02 CDMA RNPRNO.pdf

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Optimization of CDMA 1X NetworkOptimization of CDMA 1X Network

All Rights Reserved Alcatel-Lucent 2009


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Study objectiveStudy objective

It is required that after the course study, you should:

Have a general concept about networkplanning

Have an understanding of characteristics ofCDMA network planning

contents of network planning

Have an understanding of the main



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Contents of the courseContents of the course

Process & Characteristics

Chapter 2 CDMA 1X Network Planning

Chapter 3 CDMA 1X Network

Optimization



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Reasons for Network PlanningReasons for Network Planning



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Objectives Of Network PlanningObjectives Of Network Planning

To establish the largest radio networkTo establish the largest radio network

both inboth incapacitycapacityandandcoveragecoveragewith awith a

To establish the largest radio networkTo establish the largest radio network

both inboth incapacitycapacityandandcoveragecoveragewith awith a

cer a ncer a ncoscos an un er ean un er e

precondition of meeting theprecondition of meeting theQoSQoSofofnetwork, and further, adapt to thenetwork, and further, adapt to the

cer a ncer a ncoscos an un er ean un er e

precondition of meeting theprecondition of meeting theQoSQoSofofnetwork, and further, adapt to thenetwork, and further, adapt to the

future network development andfuture network development and

expansion.expansion.

future network development andfuture network development and

expansion.expansion.

CoverageCoverage QualityQuality CostCostCapacityCapacity


Realization of excellent balance of all aspects via network planning


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CDMA 1X Network planning flowCDMA 1X Network planning flow

Analysis of

traffic coverage

EmulationNetwork optimization

Site surveyInstallation and

Integration

System design



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Steps in Network planningSteps in Network planning



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Coverage, capacity and qualityCoverage, capacity and quality

zRelationship among coverage, capacity and quality The three factors influence each other

and at the same time inter-depend on

each other. Therefore, coverage cannot

be separated from capacity and quality

for discussion.

With the increase network capacity, thecoverage scope w e e n e y re uce ,

and vice versa.

To achieve wider coverage, the total

reduced to increase the seizure rate of

pilot channel, but this may affect the

ca acit and the ualit of conversation.



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Optimization



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Chapter 2 CDMA 1X Network PlanningChapter 2 CDMA 1X Network Planning

zz

SectionSection 11 CoverageCoverage PlanningPlanning

zz SectionSection 22 CapacityCapacity PlanningPlanning

zz SectionSection 33 PowerPower PlanningPlanning



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Link BudgetLink Budget -- Whats it for?Whats it for?



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Composition of Wireless LinkComposition of Wireless Link



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Link budget modeLink budget modell

Electric waveService

requirement

MS

Soft phenomenon

of CDMA

Equipmentarameter

Radio resource

management



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Link budget modelLink budget model

Forward link

Receive/transmitpower

Antenna gainFeeder lossInterference

marginAntenna

gainPath Loss

Transmit-receivepower

Soft handoffgain

Fadingmargin

Reverse link

Both forward and reverse links within the coverage area should reach balanceBoth forward and reverse links within the coverage area should reach balance

Classification of parameters involved in link budget of CDMA 1X:lassification of parameters involved in link budget of CDMA 1X: Parameter related to equipment:arameter related to equipment: transmission power, receiver sensitivity, partstransmission power, receiver sensitivity, parts

and feeder loss, antenna lossand feeder loss, antenna loss

Parameters related to radio environment:arameters related to radio environment: fast fading margin, slow fadingfast fading margin, slow fadingmar in and cluster lossmar in and cluster loss

Parameter related to equipment:arameter related to equipment: transmission power, receiver sensitivity, partstransmission power, receiver sensitivity, partsand feeder loss, antenna lossand feeder loss, antenna loss

Parameters related to radio environment:arameters related to radio environment: fast fading margin, slow fadingfast fading margin, slow fadingmar in and cluster lossmar in and cluster loss

