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Chapter 1- Introduction to UMTS OptimizationMobile Comm Professionals,IncMastering UMTS Optimization

AgendaOptimization OverviewPhysical Layer Processing OverviewWCDMA Measurement OverviewPrinciples of 3G network OptimizationsSingle Site OptimizationRF OptimizationParameters OptimizationNetwork Monitoring

Optimization Overview (1/3)Optimize a network is to tune its design and configuration parameters to meet its predefined target performance. Network optimization can be either before commercial launch or after. When it is before, it is called Initial Tuning.Optimization Process is divided in to two part:Pre-Launch Optimization.Post-Launch Optimization.

Physical Layer Processing Overview

WCDMA Radio Interface Channels

Channel Mapping In DLBCCHDTCHCTCHDCCHPCCHCCCHBCHPCHFACHHS-DSCHDCHP-SCHS-SCHPCCPCHCPICHSCCPCHPICHAICHHS-PDSCHHS-SCCHDPDCHDPCCHLOGICAL CHANNELTRANSPORT CHANNELPHYSICAL CHANNEL

Channel Mapping In ULDTCHDCCHCCCHRACHDCHE-DCHPRACHDPDCHDPCCHHS-DPCCHE-DPDCHE-DPCCHLOGICAL CHANNELTRANSPORT CHANNELPHYSICAL CHANNEL

Call FlowRRC ConnectionSignaling between RNC and CNRAB EstablishmentConversation/ Data TransferRRC ReleaseRAB ReleaseSignaling Release

Mobile Originating Call Diagram (1/3)

Mobile Originating Call Diagram (2/3)

Mobile Originating Call Diagram (3/3)

Optimization Flow Chart (1/2)Performance problem dropped calls,loss of data connections low throughput.InputPerformance dataKPIDrive testAssesment and analysisNetwork status based on inputsNetwork analysisSolutionsInitial solutions based on assessment / analysisJob OrderOfficial work order (WO) for optimization tasks

ImplementationImplementation of the optimization task (based on WO)Solution verificationVerification, that ordered tasks have been done properlyCriteria CheckIs network performance fulfilling accepted criteriaMonitoring / data collectionPerformance data collectionDeeper performance monitoringAnalysisDeeper performance data analysisSolutionsPrimary solutions based on analysisProject reportFinal project reportOptimization Flow Chart (2/2)

WCDMA Measurement Overview

The Cell Selection ProcessWCDMA Measurement Parameters

CPICH Ec/No = CPICH RSCPUTRA carrier RSSIRSCPThe UE measures the RSCP on the Primary-CPICH. The reference point for the measurement is the antenna connector of the UE. The received code power may be high, but it does not necessarily indicate the quality of the received signalRSSIOn the overall noise level.The UE measures the received wide band power, which includes thermal noise and receiver generated noise. The reference point for the measurements is the antenna connector of the UE. P-CPICH as Measurement Reference

UTRA Carrier RSSICPICH RSCPCPICH Ec/NoWCDMA Measurement Parameters

Principles of 3G network optimizations

Single Site Optimization

Single site verification involves the following aspects:Parameter setting check in idle modeServices call (CS/PS) function check in connected mode.CPICH RSCP & Ec/IoInstallation problems check..

Single Site OptimizationFlow Chart

RNP configuration...

No.Site IDSite NameLOCELL IDCELL IDCell namePSCRAMBCODEMAXTXPOWERLACRACDownlink frequency No.

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Sheet3

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Physical AuditPhysical Audit:In this we familiarize the following information about NodeB before test, including:Site locationCell IDScramble CodeOmnidirectional/Directional siteAzimuthTesting Point Selection:It is the point where the signals of target cell are strong and other cells are weak.

Verification in Idle Mode:-Verification in idle mode includes the following aspects:Cell ID CheckScramble CheckLAC/RAC CheckCPICH_RSCP/CPICH_EcIo (Near Site) Test

Cell ID Check:Check whether the Cell ID number of the cell to be measured is consistent with the planned data.Idle Mode Verification

Scrambling Code CheckCheck whether the scramble code configuration is consistent with the planned configuration.

MethodPress the application key to start testing mode of the software. then software displays the basic information of the serving network, including the primary scramble code (P-SC) information.

LAC/RAC Check: -Press the application key to start testing mode of the software. Query WCDMA-Network Information, and the software displays the basic information of the serving network, including LAC and RAC.CPICH RSCP and CPICH Ec/Io near site test: -

In the major transmission direction of antenna, fix a location with line-of-sight distance from the antenna within 100 meters from the NodeB. Power on the test UE and start testing mode by pressing the application key.

Query WCDMA-Power/RRC, and the software displays the information about the received signals, including the received signal strength Rx (CPICH_RSCP) and the received signal-to-interference radio (SIR) (CPICH Ec/Io).

