT and NRT services (UL and DL) Doubles temporarily the physical channel data rate, possible for all services Needs 3 dB more UE power due to halved spreading ratio If new channelization code is available from code tree in DL

WCEL: AltScramblingCodeCM/0=used (def), 1=not used

Higher Layer Scheduling, HLS (UL and DL) Only possible for PS services (RT or NRT) Does not cause extra load to the cell but reduces DCH user data HLS data rate or HLS data rate possible

Double frame is used in case of puncturing and HLS data rateSingle frame is used in case of spreading factor halving and HLS data rate.


Compressed mode parameters CM can be activated/deactivated by CMmasterSwitch (RNC) /0=in use (def) HLS rate configurable using HLSModeSelection (RNC)/def 0=1/2 HSL , 1=3/4 HSL

Method used for voice: HLS not possible UL LowerULAMRmodeCM (RNC) /7.4 kbits/s defines AMR mode corresponding to SF/2 DL selection bit puncturing and SF/2 based on MinDLAMRmodeCM (RNC)/7.4 kbits/s

(range 4.75...12.2 kbits/s)

Method used for RT and NRT services SF/2 is allowed if: UE DL Tx Power < Max_UE_DL_Tx_Pwr PowerMarginCMcodeHalving (RNC)/3 dB (range 0..10, step 0.25)

Maximum number of UEs in CM is controlled through MaxNumbUECMcoverHO (RNC)/16 (range 0..255)

The number of UEs in DL CM depends on the PtxTotal value The number of UEs in UL CM depends on the PrxTotal value


How many UEs in Compressed Mode ?

PtxTarget/PrxTarget

DL/ULtransmission power

Load

PtxOffset/PrxOffset

New UEs can be switched to CM when:Pxx_Total < Pxx_Target &

# of UEs in CM < MaxNumbUECMcoverHO

One new UE in CM can be allowedif the limit is not reached

No new UE can be in CM here


Applicable methods for related services

Service UL CM method DL CM Method

AMR SF/2, HLS SF/2, Puncturing

PS NRT SF/2, HLS SF/2, HLS

CS Data SF/2 SF/2

AMR+PS 1. If the PS bit rate >> AMR bit rate it is possible to create idle gaps by applying frame compression to just the PS DCH. In this case the CM method selection is as in the case of stand-alone PS NRT.2. If both DCHs must be compressed then only the methods applicable to both can be used: i.e. in DL only SF/2 is possible

CM method Frame ModeSF/2 Single Frame

HLS Single Frame HLS Double Frame

Puncturing Double Frame


Selection of DL CM Method

Channel coding>DLPuncturingLimit

Use puncturing(for AMR speech)

SF/2 code available Use SF/2 with thesame scrambling code

Reduce bit rate(for packet data)

DL CM is started with Puncturing instead of SF/2because puncturing needs less power, allow more puncturing if downlink capacity is orthogonal code limited

Link level powerlimit reached

Use SF/2 with anotherscrambling code

Yes

Yes

NoNo

Yes

AMR rate>MinDLAMRModeCM

Lower AMR rate (+ puncturing)

Yes

No

No

Alternative scrambling codeis used when the SF/2 codeis reserved

UL: LowerULAMRModeCMfor AMR rate


Compressed mode method in RAN 1.5.2

Id Compressed mode method1 Puncturing (Not supported in RAN 1.5)

2 SF/23 SF/2 with alternative scrambling code4 HLS 1/25 HLS 3/4

Compressed mode method in NRT PSTriggering reason: Too high UE Tx powerParameter HHOMaxAllowedBitRateUL should be checkedCompressed mode method in Downlink (in priority order): 1,2,3,4,5Compressed mode method in Uplink (in priority order): 2,4,5Triggering reason: Too high DL DCH powerParameter HHOMaxAllowedBitRateDL should be checkedCompressed mode method in Downlink (in priority order): 4,5Compressed mode method in Uplink (in priority order): 2,4,5Triggering reason: Low CPICH EcNo, Low CPICH RSCP, poor UL DCHCompressed mode method in Downlink (in priority order): 2,3,4,5Compressed mode method in Uplink (in priority order): 2,4,5


