W-RF Tuning Guide-20081129-A-3.1

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WCDMA RF Tuning Guide Internal Open

Product name Confidentiality level

WCDMA RNP For internal use only

Product version

Total 63 pages3.1

WCDMA RF Tuning Guide

(For internal use only)

Prepared by He Fengming Date 2006-01-18

Reviewed by Xie Zhibin, Jiao Anqiang,Hua Yunlong, Hu Wensu,Wan Liang, Ai Hua, andYan Lin

Date

2006-03-15

Reviewed by Qin Yan Date 2006-03-15

Approved by Date

Huawei Technologies Co., Ltd.All Rights Reserved

2008-11-29 All rights reserved Page1 , Total63


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Revision Records

Date Revisedversion Description Author

2004-12-05 1.00 Initial transmittal Zhou Xinjie

2005-03-02 1.01 Revising it according to review Zhou Xinjie

2006-01-18 3.0 Simplifying tasks of RF optimization,enhancing operability, and addingcontent based on KPI optimization

He Fengming

2006-02-27 3.01 Replacing CQT method with indoor test; Clarifying solution scale ofinterference and access problems;

Deleting content of removing neighborcells; updating RF optimization flowchat

He Fengming

2006-03-15 3.02 Removing content of repeaters andbaseline; Adding optimization targetand method for SHO Factor based onDT; updating partial cases; addingcases for cluster division; Combiningblind coverage and coverage voids toweak coverage; adding simple methodfor removing neighbor cells

He Fengming

2006-04-18 3.03 According to the review by changecontrol board (CCB), changing theinterval of VP tests to 15s, addingother simple causes to imbalance ofuplink and downlink, correcting somegrammatical mistakes.

He Fengming

2006-05-13 3.1 Adding HSDPA-related content;changing the RF optimizationobjectives of unloaded R99 andHSDPA networks in urban andsuburban areas

Wu Yue and WangDekai

2006-10-19 3.11 Update the content of 3.1 optimization

target. change the size of TB in CQImapped table

Wang Dekai

2008-08-01 3.12 Update content of 3.4 and 5.1 Zhu Yubai

2008-11-29 3.13 According to the request of WBS,change the document structure.Adding the differences in differ RFoptimization phases, and updatedocument content according comment

Gao Ying



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Contents

1 Introduction to RF Optimization...................................................9

1.1 Contents of RF Optimization................................................................................................................9

1.2 Document Structure...........................................................................................................................10

2 Basic Processes for RF Optimization...........................................11

2.1 Flow Chat of RF Optimization.............................................................................................................12

2.2 Detailed Sections of RF Optimization.................................................................................................13

2.2.1 Test Preparations..........................................................................................................................13

2.2.2 Data Collection.............................................................................................................................14

2.2.3 Problem Analysis..........................................................................................................................14

3 Test Preparations......................................................................15

3.1 Deciding Optimization Goal................................................................................................................15

3.2 Dividing Clusters................................................................................................................................17

3.3 Deciding Test Route...........................................................................................................................18

3.4 Preparing Tools and Data...................................................................................................................19

3.4.1 Preparing Software.......................................................................................................................19

3.4.2 Preparing Hardware......................................................................................................................19

3.4.3 Preparing Data..............................................................................................................................20

4 Data Collection..........................................................................21

4.1 Drive Test...........................................................................................................................................21

4.1.1 DT Types......................................................................................................................................21

4.1.2 Setting DT Indexes.......................................................................................................................22

4.2 Indoor Test..........................................................................................................................................24

4.3 Collecting RNC Configuration Data....................................................................................................245 Coverage Problem Analysis........................................................26

5.1 Coverage Problem Types...................................................................................................................26

5.1.1 Weak coverage.............................................................................................................................26

5.1.2 Cross-cell Coverage.....................................................................................................................29

5.1.3 Unbalanced Uplink and Downlink.................................................................................................29

5.1.4 No Primary Pilot............................................................................................................................30

5.2 Coverage Analysis Processes............................................................................................................31

5.2.1 Downlink Coverage Analysis.........................................................................................................31

5.2.2 Uplink Coverage Analysis.............................................................................................................34

5.3 Coverage Problem Cases..................................................................................................................35



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5.3.1 Weak Coverage Cases Due to Improper Engineering Parameters...............................................35

5.3.2 Cross-cell Coverage Due to Improper NodeB Location................................................................37

5.3.3 Coverage Restriction Due to Improper Installation of Antennas....................................................38

6 Pilot Pollution Problem Analysis.................................................40

6.1 Pilot Pollution Definition and Judgment Standards.............................................................................40

6.1.1 Definition.......................................................................................................................................40

6.1.2 Judgment Standards.....................................................................................................................40

6.2 Process for Analyzing Pilot Pollution Problem....................................................................................40

6.3 Causes and Influence Analysis...........................................................................................................41

6.3.1 Causes Analysis...........................................................................................................................41

6.3.2 Influence Analysis.........................................................................................................................43

6.4 Solutions to Pilot Pollution..................................................................................................................43

6.4.1 Antenna Adjustment......................................................................................................................43

6.4.2 PICH Power Adjustment...............................................................................................................446.4.3 Using RRU and BBU....................................................................................................................45

6.5 Optimization Cases for Eliminating Pilot Pollution..............................................................................47

6.5.1 Data Analysis before Optimization................................................................................................47

6.5.2 Data Analysis after Optimization...................................................................................................50

7 Handover Problem Analysis........................................................53

7.1 Neighbor Cell Optimization.................................................................................................................53

7.1.1 DT Data Analysis..........................................................................................................................53

7.1.2 Removing Redundant Neighbor Cells...........................................................................................57

7.2 SHO Factor based on DT Analysis.....................................................................................................58

7.2.1 Definition of SHO Factor based on DT.........................................................................................58

7.2.2 General Principles and Methods in Optimization..........................................................................58

8 Adjustment Methods.................................................................60

9 Summary..................................................................................61

10 Appendix: Coverage Enhancement Technologies........................62

10.1 Coverage-enhancing Technologies..................................................................................................62

10.1.1 TMAs..........................................................................................................................................62

10.1.2 Receive and Transmit Diversity..................................................................................................62

10.1.3 RRU............................................................................................................................................62

10.1.4 Micro Cells..................................................................................................................................62



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Tables

Table 1.1List of RF optimization objectives in R99 networks.............15

Table 1.2Relationship among the CQI reported by UE, pilot Ec/Io, andthroughput rate at MAC-HS layer....................................................16

Table 1.3Mapping relationship of HSDPA Catogory12 UE CQI and TBsize ..............................................................................................17

Table 2.1Recommended software for RF optimization ......................19

Table 2.2Recommended hardware for RF optimization .....................19

Table 2.3Data to be collected before optimization............................20

Table 4.1Configured parameters to be checked................................24

Table 37.1Changing conditions for judging neighbor cells.................54



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Figures

Figure 1.1RF optimization flow chat................................................13

Figure 1.2Divided clusters in a project............................................18

Figure 1.3 DT test set 1.................................................................22

Figure 1.4DT test set 2...................................................................23Figure 1.5Chart 5 RSCP distribution in cluster xx.............................27

Figure 1.6Chart 6 RSCP distribution histogram in cluster xx.............27

Figure 1.7Chart 7 Ec/Io distribution in cluster xx..............................28

Figure 1.8Chart 8 Ec/Io distribution histogram in cluster xx.....................................................................................................28

Figure 1.99 SC distribution in cluster xx..........................................31

Figure 1.10RSCP for 1st Best ServiceCell.........................................32

Figure 1.11Distribution of pilot SC for the 1st Best ServiceCell.........33

Figure 1.12Analyzing comparison of UE and scanner coverage.........34

Figure 1.13Distribution of UE transmit power..................................35

Figure 1.14Coverage near Xiajiao Sugar Plant (before optimization).36

Figure 1.15Coverage near Xiajiao Sugar Plant (after optimization).. .36

Figure 1.16Cross-cell coverage before optimization.........................37

Figure 1.17Few cross-cell coverage areas after optimization............38

Figure 1.18Coverage restriction due to antenna blocked by roof.......38

Figure 1.19Optimizing antennas by adjusting feeders......................39

Figure 1.20Pilot pollution due to improper antenna azimuth.............43Figure 1.21Pilot pollution due to improper antenna down tilt...........44