Parameter related to CDMA technology:arameter related to CDMA technology: system load affection, soft handoffsystem load affection, soft handoffgain andgain and EbEb//NtNt

Parameters related to service:arameters related to service: service type, data rate, maximum transmissionservice type, data rate, maximum transmissionower of each traffic channelower of each traffic channel

Parameter related to CDMA technology:arameter related to CDMA technology: system load affection, soft handoffsystem load affection, soft handoffgain andgain and EbEb//NtNt

Parameters related to service:arameters related to service: service type, data rate, maximum transmissionservice type, data rate, maximum transmissionower of each traffic channelower of each traffic channel


Propagation model:ropagation model: classicalclassical--OkumuraOkumura HataHata model,etcmodel,etc.. Propagation model:ropagation model: classicalclassical--OkumuraOkumura HataHata model,etcmodel,etc..


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Transmitter SideTransmitter Side



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Receiver SideReceiver Side



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Link budget parametersLink budget parameters

Sensitivity of S_BS BTS receiver The BTS receiver sensitivity finalizes the minimum receive level required for the

traffic channel to ensure certain call quality.

_ = g g _

9 Eb/Nt Demodulation threshold of BTS receiver can be obtained via linkemulation and on-the-spot survey. It is related to service type, propagation

,

(received diversity of antenna, power control and soft handoff).

9 Rb data rate (before channel coding)

9 KT thermal noise density, equaling to -174dBm/Hz under the condition of

normal temperature

9 W spread spectrum bandwidth

9 NF_BS receiver noise indices, typical value: 5dB, Huaweis BTS: 3.2dB

9 The sensitivity can also be affected by interference. Thus the design loadshould be added with interference margin in actual application.

Sensitivity of S_MS MS receiver


_ _

NF_MS MS noise index, and the typical value is 8dB


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Link Budget ParametersLink Budget Parameters

Soft handoff gain G_HO9 In link budget, maximum path losses of both forward and

reverse links are calculated. If the MS is located in the cell

e ge, ga n roug y so an o s ou a so e a en n o

consideration.

,

certain coverage probability is decreased due to the

existence o independent propagation path, and this gain is

called softhandoff gain, that is, G_HO, in link budget.



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Penetration LossPenetration Loss



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Path LossPath Loss



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Link budget analysis of reverse linkLink budget analysis of reverse link

Comparison of service of different rates between IS-95 and CDMA2000-1X

Service typeService type

ISIS--9595 CDMA2000CDMA2000--1X1X

9.6kbps voice9.6kbps voice 9.6kbps voice9.6kbps voice 19.2 kbps19.2 kbps 38.4 kbps38.4 kbps 76.8 kbps76.8 kbps 153.6 kbps153.6 kbps

Coverage radiusCoverage radius

ratioratio 1.001.00 1.161.16 0.990.99 0.860.86 0.730.73 0.630.63

The reason of causing different coverage radii is the dif ference of service rate andthe difference of demodulation threshold of reverse link

In comparison with voice service, the maximum allowable path loss and coveragedistance is reduced in data service. And the coverage shrinkage of data service of

different rates is different as well.


The coverage shrinkage level is slightly increased along with the raise of antenna.


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Analysis of link budget of forward linkAnalysis of link budget of forward link

The increase of forward power of data service, especially the highspeed data, may result in the BTS power becoming the factor limiting

e coverage scope, w c n urn causes a e orwar

coverage is limited.

subscribers of differentservice rates.

,the data rate to forward coverage is much greater

When lannin is erformed to the area with hi h re uirements o

high speed data, analysis should be made by associating the forwardpower distribution. When the forward coverage is limited, thenplanning should be made according to the forward coverage distance.