CM Pattern Parameters

TG Pattern 1

TGPattern 2

TG Pattern 1

TGPattern 2

TGPattern 2

TG Transmission Gap TGL Transmission Gap Length (3,4,5,7,10,14 SL)TGPL Transmission Gap Pattern Length (1-144 Frames) TGD Transmission Gap start Distance (15-269 SL)TGSN Transmission Gap Starting slot Number (1-14 SL)TGPRC TG Pattern Repeat Count

TG Pattern 1 TG Pattern 2

TGPL1 TGPL2

TGSNTGL1 TGL2TGL1TGL2

TGD TGD

#1 #2 #3 #4 #TGPRC

TGCNF transmission gap pattern sequence

GapPositionSingleFrame

TGSN


IFHO/ISHO Process Overview

HO Triggering Thresholds set in RNCHO Triggering Thresholds set in RNC

Event Triggered Coverage/Capacitybased HO fulfilled in RNC

Event Triggered Coverage/Capacitybased HO fulfilled in RNC

RNC commands selected UE(s) to startIF/IS measurements

RNC commands selected UE(s) to startIF/IS measurements

Measurements are done in Compressed Mode (CM)

Measurements are done in Compressed Mode (CM)

UE reports GSM cells withstrongest RSSI signals to RNCUE reports GSM cells with

strongest RSSI signals to RNC

RNC makes HO decision andcommands UE to target cell

RNC makes HO decision andcommands UE to target cell

RSSI measurements and BSICverification for GSM cells

RSSI measurements and BSICverification for GSM cells

Different decision methods for IF HOOnly one decision method for IS HO

5 Coverage/Capacity HO Reasons

About 25 HO parameters

Reporting cells are active set cells (max 3) + max 6 IFHO, max 6 ISHO neighb.

Max 32 neighbours could be measured

(31 Intra-Freq neighbours)48 Inter-Freq neighbours 32 Inter-System neighbours can be measured


IFHO/ISHO measurements- difference

IF measurements

IS measurements

WCDMA

IS-HOMeasurement

Trigger Target Cell found

RSSI meas. BSIC verification

IS-HODecision

WCDMA

IF-HOMeasurement

TriggerTarget Cell found

IF -measurements

IF-HODecision


IF/IS Handover Triggering Reasons

1. DL DPCH approaches itsmaximum allowed powerFMCI: IFHOcauseTxPwrDLFMCG: GSMcauseTxPwrDL

2. Quality deterioration report from UL outer loop PCFMCI: IFHOcauseUplinkQualityFMCG: GSMcauseUplinkQuality

4. UE Tx power approaches itsmaximum allowed power, event 6A/6DFMCI: IFHOcauseTxPwrULFMCG: GSMcauseTxPwrUL

5 . Low measured absoluteCPICH RSCP, events 1E/1FFMCI: IFHOcauseCPICHrscp, FMCG: GSMcauseCPICHrscp

3. Low measured absolute CPICH Ec/No, event 1E/1FFMCI: IFHOcauseCPICHEcNoFMCG: GSMcauseCPICHEcNo

HO trigger

6 . Others (Not implemented in RAN 1.5):e.g. Traffic & load reason IS-HO, etc

Frequency Measuring Control for Inter-Frequency = FMCIFrequency Measuring Control for Inter-System (GSM) = FMCG


Measurement triggering: DL Coverage RNC orders UE to make IF measurements when DL TX power of a single radio link reaches threshold

defined as: DL_code_PWR -PowerOffsetDLdpcchPilot > CPICH Pwr + DL Tx Pwr + DL_TPCH_TXPWR_Threshold

DL_CODE_PWR = measured DL code power PowerOffsetDLdpcchPilot = power offset for the DPCCH pilot bits relative to the DPDCHs power

default = 3 dB, range 0...6 dB, step size 0.25 dB DL Tx Pwr (DPCH) = measurement on DPCH Tx power, (reported by BTS)

RLMeasRepPeriod (WBTS) / default=500ms, range 0..2000ms, step 100ms CPICH Pwr = Tx power of the CPICH of an active cell

PtxPrimaryCPICH (serving RNC) or AdjsCPICHTxPwr (drifting RNC)/33 dBm, range -1050 dBm, step 0.1 dBm

DL_TPCH_TXPWR_Threshold = depends on the service type FMCI: InterfreqDLTxPwrThrAMR/CS/RtPS/NrtPS -1/-3/-3/-1 dB(range -10 dB..0, step 0.5 dB) FMCG: GSMDLTxPwrThrAMR/CS/RtPS/NrtPS -1/-3/-3/-1 dB(range -10 dB..0, step 0.5 dB)

