Parameter Optimization

Review

Parameter optimization is an important step after RF Optimization.

Parameter

optimization

improves

service

quality and utilization of network resources.

Review

Objectives

Upon completion of this course, you can:

Understand the process of parameter optimization

Master the contents of parameter optimization

Contents

Parameter optimization procedure Parameter optimization contents

Parameter Optimization Process

Data Input and Find Problems

Find problems from the input data, such as: Low success rate of call setup Low success rate of handover High rate of call drop

Verify Parameter Problems

Parameter Classification

Mobile Management Parameters Power Control Parameters Power Configuration Parameters Load Control Parameters Other Parameters

Determine Parameter Values

List the form for changing parameters

(original parameter values vs. new parameter values)

List MML commands for changing parameters

Note: Maybe some tradeoff considerations need to be considered to assure the maximal improvement in the whole view such as coverage and capacity, fast and stable, improvement and risk, cost (or efforts) and gain.

Impact

Impact on customer service and other networks

Impact on OMC (efforts, maintenance)

Prepare Test Plan and Change Parameters

Prepare test schedule, routes, tools and be ready to get Information.

Change parameters and make records.

Course Contents

Parameter optimization Procedure Parameter optimization Contents

Parameter Optimization Contents

Mobile Management parameter optimization Power Control parameter optimization Power Configuration parameter optimization Load Control parameter optimization

Note: There are too many parameters to introduce. Only some parameters about network optimization are mentioned here and maybe more parameters need to be added in the future.

Mobile Management Parameter Optimization

Cell Selection & Reselection The changing of cell on which UE camped in idle mode or in Cell FACH, Cell PCH, URA PCH states. That assures UE camping the most suitable cell, receiving system information and establishing an RRC connection on a best serving cell.

Handover

The changing of cells with which UE connected in DCH mode. That assures seamless coverage and load balancing.

Cell Selection & Reselection Procedurego here whenever a new PLMN is selected cell information stored for the PLMN

1

no cell information stored for the PLMN

Stored information Cell Selection no suitable cell found

no suitable cell found

Initial Cell Selection

suitable cell found

2

suitable cell found no suitable cell found

Cell Selection when leaving connected mode

suitable cell found

Camped normally

NAS indicates that registration on selected PLMN is rejected (except with cause #14 or #15 [5][16])

return to idle mode

leave idle mode

trigger suitable cell found

Connected mode

Cell Reselection Evaluation Process

no suitable cell found go here when no USIM in the UE

no acceptable cell found

Any Cell Selection

USIM inserted acceptable cell found

1

Cell Selection when leaving connected mode

acceptable cell found

Camped on any cell

suitable cell found

2

return to idle mode

leave idle mode

trigger acceptable cell found

Connected mode (Emergency calls only)

Cell Reselection Evaluation Process

no acceptable cell found

Cell Selection Criteria (S Criteria)

The cell selection criterion S is fulfilled when:for FDD cells: for TDD cells: Srxlev > 0 AND Squal > 0 Srxlev > 0

Where:Squal = Qqualmeas Qqualmin Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

When a UE wants to select a UMTS cell, the cell must satisfy S criterion.

Cell Selection Parameters

Cell Re-selection Measure ConditionUse Squal for FDD cells and Srxlev for TDD for Sx 1. If Sx > Sintrasearch, UE need not perform intra-frequency measurements. If Sx Sintersearch, UE need not perform inter-frequency measurements. If Sx SsearchRAT m, UE need not perform measurements on cells of RAT m". If Sx Tother_RAT + H/2 Tother_RAT : the inter-system handover decision threshold; Mother_RAT : the inter-system (GSM RSSI) measurement result received by RNC; CIO: Cell Individual Offset, which is the inter-system cell setting offset; H : refers to hysteresis, If the formula is met, a trigger-timer called TimeToTrigForSysHo will be started, and a handover decision will be made when the timer times out; Note: if the inter-system quality satisfies the following condition before the timer times out: Mother_RAT + CIO < Tother_RAT - H/2 The timer will be stopped, and RNC will go on waiting to receive the next inter-system measurement report. The length of the trigger-timer is called time-to-trigger.