Figure 1.22Pilot pollution due to improper distribution of cells.........45

Figure 1.23Pilot pollution due to ambient factors............................46

Figure 1.24Survey photo of each cell related to pilot pollution.........46

Figure 1.25Pilot pollution near Yuxing Rd........................................47

Figure 1.26Best ServiceCell near Yuxing Rd.....................................47

Figure 1.27The 2nd best ServiceCell near Yuxing Rd........................48

Figure 1.28The 3rd best ServiceCell near Yuxing Rd.........................48



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Figure 1.29The 4th best ServiceCell near Yuxing Rd.........................48

Figure 1.30Composition of pilot pollution near Yuxing Rd.................49

Figure 1.31RSSI near Yuxing Rd......................................................49

Figure 1.32RSCP of Best ServiceCell near Yuxing Rd........................50Figure 1.33RSCP of SC270 cell near Yuxing Rd.................................50

Figure 1.34Pilot pollution near Yuxing Rd. after optimization...........51

Figure 1.35Best ServiceCell near Yuxing Rd. after optimization........51

Figure 1.36RSCP of best ServiceCell near Yuxing Rd. after optimization.....................................................................................................52

Figure 1.37RSCP of SC270 cell near Yuxing Rd. after optimization....52

Figure 1.38Generating neighbor cell analysis report by using Assistant.....................................................................................................55

Figure 1.39Result of missing neighbor cells.....................................55

Figure 1.40Variation of active set Ec/Io recorded by UE before calldrop..............................................................................................56

Figure 1.41Variation of active set Ec/Io recorded by scanner beforecall drop........................................................................................57

Figure 1.42RSCP for candidate of 4th Best ServiceCell.....................59



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WCDMA RF Tuning Guide

Key words: WCDMA, network optimization, and RF optimization

Abstract: This document describes tasks to be completed during RF optimization stage in WCDMA network

optimization. The tasks include RF optimization goal, flow, procedure, input and output, and

precautions concerning RF optimization.

Acronyms and abbreviations:



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1 Introduction to RF OptimizationDuring RF optimization stage, as one of RNO, you optimize radio frequency (RF) signals. Thisaims to control pilot pollution and SHO Factor based on DT in optimizing signal coverage, sothat the distribution of radio signals is normal in next service parameters optimization stage.

1.1 Contents of RF Optimization

RF optimization includes the following aspects:

Pilot signal coverage optimization

It includes the following two parts:

Weak coverage optimization for ensuring seamless coverage by pilot signals in the

network

Primary pilot cell optimization for ensuring proper coverage areas by each primary pilotcell, clear edge of primary pilot cells, and that alternation of primary pilot cells is reducedas possible.

Pilot pollution optimization

Pilot pollution refers to those excessive pilots of approximately equivalent strength cover anarea 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 optimizationIt consists of two parts:

Checking missing neighbor cells, verifying and perfecting list of neighbor cells, solvinghandover, call drop, and downlink interference problems.

Ensuring proper SHO Factor based on DT by adjusting engineering parameters properly.


Acronyms andabbreviations

Full spelling

CPICH Common Pilot ChannelDT Drive TestKPI Key Performance Indicator

MML Man Machine LanguageOCNS Orthogonal Channel Noise Simulator OMC Operation and Maintenance Center PS Packet-Switched domainRF Radio FrequencyRNC Radio Network Controller RSCP Received Signal Code Power RTWP Received Total Wideband Power VIC Very Important CellVIP Very Important PeopleVP Video PhoneRNO Radio Network PlanningTMA Tower Mounted Amplifier

HSDPA High Speed Downlink Packet AccessCQI Channel Quality Indicator


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Interference optimization

Exclude interference caused by pilot pollution and missing neighbor, According to theinterior network interference problem, find out the interference due to coverage and handover

problem, and solve problem effectively. Interference optimization will be included in the first

three problems.

1.2 Document Structure

This document consists of the following chapters:

Chapter 1 Introduction to RF Optimization Chapter 2 Basic Processes for RF Optimization Chapter 3 Test Preparations Chapter 4 Data Collection Chapter 5 Coverage Problem Analysis Chapter 6 Pilot Pollution Problem Analysis Chapter 7 Handover Problem Analysis Chapter 8 Adjustment Methods Chapter 9 Summary Chapter 10 Appendix



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2 Basic Processes for RFOptimization

According to the network optimization character and execute phase, pertinence RF optimizationmethod should be taken, at present it mainly include four kinds as below:

1. Cluster optimization phase

Once all the sites are installed and verification is complete, RF optimization starts. In somesituations for a tight schedule, RF optimization might start after the construction of partial sites iscomplete. RF optimization is usually performed after 80% of total sites in a cluster areconstructed.

2. Full network optimization

Carry out after cluster optimization, the main object is to satisfy full network coverage

requirement, and take related test according KPI. Take optimization from all round, solve theinterference and coverage problems between neighbor cluster, most of work is same as thecluster optimization.

3. Network performance upgrade phase

When the program enter to maintenance phase, provide the radio network performanceupgrade service to customers, according to the quality of network decrease or request toimprove the quality of network, through out concentrate time and human resource, improvenetwork performance and service quality. The main job Includes coverage optimization, usercomplains solution, transfer RF optimization experience to customer. According to DT/CQT test,find and solve network problem, take in detail problem analysis and adjust scheme, checknetwork performance if it has been reached to the target after optimization. At the same time,communicate with customers, provide them technique guidance and network optimizationexperience.

4. Provide network continuous optimization service phase

Huawei radio network optimization service include: Through out long-term daily networkperformance monitor, regularly preventive estimate check and continuously optimization toguarantee network quality stabilization. At the same time of improving network performance,transfer maintenance experience to customers. As to guarantee network coverage, providecustomers technique solution about RF optimization, according to DT/CQT test data, find andsolve coverage or interference problem.

RF optimization stage is one major stage of RNO. It aims at the following aspects:



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Optimizing signal coverage Control pilot pollution Control SHO Factor based on DT

RF optimization also involves optimizing list of neighbor cells.

When the indexes like DT and traffic measurement after RF adjustment meets KPIrequirements, RF optimization stage ends. Otherwise you must reanalyze data and adjustparameters repeatedly until all KPI requirements are met. After RF optimization, RNO comes toparameter optimization stage.

2.1 Flow Chat of RF Optimization

RF optimization includes the following four parts:

Test preparations Data collection Problem analysis Parameter adjustment

It shows the RF optimization flow chat.



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Figure 1.1 RF optimization flow chat

In 2.1, the data collection, problem analysis, and parameter adjustment might be repeatedly

performed according to optimization goal and actual on-site situations until RF indexes meetKPI requirements.

2.2 Detailed Sections of RF Optimization

2.2.1 Test Preparations

During test preparations, proceed as below:

1. Decide KPI goals for optimization according to the contract

2. Divide clusters properly and decide test route with the operatorThe KPI test acceptance route is especially important.

3. Prepare tools and materials for RF optimization.



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This ensures smooth RF optimization.

2.2.2 Data Collection

Collect the following data: UE and scanner data

Collect UE and scanner data by the following methods:

DT

Indoor test

Signaling tracing Call data tracing at RNC side Configuration data

The configuration data and the call data tracing help to locate problems.

Data collection is a precondition for problem analysis.

2.2.3 Problem AnalysisYou can locate problems by analyzing collected data. After analyzing coverage problems, pilotpollution problems, and handover problems, provide corresponding adjustment solutions. Afteradjustment, test the adjustment result. If the test result cannot meet KPI requirements,reanalyze problems and readjust parameters until all KPI requirements are met.

Due to weak coverage, pilot pollution, and missing neighbor cells, the following problems arerelated to location:

Downlink interference Access problems Call drop problems

The previous problems occur regularly. You can solve them by repeated optimization.

If the coverage is good, pilot pollution and missing neighbor cells are not present, the accessand call drop problems need to be solved during parameter optimization stage. You can refer tocorresponding guidebooks. The period for solving uplink interference problems (RTWP is overhigh but no high traffic matches it) is long, even as long as the RF optimization ends. Forsolutions, see WCDMA Interference Solution Guide.