In Addition, the DL data rate allocated to the user must not exceed WCEL: HHoMaxAllowedBitrateDL/64 kbits/s

NOTE: Either WCDMA or GSM will be measured, not both systems

-100dBm 3dB > 33dBm+XXX+(-1dB)


Measurement triggering: DL Coverage

Node BRNC

DCH Data Frame

IubUE

PO1TPCPilotbitsTFCI Data 2 bitsData 1 bits

PO3PO2DL_CODE_PWR PowerOffsetDLdpcchPilot

CPICH_POWER + MAX_DL_DPCH_TXPWR + DL_DPCH_TXPWR_THRESHOLD

Max Power on DPCH (e.g. 33 dBm)

Serving WCDMA cell time

Its time to triggerHO measurements

in the UE

e.g. Radio Link Measurement Report(e.g. Transmitted Code Power Value)

HHoMaxAllowedBitrateDL

Example Speech:Power Data Bits > 33dBm + (-3dB) + (-1dB)

Power Data Bits > 29 dBm (~1W)

Max Power on Channel


Measurement triggering: UL Quality RNC starts inter-frequency measurements based on UL outer-loop power control reports.

Enable reports from Outer-loop Power Control Controller to trigger inter-freq HO, RNC:EnableULQualDetRep/default 0=no, 1=yes

Time duration for which BER/BLER target has not been reached, despite SIR target at maximum level, RNC: ULQualDetRepThreshold/5 s, 0.5..5, step 0.5s

Periodic report, every RNC: ULQualDetRepThreshold seconds, while BLER/BLER target is not reached.

In addition, the UL data rate allocated to the user must not exceed WCEL: HHoMaxAllowedBitrateUL/32 kbits/s


Measurement triggering: UL QualityT

a

r

g

e

t

S

I

R

Max SIR target

Min SIR target

Actual SIR target

1st Quality deterioration report from PC to HC inside RNC

2nd Quality deterioration report (while the condition issatisfied the message is periodically repeated)

default 5s time

SIR SIR

RNC

ULQualDetRepThreshold

EnableULQualDetRepHHoMaxAllowedBitrateUL

RNC


Measurement triggering: CPICH Ec/No RNC starts IF measurement when event 1F occurs for at least one cell of the active

set: A Primary CPICH becomes less than an absolute threshold

RNC stops IF measurement when event 1E occurs for at least one cell of the active set : A Primary CPICH becomes better than an absolute threshold

Filtering applied before event evaluation in the UE: FMCS: EcNoFilterCoefficient/0= 200ms filtering period

Event 1F parameters: Triggering conditions: Active set cells hysteresis: not used in 1F Threshold used frequency: FMCS : HHoEcNoThreshold / - 22 dB (range 0..-24 dB) Time-to-trigger: FMCS: HHoEcNoTimeHysteresis / 640 ms (range 0..5000ms) Amount of reporting: infinity Reporting interval: not applied. Reporting cell status: max 3 active cells.


Measurement triggering: CPICH Ec/No Event 1E parameters:

Triggering conditions: Active set cells Hysteresis: not used in 1F Threshold used frequency: FMCS : HHoEcNoCancel/ -20 dB Time-to-trigger: FMCS: HHoEcNoCancelTime/ 1280 ms Amount of reporting: infinity Reporting interval: not applied. Reporting cell status: max 3 active cells.


Measurement triggering: CPICH Ec/NoReporting event: 1E: A P-CPICH exceeds an absolute threshold (triggered if one)

1F: A P-CPICH falls below an absolute threshold (triggered if all)

time

Cell 1 Cell 2

Cell 3

absolutethreshold

e

.

g

.

P

-

C

P

I

C

H

E

c

/

N

o

1E: HHoEcNoCancel

1E: HHoEcNoCancelTime

1F: HHoEcNoThreshold

1F: HHoEcNoTimeHysteresis


Measurement triggering: CPICH RSCP

UE continually monitors pilot channels of BTSs in AS

If RSCP of a Node B falls below threshold, HHoRscpThreshold, UE sends event 1F report

RNC starts IF measurements when event 1F occurs for all cells in AS

RNC stops IF measurements when event 1E occurs for at least one cell of AS

UE filtering applied before event evaluation using HHoRscpFilterCoefficient (FMCS) /200ms, range 2001600ms


Measurement triggering: CPICH RSCP Event 1E (A primary CPICH exceeds an absolute threshold) parameters:

Triggering conditions: Active set cells hysteresis: not used in 1E Threshold used frequency: (FMCS) : HHoRscpCancel/ - 100 dBm Time-to-trigger: (FMCS): HHoRscpCancelTime/ 1280 ms Amount of reporting: infinity Reporting interval: not applied. Reporting cell status: max 3 active cells.