LAC/RAC & CPICH RSCP/ Ec/Io Check

RF Optimization TargetsRF optimization includes the following aspects: Coverage optimizationPilot pollution optimizationHandover optimization

Acceptance ContentReference valuesRemarksCoverage probability 95%Test on the acceptance route, which shall exclude the uncovered area.For the planned full coverage service, the downlink CPICH Ec/Io 12dB & RSCP 95dBmCPICH Ec/Io 12dB 95%Scanner tested result, outdoor unloadedCPICH RSCP 95dBm 95%Scanner tested result, outdoor unloadedSofter handover ratio30%40%The softer handover ratio in RF optimization phase shall be 5%10% lower than the target ratio, because the later optimization causes softer handover ratio to increases.Pilot pollution ratio5%

RF Optimization Process

RF Optimization Common Measurement Most RF problems can be solved through the following adjustmentAntenna tiltAntenna azimuthAntenna locationSplit sectorRemove sectorCombine sectorAntenna heightAntenna typeTMARRUSite locationNew site

Coverage Analysis

Coverage Analysis ProcessCoverage analysis part is divided in to two parts Downlink and Uplink coverage analysis.

Downlink coverage analysis: - Involves analyzing CPICH RSCP and CPICH Ec/Io obtained by drive test.

Uplink coverage analysis: - Analyzing UE transmit power obtained in DT

Downlink Coverage Analysis (1/2)Downlink coverage analysis - Pilot Coverage quality AnalysisAreas of Ec/Io should be checked against RSCP levels as follows:

Pilot Coverage is depend on the RSCP (Received signal code Power), if the RSCP Level is poor, than the fundamental cause of low Ec/Io is poor coverage.

Downlink Coverage Analysis (2/2)Downlink coverage analysis - Pilot Coverage quality Analysis

If RSCP level is good, the poor Ec/Io will imply strong system interference. Such scenario could arise when two sectors are pointing at each other.

The distribution of UE transmit powerUplink Coverage Analysis

UE_Tx_Power= 95%The test result of voice service by test handset. Assume the maximum transmit power of UE is 21 dBm

Pilot Pollution OptimizationPilot Pollution:- When the number of strong cells, exceeds the active set size, there is pilot pollution in that area. Typically the active set size is 3, so if there are more than 3 strong cells then there is pilot pollution.

Figure: - According to the conditions of Pilot Pollution, the SC4,SC5,SC6 are Pilot Pollution, the RSCP of SC6 is more then 5dB lower than the best serve cell, so it is not Pilot Pollution.Judgment Standards :Pilot Pollution Analysis (1/2)

Estimated Active Set Size Example :Causes for Pilot PollutionImproper Cell DistributionHighly-mounted AntennaImproper Antenna AzimuthImproper Antenna Down TiltImproper PICH PowerPilot Pollution Analysis (2/2)

Pilot Pollution SolutionSolutions of Pilot Pollution :Antenna AdjustmentP-CPICH Power Adjustment Using RRU or Micro Cells

HandoverBasic Concept about HandoverProviding the continuous service in mobile system is the basic element in QoSProviding continuous communication service is the main purpose of handover.The load balance: sharing the resourceThe hierarchy divided by speed and service: high efficiency of using resourcePurpose of Handover Active setMonitor setDetection setEvent reportEvent to periodic reportPeriodic reportRadio link (RL)Radio link set (RLS)Maximum-ratio combiningSelective combiningSoft handover gainPilot channel (CPICH)

Types Of Handover

Classify by System ChangeClassify by Signaling FlowClassify by Frequency ChangeDescriptionIntra- systemSoft handoverIntra-frequencyLow-rate services (e.g. AMR, VPHard handoverHigh-rate services (e.g. PS384K)No Iur interface between to RNCsInter-frequencyFor the purpose of coverage or load balancing (e.g. handover between carriers with different load, handover to the carrier that supports the HSDPA service.

WCDMA-to-GSM handover)Inter-system (Inter-RAT)

Neighbour cell optimization can be analysed by:Scanner Data UE Data Analysis

Add: Missing neighboursRemove: These neighbours that were not measured but are in the neighbour list.

SHO Factor based on DT Analysis: If the SHO Factor based on DT is over large, decrease or change the handover areas by using the following methods for shrinking coverage areas:

Increase the down tilt Adjust azimuth Decrease the antenna height Decrease the PICH power Handover Optimization

Handover Problem Analysis - Neighbor cell optimizationHandover Analysis (1/2)We can also analyze a missing neighbor cell by UE DT data.The daemon analysis tool can seldom analyze UE data automatically and generate missing neighbor cells but we can Compare the active set Ec/Io distribution diagram measured by UE and that measured by scannerThe spots with missing neighbor cells has a poor Ec/Io measured by UE and a strong Ec/Io scanned by scanner .

