018 WCDMA Coverage Problem Analysis

HUAWEI Mexico Training Center 1

HUAWEI TECHNOLOGIES CO., LTD. All rights reserved

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Coverage Problem Analysis

ISSUE 1.0


Upon completion of this course, you will be

able to:

�Learn how to analyze coverage

problem and solve it

�Learn how to Improve coverage

capability



Chapter 1 Coverage problem typesChapter 1 Coverage problem types

Chapter 2 Coverage analysis stepsChapter 2 Coverage analysis steps

Chapter 3 Coverage improvementChapter 3 Coverage improvement

Chapter 4 Typical cases analysisChapter 4 Typical cases analysis

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Coverage problem types

Dead zone

Uplink/Downlink unbalance

Coverage hole

Coverage overshoot

Pilot pollution




� The zone in which pilot signal is lower than the minimum access

level, e.g., valley, lift, tunnel, indoor zone of high buildings

� Solutions

�Adjust antenna for increasing coverage (using high gain

antenna, increasing the height of the antenna, etc.)

�Add RRU (Radio Remote Unit) or repeater

�Add a new site (macro site or mini site)

�Use loss cable

Dead zoneDead zone



� The zone in which pilot signal is higher than the minimum

access level but lower than the request of the services (voice,

video phone PS64 etc.)

� Solutions

�Adjust antenna for increasing coverage (using high gain

antenna, increasing the height of the antenna, etc.)

�Use RRU (Radio Remote Unit), repeater or mini site

Coverage holeCoverage hole




� The coverage of a site is more than the range of our plan

� Solutions

�Adjust the down tilt or azimuth of antenna

�Avoid the beam of antenna straight to the road

�Use the buildings around the site

�Reduce the power of CPICH channel to decrease

coverage

Coverage overshootCoverage overshoot



� In some place, UE can receive so many pilots, but there is no one

main pilot

we can judge pilot pollution exist or not through following

method:

There are more than 3 cells which pilot signal level

and

� Solutions

�Adjust the position of sites or adjust antenna

�Reduce the power of CPICH channel

�Combine some sector or delete some sector if capacity is enough

Pilot pollutionPilot pollution

dBmRSCPCPICH 95_ −> dBRSCPCPICHRSCPCPICHthst

5)__( 41 <−




� Interference of uplink can cause unbalance of

uplink/downlink

� When downlink cell loading is too large, it can

cause unbalance of uplink/downlink (cell breath)

Uplink/Downlink unbalanceUplink/Downlink unbalance








Coverage analysis steps

Step 1: Preparation

Step5: Consumer complaint analysis

Step 2: Drive test data analysis

Step3: Performance analysis

Step4: Signaling analysis


Step 1: Preparation

� Before coverage analysis, you must know some basic

information, it include:

�The position of the sites

�The configuration of the sites

�The configuration of antenna (gain, direction, downtilt,

etc.)

�The coverage planning of CPICH

�The loading distribution of different services

Coverage planningCoverage planning



Step 1: Preparation

� Drive test data analysis software: Genex

Assistant

� Performance analysis tool: RNC traffic statistics

console

� UL RTWP (Received Total Wideband Power)

alarm console

� Test log

Analysis toolsAnalysis tools


Step 1: Preparation

� CPICH TX Power

� MaxFACHPower

� Sintrasearch、Sintersearch、Ssearchrat

� PreambleRetransMax

� Intra－FILTERCOEF

� Intra－CellIndividualOffset

� RLMaxDLPwr、RLMinDLPwr

Parameters related to coverageParameters related to coverage



Step 2: Drive test data analysisDownlink coverage analysis Downlink coverage analysis -- EcEc

Coverage hole


Step 2: Drive test data analysisDownlink coverage analysis Downlink coverage analysis -- main cellmain cell

No main cell



Step 2: Drive test data analysisDrive test data comparison between UE and scannerDrive test data comparison between UE and scanner

SHQ position



Downlink coverage analysis Downlink coverage analysis -- soft handover proportionsoft handover proportion