Event 1F (A primary CPICH falls below an absolute threshold) parameters: Triggering conditions: Active set cells Hysteresis: not used in 1F Threshold used frequency: HHoRscpThreshold (FMCS)/ - 105 dBm Time-to-trigger: HHoRscpTimeHysteresis (FMCS)/ 640 ms Amount of reporting: infinity Reporting interval: not applied. Reporting cell status: max 3 active cells.


Measurement triggering: UL Coverage RNC orders IF measurements when one of the following event occurs:

Event 6A: The UE Tx power becomes larger than an absolute threshold Event 6D: The UE Tx power reaches its maximum value Also GSM measurements could be measured first depending on UE Tx power values

in IFHO and ISHO parameters Only lower threshold is send to UE, so either WCDMA or GSM is measured first,

but also other RAT could be measured if not good enough neighbour is found In addition, the UL data rate allocated to the user must not exceed WCEL:

HHoMaxAllowedBitrateUL/32 kbits/s RNC calls off inter-frequency measurements when event 6B occurs: the UE Tx power

becomes less than an absolute threshold. Filtering applied before event evaluation in the UE.

FMCI : InterfreqUETxPwrFilterCoeff/8=10ms (range 10..480ms) FMCG: GSMUETxPwrFilterCoeff/8 =10ms (range 10..480ms)

NOTE: Not all UE vendors support 6A event


Measurement triggering: UL Coverage Event 6A parameters:

Time-to-trigger: 0s UE Transmitted Power threshold = min (UEtxPowerMaxDPCH, Pmax)

UE_TX_POWER_thresholdwhere:

UEtxPowerMaxDPCH is the maximum allowed UL tx power on DPCH in the active cell (range -50..24 dBm, step 1, default 21 dBm)

Pmax is the maximum RF output power UE_TX_POWER_Threshold depends on the type of service:

FMCI: InterfreqUETxPwrThrAMR/-3 dB (range -10..0, step1) FMCI: InterfreqUETxPwrThrCS/-3 dB (same range and step) FMCI: InterfreqUETxPwrThrNrtPS/-3 dB FMCI: InterfreqUETxPwrThrRtPS/-3 dB FMCG: GSMUETxPwrThrAMR/CS/NrtPS/RtPS -1/-3/-1/-3/ dB

Event 6B parameters: time-to-trigger: FMCI: InterfreqUETxPwrTimeHyst/1280 ms FMCG: GSMUETxPwrTimeHyst/1280 ms

Event 6D parameter:Time-to-trigger: 0s


Reporting Events 6A, 6B and 6D

timetime totrigger

U

E

T

x

P

o

w

e

r

UE Transmitted Power Tx Threshold

6B6A

6Dmin(UEtxPowerMaxDPCH, P_MAX)

6A: The UE Tx power exceeds an absolute threshold 6B: The UE Tx power falls below an absolute threshold 6D: The UE Tx power reaches its maximum value

InterfreqUETxPwrTimeHystGSMUETxPwrTimeHyst


Node B

UTRAN

RNCUE

Measurement Control [ ]

I am in the CELL_DCH sub-state

Measurement Type: Inter-frequency measurements Reporting events:

2A: Change of best frequency2B: The estimated quality of the currently used frequency is belowa certain threshold and the estimated quality of a non-used frequency is above a certain threshold.2C: The estimated quality of a non-used frequency is above a certain threshold2D: The estimated quality of the currently used frequency is belowa certain threshold2E: The estimated quality of a non-used frequency is below a certain threshold2F: The estimated quality of the currently used frequency is above a certain threshold

IFHO Measurements

System Information [ ]

SIB 11/12 EcNoFilterCoefficient


IFHO measurements After HO triggering message is sent to RNC, a RRC message Measurement Control is

sent to UE containing details of the measurement that the UE must execute. Measurement reporting is periodical. Max 6 IF cells can be reported

Upon reception of the measurements reported by the UE, RNC applies a sliding averaging window to the CPICH Ec/No & CPICH RSCP measurements. The averaged levels are used as input to the inter-frequency decision algorithm.