Handover Problem Analysis Handover Analysis (2/2)UE SHO PerformanceThe success rates for event 1a, 1b & 1c and can be obtained from software

Parameters OptimizationParameter optimization includes field test and statistics analysis.

Purpose of Parameters OptimizationIncrease the access success ratioDecrease the call drop ratioIncrease the quality of service

The tools and data for analysis:scanner and UERNC record dataStatistic tools and KPIMSC & SGSN record if necessary.

Drive testing is done continually to monitor the health of the network.

The contents of drive test are as follows :The call setup test for voice service The continuous call test for voice service Idle mode testThe call setup test for video phone serviceThe continuous call test for voice serviceThe call setup test for PS serviceThe continuous call test for PS serviceDrive Test

Drive Test Data Analysis

Drive Test Data Analysis:

Analyzing and finding out the solution for access failureAnalyzing and finding out the solution for drop callAnalyzing and finding out the solution for service quality related problems

Adjustment Recommandation and Implmentation:-

Common Control Channel Power Allocation parametersRL Maximum Power parametersIntra- frequency Handover parameters Inter- frequency Handover parametersInter-RAT Handover parameters Power Control parametersAccess parametersOther related parametersRecommendations

Network MonitoringMake Service verification in the whole optimisation area for performance acceptance.Make sure that KPIs are measured in areas of acceptable coverage is achievedIt is recommended that the Minimum RF conditions for field measurements for all KPIs is as described below:Best server CPICH RSCP > -100 dBmBest server CPICH EcNo > -11 dBmCPICH EcNo of the 4th strongest cell > 6dB below best server (= below drop window)KPI target examples for AMRCall setup success rate, 98 %Call drop rate, 2 %Overall call success rate, 96 %Call connection time

OMC/NMS Functional ArchitectureOperating SystemCommunications HandlerDatabaseMMIEvent/ Alarm ManagementSecurity ManagementFault ManagementPerformance ManagementConfiguration Management

Operation And Maintenance Centre For Radio (OMC-R)Network Component

The optimization report should be presented after the project passes the customer acceptance. The optimization report should include: Project background introductionExisting network statusAcceptance criteriaOptimization processProblem analysis and adjustment recommendation, and the effect for the implemented part.Acceptance test and resultLeftover problems and suggestions from the optimization point of view. Updated Site Configuration Parameter table and Radio Part Parameters.Optimization Reports

SummaryOptimization OverviewPhysical Layer Processing OverviewWCDMA Measurement OverviewPrinciples of 3G network OptimizationsSingle Site OptimizationRF OptimizationParameters OptimizationNetwork Monitoring

HAPPY LEARNING

MobileComm Professionals, Inc.www.mcpsinc.com

Third Generation networks are already commercially launched and the transition from voice to data services is at hand. So they must care about the performance and investment of the network. Unfortunately, they are contradictory. The feasibility of the investment can be obtained easily through certain estimation methods and tools. But increasing network performance is a complex process, because the network must not only meet the need of existing subscribers but can also introduce new competitive services on the base of continuously increasing capacity in the future development. As a result, network optimization is a repeated long-term process.**Pre-Launch Optimization ( L1-Optimisation)Initial step to fine tune and optimise WCDMA network based on L1 (Physical layer) when network have low load. (or unload) Optimisation is mainly based on drive test measurement and aim to verify and improve on coverage design ( CPICH Ec/No, CPICH RSCP), SC planning, neighbour planning and parameter settings related to call setup ,call drop and mobility performanceTo ensure on the readiness of network before launch, optimiser also need to verify on hardware stability ,system capacity (enough to handle the forecast load) and QOS of all services.Post-Launch Optimization Further step to optimise network when there is an actual load ( RT and NRT). Optimisation is based on both traffic statistic and drive test measurement. There will be more parameters tuning e.g. load control, admission control , package scheduler and also mobility management. **Logical channel: Carrying user services. Divided into 2 types, based on services it carried: Control channel and service channel. Transport channel: Between radio interface layer 2 and physical layer. Services provided by physical layer for MAC layer. Based on information transported, can be divided into dedicated channel and common channel.

Physical channel: It is the ultimate embodiment of all kinds of information when they are transmitted on radio interfaces. Each channel that uses dedicated carrier frequency, code (spreading code and scramble) and carrier phase can be regarded as a dedicated channel.

