Parameter Optimization

Review Parameter optimization is an important step after RF Optimization.

Parameter optimization improves service quality and utilization of network resources.

Review

New Sites Intergrated

Single Site Verification

Cluster of Sites ready?

RF Optimisation

Services Testing & Parameter Optimisation

Regular Reference RouteTesting & Stats Analysis

Re- optimisation Needed?

YES

NO

YES

NO

ObjectivesUnderstand the process of parameter optimizationMaster the contents of parameter optimization Upon completion of this course, you can:

ContentsParameter optimization procedureParameter optimization contents

Parameter Optimization Process

Data Input and Find Problems

Other Process

Verify Parameter Problems

Classify Parameter Problems

Determine Parameter Values to be Modified and List MML Commands

Evaluate Changing Effects

Prepare Test Plan and Implement Changing

Test , Get Data again and Compare

Problems Eliminate Or Need not Change more

End

Determine whether Changing

End

N

N

Y

Y

Y

N

Data Input and Find ProblemsFind 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 Problems

No Hardware/Software Problem

No RF Problems

Related with EnvironmentOr Speed

Parameters never OptimizedBefore

Parameter ClassificationMobile Management ParametersPower Control ParametersPower Configuration ParametersLoad Control ParametersOther 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.

ImpactImpact on customer service and other networks

Impact on OMC (efforts, maintenance)

Prepare Test Plan and Change ParametersPrepare test schedule, routes, tools and be ready to get Information.Change parameters and make records.

Course ContentsParameter optimization ProcedureParameter optimization Contents

Parameter Optimization ContentsMobile Management parameter optimizationPower Control parameter optimizationPower Configuration parameter optimization Load Control parameter optimizationNote: 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 OptimizationCell 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 Procedure

Cell Selection Criteria (S Criteria)The cell selection criterion S is fulfilled when:

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

for FDD cells:Srxlev > 0 AND Squal > 0

for TDD cells:Srxlev > 0

Squal = Qqualmeas Qqualmin

Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Cell Selection Parameters

Cell Re-selection Measure Condition Use 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

Cell Reselection Criteria (R Criteria)All cells should satisfy S Criteria.Select the Cell with the highest R value using the following method to compute. The cells shall be ranked according to the R criteria specified above, deriving Qmeas,n and Qmeas,s and calculating the R values using CPICH RSCP, P-CCPCH RSCP and the averaged received signal level for FDD, TDD and GSM cells, respectively.The offset Qoffset1s,n is used for Qoffsets,n to calculate Rn, the hysteresis Qhyst1s is used for Qhysts to calculate Rs. If an FDD cell is ranked as the best cell and the quality measure for cell selection and re-selection is set to CPICH Ec/No, the UE shall perform a second ranking of the FDD cells according to the R criteria specified above, but using the measurement quantity CPICH Ec/No for deriving the Qmeas,n and Qmeas,s and 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. Following this second ranking, the UE shall perform cell re-selection to the best ranked FDD cell.In all cases, the UE shall reselect the new cell, only if the following conditions are met:-the new cell is better ranked than the serving cell during a time interval Treselection.-more than 1 second has elapsed since the UE camped on the current serving cell.

Cell Reselection Parameters

Cell Reselection Parameters

Cell Reselection from GSM to UMTSIf the 3G Cell Reselection list includes UTRAN frequencies, the MS shall, at least every 5s update the value RLA_C for the serving cell and each of the at least 6 strongest non-serving GSM cells. The MS shall then reselect a suitable (see TS 25.304) UTRAN cell if its measured RSCP value exceeds the value of RLA_C for the serving cell and all of the suitable (see 3GPP TS03.22) non-serving GSM cells by the value XXX_Qoffset for a period of 5seconds and, for FDD, the UTRAN cells measured Ec/No value is equal or greater than the value FDD_Qmin. In case of a cell reselection occurring within the previous 15seconds, XXX_Qoffset is increased by 5dB. where Ec/No and RSCP are the measured quantities.FDD_Qmin and XXX_Qoffset are broadcast on BCCH of the serving cell. XXX indicates other radio access technology/mode. Note:The parameters required to determine if the UTRAN cell is suitable are broadcast on BCCH of the UTRAN cell. An MS may start reselection towards the UTRAN cell before decoding the BCCH of the UTRAN cell, leading to a short interruption of service if the UTRAN cell is not suitable.Cell reselection to UTRAN shall not occur within 5seconds after the MS has reselected a GSM cell from an UTRAN cell if a suitable GSM cell can be found. If more than one UTRAN cell fulfils the above criteria, the MS shall select the cell with the greatest RSCP value.

Cell Reselection Parameters from GSM to UMTS

Handover Procedure

Node BNode BNode BIntra-frequency cellsNeighbor cells both from same NodeB or other NodeBsMeasurement report Handover decisionMeasurement controlMeasurement and filteringHandover execution

Soft Handover Example

Soft Handover Procedure

Soft Handover Event 1A1A (add a cell in Active Set) MNew : the measurement result of the cell entering the reporting range.CIONew : the individual cell offset for the cell entering the reporting range if an individual cell offset is stored for that cell. Otherwise it is equal to 0.Mi : measurement result of a cell not forbidden to affect reporting range in the active set.NA : the number of cells not forbidden to affect reporting range in the current active set.MBest : the measurement result of the cell not forbidden to affect reporting range in the active set with the highest measurement result, not taking into account any cell individual offset.W : a parameter sent from UTRAN to UE.R1a : the reporting range constant.H1a : the hysteresis parameter for the event 1a.