From each cell in active set (max=3) also intra-frequency measurements are done at same time

RNCRRC: Measurement control message

("carrier 2" measurements)

UE

RNC

CPICH Ec/No and CPICH RSCP measurements are reported through Measurement report messages

UE

RRC: Measurement report


In one measurement report there is both intra-and inter-frequency

results, no measurement filtering is used in UEAdjiMeasRepInterval

(default 0.5s)

3 neighbour info send to UE:UTRA RF channel, cell

individual offset (Ec/No) and primary scrambling code


IFHO measurement control When there are more than 32 neighbouring inter-frequency cells, list of cell to be monitored is

built with priority: HOPI: AdjiPriorityQuality/0, 0..7 (0=lowest priority) HOPI: AdjiPriorityCoverage/0, 07 (0=lowest priority)

Only periodic inter-frequency measurements are used

No filtering in the UE

Reporting cell status: up to 6 monitored set cells.

Inter-frequency HO could be forbidden during the first measurements reports from the UE, to let the UE report all the candidate inter-frequency cells in its neighbourhood. FMCI AdjiSearchPeriod / default=0 MeasReport Range 0 ... 20 MeasReport, step 1 MeasReport

Reporting interval: FMCI AdjiMeasRepInterval / 0.5 s def (1,2,3,4s possible also) Inter-frequency measurement stops if RNC has not been able to perform inter-frequency

handover after N reports. N is configured by FMCI: AdjiMaxMeasPeriod / 20, 1..20 step 1 measurement report

RNC can not initiate inter-frequency measurements if: The UE has recently performed an inter-frequency HO. FMCI AdjiMinHoInterval / 10s,

0..60, step 1 s An inter-frequency HO recently failed for this UE. FMCI AdjiMinMeasInterval / 10s,

0..60 step 1s


ISHO measurements After HO triggering message is sent to RNC, a RRC message Measurement Control is

sent to UE containing details of the measurement that the UE must execute. Measurement reporting is periodical. Max 6 GSM cells could be measured by UE and reported to RNC.

Upon reception of the measurements reported by the UE, RNC applies a sliding averaging window to the RXLEV measurements. The averaged levels are used as input to the IS-HO decision algorithm.

RNCRRC: Measurement control message

(GSM RSSI measurements)

UE

RNC

RXLEV measurements are reported throughMeasurement report messages

UE



The first measurement report has info from the best GSM cell:

BCCH freq & RSSI, no filteringused in UE

GsmMeasRepInterval (default 0.5s)


ISHO measurements Only periodic inter-system measurements are used

No filtering in the UE

Reporting cell status: up to 6 monitored set cells.

Reporting interval: FMCG GSMMeasRepInterval / 0.5 s def (1,2,3,4s also) Inter-system measurement stops if RNC has not been able to perform inter-system handover

after N reports. N is configured by FMCG: GSMMaxMeasPeriod / 20, 120, step 1 MeasReport RNC can not initiate inter-system measurements if:

The UE has recently performed an inter-system HO. FMCG: GSMMinHoInterval / 10s, 060, step 1s

An inter-system HO recently fails for this UE. FMCG: GSMMinMeasInterval / 10s, 060, step 1s


ISHO: BSIC Verification After the selection of the target GSM cell, the RNC sends to UE the RRC message

"Measurement control which includes details to measure BSIC .

UE stops RSSI measurements and updates the transmission gap pattern to the pattern used for BSIC decoding. The measurement reports are sent periodically to RNC.

If the UE is unable to decode the BSIC during the given period, the BSIC measurement operation is aborted.

RNC

RRC: Measurement control message (BSIC decoding)

WCDMA

IS-HO trigger Target Cell foundIS-HO

command

RSSI meas. BSIC verification

Numbers of GSM cells in the neighbour cell list

Reporting intervalSliding averaging windowTransmission gap pattern forRSSI measurements

TBSIC depends on :

Transmission gap pattern forBSIC decoding

TRSSI depends on


It is not sufficient to have triggers, which detect that a handover has to be done. Criteria are required to decide, whether to carry out an intra-frequency, inter-frequency, or inter-RAT handover if there is the possibility for a handover at all!