*Logical to Transport channel mappingSynchronisation Channel (SCH) carrying the Logical SCH.Broadcast Channel (BCH) carrying the Logical BCCH.Paging Channel (PCH) carrying the Logical PCH.Forward Access Channel (FACH) carrying information coming from the Logical CCCH and DCCH, i.e. from common and dedicated control channels.Dedicated Channel (DCH): this is the only dedicated transport channel, the others are common ones. The DCH carries information coming from the Logical DTCHs and DCCH. It should be noted that one DCH may carry several DTCHs depending on case. For example, a user may have a simultaneous voice call and video call active. The voice call uses one Logical DTCH and the video call requires another Logical DTCH. Both of these, however, use the same DCHTransport to physical channel mappingWhen the information is collected from the Logical Channels and organised to the Transport Channels it is in ready-to-transfer format. Before transmitting the Transport Channels are arranged to the Physical Channels. The synchronisation information carried by the Transport SCH is inserted to two Physical Channels, Primary and Secondary Synchronisation Channels (SCH-1 and SCH-2).There are two Common Control Physical Channels, Primary and Secondary one. Respectively, the primary one is CCPCH-1 and the secondary is CCPCH-2. Roughly, the CCPCH-1 carries broadcast control information (similar type of information than the GSM BCCH). The CCPCH-2 is a combination of two Transport Channels: it carries paging related information and the information currently included in the Forward Access Channel.The two dedicated Physical Channels are Dedicated Physical Data Channel (DPDCH) carrying user traffic and Dedicated Physical Control Channel (DPCCH) carrying related control information. When these are timely multiplexed together the combination is called DPCH, Dedicated Physical Channel.

The Transport Channel RACH carries the initial access information when the UE accesses the network. This information is transferred to the network via the Physical Random Access Channel, PRACH.The user traffic and control information share a Transport Channel named DCH, Dedicated Channel. The information the DCH carries is divided into two physical channels DPDCH and DPCCH with the used modulation methodWhen there is a need to send a short packet (and dedicated resources are not necessary) the information to be sent is carried by the Transport Channel CPCH. This information is sent through the Physical Common Packet Channel, PCPCH.To learn optimization process, understanding of call flow over air interface is very important. Call flow consist of some important phases which start with RRC connection i.e. Radio Resource Control Connection, this is the connection between UE and Radio Network Controller (RNC). After RRC Connection RNC setup signaling with the core network (CN).

When the signaling is completed CN response the UEs request and order the RNC to setup the radio bearer, this step is knows as RAB establishment. Once the RAB is assigned to the UE then call or data transfer is started.

After the call completion first release the signaling link between RNC and CN, release the radio bearer by RAB release process. Lastly release the RRC connection between UE and RNC.*Here we will learn about the Step by step procedure of mobile originating call flow:-RRC Connection Request: The Mobile user decides to initiate a voice call. The first message the UE will send on CCCH is RRC Connection Request. This will contain among other things, Initial UE Identity and Establishment Cause.RRC Connection Setup: Node B allocates the resources and starts PHY Reception. While transmitting the response it includes the Transport layer addressing information that includes the Identity of the Iub data transport bearer.RRC Connection Complete: RRC Connection Setup complete will be sent on DCCH. Integrity and Ciphering relatedparameters and UE capability information will be sentback to Node B.

*Connecting Slide:Initial Direct Transfer: First Signaling message for the CN is now sent by the UE. It indicates that a UE originated Voice call is required. The UE identity (TMSI) will also be passedin this message.CM Service Request: The Signaling message for the CN will be forwarded to appropriate CN Domain (CS Domain for voice call). Along with the CM service request,it will also include LAI.CM Request Accept: Node B send the acknowledgment to the UE about the acceptance of CM service.Radio Bearer Setup: Node B sends the RB Setup message to add the new DCH's. The message will be received using the old configuration.Radio Bearer Setup Complete: After the activation time the UE will respond with complete message using the new configuration.

*Connecting SlideMeasurement Control & Measurement Report: The network decides that inter frequency measurements need to be performed and sends the MEASUREMENT CONTROL MESSAGE with Measurement type set to Inter-Frequency measurements.Active Set Update: The network initiates Intra-Frequency measurements to check if there are any other cells the UE can connect simultaneously to improve the quality of the data being transferred between the RNC and the UE. If a suitable cell is found then Active Set Update procedure is initiated. Using this Active Set Update message, the network adds or deletes more than one radio link to the UE. The only requirement is that from the start till the end of this Active Set Update procedure, one Radio Link should remain common. Active Set Update Complete: This message is send to Node B by UE indicating successful handling of the message received from Node B.RRC Connection Release: The release of RRC connection message send from Node B to UE, this procedure is the request for UE to release all radio bearer. RRC Connection Release Complete: The RRC connection release complete message send from UE to Node B, result of this procedure indicate all existing radio bearer for the UE are released.