Output an updated list of engineering parameters and list of cell parameters after RFoptimization. The list of engineering parameters reflects adjustment of engineering parameters(such as down tilt and azimuth) during RF optimization stage. The list of cell parameters reflectsthe adjustment of cell parameters (such as neighbor cell configuration) during RF optimizationstage.



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3 Test PreparationsTest preparations include the following four aspects:

Deciding optimization goal Dividing clusters Deciding DT route Preparing tools and data

3.1 Deciding Optimization Goal

The key of RF optimization is to solve problems as below:

Weak coverage

Pilot pollution

High SHO Factor based on DT

Actually, different operators might have different standards on KPI requirements, indexdefinition, and attention. Therefore the RF optimization goal is to meet the coverage andhandover KPI requirements in the contract (commercial deployment offices) or planning report(trial offices).

Define the indexes as required by contract as below:

The index definition is the percentage ratio of the sampling points with the index (such asCPICH Ec/Io) greater than the reference value in all sampling points.

Usually after RF optimization, the network must meets the index requirements listed in 3.1.

Note:3.1 provides reference indexes, only for guiding RNO engineers to clarify the RF optimizationobjectives, not for actual project bidding. Different projects may have different indexes. Thecontract decides the actual indexes and values.

3.1 lists the RF optimization objectives according to analysis of and suggestion to coverage byexisting network.

Table 1.1 List of RF optimization objectives in R99 networks

Index Reference Remarks



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CPICH Ec/Io 9dB 97% inurbanarea

According to test result from the scanner,in unloaded and outdoor conditions, inplanning coverage areas, test in a grid-like route to cover all cells.

97% in

suburbanarea

CPICH RSCP 95dBm 98% inurbanarea

According to test result from the scanner,in unloaded and outdoor conditions, inplanning coverage areas, test in a grid-like route to cover all cells. The coveragelevel request is basic. If operators havepenetration loss request, add thepenetration loss to the coverage level.

95% insuburbanarea

SHO Factor based on DT 30%40% The SHO Factor based on DT should be5% to 10% lower than the goal, because

the following optimizations cause the softhandover factor to increase

Pilot pollution ratio 5%

The RF optimization of HSDPA services aims to improve the ratio of test phone; the mainmethod is improving distribution of UE CQI.

3.1lists the relationship among the CQI reported by UE, pilot Ec/Io, and throughput rate at MAC-HS layer (MPO = 7.5 dB).

Table 1.2 Relationship among the CQI reported by UE, pilot Ec/Io, and throughput rate at MAC-HSlayer

9 > CQI 15 > CQI 9 CQI 15

Subscribers' feeling Poor Fair Good

throughput rate atMAC-HS layer forsingle subscriber

0466 Kpbs 466kbps to1.39Mbps

> 1.39 Mbps

Ec/Io < 15dB 15dB to 9dB 9dB

The throughput rate provided in is based on the test in the following conditions:

The codes and lub are not restricted. The category 12 UE has a subscribed rate of 2 Mpbs. The subscribed type is background or interactive service Power is dynamically distributed. Namely, without R99 subscribers, all the power is usedby the HSDPA subscriber to guarantee rate as high as possible.

According to the requirements on RF optimization of unloaded R99 network, the CPICH Ec/Io 9 dB. After HSDPA is introduced, power is dynamically distributed, and the single HSDPAsubscriber at cell edge uses all the power. Meanwhile, the downlink load reaches 90%, andCPICH Ec/Io 15.5dB.

If operators' requirement on throughput rate at cell edge is not the recommended, search therequired value in 3.1.

3.1 lists the mapping relationship of HSDPA Catogory12 UE CQI and TB size. The CQI that is

larger than 13 or smaller than 5 are excluded. The rate at MAC-HS layer for the subscriber is



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(TBsize / 2ms) * (1 BLER), wherein, the BLER is 10%.

Table 1.3 Mapping relationship of HSDPA Catogory12 UE CQI and TB size

CQI TB Size

5 365

6 365

7 365

8 699

9 699

10 1036

11 1380

12 2046

13 2404

14 2726

15 3090

16 3440

As previously mentioned, to optimize HSDPA is to optimize Ec/Io of target networks.

But the main difference between HSDPA and R99 networks optimization is R99 has softhandover, but HSDPA doesnt. So HSDPA traffic doesnt have soft handover plus, first cut offthen connect. Data transfer will be broken in this process, For SDPA, pilot pollution and pingpang handover is more sensitive. Pay more attention to pilot coverage environmentoptimization.

Therefore, in terms of optimization method, the HSDPA and R99 networks are consistent. Thefollowing optimization flow will not distinguish HSDPA networks from R99 networks.

3.2 Dividing Clusters

According to the features of UMTS technologies, the coverage and capacity are interaction andthe frequency reuse factor is 1. Therefore RF optimization must be performed on a group of or a

cluster of NodeBs at the same time instead of performing RF optimization on single site one byone. This ensures that interference from intra-frequency neighbor cells are considered duringoptimization. Analyze the impact of the adjustment of an index on other sites before adjustment.

Dividing clusters involves approval by the operator. The following factors must be consideredupon dividing clusters:

According to experiences, the number of NodeBs in a cluster depends on the actual

situation. 1525 NodeBs in a cluster is recommended. Too many or few NodeBs in a cluster is

improper. A cluster must not cover different areas of test (planning) full coverage services. Refer to the divided clusters for network project maintenance of the operator. Landform factor

Landforms affect signal propagation. Mountains block signal propagation, so they are naturalborders for dividing clusters. Rivers causes a longer propagation distance, so they affect



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dividing clusters in various aspects. If a river is narrow, the signals along two banks will interact.If the transportation between two banks allows, divide sites along the two banks in the samecluster. If a river is wide, the upstream and downstream will interact. In this situation, thetransportation between two banks is inconvenient, dividing clusters by the bank according toactual situation.

A cell-like cluster is much usual than a strip-like cluster. Administrative areas

When the coverage area involves several administrative areas, divide clusters according to

administrative areas. This is easily acceptable by the operator. DT workloadThe DT must be performed within a day for a cluster. A DT takes about four hours.

3.2 shows divided clusters in a project.

Figure 1.2 Divided clusters in a project

In 3.2:

JB03 and JB04 belong to dense urban areas. JB01 belongs to express way areas. JB02, JB05, JB06, and JB07 belong to urban areas. JB08 belongs to suburban area. The number of NodeBs in a cluster is 1822.

3.3 Deciding Test RouteConfirm the KPI DT acceptance route with the operator before DT. If the operator already has adecided DT acceptance route, you must consider this upon deciding the KPI DT acceptanceroute. If the objective factors like network layout cannot fully meet the coverage requirements ofdecided test route by the operator, you must point this out.

The KPI DT acceptance route is the core route of RF optimization test routes. Its optimization isthe core of RF optimization. The following tasks, such as parameter optimization andacceptance, are based on KPI DT acceptance route. The KPI DT acceptance route must covermajor streets, important location, VIP, and VIC. The DT route should cover all cells as possible.The initial test and final test must cover all cells. If time is enough, cover all streets in theplanned area. Use the same DT route in every test to compare performances more accurately.Round-trip DT is performed if possible.



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Consider actual factors like lanes and left-turn restriction while deciding test route. Beforenegotiating with the operator, communicate these factors with local drivers for whether the routeis acceptable.

3.4 Preparing Tools and DataPrepare necessary software (listed in 3.4.1), hardware (listed in 3.4.2), and various data (listedin 3.4.3), because the following test and analysis are based on them.

Detail test process, link test instruments and test items, consult

3.4.1 Preparing Software

3.4.1 lists the recommended software for RF optimization

Table 2.1 Recommended software for RF optimization

No. Software Function Remarks

1 GenexProbe/Nemo

DT AboveV1.3

2 GenexAssistant/Actix

Analyzing DT data and checking neighborcells

AboveV1.41

3 Genex Nastar Analyzing performance, checking health,and locating problems

4 Mapinfo Displaying maps and generating route data

5 GoogleEarth NodeB location and enviorment display,

height display

3.4.2 Preparing Hardware

3.4.2 lists the recommended hardware for RF optimization

Table 2.2 Recommended hardware for RF optimization

No. Device Specification Remarks

1 Scanner DTI Scanner

2 Test terminal anddata line

U626, E620, Qualcomm, and so on At least two testterminals. If thereis HSDPArequest, use thedata card E620.U626 does notsupport HSDPA.