Conditions shown here have to be satisfied, before an inter-frequency handover can be conducted. The best neighbouring cell must fulfil following criteria (best according to Ec/No):

Quality Criterion in case trigger was DL DPCH Power or CPICH Ec/No:AVE_RSCP_NCELL (n) > AdjiMinRSCP(n) + max(0, AdjiTxPwrDPCH(n) - P_MAX)

Signal level from new cell > required Signal level in new cell + adjustment due to allowed power

AVE_EcNo_NCELL (n) > AVE_CPICH_EcNo + AdjiEcNoMargin(n)EcNo on new cell better than EcNo in old cell + margin

Pathloss Criterion in case trigger was UE Tx Power, CPICH RSCP or UL DPCH Quality:AVE_EcNo_NCELL (n) > AdjiMinEcNo(n)

EcNo on new cell better than required EcNo in new cell (default 14 dB)

CPICH_POWER - AVE_CPICH_RSCP > CPICH_POWER_NCELL (n) - AVE_RSCP_NCELL (n) + AdjiPlossMargin(n)

PathLoss in old cell > PathLoss in new cell + Margin (default 2 dB) (continued)

IFHO Decision


best active setcell

best inter-frequencycell

HO?

a) AVE_EcNo_NCELL (n) > AdjiMinEcNo(n)b) AVE_EcNo_NCELL (n) > AVE_CPICH_EcNo + AdjiEcNoMargin(n)

Quality Criteria

AdjiMinEcNo(n)

A

V

E

_

E

c

N

o

_

N

C

E

L

L

(

n

)

AVE_CPICH_EcNo

AVE_EcNo_NCELL (n) > AVE_CPICH_EcNo

AdjiEcNoMargin(n)

AVE_EcNo_NCELL (n)

IFHO Decision


The meaning of the parameters is: AVE_RSCP_NCELL (n) and AVE_EcNo_NCELL (n) are the averaged CPICH Ec/No and RSCP values of the

best (according to CPICH Ec/No) neighbour cell (n). AVE_CPICH_EcNo is the averaged CPICH Ec/No of the best active set cell. P_MAX is the maximum UE power capability. AdjiMinRSCP(n) determines the minimum required CPICH RSCP (dBm) level in the best neighbour cell

(n). AdjiTxPwrDPCH indicates the maximum transmission power level that an UE may use on the DPCH in

the neighbour cell AdjiEcNoMargin(n) determines the margin (dB) by which the CPICH Ec/No of the best neighbour cell

(n) must exceed before the inter-frequency handover is possible. AdjiMinEcNo(n) determines the minimum required CPICH Ec/No (dB) in the best neighbour cell (n). AdjiPlossMargin(n) determines the margin (dB) by which the propagation loss of the best active set cell

must exceed the propagation loss of the best neighbour cell (n) before the inter-frequency handover is possible.

IFHO Decision


AVE_RSCP_NCELL (n) > AdjiMinRSCP(n) + max(0, AdjiTxPwrDPCH(n) - P_MAX)

RSCP Criterion

CPICH_POWER - AVE_CPICH_RSCP > CPICH_POWER_NCELL (n) - AVE_RSCP_NCELL (n) + AdjiPlossMargin(n)

AdjiMinRSCP(n)

max(0, AdjiTxPwrDPCH(n) - P_MAX)

Pathloss Criterion

best inter-frequencycell

best active setcell

AdjiPlossMargin(n)

IFHO Decision


The following conditions have to be satisfied, before an inter-frequency handover can be conducted. The best neighbouring cell must fulfil following criterion (best according to Ec/No):AVE_RXLEV_NCell(n)

> AdjgRxLevMinHO(n) + max(0, AdjgTxPwrMaxTCH(n) - P_max)where

AVE_RXLEV _Ncell(n) is the averaged GSM carrier RSSI value of the GSM neighbour cell(n), averaging done directly from dBm values (no linear averaging); GSMMeasAveWindow / 6, 132 meas report.

AdjgRxLevMinHO(n) determines the minimum Required RSSI (dBm) level of the neighbour cell(n). AdjgTxPwrMaxTCH(n) indicated the maximum Tx power level (dBm) an UE may use in GSM neighbour

cell(n). P_MAX is the maximum UE power capability.