Inter-system Handover Parameters

Parameter Optimization Contents

Mobile Management parameter optimization Power Control parameter optimization Power Configuration parameter optimization Load Control parameter optimization

Power Control parameter optimization

Power

Control Characteristics

Minimize the interference in the network, thus improve

capacity and quality

Maintain the link quality in uplink and downlink by adjusting the powers

Mitigate the near far effect by providing minimum required power level for each connection

Provides protection against shadowing and fast fading

Power Control Classification

Open Loop Power ControlOpen loop power control is used to determine UEs initial uplink transmit power in PRACH and NodeBs initial downlink transmit power in DPDCH. It is used to set initial power reference values for power control. Outer Loop power control Outer loop power control is used to maintain the quality of communication at the level of bearer service quality requirement, while using as low power as possible. Inner loop power control (also called fast closed loop power control) Inner loop power control is used to adjust UEs uplink / NodeBs downlink Dpch Power every one slot in accordance with TPC commands. Inner loop power control frequency is 1500Hz.

Open Loop Power Control - Uplink

Preamble_Initial_Power = Primary CPICH TX power - CPICH_RSCP + UL interference + Constant Value

where Primary CPICH TX power, UL interference and Constant Value are broadcasted in the System Information and CPICH_RSCP is the measured value by UE

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Open Loop Power Control - Downlinklortnoc lortnoc rewo p laitini kniln wo d eht enim rete D rewo p laitini kniln wo d eht enim rete D HC D HC D

Ec Eb R )cpich E v P ) P! v v (P CPICH /( total Io Io W Where R is the user bit rate. W is the chip rate (3.84M). Pcpich is the Primary CPICH transmit power. Eb/Io is the downlink required Eb/Io value for a bearer service. (Ec/Io)cpich is measurement value reported by the UE. is downlink cell orthogonal factor. Ptotal is the current cells carrier transmit power measured at the NodeB and reported to the RNC.

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eulav de rusaem eulav de rusaem eht st ro pe r HCA R eht st ro pe r HCA R

Open Loop Power Control Parameters

Outer Loop Power Controlgninibmoc gninibmoc ytisrevid orcaM ytisrevid orcaMOuter loop control is used to setting SirTarget (Signal to Interference Ratio Target) for inner loop power control. It is divided into uplink outer loop power control and downlink outer loop power control. The uplink outer loop power control is controlled by SRNC (serving RNC) for setting a target SIR for each UE. This target SIR is updated according to the estimated uplink quality (Block Error Ratio/ Bit Error Ratio). If UE is not in DTX (Discontinuous Transmission)status (that means RNC can receive uplink traffic data), RNC will use Bler (Block Error Ratio) to compute SirTarget . Otherwise, RNC will use Ber (Bit Error Ratio) to compute SirTarget. The downlink outer loop power control is controlled by the UE receiver to converge to required link quality (BLER) set by the network (RNC) in downlink.tegrat tegrat RIS teS RIS teS

CNRD

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CNRS

Outer Loop Power Control Parameters

Inner Loop Power ControlThe inner loop power control adjusts the UE or NodeB transmit power in order to keep the received signal-to-interference ratio (SIR) at a given SIR target, SIRtarget.

It is also divided into uplink inner loop power control and downlink inner loop power control.

Uplink Inner Loop Power ControlUTRAN behaviour The serving cells (cells in the active set) should estimate signal-to-interference ratio SIRest of the received uplink DPCH. The serving cells should then generate TPC commands and transmit the commands once per slot according to the following rule: if SIRest > SIRtarget then the TPC command to transmit is "0", while if SIRest < SIRtarget then the TPC command to transmit is "1".

UE behaviour Upon reception of one or more TPC commands in a slot, the UE shall derive a single TPC command, TPC_cmd, for each slot, combining multiple TPC commands if more than one is received in a slot. This is also valid when SSDT transmission is used in the downlink. Two algorithms shall be supported by the UE for deriving a TPC_cmd. Which of these two algorithms is used is determined by a UE-specific higher-layer parameter, "PowerControlAlgorithm", and is under the control of the UTRAN. If "PowerControlAlgorithm" indicates "algorithm1", then the layer 1 parameter PCA shall take the value 1 and if "PowerControlAlgorithm" indicates "algorithm2" then PCA shall take the value 2.

Uplink Inner Loop Power Control

The step size DTPC is a layer 1 parameter which is derived from the UE-specific higherlayer parameter "TPC-StepSize" which is under the control of the UTRAN. If "TPCStepSize" has the value "dB1", then the layer 1 parameter DTPC shall take the value 1 dB and if "TPC-StepSize" has the value "dB2", then DTPC shall take the value 2 dB. The parameter "TPC-StepSize" only applies to Algorithm 1 . For Algorithm 2 DTPC shall always take the value 1 dB.