*Optimization process includes different steps, before starting the process we should know about the performance and the problem of the network. Then will start the optimization project by collecting the input data (OSS, KPI, DT, CC etc.) which help us for the analysis and assessments of the network. Next step is Solution, we check the solution come form the analysis of the input data which can be change in the physical parameter of the site, neighbor creation, change in the frequency plan or many more. This solution will be further send for the implementation as job order. Once the implementation part is complete we need to verify is solution sufficient to resolve the problem of the network. If the network is still facing any problem then we will monitor and collect the data of 3 to 5 days and do the analysis on the data, after analysis the again send the solution for the implementation. If the problem is resolved then projects end by preparing the reports.

***When the UE has information oncarrier frequencies of the PLMNpreviously stored on the USIM, it mayuse the stored information cellselection procedure. The UE may optionally have otherinformation, such as primary scrambling code group or the neighboring cells list stored on the USIM before UE switch-off or going out from acoverage area. This information ensures the simplification of the cell search procedure and speeds up the search for a suitablecell. After synchronization, the UE reads system information on the BCCH. If all requirements for asuitable cell are fulfilled, the UE selects thatcell and tries to register.

If the UE does not find a suitable cell of the PLMN on which it waspreviously registered, and it has already used thestored information cell selection procedure, the initial cell selection procedure is started. Thisprocedure does not require knowledge of radio frequency channels in the WCDMA band. The UE scans all WCDMA radio frequency channels to find a suitable cell. Oneach carrier, the UE searches for the cell withthe highest signal level, according to the cellsearch procedure, and reads the system information on the BCCH.

**UTRA Carrier RSSI (Received Signal Strength Indicator) is a parameter in dBm that describes the total signal strength of a UTRA-carrier frequency. Accordingly, the UTRA- Carrier RSSI represents the receivable energy of all cell at a certain location. CPICH RSCP (Received Signal Code Power) is a parameter in dBm that describes the total signal strength of a P-CPICH of any given cell. Note that the spreading code of the P-CPICH is identical for all cell while the primary scrambling code is different.CPICH Ec/No (Energy per chip vs. Total Power) is the relative parameter in dB that sets the CPCIH RSCP in relation to UTRA-carrier RSSI. [CPICH Ec/No= (CPICH RSCP/ UTRA-carrier RSSI)]**First network optimization phase is Single Site Verification. Single site verification is similar to basic feature verification except that only a limited number of tests are performed, and these tests are done for each Node B. Typically, a good RF environment is chosen for this test. However, it is best to run the verification independently for each cell of each site. Since this is a functional test and not a performance test, only a few calls in each cell are required. The single site verification test is a part of the WCDMA network optimization to ensure that the basic functions of the cell are normal, such as call access, call quality, handover and so on.

*Single site verification includes preparations before test, single site test, and solving problems. In the stage of preparations before test, you must input the Radio Parameter Planning Data Table output in radio network planning (RNP). After check configured data, output the Radio Parameter Configuration Data Table and select proper test points and test route.In the stage of single site test, output the Single Site Verification Checklist according to the template.In the stage of solving problems, on-site engineers and product support engineers solve the function problems.

*On-site engineers verifies single sites by test UEs and check the cell status and service connection conditions in the Verification in Idle Mode and Verification in Connected Mode. In this sections take handset as example for completing single site verification. For handsets of other types, the method for starting testing mode and measurement interface is different, but this sections can still serve as reference.Method:-To ensure that the services to be tested are provided by the cell to be measured, the most ideal method is to disable power amplifiers of other cells except the cell to be measured. In this situation, no requirements are on the testing points.

If you cannot disable the power amplifier of other cells, select a testing point near the center of the cell, with line-of-sight distance to the NodeB. In this way, the signals are strong enough and do not fluctuate. For a macro cell, select a testing point 100 meters from NodeB in the direction of major transmission of cell antenna, with line-of-sight distance to NodeB.

*Method: Press the application key to start testing mode of the software. Query WCDMA -Network Information, and the software displays the basic information of the serving network, including Cell ID. Check whether the ID of the serving cell (CI) is consistent with the planned one in frequency check. If not, the UE might receive signals from other cells.

Note:If the ID of the serving cell is consistent with the planned one, you do as below: Move the UE to a location with stronger signals and wait for two minutes. If the measured CI is inconsistent with the planned one, the UE does not reselect a cell. You must power off the UE, and then power on the UE to ensure that the UE camps on the cell with strongest signals, namely, the primary serving cell. Only when both the frequency and CI are consistent can the test pass.If the ID of the serving cell is inconsistent with the planned one, you do as below: You must lock frequency. Press Locking Frequency, and then Start Locking Frequency. After typing the frequency point, click OK to complete locking frequency. After frequency locking, you must restart testing mode. If the frequency and CI are consistent, the single site verification test passes.If you cannot find the serving CI for a long time, possibly the signals of the primary serving cell are transmitted abnormally, and the antenna-feeder are reversely connected. You must adjust them and then restart the test.

*NoteBased on consistency of CI, check whether the P-SC is consistent with the planned one. If yes, the site passes the test. If no, you must readjust and retest.