If several GSM cells fulfil the equation above, cells are ranked based on HOPG: AdjgPriorityCoverage/0, range 07

A cell is ranked higher than another cell if it has a higher priority level even though its signal strength condition was worse

Inter-system HO could be forbidden during the first measurements reports from the UE, to let the UE report all the candidate inter-system cells in its neighbourhood.

FMCG NcellSearchPeriod / 0

ISHO Decision


AdjgRxLevMinHO(n)

max(0, AdjgTxPwrMaxTCH(n) - P_max)

AVE_RXLEV_NCell(n) > AdjgRxLevMinHO(n) + max(0, AdjgTxPwrMaxTCH(n) - P_max)

GSM cell

ISHO Decision


Load based handover GSM -> WCDMA

100%

80%

0%

Load reason handoversfor speech

Load of GSM cellLoad of GSM cellLoad of GSM cellLoad of GSM cell

Packet Data to WCDMAregardless of GSM load

Packet Data to WCDMAregardless of GSM load

Speech to WCDMAonly with high GSM load

Speech to WCDMAonly with high GSM load

Higher bit ratesfor data users

Higher bit ratesfor data users

More capacity for speech

More capacity for speech

Packet BCCH parameters can be usedto push GPRS mobiles to WCDMA

Packet BCCH parameters can be usedto push GPRS mobiles to WCDMA

BSS10.5


GSMGSM

GSMGSM

Load and Coverage Reason Handover

GSMGSM

GSM highloaded

WCDMA lowloaded

GSMGSM GSMGSM

WCDMAWCDMA WCDMAWCDMA

Load reason handover for speech and for HSCSD

Load reason handover for speech and for HSCSD

WCDMAWCDMA GSMGSM

Load reason handover

Coverage reason handover

WCDMA can be usedto relieve GSM overload

GSM can be used to extend WCDMA coverage area

WCDMA can be usedto relieve GSM overload

GSM can be used to extend WCDMA coverage area

Mobile moving

RAN1/ph1.5 and BSS10.5


Load based Handover Process: GSM-> WCDMA

Handover Triggering Thresholds set in BSCHandover Triggering Thresholds set in BSC

Inter-RAT measurements starts in case The RXLEV of the serving cell is above or

below the given threshold Qsearch_C

Inter-RAT measurements starts in case The RXLEV of the serving cell is above or

below the given threshold Qsearch_C

Handover Decision is done in case ofLoad of the serving cell > Load_Thresholdand CPICH Ec/No> min Ec/No Threshold

Handover Decision is done in case ofLoad of the serving cell > Load_Thresholdand CPICH Ec/No> min Ec/No Threshold

MS selects the target UTRAN cell based on measurement results

MS selects the target UTRAN cell based on measurement results

Handover command is send to MSCHandover command is send to MSC

In the S10.5 MS is measuring the UTRAN cells continuously if they are defined as a neighbour,

The number of GSM neighbour reported could be 3-6 depending on the set value of parameter FDD_MULTIRAT_REPORT (0,1,2=def,3).The load is measured in the cell level by comparing the occupied TCHs to the available TCHs (20 s interval used)

Load Threshold for Speech Calls or Transparent Data inter-RAT Handover:utranHoThScTpdc (Min Traffic Load TDHO), default = 80%minEcnoThreshold (Min CPICH EC/NO Threshold), default 15 dB

Parameters are sent from the BSC to the mobilein the Measurement Information message


Cell Reselection Algorithm from GSM to FDD-WCDMA (cs)Cell Reselection List

GSM MS starts WCDMA measurements if :RLA_C< F(Qsearch_I) for 0


Cell Re-selection Parameters Range of Qsearch_I and Qsearch_P (either Below or Above values comp. to RLA_C)

Recommended value is 7 (measure always)

Range of FDD_Qoffset and FDD_GPRS_Offset Recommended value is 0 (select always if acceptable)

00

-98-98

88

-78-78

11 22

-94 -94 -90-90

99 1010

-74-74 -70-70

33

-86-86

1111

-66-66

44

-82-82

1212

-62-62

55

-78-78

1313

-58-58

66 77

-74-74 AlwaysAlways

1414 1515

-54-54 NeverNever

R_Below

dBm

R_Upper

dBm

00

-Always-Always

88

00

11 22

-28 -28 -24-24

99 1010

44 88

33

-20-20

1111

1212

44

-16-16

1212

1616

55

-12-12

1313

2020

66 77

-8-8 -4-4

1414 1515

2424 2828

Range

dBm

Range

dBm


Cell Re-selection Parameters Range of FDD_Qmin

Recommended value is 7 (-13 dBm)