3 Laptop PM1.3G/512M/20G/USB/COM/PRN

4 Vehicle mountedinverter

DC to AC, over 300W



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5 GPS Common GARMIN GPS inner set inDTI Scanner.GPS antennashould be installwhen test

3.4.3 Preparing Data

3.4.3 lists the data to be collected before optimization

Table 2.3 Data to be collected before optimization

No. Needed data Whether isnecessary

Remarks

1 List of engineering parameters Yes

2 Map Yes By Mapinfo or in paper

3 KPI requirements Yes

4 Network configuration parameters Yes

5 Survey report No

6 Single site verification checklist No

7 Floor plan of the target buildings Yes For indoor test

8 Project configuration document Yes Check Missingneighbor cell



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4 Data CollectionDuring RF optimization stage, the key is the optimization of radio signals distribution, with themajor means of DT and indoor test. Before test, confirm with the customer care engineers thefollowing aspects:

Whether the target NodeBs, RNCs, and related CN are abnormal due to being disabled,

blocked, congested, and transmission alarms. Whether the alarms have negative impact on the validity of test result data.If the alarms exist, solve the problems before test.

DT is a major test. Collect scanner and UE data of radio signals by DT test. The data isapplicable in analyzing coverage, handover, and pilot pollution problems.

Indoor test involves the following areas:

Indoor coverage areas

Indoor coverage areas include inside buildings, department stores, and subways. Inside areas of important facilities

Inside areas of important facilities include gymnasiums and government offices. Areas required by the operatorAreas required by the operator include VIC and VIP.

Test the previous areas to locate, analyze, and solve the RF problems.

Indoor test also involves in optimizing handover of indoor and outdoor intra-frequency, inter-frequency, and inter-system.

The DT and indoor test during RF optimization stage is based on VP service. According to thecontract (commercial deployment offices) and planning report (trial offices), if seamlesscoverage by VP service is impossible in areas, such as, suburban areas and rural areas, thetest 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 (trialoffice), such as office buildings, press centers, and hot spot areas, the test is based on theabove services.

4.1 Drive Test

4.1.1 DT Types

According to different full coverage services in the planned areas, DT might be one of thefollowing:

3G ONLY continuous call test by using scanner + unloaded VP

According to simulation result and experiences, if the test result meets requirements on VP



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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 service 3G ONLY continuous call test by using scanner + unloaded PS384K 3G ONLY continuous call test by using scanner + unloaded HSDPA

4.1.2 Setting DT Indexes

The following paragraphs take VP service for example.

Setting DT indexes proceeds as below:

Start Genex Probe software

Select Configuration > Test Plan Configuration > New

Set DT indexes as shown

For setting of voice, PS384K, and HSDPA services, see WCDMA Test Guide

Figure 1.3 DT test set 1



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Figure 1.4 DT test set 2

For setting DT, see the following table.

Index Meaning

Enable Whether to implement this index. True for implementation. False for non-implementation. The recommended value is True.

CallNumber

Called number. Whether the called terminal supports VP must beconfirmed.

SetupTime (s)

The maximum time for setting up calls. It ranges from 2030s. Therecommended value is 25s.

Calling

Time (s)

The time for a single call from call start to normal end of call. Set it great

enough according to actual DT route. The recommended value is 99999s.

Idle Time(s)

Call internal time. The recommended value is 10s.

Call Count Total call times. Set it great enough according to actual DT route. Therecommended value is 999 times.

Collect call data tracing at RNC side while performing drive test. This help to locate and analyzeproblems.

Data to be collected includes:

Traced signaling messages of single subscriber

For the detailed description and collection method of call tracing data, see WCDMA Equipment



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Room Operations Guide. CDT trace signaling messages

For the detailed description and collection method of call tracing data, see WCDMA Equipment

Room Operations Guide.

4.2 Indoor Test

GPS signals are unobtainable in door test. Obtain the plan of the target area before test.

Indoor test consists of walking test and vertical test. Perform walking test to obtain horizontalsignals distribution inside buildings by selecting Indoor Measurement > Walking Test. Performvertical test to obtain vertical signals distribution by selecting Indoor Measurement > VerticalTest. For the detailed method, see WCDMA Test Guide .

Indoor test services are services by seamless coverage required in the contract (commercialdeployment office) or planning report (trial office). The method for indoor test and requirementson collecting call tracing data are the same as DT.

4.3 Collecting RNC Configuration Data

During RF optimization stage, collect neighbor cell data of network optimization and other dataconfigured in RNC database. In addition, check whether the configured data is consistent withthe previously checked/planned data.

While checking configured data, feed back the improperly configured data (if found) to productsupport engineers. During checking, pay special attention to handover reselection parametersand power setting parameters, as listed in 4.3.

Table 4.1 Configured parameters to be checked

Type Content to be checked

Handoverreselectionparameter

IntraFreqNCell (intra-frequency neighbor cell)

InterFreqNCell (inter-frequency neighbor cell)

InterRATNCell (inter-system neighbor cell)

Powerconfigurationparameter

MaxAllowedULTxPower (maximum uplink transmit power of UE)

PCPICHPower (PCPICH transmit power)

HSDPA cellconfiguration

Whether the HSDPA cell is activated

HS-PDSCH code configuration

HS-SCCH configuration

HS-PDSCH and HS-SCCH power configuration

For handover reselection parameters, check list of neighbor cells, including intra-frequency,inter-frequency, and inter-system neighbor cells.

Output an updated Radio Parameter Configuration Data Table and parameter revision records.This is useful in problem analysis and following optimization stages.

Collecting data proceeds as below:

1. Start RNC LMT

2. Collect MML scripts

3. Convert neighbor cell configuration data in MML scripts to Excel files by using Nastar orMMLs2MDB



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4. Save the data in the format in which the data can be imported to Assistant.

For details, see WCDMA Equipment Room Operations Guide and Nastar, Assistant UserManual.



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5 Coverage Problem AnalysisCoverage problem analysis is the key to RF optimization. It involves signal distribution. Thecoverage problems to be analyzed include:

Weak coverage Cross-cell coverage Unbalance uplink and downlink No primary pilot cell

5.1 Coverage Problem Types

5.1.1 Weak coverage

Introduction

Weak coverage refer to that the RSCP of pilot signals in a coverage area is smaller than 95dBm. It might be in:

Valley areas Hillside back Elevator well Tunnel Underground garage Basement Areas inside high buildings

If the pilot signals are weaker than that required by full coverage services (such as VP and

PS64K), or just meet the requirements, if the PICH Ec/Io cannot meets the lowest requirementson full coverage services due to increased intra-frequency interference, problems like difficultaccess of full coverage services will occur.

If the RSCP of pilot signals is weaker than that of minimum access threshold in a coveragearea, the UE cannot camp on the cell, so the UE drops off the network due to failing in locationupdating and location registration.

Weak coverage can be determined as these rules

1.Observe the scanner Best RSCP and EcIo (network unload) distribution chart, see chart 5



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Figure 1.5 Chart 5 RSCP distribution in cluster xx

Figure 1.6 Chart 6 RSCP distribution histogram in cluster xx

From chart 6 get RSCP KPI ratio, According client request, such as (>-98dbm,95%)



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Figure 1.7 Chart 7 Ec/Io distribution in cluster xx

Figure 1.8 Chart 8 Ec/Io distribution histogram in cluster xx

2. If exist poor signal quality area, according Legend distribution (commonly red area), contrastSC for RSCP distribution chart one by one, find the weak cover cell



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Solutions

For previous problems, use the following methods:

Check the move or build schedule of poor coverage NodeB, use GoogleEarth to observeclutter and terrain, and learn about DT test and traffic implement, separate man-made and non-

man-made reason. If necessary, CDT is useful for Troubleshooting. Increase pilot transmit power, adjust antenna down tilt and azimuth, increase antennaheight, use antennas with higher gain to optimize coverage. If subscribers are abundant in the non-overlapped areas of neighbor NodeBs or the non-

overlapped areas are great, construct new NodeBs or expand the coverage range of neighbor

NodeBs. This ensures a software handover area with enough great size. Pay attention to thatincreasing of coverage areas might cause intra-frequency and inter-frequency interference. Construct new NodeBs or add RRU in valley and hillside back areas with weak coverage

to expand coverage range. Use RRU, indoor distributed system, leakage cable, and directional antenna to solve

problems in signal dead zone like elevator well, tunnel, underground garage, basement, areas

inside buildings.