*Note

The threshold of CPICH RSCP and CPICH Ec/Io are related to site types (macro cell, micro cell) and loading conditions. You must determine them according to the actual situations.For macro cells, CPICH RSCP > 70 dBm.For micro cells, CPICH RSCP > 60 dBm.For no-load cells, CPICH Ec/Io > 6 dB.For load-on cells, CPICH Ec/Io > 10 dB.

If the operator also runs a 2G network and the 3G sites and 2G sites share sites, you can compare the coverage of corresponding 2G sites for checking signal coverage problems.If no special note is for a cell, the related CPICH RSCP: 75 dBm, CPICH Ec/Io: 8dB.

If CPICH RSCP < 75dBm, you must check for the following problems:Abnormal power amplifierAbnormal connection of antenna-feederInconsistency of antenna tile/direction angle from planned oneBlocking by buildingsIf CPICH Ec/Io < 8dB (when loading, the CPICH Ec/Io < 10dB), you must inform of RNO engineers.

*After the completion of site installation and verification part, we start with the RF Optimization. RF Optimization includes three main aspects Coverage Optimization, Pilot pollution Optimization and Handover Optimization.

Coverage Optimization1.Weak coverage optimization for ensuring seamless coverage by pilot signals in the network2.Primary pilot cell optimization for ensuring proper coverage areas by each primary pilot cell, clear edge of primary pilot cells, and that alternation of primary pilot cells is reduced as possible.

Pilot Pollution OptimizationPilot pollution refers to those excessive pilots of approximately equivalent strength cover an area without a primary pilot. Pilot pollution might cause increasing of downlink interference, call drop due to frequent handover, low network capacity. The problems must be solved by adjusting engineering parameters.

Handover Optimization1.Checking missing neighbor cells, verifying and perfecting list of neighbor cells, solving handover, call drop, and downlink interference problems.2.Ensuring proper SHO Factor based on DT by adjusting engineering parameters properly.

*RF optimization includes the following four parts:

Test preparations, Data collection, Problem analysis, Parameter adjustment the data collection might be repeatedly performed according to optimization goal and actual on-site situations until RF indexes meet KPI requirements.

*The DT and indoor test during RF optimization stage is based on VP service. According to the contract (commercial deployment offices) and planning report (trial offices), if seamless coverage by VP service is impossible in areas, such as, suburban areas and rural areas, the test is based on voice services. For areas with seamless coverage by PS384K service or HSDPA service required by the contract (commercial deployment office) or planning report (trial office), such as office buildings, press centers, and hot spot areas, the test is based on the above services.

According to different full coverage services in the planned areas, DT might be one of the following:3G ONLY continuous call test by using scanner + unloaded VPAccording to simulation result and experiences, if the test result meets requirements on VP service coverage, the test result will also meet identical coverage requirements of PS144K, PS128K, and PS64K services.3G ONLY continuous call test by using scanner + unloaded voice service3G ONLY continuous call test by using scanner + unloaded PS384KIndoor test consists of walking test and vertical test. Perform walking test to obtain horizontal signals distribution inside buildings. Perform vertical test to obtain vertical signals distribution. During RF optimization stage, collect neighbor cell data of network optimization and other data configured in RNC database. In addition, check whether the configured data is consistent with the previously checked/planned data.While checking configured data, feed back the improperly configured data (if found) to product support engineers. During checking, pay special attention to handover reselection parameters and power setting parameters

*For coverage optimization the process we follow is coverage analysis. Coverage problem analysis is key to RF Optimization. It involves signal distribution. The coverage problems to be analyzed include:

Weak coverage refer to that the RSCP(Received Signal Code Power) of pilot signals in a coverage area is less than -95 dBm. Overshoot coverage refers to that the coverage range of some Node Bs is beyond the planned range and discontinuous primary pilot coverage areas form in coverage areas of other Node Bs.Unbalanced between uplink and downlink refers to the following situations in uplink and downlink symmetric services.No primary pilot areas refer to the areas with no primary pilot or the primary cell changes frequently.

*Coverage analysis part is divided in to two parts Downlink and Uplink coverage analysis.

Downlink coverage analysis involves analyzing CPICH RSCP and CPICH Ec/Io obtained by drive test. The quality standard of CPICH RSCP must be combined with the optimization standard. It is further categorize in four parts:

Analyzing Pilot Coverage Strength- Usually, the strongest RSCP received by each scanner in the coverage area must be above 95 dBm.