After deriving of the combined TPC command TPC_cmd using one of the two supported algorithms, the UE shall adjust the transmit power of the uplink DPCCH with a step of DDPCCH (in dB) which is given by: DDPCCH = DTPC v TPC_cmd.

Uplink Inner Loop Power Control

Algorithm 1 for processing TPC commandsWhen a UE is not in soft handover, only one TPC command will be received in each slot. In this case, the value of TPC_cmd shall be derived as follows: - If the received TPC command is equal to 0 then TPC_cmd for that slot is 1. - If the received TPC command is equal to 1, then TPC_cmd for that slot is

Algorithm 2 for processing TPC commandsWhen a UE is not in soft handover, only one TPC command will be received in each slot. In this case, the UE shall process received TPC commands on a 5-slot cycle, where the sets of 5 slots shall be aligned to the frame boundaries and there shall be no overlap between each set of 5 slots. The value of TPC_cmd shall be derived as follows: - For the first 4 slots of a set, TPC_cmd = 0. For the fifth slot of a set, the UE uses hard decisions on each of the 5received TPC commands as follows: If all 5 hard decisions within a set are 1 then TPC_cmd = 1 in the 5th slot. If all 5 hard decisions within a set are 0 then TPC_cmd = -1 in the 5th slot. Otherwise, TPC_cmd = 0 in the 5th slot.

Downlink Inner Loop Power Control

UE behaviourThe UE shall generate TPC commands to control the network transmit power and send them in the TPC field of the uplink DPCCH. The UE shall check

the downlink power control mode (DPC_MODE) before generating the TPC command:

If DPC_MODE = 0 : the UE sends a unique TPC command in each slot and the TPC command generated is transmitted in the first available TPC field in the uplink DPCCH;

If DPC_MODE = 1 : the UE repeats the same TPC command over 3 slots and the new TPC command is transmitted such that there is a new command at the beginning of the frame.

The DPC_MODE parameter is a UE specific parameter controlled by the UTRAN.

Downlink Inner Loop Power Control

UTRAN behaviourUpon receiving the TPC commands UTRAN shall adjust its downlink DPCCH/DPDCH power accordingly. For DPC_MODE = 0, UTRAN shall estimate the transmitted TPC command TPCest to be 0 or 1, and shall update the power every slot. If DPC_MODE = 1, UTRAN shall estimate the transmitted TPC command TPCest over three slots to be 0 or 1, and shall update the power every three slots.

Inner Loop Power Control Parameters

Parameter Optimization Contents

Mobile Management parameter optimization Power Control parameter optimization Power Configuration parameter optimization Load Control parameter optimization

Physical Channels Types

Common Channel Parameters

All channels power refers to PCPICH power expect PCPICH.

Dedicated Channel Parameters

Dedicated Channel Power refers to PCPICH Power.

Parameter Optimization Contents

Mobile Management parameter optimization Power Control parameter optimization Power Configuration parameter optimization Load Control parameter optimization

Load Control Parameter Optimization

Call

Admission Control (CAC)

Call admission control is used to control cells load by admission/rejection request to assure a cells load under control.

Dynamic Channel Configuration Control (DCCC)Dynamic Channel Configuration Control is used to dynamically change a connections load to improve cell resource utilization and control cells load.

Call Admission Control Procedure

Call Admission Control Parameters

Different service type can be configured different threshold. That means leave some resources for important service ( or request), such as HO > Conversation > Other. Ul(Dl)TotolKThd is used when NodeB load report is not available . It uses equivalent 12.2k-voice users number method.

Dynamic Channel Configuration Control

Dynamic channel configuration control (DCCC) aims to make full use of radio resource (codes, power, CE )

- Configured bandwidth is fixed with no DCCC - Configured bandwidth is changing with DCCC - Traffic rate

Rate or band

DCCC ProcedureTraffic Volume measurement control

UE and RNC Measurement

Measurement report

DCCC decision

DCCC execution

Traffic Volume MeasurementTransport Channel Traffic Volume Threshold

Time

Reporting event 4A

Reporting event 4A

Transport Channel Traffic Volume

Threshold Time

Reporting event 4B

Reporting event 4B

Reporting event 4B

DCCC Decision

1) 4a event report -> increase bandwidth 4b event report -> decrease bandwidth 2) if current bandwidth