5.1.2 Cross-cell Coverage

Introduction

Cross-cell coverage refers to that the coverage range of some NodeBs is beyond the plannedrange and discontinuous primary pilot coverage areas form in coverage areas of other NodeBs.

For example, if the NodeBs with a height much higher that the average height of adjacentbuildings transmit signals along upland or roads over far, a primary pilot coverage area form inthe coverage area of other NodeBs, an "island" forms. Therefore, if a call accesses the "island"and the nearby cells of the "island" is not configured as the neighbor cells, call drops once theUE leaves the island. Though the nearby cells of the "island" is configured as the neighbor cells,the "island" is over small, call also drops due to delayed handover.

If the two-side areas along a gulf are improperly planned, cross-cell coverage occurs on theseareas due to short distance between two sides of the gulf. Consequently, interference occurs.

The difference between cross-cell coverage and weak coverage is not absolute. PSC signalquality is poor, but a quite far SC signal is strong, and become PSC in this area. To solve thisproblem, enhance the signal from PSC in this area or weaken the signal from far SC. Afteradjust, good method should have small influence to other cell, it depends on environment andpersonal experience.

Solutions

For the previous problems, use the following methods:

For cross-cell coverage, prevent antennas from transmitting signals straightforward alongroads or reduce cross-cell coverage areas by using sheltering effect of adjacent buildings.

Meanwhile you must avoid intra-frequency interference to other NodeBs. For over high NodeBs, change the site. You might have difficulties in finding new sites

due to property and equipment installation. In addition, too large mechanism down tilt causesaberration of antenna direction maps. Therefore you can eliminate the "island" effect and

reduce NodeB coverage areas by adjusting pilot transmit power and using electric down tilt.

5.1.3 Unbalanced Uplink and Downlink

Introduction

Unbalanced uplink and downlink refers to the following situations in uplink and downlink



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symmetric services:

The downlink coverage is good but the uplink coverage is restricted. More specific, the

UE transmit power reaches the maximum which still cannot meet uplink BLER requirements. The downlink coverage is restricted. More specific, the downlink DCH transmit power

reaches the maximum which still cannot meet downlink BLER requirements.If the uplink and downlink are unbalanced, call drops easily. The probable cause is restricteduplink coverage.

Solutions

For the unbalanced uplink and downlink problems, check for interference by monitoring RTWPalarms of NodeB. For the method, see WCDMA Interference Solution Guide.

Other causes may lead to unbalanced uplink and downlink, such as:

Uplink and downlink gain of repeaters and interference amplifier are faulty. In an Rx/Tx detach system, the Rx diversity antenna-feeder system is faulty. NodeB problems, such as power amplifier failure

For previous problems, check the work state whether there are alarms, whether it is normal.

Solve the problem by replacing NEs, isolating faulty NEs, and adjust NEs.

5.1.4 No Primary Pilot

Introduction

No primary pilot areas refer to the areas where no primary pilot is or the primary cell changesfrequently. In no primary pilot areas, UE hands over frequently, so the system efficiency islowered and probability of call drop increases.

Solutions

In no primary pilot areas, you can enhance the coverage by strong signals of a cell (or nearcells) and reduce the coverage by weak signals of other cells (or far cells) by adjusting antenna

down tilt and azimuth.Analyze call drop reasons, no primary pilot areas is similar with pingpang handoff. The causesare needle phenomena and corner phenomena. Through out observe the signal flow of call droppoint and EcIo distribution, as shown in chart 9. Observe Best SC distribution, if no primary pilotareas phenomena happened, then tow or above colors appear in this area.



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Figure 1.9 9 SC distribution in cluster xx

Caution: if SC is not consistent with DT data, we should make sure whether SC configureincorrect or antenna connect in reverse.

5.2 Coverage Analysis Processes

5.2.1 Downlink Coverage Analysis

Downlink coverage analysis involves analyzing CPICH RSCP obtained by drive test.

The quality standard of CPICH RSCP must be combined with the optimization standard.Assume that the optimization standard is as below:

CPICH_RSCP 95 dBm >= 95% Scanner test result in outdoor unloadedconditions

The corresponding quality standard is:

Good if CPICH_RSCP 85 dBm Fair if 95 dBm CPICH_RSCP < 85 dBm Poor if CPICH_RSCP < 95 dBm

Mark the areas with weak coverage or common seamless coverage of large areas for furtheranalysis. Mark the areas with downlink coverage voids, analyze the distance relations withneighbor NodeBs and environments, and check the following:

Whether the CPICH RSCP of neighbor sites is normal Whether coverage can be enhanced by adjusting antenna down tilt and azimuth.

During adjusting antennas, avoid new coverage voids while eliminating some coverage voids. Ifthe coverage voids cannot be eliminated by adjusting antennas, construct sites to solve it.



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Anayzing Pilot Coverage Strength

Usually, the strongest RSCP received by each scanner in the coverage area must be above 95dBm.

Start Assistant. Analyze scanner-based RSCP for 1st Best ServiceCell, and you can obtain the

distribution of weak coverage area, shown in 5.2.1.In 5.2.1, RSCP in weak coverage areas is smaller than 95 dBm in the DT route. According toscanner and UE, the pilot RSCP is acceptable. If the scanner antenna is mounted outside thecar, and the UE is inside the car, there is a penetration loss of 5 to 7 dB. Use scanner data toavoid incomplete pilot information measured by UE due to missing neighbor cells.

Figure 1.10 RSCP for 1st Best ServiceCell

Analyzing Primary Pilot Cell

Cell primary pilot analysis is analyzing cell scramble information obtained in DT. Through outobserve SC distribution in cells, find covering problem. Engineer can get cells distribution clearlyby analyzing SC, it is benefit to trouble shooting and solve problem.

The content to be checked include (by Assistant):

Weak coverage cell

Start Assistant. Analyze scanner-based RSCP for SC, and you can obtain the signal distribution

of each cell (scramble). According to DT data, if the scramble signals of a cell are not present,

probably some sites cannot transmit signals during test. If a cell cannot transmit signals duringDT, the DT of relative areas must be re-performed. Very weak coverage might be result of

blocked antennas, so you must check the survey report of the site and check installation of on-

site antennas. No (poor) coverage cell might be due to that the DT route does not cover the cellcoverage area. In this case, reevaluate the DT route for the rationality and perform DT again. Cross-cell coverage cell

Start Assistant. Analyze scanner-based RSCP for SC, and you can obtain the signal distribution

of each cell (scramble). If the signals of a cell are widely distributed, even in the neighbor cellsand the cells next to its neighbor cells, the signals of the cell is present, the cell encounters a

cross-cell coverage which might be due to over high site or improper down tilt of antenna. The

cross-cell coverage cells interferes neighbor cells, so the capacity declines. You can solve the



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problem by increasing the down tilt of antenna or lowering the height of antenna. Avoidforming new weak coverage areas while solving cross-coverage problems. Pay special attention

to the adjustment of engineering parameters which might cause coverage voids. Be

conservative that cross-cell coverage is better than coverage voids if no other choices areavailable. No primary pilot cellStart Assistant. Analyze scanner-based SC for 1st Best ServiceCell, and you can obtain the

scramble distribution of the best cell. If multiple best cells changes frequently in an cell, the cellis a no primary pilot cell, as shown in 5.2.1No primary pilot cell forms due to the following

causes:

Cross-cell non-seamless coverage due to over high site

Pilot pollution in some areas

Coverage voids at edges of coverage areas

Therefore intra-frequency interferences forms which causes ping-pong handover and affects

performances of service coverage.