Analyzing Pilot Coverage Quality- In parallel with the analysis of RSCP coverage, the Ec/Io plot should also be analysed. The -8 dB threshold takes into account the expected future interference increase as a result of increased traffic.Analyzing Primary Pilot Cell- Cell primary pilot analysis is analyzing cell scramble information obtained in DT. Analyzing comparison of UE and Scanner Coverage- Missing neighbor cells, improper parameters of soft handover, cell selection and reselection cause the consistent between scanner primary pilot cell and camped cell in idle mode or Best Service Cell in the active set in connection mode of UE.

Uplink coverage analysis is analyzing UE transmit power obtained in DT. This is also further divided into two parts:

Analyzing Uplink Interference- Check for uplink interference by tracing and analyzing RTWP data.Analyzing distribution of UE Transmit Power- The distribution of UE transmit power reflects the distribution of uplink interference and uplink path loss.In next slides we will study these points one by one in detail.

***Uplink coverage analysis: Uplink coverage analysis is analyzing UE transmit power obtained in DT. The quality standards of UE transmit power must be combined with optimization standards. Assume the optimization indexes of UE transmit power as below:Good if UE_Tx_Power 0 dBmFair if 0 dBm < UE_Tx_Power 10 dBm Poor if UE_Tx_Power > 10 dBm

Check whether the uplink coverage voids (Poor UE Tx Power) exist with the downlink CPICH RSCP coverage voids in the geographical areas. Solve the problem with both uplink and downlink weak coverage by analyzing downlink coverage analysis. If only the uplink coverage is poor without uplink interference, solve the problems by adjusting down tilt and azimuth of antenna, and adding TMAs.

Uplink - Distribution of UE Transmit Power:The distribution of UE transmit power reflects the distribution of uplink interference and uplink path loss.In this Figure , UE transmit power is lower than 10 dBm normally. Only when uplink interference and coverage area edge exist will the UE transmit power increase sharply to 21 dBm (Some UEs that support HSDPA, with a power class of 3, the maximum transmit power is 24 dBm), and the uplink is restricted. Comparatively restricted uplink coverage occurs much easily in macro cells than in micro cells.*Pilot pollution exists if all the following conditions are met:The number of pilots that meet the following condition is more than 4 and CPICH_RSCP > -100dBmIf some cells are frequently seen as polluters (e.g. >8% time) should be marked and investigated. Usually, the max number of active cell is 3, so if number of strong pilot is more than 3,then it is a pilot pollution point.If (CPICH_RSCP1st - CPICH_RSCP4th) < 5dB ,it means the best serve cell is not dominant

**Looking at the estimated active set based on the scanner data is a very useful measurement of pilot pollution , In order to see areas of excessive SHO candidates, the estimated active set size is allowed to exceed maximum of 3 .Locations where there are more than 3 pilots in the active set should be marked and sources of the interference should be identified for elimination This can be done in conjunction with the Pilot pollution analysis.

Improper Cell Distribution: Due to restriction to site location and complex geographic environment, cell distribution might be improper. Improper cell distribution causes weak coverage of some areas and coverage by multiple strong pilots in same areas.Highly-mounted Antenna: If a NodeB is constructed in a position higher than around buildings, most areas will be with in the line-of sight range. Therefore signals are widely transmitted. Over high site cause difficult control of cross-cell coverage, which causes pilot pollution. Improper Antenna Azimuth: The sector azimuth of each antenna is set to cooperate with each other. If the azimuth is improperly set ,might lead to pilot pollution Therefore we must adjust the antenna according to actual propagation.Improper Antenna Down Tilt: If the antenna down tilt is improper, signals are received in the areas which are covered by this site. Therefore interferences to other areas causes pilot pollution. Even worse, interferences might cause call drop.Improper PICH Power: When the Node Bs are densely distributed with a small planned coverage rang and the PICH power is over high, the pilot covers an area larger than the planned area. This causes pilot pollution.

*Antenna Adjustment: According to the test, change pilot signal strength of an area with pilot pollution by adjusting antenna down tilt and azimuth. This changes the distribution of pilot signals in the area. The principle for adjustment is enhancing primary pilot and weakening other pilots.

P-CPICH Power Adjustment: Pilot pollution is caused by the coverage by multiple pilots. A direct method to solve the problem is to form a primary pilot by increasing the power of a cell and decreasing the power of other cells.

Using RRU or Micro Cells: If adjusting power and antenna is not effective to solving pilot pollution, use RRU or micro cells. It aims to bring a strong-signal coverage in the area with pilot pollution, so the relative strength of other signals decreases.