FDD_REP_QUANT defines the reporting quantity for UTRAN cell (1=Ec/No or 0=RSCP, default 1)

3G_Search_PRIO parameter allows to extend the BSIC reporting interval from 10 s to 13s by checking the BSICs from non-serving BCCH carriers and also make WCDMA measurements as often as possible. Range is 0=no, 1=yes, default value 1

Defined in the SI2quater and PSI3quater if PBCCH is allocated.

ParameterParameter

Name for Sys Info (SI)Name for

Sys Info (SI)

Qsearch_IQsearch_I

2quater2quater

Qsearch_PQsearch_P Qsearch_PQsearch_P

2quater2quater 3quater3quater

FDD_QMinFDD_QMin

2ter2ter

FDD_(GPRS)Qoffset

FDD_(GPRS)Qoffset

2quater2quater

FDD_REP_QUANT

FDD_REP_QUANT

2ter2ter

00

-20-20

11 22

-19 -19 -18-18

33

-17-17

44

-16-16

55

-15-15

66 77

-14-14 -13-13

Range

dBm

3G_search_PRIO

3G_search_PRIO

2(3)quarter(PBCCH)

2(3)quarter(PBCCH)


Cell Re-selection Example-Weaker WCDMANon GPRS case

t

Serving GSM Cell

Neighbour WCDMA Cell

Ec/NoRSCP/RLA_C

5 sec.

Cell re-selection to WCDMA

FDD_Qmin=0(-20 dB)

FDD_Qoffset =6 (-8 dB)

Qsearch_I=0 (-98 dBm)

RLA_C

Measurements starts (serving cell)

Minimum Quality Requirement for WCDMA Ec/N0

RSCP


Cell Re-selection Example-Weaker WCDMAGPRS case

t

Serving GSM Cell (Best)

Neighbour WCDMA Cell

Ec/NoRSCP/RLA_C

5 sec.

Cell re-selection to WCDMA

FDD_Qmin=-20 dB

FDD_GPRS_Qoffset =10 (8 dB)Qsearch_P=0(-98 dBm)

RLA_P

Measurements starts (serving cell)

Minimum Quality Requirement for WCDMA

Ec/N0

RSCP


First ranking of all the cells based on CPICH RSCP (WCDMA) and RSSI (GSM)

Rs = CPICH RSCP + Qhyst1Rn= RXLEV(n) - Qoffset1

Rn higher in GSM cell

YesNo

Cell re-selection to GSMSecond ranking only for

WCDMA cells

Neighbour WCDMA or GSM cell calculation with offset

parameter

Serving WCDMA cell calculation, with

hysteresis parameterGSM cell measurementsavailable If :

CPICH Ec/No-QqualMin < Ssearch_RAT

WCDMA-> GSM cell reselection


Nokia Strategy: reselect to GSM early Note: GSM cell could be 15 dB weaker

Qmeas (CPICH Ec/No)

t

Serving WCDMA Cell

Neighbour GSM Cell

Qhyst1=0 dBAdjgQoffset1=-15 dB

SsearchRAT= 2 (4 dB)

Rs

Qqualmin= -18 dB

SqualsRs

about -100 dBm level in GSM


How to avoid ping pong ? When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of

serving cell is below Ssearch_RAT + QqualMin.

When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of the candidate is above FDD_Qmin.

Therefore, to avoid ping pongs between 3G and GSM the following condition should be met:

FDD_Qmin >= QqualMin+Ssearch_RAT

QqualMin=-18 dB

Ssearch_RAT=4 dB

CPICH Ec/Io

FDD_Qmin >= -13 dB

QqualMin +Ssearch_RAT

t

Camping on 3G Camping on GSM Camping on 3G


Chapter 6-Handover Control-

1. What characterises intra frequency WCDMA hard handover?

2. Which handover types are mobile evaluated handovers?

3. What is the difference between soft and softer handover?

4. What conditions must be met, before a cell can be added to the active set?

5. What type of situations initiate inter-frequency handover?

Date post:	09-Oct-2015
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