Figure 1.11 Distribution of pilot SC for the 1st Best ServiceCell

Analyzing comparison of UE and Scanner Coverage

Missing neighbor cells, improper parameters of soft handover, cell selection and reselectioncause the consistent between scanner primary pilot cell and camped cell in idle mode or BestServiceCell in the active set in connection mode of UE. After optimization, the Ec/Io for 1st Best

ServiceCell of UE and scanner is consistent. In addition, the coverage map of UE is marked byclear bordering lines of Best ServiceCell, as 5.2.1.



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Figure 1.12 Analyzing comparison of UE and scanner coverage

5.2.2 Uplink Coverage Analysis

The corresponding quality standard is:

Good if CPICH_RSCP 85 dBm Fair if 95 dBm CPICH_RSCP < 85 dBm

Poor if CPICH_RSCP < 95 dBm

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:

UE_Tx_Power 10dBm

>= 95% The test result of voice service by testhandset. Assume the maximum transmitpower of UE is 21 dBm.

The defined corresponding quality standards are:

Good if UE_Tx_Power 0 dBm

Fair if 0 dBm < UE_Tx_Power 10 dBm Poor if UE_Tx_Power > 10 dBm

For areas with poor index, judge whether the increasing of UE transmit power is due to call dropor poor uplink coverage. Geographically displayed on the map, the former is as a point ofsudden increment with call drop while the latter is an area with seamless coverageunnecessarily with call drop.

Mark the areas with weak coverage or large common seamless coverage for further analysis.Check whether downlink CPICH RSCP coverage voids exist in the areas with uplink coveragevoids. Solve the problem with both uplink and downlink weak coverage by analyzing downlinkcoverage analysis. If only the uplink coverage is poor without uplink interference (see WCDMAInterference Solution Guide), solve the problems by adjusting down tilt and azimuth of antenna,and adding TMAs.



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Analyzing Uplink Interference

Check for uplink interference by tracing and analyzing RTWP data. For details, see WCDMAInterference Solution Guide.

Distribution of UE Transmit Power

The distribution of UE transmit power reflects the distribution of uplink interference and uplinkpath loss. In 5.2.2, UE transmit power is lower than 10 dBm normally. Only when uplinkinterference and coverage area edge exist will the UE transmit power increase sharply to 21dBm (Some UEs that support HSDPA, such as E620, with a power class of 3, the maximumtransmit power is 24 dBm), and the uplink is restricted. Comparatively restricted uplink coverageoccurs much easily in macro cells than in micro cells.

Figure 1.13 Distribution of UE transmit power

5.3 Coverage Problem Cases

5.3.1 Weak Coverage Cases Due to ImproperEngineering Parameters

Phenomenon

In 5.3.1, the pilot RSCP is lower than 95 dBm in the marked red area. This belongs to weak

coverage, which might cause call drop.



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Figure 1.14 Coverage near Xiajiao Sugar Plant (before optimization)

Analysis

In 5.3.1, the problem lies in that Xiajiao Sugar Plant sector B mainly covers the marked area butMaterials Building sector A partially covers the marked area. Initially engineers considerenhancing the coverage of the marked area by adjusting the two cells. According to the surveyreport, other buildings opposite Materials Building prevent sector A from transmit signals, soadjusting antenna fails to enhance the coverage of the areas.

Solutions

Keep the parameter configuration of Materials Building sector A, but adjust the azimuth ofXiajiao Sugar Plant sector B from 170 to 165, down tilt from 10 to 8.

5.3.1 shows the coverage near Xiajiao Sugar Plant (after optimization)

Figure 1.15 Coverage near Xiajiao Sugar Plant (after optimization)

In 5.3.1, the coverage in the marked area is enhanced clearly after adjusting engineering



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parameters of Xiajiao Sugar Plant.

5.3.2 Cross-cell Coverage Due to Improper NodeBLocation

Phenomenon

In a trial office, the Erqi Rd. NodeB is 60-meter high, over 20 meters than nearby buildings. Thiscauses cross-cell coverage easily and brings intra-frequency interference to other NodeBs, asshown in 5.3.2.

Figure 1.16 Cross-cell coverage before optimization

Aanalysis

For a high NodeB problem, adjust fixed electric down tilt of antenna from 2 to 6. Because theErqi Rd. NodeB is at the edge of network coverage, reduce interferences to other NodeBs byadjusting antenna down tilt and azimuth. In this case, no equipment is removed. Engineerssolve the cross-cell coverage by increasing mechanism down tilt and adjusting azimuth.

Solutions

After adjustment of down tilt to 4, the most cross-cell coverage areas are eliminated, with only

few cross-cell coverage areas, as shown in 5.3.2.



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Figure 1.17 Few cross-cell coverage areas after optimization

For similar high NodeBs, you can combine adjustable down tilt of electric antenna andmechanism antenna to better control signal coverage.

5.3.3 Coverage Restriction Due to ImproperInstallation of Antennas

Phenomenon

From 5.3.3, the antenna of a project is mounted on a roof (10-meter tall).

Figure 1.18 Coverage restriction due to antenna blocked by roof

At the optimization stage after network construction, in front of the traffic lights below antennas,

video quality declines due to VP mosaic and PS384K service is reactivated.



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Analysis

In terms of planning, 3G and 2G antennas are mounted in a co-location site. According tocoverage test data of 2G antenna, 2G signals does not fluctuate sharply under the site andunder the traffic lights. Namely, if the 3G and 2G antennas are in the same location, 3G signalswill cover the areas around traffic lights. The problem lies in that the 3G antenna is mounted tooclose to the wall on the roof and the wall blocks signals so the special installation conditions ofantennas are not met. In addition, the 2G antenna and its installation parts affect the pattern of3G antenna. This changes the radiation pattern of 3G antenna. According to the installationscene, adjusting location of 3G antenna is difficult.

Solutions

According to discussion between 2G and 3G engineers, the minimum adjustment solutionwithout affecting 2G coverage is as below:

Connect the 3G and 2G TX/RX feeder to two feeders of outside wideband polarization antenna

Connect the 3G and 2G RX feeder to two feeders of inner wideband antenna.

5.3.3 shows the connection.

Figure 1.19 Optimizing antennas by adjusting feeders



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6 Pilot Pollution Problem Analysis6.1 Pilot Pollution Definition and JudgmentStandards

6.1.1 Definition

The pilot pollution is that excessive strong pilots exist in a point but no primary pilot is strongenough.

6.1.2 Judgment Standards

Pilot pollution exists if all the following conditions are met:

The number of pilots that meet the following condition is more than ThNCPICH_RSCP > ThRSCP_Absolute (CPICH_RSCP1st - CPICH_RSCP(ThN +1)th)< ThRSCP_Relative

Assume that ThRSCP_Absolute = 100 dBm, ThN = 3, and ThRSCP_Relative = 5 dB, and then pilot pollutionexists if all the following conditions are met:

More than three pilots meet the following conditionCPICH_RSCP > 100 dBm. (CPICH_RSCP1st - CPICH_RSCP4th) < 5 dB

6.2 Process for Analyzing Pilot PollutionProblem

The process for analyzing pilot pollution problem proceeds as below:

1. Start Assistant. Analyze scanner-based RSCP for 1st Best ServiceCell and EcIo for 1st BestServiceCell. Select the areas with high RSCP and poor EcIo as candidate areas with pilotpollution.

2. Analyze scanner-based Whole PP. Select the areas corresponding to candidate areas as the



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key areas with pilot pollution.

3. Locate the cells that cause pilot pollution of the key areas.

4. Based on RSCP for 1st Best ServiceCell, judge whether the pilot pollution is caused byexistence of multiple strong pilots or lack of a strong pilot. For the former cause, you can solve

the problem by weakening other strong pilots. For the latter cause, you can solve the problemby strengthening some strong pilot.

5. Analyze the RSCP and Ec/Io distribution of areas related to pilot pollution and confirm thecells that need eliminating the coverage of an area and that need enhancing the coverage of anarea. Based on the actual environment, analyze the specific causes to pilot pollution (foranalyzing causes, see 6.3.1). For specific causes, provide solutions to pilot pollution (forsolution, see 6.4). While eliminating pilot pollution in an area, consider the influence to otherareas and avoid causing pilot pollution or coverage voids to other areas.