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zz SectionSection 11 CoverageCoverage PlanningPlanning





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Soft capacity attribute of CDMA 1X systemSoft capacity attribute of CDMA 1X system

z Soft blocking of air interface

Soft capacity attribute of CDMA 1X system

z Factors affecting the uplink load of sector

Quantity of the subscriber

MS interference of Ncell (neighbor cell)

Setting points of destination FER and Eb/Nt and MS environment

Allocation ratio of voice service and data service

Allocation ratio of data rate service, duty ratio and voice activation

factor, etc.

Power control error.

zz ConclusionConclusion:: TheThe CDMACDMA capacitycapacity fluctuatesfluctuates alongalong withwith thethe changechange ofof


environmentenvironment


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Capacity of CDMA 1X systemCapacity of CDMA 1X system

z The foundation for capacity analysis is traffic measurement and calculation. In addition

System capacity represented by throughput adopted

to the busy hour Erlang used for voice service, more measurements are required for

packet data service subscribers. The traffic per voice service subscriber is measured by

.

Erlang) per voice service subscriber and the other is throughput per voice service

subscriber in bps calculated as follows Throughput = Traffic strength * data rate *activation factor.

rAvS =

z The BHE and Throughput calculation for PSD service should be approached in different

way for the reasons: 1. Different channel assignment scheme for PSD; 2. Different



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Analysis of soft capacity of CDMA 1X systemAnalysis of soft capacity of CDMA 1X system

CDMA system has different capacities under difference

networking condition (cellular layout)

The variance of total capacities of the equipment is not great

un er t e same env ronment an networ ng con t on

The moving speed affects the system capacity greatly Both ofthe main components of reverse interference depend on the

. ,

interference is the main component in the central area, and

the Ncell interference is the main component on the edge of

The capacity of the forward link is finalized

by the total transmission power of cell and

traffic channel and other supplementary

channels (the supplementary channels

include ilot a in and s nchronization


channels, etc)


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Analysis of soft capacity of CDMA 1X systemAnalysis of soft capacity of CDMA 1X system

If the power amplifier cannot provide enough forward power,

then the system capacity will be forward limited. For example,

improper cellular distribution may result in most of the

subscribers being located on the edge of the cell, or severe

cross-cell coverage, which in turn causes the power of forward

traffic channel and the soft handoff rate to be too great.

Further, the increase of soft handoff may increase the reverse

capacity but reduce the forward capacity.

Maximum number of MSs supported by the forward link and

reverse link of CDMA system are different. Generally, the

capac y o sys em s na ze y e capac y o e

reverse link. The reverse capacity and load are used for design

reference, while emulation is adopted for analysis of forward


capac ty.


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What is Capacity?What is Capacity?



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Units for CapacityUnits for Capacity



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Minutes of UseMinutes of Use



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Conversion TriangleConversion Triangle



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Capacity Flow DefinitionCapacity Flow Definition



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Busy Hour MethodologiesBusy Hour Methodologies



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Hourly Traffic VariationHourly Traffic Variation



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Daily Traffic VariationDaily Traffic Variation



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Seasonal Traffic VariationSeasonal Traffic Variation


l T bl & i T bll T bl & i T bl


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Erlang Table & Poisons TableErlang Table & Poisons Table


Bl ki P b biliti d GOSBl ki P b biliti d GOS


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Blocking Probabilities and GOSBlocking Probabilities and GOS


G d f S iG d f S i GOSGOS


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Grade of ServiceGrade of Service GOSGOS


T ffi C it i O BTST ffi C it i O BTS


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Traffic Capacity in One BTSTraffic Capacity in One BTS




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zz SectionSection 11 CoverageCoverage PlanningPlanning




Power PlanningPower Planning


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Power PlanningPower Planning

Principle of power planning: Power of pilot channel: 10-20% of total power Power of a in channel: ilot -4.5dB The rate of a in channel is

4800)

Power of synchronization channel: pilot -10dB Power of traffic channel: remnant power

Guarantee

correctaccess

e ng pr nc p es o p o power: Establish proper cell scope Allow channel estimation of receiver

andnormal

conversation

Guarantee the power amplification resources needed for the forward

traffic channel within the coverage area. The above settings are the static ones. But cell breath is a dynamic

allocation modification of pilot and power of traffic channel. The purposeis to adapt to the dynamic coverage and capacity variance