Pilot pollution




Uplink coverage analysis Uplink coverage analysis –– uplink interferenceuplink interference



Uplink coverage analysis Uplink coverage analysis –– uplink power distributionuplink power distribution

Uplink

coverage

limitation



Step 3: Performance analysis

� KPI

�Coverage problem can affect the following index:

− access successful rate

− congestion rate

− call drop rate

− HO successful rate

� Traffic distribution

�Too heavy traffic can cause coverage decrease (cell breath)


Step 4: Signaling analysis

� When call is dropped or handover is failure

during drive test, we can use signaling tracing

function to analyze the causes

� If the causes is Ec too low, it is coverage problem



Step 5: Consumer complaint analysis

� When some VIP consumer complain that they

can not take a call in their room, maybe we

need to go to their house to test

� if the receive signal is too weaker, it is

coverage problem and we need to increase the

signal strength level.








Coverage improvement

Site configuration adjustment

TMA (Tower Mounted Amplifier)

Sector adjustment

Diversity technologies

RRU, Repeater


Site configuration adjustment

� Different kinds of site can support different output and different capacity

� Site configuration Huawei NodeB can support

�Macro site: BTS3812E (indoor), BTS3812A (outdoor)

− Maximum output: 30W (support TD)/40W (not support TD)

− Support 1×1, 3×1, 3×2, 3×4, 6×2, etc

�Mini site: BTS3802C

− Maximum output: 20W (support TD) /30W (not support TD)

− Support 1×1, 1×2, 2×1

�Distributed site: BBU & RRU



RRU, Repeater

� RRU (Radio Remote Unit): typical feeder loss is 2 –

3 dB. RRU makes RF part as close as possible to

the antenna to reduce the feeder lost to the least

� Repeater: it is mainly used in areas where it is

difficult to extend the coverage, or used as a low-

cost solution for network construction

Fiber


TMA (Tower Mounted Amplifier)

� TMA is recommended to be used under the conditions below

� A large coverage area, e.g. rural, suburban or highway,

because UL coverage is limited for the most of time but DL

coverage is usually not limited

� An area, e.g. dense urban or urban, according to RNP, DL

capacity is not limited. UL sensitivity and coverage area can

be increased by using TMA








Case 1: coverage hole

� Through drive test map, it was found that Ec was less than -90dBm in

some area

Case descriptionCase description

The area in which

Ec<-90dBm




� According to RNP, the coverage was also discontinuousCase analysisCase analysis

The area in

whichEc<-90dBm

The distance

between sites

was too far



� The reason of this case was that the site position was unreasonable

� But in this area, the operator didn’t want to build new site room, all of

WCDMA sites should be installed in GSM site room, so we just could

use some coverage improvement technologies

� Increasing output of site

� Increasing the height of antenna

�Adjust tilt angle

� A good network planning is the basis of coverage!

Case solutionCase solution



Case 2: coverage overshoot

� Through drive test map, it was found that the

coverage of a site was too far


Red color

showed the

coverage of

the site was too far


Case 2: coverage overshoot

� Decreasing output of site

� Decreasing tilt angle

� Changing the direction of antenna

� Decreasing the height of antenna if possible




Case 3: coverage limitation

� It was found that the quality of Video Phone was very bad

in a special position


Qos of VP badly in this position

WCDMA antenna

GSM antenna



� In this site, WCDMA and GSM site were installed in the same

room. We tested GSM network signal and found it was very

good. But the position of GSM antenna was near to the edge

of the wall, and the position of WCDMA antenna was far from

the edge of the wall

� Because the position of WCDMA antenna was far from the

edge of the wall, the wall would affect the signal heavily

Case analysisCase analysis




� If possible, change the position of antenna

� If the antenna installation platform is too small, we must

confirm one antenna is near to the edge of the wall



Summary

� Coverage problem types

� Coverage analysis steps: five steps

� Coverage improvement technologies

� Typical cases analysis

SummarySummary


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Thank You

018 WCDMA Coverage Problem Analysis

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