6. Retest after adjustment. Analyze RSCP, Ec/Io and Whole PP. If they cannot meet KPIrequirements, re-optimize the network by selecting new key areas until KPI requirements aremet.

Note:In the new optimization, do not adjust the cells that was adjusted in last optimization. You canadd other key areas analyzed by Whole PP (the part that does not correspond to the candidateareas)

6.3 Causes and Influence Analysis

6.3.1 Causes Analysis

Ideally the signals in a cell are restricted within its planned range. However the signals cannotreach the ideal state due to the following factors of radio environment:

Landform Building distribution Street distribution Waters

Pilot pollution is the result of interaction among multiple NodeBs, so it occurs in urban areaswhere NodeBs are densely constructed. Normally typical areas where pilot pollution occurseasily include:

High buildings Wide streets Overhead structure Crossroad Areas round waters

When make sure pilot pollution severe areas, we should exclude weak cover, no primary pilot celland so on.

Improper Cell Distribution

Due to restriction to site location and complex geographic environment, cell distribution might be



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improper. Improper cell distribution causes weak coverage of some areas and coverage bymultiple strong pilots in same areas.

Over High NodeB or 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. Cross-cell coverage is difficultto control over high site, which causes pilot pollution.

Improper Antenna Azimuth

In a network with multiple NodeBs, the antenna azimuth must be adjusted according to thefollowing factors:

NodeB distribution of the entire network Coverage requirements Traffic volume distribution

The sector azimuth of each antenna is set to cooperate with each other. If the azimuth isimproperly set:

Some factors might cover the same area. This causes excessive pilot pollution.

Weak coverage exists in some areas without primary pilot.The previous two situations might lead to pilot pollution. Therefore you must adjust the antennaaccording to actual propagation.

Improper Antenna Down Tilt

Setting antenna down tilt depends on the following factors:

Relative height to around environment Coverage range requirements Antenna types

If the antenna down tilt is improper, signals are received in the areas which are covered by thissite. Therefore interferences to other areas cause pilot pollution. Even worse, interferencesmight cause call drop.

Improper PICH Power

When the NodeBs are densely distributed with a small planned coverage rang and the PICHpower is over high, the pilot covers an area larger than the planned area. This causes pilotpollution.

Ambient Factors

The signals cannot reach the planned state due to the following factors of radio environment:

Landform Building distribution Street distribution Waters

The ambient factors include:

High buildings or mountains block signals from spreading

The signals of a NodeB to cover a target area are blocked by high buildings or mountains, so

the target area will have no primary pilot. This causes pilot pollution. Streets or waters influences signalsWhen the antenna direction is pointing a street, the coverage range is expanded by the street.

When the coverage range of a NodeB overlaps with the coverage range of other NodeBs, pilot

pollution occurs. High buildings reflect signals

When high glassed buildings stand near a NodeB, they will reflect signals to the coverage range

of other NodeBs. This causes pilot pollution.



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6.3.2 Influence Analysis

Pilot pollution causes the following network problems.

Ec/Io Deterioration

Multiple strong pilots interferes useful functional signals, so Io increases, Ec/Io decreases,BLER increases, and network quality declines.

Call Drop Due to Handover

More than three strong pilots or no primary pilot exists in multiple pilots, frequent handoveroccurs among these pilots. This might cause call drop.

Capacity Decline

The interference of the areas with pilot pollution increases, the system capacity declines.

6.4 Solutions to Pilot Pollution

6.4.1 Antenna AdjustmentAccording to the test, pilot signal strength of an area with pilot pollution is changed by adjustingantenna down tilt and azimuth. This changes the distribution of pilot signals in the area. Theprinciple for adjustment is enhancing primary pilot and weakening other pilots.

To enhance pilot coverage of an area, adjust the antenna azimuth pointing the area. Toweakening pilot coverage of an area, adjust the antenna azimuth pointing the opposite directionof the area. Adjusting down tilt is similar. You can increase the cell coverage range by reducingantenna down tilt and reduce cell coverage range by increasing antenna down tilt.

Adjusting antennas is restricted to a range. If the down tilt is over small, you might enhance cellcoverage but causes cross-cell coverage. If the down tilt is over large, you might weaken cellcoverage but you might change the antenna pattern.

6.4.1 shows the pilot pollution due to improper antenna azimuth.

Figure 1.20 Pilot pollution due to improper antenna azimuth

In 6.4.1, the area marked in black encounters pilot pollution due to improper azimuth of theantenna of SC100 sector (scramble No. is 100). The SC100 sector covers the area with anantenna azimuth of 90, so the coverage is poor with weak signals and no primary pilot, whichcause pilot pollution.

After adjustment of the antenna azimuth from 90 to 170, the primary pilot signals becomestronger and pilot pollution is eliminated.

6.4.1 shows the pilot pollution due to improper antenna down tilt.



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Figure 1.21 Pilot pollution due to improper antenna down tilt

In 6.4.1, the area marked in blacked encounters pilot pollution due to improper antenna downtilt. The down tilt of SC360 cell is 2, so the coverage area is large, cross-cell coverage isdifficult to control, and interferences to other areas form.

After adjustment of antenna down tilt of SC360 cell from 2 to 7, the cross-cell coverage bySC360 cell is eliminated and pilot pollution is eliminated.

Some areas with pilot pollution are inapplicable to the previous adjustment. You can use thefollowing methods based on actual situation:

Change the antenna to a different type Add reflection device or isolation device Adjust installation position of antenna Adjust NodeB location

6.4.2 PICH Power Adjustment

Pilot pollution is caused by the coverage by multiple pilots. A direct method to solve the problemis to form a primary pilot by increasing the power of a cell and decreasing the power of othercells.

An over large down tilt causes aberration of antenna pattern. To reduce coverage range by pilot,you can decrease PICH power. Over small down tilt causes cross-cell coverage. To increasecoverage range by pilot, you can increase PICH power. Adjusting power and adjusting antennamust cooperate.

6.4.2 shows the pilot pollution due to improper distribution of cells.



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Figure 1.22 Pilot pollution due to improper distribution of cells

In 6.4.2,

The distance between NodeB A and NodeB B is 1260 meters. The distance between NodeB A and NodeB C is 2820 meters. The distance between NodeB B and NodeB C is 2360 meters.

The distance is unbalanced, so the pilot pollution is difficult to eliminate.

The optimization is to reduce weak pilot strength and eliminate pilot pollution, detailed as below:

Ensure seamless coverage between cells by not adjusting transmit power of SC20 and

SC30 cells. Decrease the PICH power of SC10, SC40, and SC50 cells by 3 dB. These cells have

little impact on seamless coverage.

6.4.3 Using RRU and BBU

If adjusting power and antenna is not effective to solving pilot pollution, use RRU and BBU.

Using RRU and BBU cells aims to bring strong-signal coverage in the area with pilot pollution,so the relative strength of other signals decreases.

When a network expansion is necessary or more requirements is on network quality, usingRRU. RRU install easy, it can cover far areas, and it is cheap too.

6.4.3 shows pilot pollution due to ambient factors.



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Figure 1.23 Pilot pollution due to ambient factors

The area marked in black encounters pilot pollution due to ambient factors. The area is coveredby SC60 cell of NodeB A, SC110 cell or NodeB B, and SC130 cell of NodeB C. However, shown

in 6.4.3, hills prevent NodeB A from transmitting signal; high buildings prevent NodeB B andNodeB C from transmitting signals, so the signals from NodeB A, NodeB B, and NodeB C areweak. On the contrary, SC240 and SC250 cells of NodeB D have good propagation conditionsin this direction. Therefore the cross-cell coverage is serious and pilot pollution occurs.

Figure 1.24 Survey photo of each cell related to pilot pollution

High buildings or hills block the area, so no strong pilot is present in the area. For this problem,adjusting antenna down tilt has little effect on eliminating pilot pollution. Instead adding RRUhelps solve the problem.



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6.5 Optimization Cases for Eliminating Pilot

Pollution

The following sections take an optimization by a project and describe the process for analyzingpilot pollution.1

6.5.1 Data Analysis before Optimization

Locating Pilot Pollution Point

6.5.1 shows the pilot pollution point near Yuxing Rd. SC270 cell is planned to cover the areawith pilot pollution.