*During RF optimization stage, the involved handover problem is about neighbor cell optimization and SHO Factor based on DT control. Control the size and location of handover areas by adjusting RF parameters. You can eliminate handover call drop due to sharp fluctuation and increase handover success rate. During RF optimization stage, the involved handover problem include:Neighbor cell optimization SHO Factor based on DT Analysis

Active set: the set of radio links that keep connections with the UEMonitor set: the set of signals that are from neighbor cells and are not in the active set, but can be detected by the UEDetection set: the set of signals that are from other cells and can be detected by the UE. It is not the neighbor cell of the current active set (neighbor cell missing or over-coverage).Radio link (RL): Each connection between the UE and NodeB is called a radio link (RL).Radio link set (RLS): the set of RLs that belong to the same NodeB. Softer handover occurs between cells that belong to the same RLS.Combination: For soft handover, the uplink signals are combined in RNC. The RNC will select one best signal to process. We call this selective combination. For softer handover, the uplink signals are combined in the RAKE receiver of NodeB. It is maximum ratio combination.CPICH: Common Pilot Channel. UE measure the signal strength of CPICH for handover decision.

*Handover is classified by the cell change after handover, signaling flow, or frequency change after handover.If the same frequency is used in the two cells where handover occurs:If the two cells belong to the same RNC, usually soft handover or softer handover is performed for low-rate services to obtain the best service quality.Soft handover cannot be performed between different RNCs if no lur interface is configured. Only hard handover can be performed in this situation.Because high rate data communication services, such as the PS348K service, occupy many resources, normally soft handover is not allowed. We can configure the RNC parameters so that soft handover is not performed if the service rate exceeds a certain threshold, even if these two cells belong to the same RNC.The unique signaling of soft handover is Active Set Update, and the unique signaling of hard handover is Physical Channel Reconfiguration.If the frequencies used in two cells are different, only hard handover can be performed.*Missing neighbor cells causes that a strong-pilot cell cannot be listed into the active set so the interference increases as strong as call drop occurs. For missing neighbor cell, you must add necessary neighbor cells. Redundant neighbor cells causes that the neighbor cell information is excessive and unnecessary signals cost occurs. When the neighbor cell list is fully configured, the needed neighbor cell cannot be listed. For this problem, remove redundant neighbor cells. During RF optimization stage, missing neighbor cell is a key problem. The neighbor cell optimization includes adding and removing neighbor cells.

SHO Factor based on DT Analysis: This analysis is done during RF optimization stage must 5%10% lower than the KPI target value, because the following optimizations cause SHO Factor based on DT to increase and brings difficulties in ensuring traffic measurement SHO Factor based on DT. At the end of large-scale coverage optimization and pilot pollution optimization, the SHO Factor based on DT will be within or close to the target range. The precondition for adjustment is that the adjustment will not cause new coverage voids, coverage blind zone, and more pilot pollution. If the SHO Factor based on DT is over large, decrease or change the handover areas by using the following methods for shrinking coverage areas:

***The field test can be divided into two parts: drive test on main road and test for special areas. Test for special areas is like walk survey for some indoor distributed cells. We can use scanner + UE log, RNC log, statistics counters and KPI, MSC & SGSN log to optimize the network.

*Drive test is to get information on the service coverage on the main road and to optimize the problems as access failure, drop call, power control, handover and service quality. Unlike RF optimization drive test, for parameter optimization its not needed to do the service test for all sites. So its not necessary to stick to the idea of cluster.

*To check Access failure system bugs, power control parameter, cell selection and reselection parameter etc. need to be look. For finding the reason for drop calls one should check system bugs, power control parameter, handover parameter etc. And similarly for finding the reason for Service quality one should check system bugs, power control parameter, RLC parameter etc. *The influence caused by the cell parameters adjustment should be analyzed carefully by optimization engineer. The parameters adjustment to a live network should be performed when traffic is low for example: at midnight. It is essential to do the service functional test after adjustment.

Sometimes its hard to predict accurately the impact of the parameter changes. So its necessary to benchmark before and after parameter changes. Its recommended to do the benchmark together with the statistics analysis for live network.

**Operations and Maintenance Centre (OMC)The OMC provides a central point from which to control and monitor the other network entities (i.e. base stations, switches, database, etc) as well as monitor the quality of service being provided by the network. At present, equipment manufacturers have their own OMCs which are not compatible inevery aspect with those of other manufacturers. This is particularly the case between radio base station equipment suppliers, where in some cases the OMC is a separate item and Digital Switching equipment suppliers, where the OMC is an integral, butfunctionally separate, part of the hardware.There are two types of OMC these are: OMC (R)OMC controls specifically the Base Station System. OMC (S)OMC controls specifically the Network Switching System.The OMC should support the following functions as per ITSTS recommendations: The OMC supports the following network management functions:

Event Management - General functions of the OMC include operator input and output messages, application input commands, and application output reports.Fault Management - The OMC provides fault management such as diagnostics and alarms for the MSC and BSSSecurity Management It provides an extensive range of features to ensure that access to the OMC functions is restricted to relevant personnel. Configuration Management Configuration Management allows the operator to adopt the network to the changing traffic requirements.Performance Management Supports data collection such as traffic data, handovers, statistics, plant measurements, and volume data

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