Soft Handover Event 1B1B (Remove a cell from Active Set)

MOld : the measurement result of the cell leaving the reporting range.CIOOld : the individual cell offset for the cell leaving the reporting range if an individual cell offset is stored for that cell. Otherwise it is equal to 0.Mi : measurement result of a cell not forbidden to affect reporting range in the active set.NA : the number of cells not forbidden to affect reporting range in the current active set.MBest : the measurement result of the cell not forbidden to affect reporting range in the active set with the lowest measurement result, not taking into account any cell individual offset. W : a parameter sent from UTRAN to UE.R1b : the reporting range constant.H1b : the hysteresis parameter for the event 1b.

Soft Handover Event 1C1C (a non-active primary CPICH becomes better than an active primary CPICH. If Active Set is not full, add the non-active cell into active set .Otherwise use the cell substitute the active cell.)MNew : the measurement result of the cell not included in the active set.CIONew : the individual cell offset for the cell becoming better than the cell in the active set if an individual cell offset is stored for that cell. Otherwise it is equal to 0.MInAS : the measurement result of the cell in the active set with the highest measurement result.MInAS : the measurement result of the cell in the active set with the lowest measurement result.CIOInAS : the individual cell offset for the cell in the active set that is becoming worse than the new cell.H1c : the hysteresis parameter for the event 1c.

Soft Handover Event 1D1D (Change of best cell. If the chosen cell is not in Active Set, add the cell into Active Set and modify measurement control .Otherwise only modify measurement control. )

MNotBest : the measurement result of a cell not stored in "best cell" CIONotBest : the cell individual offset of a cell not stored in "best cell" .MBest: the measurement result of the cell stored in "best cell".CIOBest : the cell individual offset of a cell stored in "best cell" .H1d : the hysteresis parameter for the event 1d.

Soft Handover Parameters

Inter-system Handover CS Domain Procedure

Inter-system Handover Measure 1) Use Inter-frequency measurement reporting Event 2d, 2f to reflect the currently used frequency quality. Event 2d: The estimated quality of the currently used frequency is below a certain threshold. The variables in the formula are defined as follows:QUsed is the quality estimate of the used frequency.TUsed 2d is the absolute threshold that applies for the used frequency and event 2d.H2d is the hysteresis parameter for the event 2d. Event 2f: The estimated quality of the currently used frequency is above a certain threshold.

The variables in the formula are defined as follows:QUsed is the quality estimate of the used frequency.TUsed 2f is the absolute threshold that applies for the used frequency and event 2f.H2f is the hysteresis parameter for the event 2f.

Inter-system Handover Measure 2 When Received 2D reports ( that means the currently used frequency signal is poor ), RNC sends Measurement Control (ID3) to let UE begin to measure other system signal . UE will send measurement result reports periodically . When Received 2F reports (that means the currently used frequency signal is not poor), RNC sends Measurement Control (ID3,but different contents) to let UE stop measuring other system signal .

3) When received the periodical reports, RNC use the following formula to judge whether should handover UE to another system .

Mother_RAT + CIO > 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 ContentsMobile Management parameter optimizationPower Control parameter optimizationPower Configuration parameter optimization Load Control parameter optimization

Power Control parameter optimizationPower 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 Control Open 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 controlOuter 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.

UE

NodeB

RNC

SIR Target

Bler/Ber

SIR

TPC Command

Outer Loop Power Control

Inner Loop Power Control

Open Loop Power Control

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 Informationand CPICH_RSCP is the measured value by UE

Open Loop Power Control - Downlink 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.

Open Loop Power Control Parameters

Outer Loop Power ControlOuter 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.

Outer Loop Power Control Parameters

Inner Loop Power Control The 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 Control

UTRAN 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 value2.

Uplink Inner Loop Power Control

The step size DTPC is a layer 1 parameter which is derived from the UE-specific higher-layer parameter "TPC-StepSize" which is under the control of the UTRAN. If "TPC-StepSize" has the value "dB1", then the layer 1 parameter DTPC shall take the value 1dB and if "TPC-StepSize" has the value "dB2", then DTPC shall take the value 2dB. 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 TPC_cmd.

Uplink Inner Loop Power ControlAlgorithm 1 for processing TPC commands When 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 commands When 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 5 received 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 ControlUE behaviour The 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 ControlUTRAN behaviour Upon 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 ContentsMobile Management parameter optimizationPower Control parameter optimizationPower Configuration parameter optimization Load Control parameter optimization

Physical Channels Types

Common Channel ParametersAll channels power refers to PCPICH power expect PCPICH.

Dedicated Channel ParametersDedicated Channel Power refers to PCPICH Power.

Parameter Optimization ContentsMobile Management parameter optimizationPower Control parameter optimizationPower Configuration parameter optimization Load Control parameter optimization

Load Control Parameter OptimizationCall 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 admisson request arrive

Get the service characteristic and the current load

Uplink call admission control evaluation

admitted?

Downlink call admission control evaluation

admitted?

call admitted

call rejected

end

n

y

y

n

Call Admission Control ParametersDifferent 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 ControlDynamic channel configuration control (DCCC) aims to make full use of radio resource (codes, power, CE )

DCCC ProcedureMeasurement reportDCCC decisionTraffic Volume measurement controlUE and RNC MeasurementDCCC execution

Traffic Volume Measurement

Threshold

Transport Channel Traffic Volume

Reporting event 4A

Time

Reporting event 4A

Threshold

Transport Channel Traffic Volume

Reporting event 4B

Time

Reporting event 4B

Reporting event 4B

DCCC Decision1) 4a event report -> increase bandwidth 4b event report -> decrease bandwidth

2) if current bandwidth

Dynamic Channel Configuration Control Parameters

Dynamic Channel Configuration Control Parameters

SummaryParameter Optimization improves network quality and solves network problems.Parameter Optimization is a complicated procedure and needs parameter and algorithm knowledge.Parameter Optimization will be combined with other optimization activities making network better !