Figure 1.25 Pilot pollution near Yuxing Rd.

Analyzing Signal Distribution of Cells Near Pilot Pollution Point

Figure 1.26 Best ServiceCell near Yuxing Rd.

1

No new complete case is available, so an old case is used here. The future version will provide newcases.



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Figure 1.27 The 2nd best ServiceCell near Yuxing Rd.

Figure 1.28 The 3rd best ServiceCell near Yuxing Rd.

Figure 1.29 The 4th best ServiceCell near Yuxing Rd.



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Figure 1.30 Composition of pilot pollution near Yuxing Rd.

From 6.5.1, 6.5.1, 6.5.1, 6.5.1, and 6.5.1, though SC20 cell is planned to cover the area, but thebest ServiceCell is as listed in the following table:

Best ServiceCell Primary Others

1st best ServiceCell SC220 SC260 and SC270

2nd best ServiceCell SC270 SC260, SC220, and SC200

3rd best ServiceCell SC200 SC270 and SC260

4th best ServiceCell SC200 SC270 and SC260

Analyzing RSSI Distribution Near Pilot Pollution Point

6.5.1 shows the RSSI near Yuxing Rd..

Figure 1.31 RSSI near Yuxing Rd.

6.5.1 shows the RSCP of Best ServiceCell near Yuxing Rd..



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Figure 1.32 RSCP of Best ServiceCell near Yuxing Rd.

As shown in 6.5.1, the RSSI of the areas with pilot pollution is not large, about 100 dBm to 90

dBm. As shown in 6.5.1, the RSCP of Best ServiceCell is between 105 dBm to 100 dBm. Thepilot pollution of the area is caused by no strong pilot, so you can solve the problem bystrengthening a strong pilot.

Analyzing RSCP Distribution of Related Cells

6.5.1 shows the RSCP of SC270 cell near Yuxing Rd.

Figure 1.33 RSCP of SC270 cell near Yuxing Rd.

The SC270 cell is planned to cover the area. 6.5.1 shows RSCP of RSCP distribution of SC270

cell. The signals from SC270 cell are weak in the area with pilot pollution.According to on-site survey, the residential area is densely distributed by 6-floor or 7-floorbuildings. The test route fails to cover the major streets, and is performed in narrow streets withbuildings around, so the signals are blocked. The suggestion is to adjust the azimuth of SC270cell from 150 to 130 and the down tilt from 5 to 3. This enhances the coverage of SC270cell.

6.5.2 Data Analysis after Optimization

After analysis of DT data, the expected result after adjustment is that the coverage area bySC270 cell increases and the coverage is enhanced.

6.5.2 shows the pilot pollution near Yuxing Rd after optimization.



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Figure 1.34 Pilot pollution near Yuxing Rd. after optimization

6.5.2 shows the best ServiceCell near Yuxing Rd after optimization.

Figure 1.35 Best ServiceCell near Yuxing Rd. after optimization

6.5.2 shows the RSCP of best ServiceCell near Yuxing Rd after optimization



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Figure 1.36 RSCP of best ServiceCell near Yuxing Rd. after optimization

6.5.2 shows the RSCP of SC270 cell near Yuxing Rd. after optimization.

Figure 1.37 RSCP of SC270 cell near Yuxing Rd. after optimization

According to the DT data, the pilot pollution near Yuxing Rd. after optimization is eliminated, thesignals from SC270 cell after optimization are stronger, and the SC270 becomes the bestServiceCell. This complies with the expected result.



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7 Handover Problem AnalysisDuring RF optimization stage, the involved handover problem is about neighbor cell optimizationand SHO Factor based on DT control.

Control the size and location of handover areas by adjusting RF parameters. You can eliminatehandover call drop due to sharp fluctuation and increase handover success rate.

For other handover problems, see WCDMA Handover and Call Drop Problem OptimizationGuide.

7.1 Neighbor Cell Optimization

The neighbor cell optimization includes adding and removing neighbor cells.

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 addnecessary neighbor cells.

Redundant neighbor cells causes that the neighbor cell information is excessive andunnecessary signals cost occurs. When the neighbor cell list is fully configured, the neededneighbor cell cannot be listed. For this problem, remove redundant neighbor cells. The relativecontent about neighbor cell optimization can check .

To avoid overfull miss neighbor cells or redundant neighbor cell, we should plan neighbor cellreasonably, according neighbor cell plan rules, complete intra-frequency, inter-frequency andinter-system neighbor cell plan. The relative content about neighbor cell plan can check .

During RF optimization stage, missing neighbor cell is a key problem. The methods for addingneighbor cells are listed below.

7.1.1 DT Data Analysis

Scanner Data Analysis

The daemon analysis tools can usually check for missing neighbor cells. The principle is asbelow:

Compare the pilots scanned by scanner and the configured pilots of neighbor cell list. Locate these pilot scrambles that meet the handover conditions and that are not in theneighbor cell list. Output them as a missing neighbor cell report.



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The following checks and methods related to missing neighbor cells are based on Assistant.

1. Type information about NodeB and neighbor cellsFor details, seeAssistant User Manual.

2. Decide conditions for judging neighbor cells

Change the conditions for judging neighbor cells by selecting Modify Dataset Property. Thedefault configuration is that if the difference between the pilot of candidate cell and the base cellis within 5 dB the candidate cell can be listed as a neighbor cell. The configuration must complywith the actual configuration of system (overall parameters), as shown in 7.1.1.

Table 37.1 Changing conditions for judging neighbor cells

The parameters and meanings are as below (according to default configuration of RNC1.5,you just list the parameters to be changed):

Parameter Meaning Recommended value

1A Threshold 1A event threshold 3 dB

1A Hysteresis 1A event hysteresis 0 dB

1A Time to Trigger Time to trigger 1A event 0.320s

1B Threshold 1B event threshold 6 dB

1B Hysteresis 1B event hysteresis 0 dB

1C Hysteresis 1C event hysteresis 4 dB

1D hysteresis 1D event hysteresis 4 dB

Count Threshold Times threshold for judging neighbor cells 10

3. Generate a missing neighbor cell report



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Figure 1.38 Generating neighbor cell analysis report by using Assistant

Proceed as shown in 7.1.1; the Assistant generates a neighbor cell analysis report in theformat of Excel. This Excel-formatted report contains four sheets: Scanner Statistic,Scanner Result, Imported Config and Scanner vs Config. Wherein, the Scanner vs Configsheet is for comparing neighbor cells generated by scanner and the configured neighborcells.

7.1.1 shows the result of missing neighbor cells.

Figure 1.39 Result of missing neighbor cells

For the missing neighbor cells generated automatically by Assistant, you must check according

to the location information of the cell on the map whether to add the missing neighbor cells tothe neighbor cell list. For the missing neighbor cells due to cross-cell coverage, the primary task



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is to solve coverage problem by adjusting RF parameters. If this fails, you can temporarily solvethe problem by adding neighbor cells.

Caution: make sure whether neighbor cell is missing or not by check in the latest configuration

file, avoid add neighbor cell repeatedly.UE Data Analysis

The daemon analysis tool can seldom analyze UE data automatically and generate missingneighbor cells, so RNO engineers must analyze the missing neighbor cells one by one forconfirmation. Missing neighbor cell might cause call drop or access failure or cause Ec/Io todeteriorate for a period. Based on data analysis by scanner, you can easily locate these pointswith missing neighbor cells, detailed as below:

1. Compare the active set Ec/Io distribution diagram measured by UE and that measured byscannerThe spots with missing neighbor cells has a poor Ec/Io measured by UE and a strong Ec/Ioscanned by scanner. Locate the areas for further analysis.

2. Check the points with poor Ec/Io and check whether the strongest scramble by scanner is

neither in active set nor in monitoring set. If yes, move to the third step for confirmation. If thescramble exists in the monitoring set, the problem is not about missing neighbor cell but aboutEc/Io deterioration due to handover (reselection) delay and soft handover failure.

3. Check the latest intra-frequency measurement control whether the neighbor cell list containsthe strong scrambles by scannerYou can also directly check the neig

W-RF Tuning Guide-20081129-A-3.1

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