CDMA RF Planning UnitCDMA RF Planning Unit 66


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CDMA RF Planning UnitCDMA RF Planning Unit -- 66


Reason for PN Planning & Neighbor List SettingReason for PN Planning & Neighbor List Setting


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Reason for PN Planning & Neighbor List SettingReason for PN Planning & Neighbor List Setting


Process of PN PlanningProcess of PN Planning


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Process of PN PlanningProcess of PN Planning


Pilot Inc SettingPilot Inc Setting


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Pilot_Inc SettingPilot_Inc Setting


Determine The Used Pilot Sets (2)Determine The Used Pilot Sets (2)


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Determine The Used Pilot Sets (2)Determine The Used Pilot Sets (2)


PN planning of the SitesPN planning of the Sites


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PN planning of the SitesPN planning of the Sites


Principle of Original Neighbor SettingPrinciple of Original Neighbor Setting


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Principle of Original Neighbor SettingPrinciple of Original Neighbor Setting


Example of Original neighbor SettingExample of Original neighbor Setting


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p g g gp g g g




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Optimization


Optimization Strategy of CDMA Radio NetworkOptimization Strategy of CDMA Radio Network


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p gyp gy

.

Consider customer satisfaction with priority.

Integrate planning with optimization closely.

General optimization priors to partial adjustment.

.


PrePre--Optimization EvaluationOptimization Evaluation -- ContentContent


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pp


Optimization strategy of CDMA radio networkOptimization strategy of CDMA radio network


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Main optimization parameters: Optimization of RF environment

TheThe optimizationoptimization isis thethe elementaryelementary oneone ofof thethe radioradio cellularcellular layoutlayout.. WhetherWhether thethe

cellularcellular layoutlayout isis successfulsuccessful oror notnot finalizesfinalizes 8585%% radioradio networknetwork quality,quality, andand thisthis isis

especiallyespecially truetrue forfor thethe CDMACDMA radioradio networknetwork..

TotalTotal transmissiontransmission owerower ofof eacheach sectorsector

AntennaAntenna configurationconfiguration (azimuth,(azimuth, downtiltdowntilt,, height,height, graphicsgraphics mode)mode)

ListList ofof neighborneighbor pilotspilots andand thethe prioritypriority sequencesequence

RatioRatio ofof softsoft handoffhandoff andand hardhard handoff,handoff, andand thresholdsthresholds

Secondary optimization parameters: Fine tuning of partial performance

SizeSize ofof searchsearch windowwindow ofof BTSBTS

SettingSetting ofof digitaldigital gaingain ofof eacheach (sub)(sub) channel,channel, thatthat is,is, powerpower allocationallocation


erer a gor ma gor m parame ersparame ers

Stages of CDMA Network optimizationStages of CDMA Network optimization


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Analyze Network System ParameterAnalyze Network System Parameter


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Search Window Neighbor Cell

PN Planning

Relationship

Soft-handoff

networkenvironment

PowerDistribution Hard handoff

Subscribersdistributionand behavior

Subscribers

require

Power Contro

The reasonsof effectingnetwork


quality

Cluster Optimization StageCluster Optimization Stage Optimization AnalysisOptimization Analysis


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Analyze network system parameterAnalyze network system parameter--Search WindowSearch WindowAnalyze network system parameterAnalyze network system parameter--Search WindowSearch Window


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y y py y py y py y p

Search Window of MobileSearch Window of MobileSearch Window of MobileSearch Window of Mobile

Dn=4km

D2=3.5km

14 chips

PN 75

Dr=3km

12 chips

16 chips PN 45

e g or ase a on Reference Base StationGPS Time

02880 6720MS Timing Reference SrchWinA 4 chips

(PN 45)

0 2880 672012 chips

30 30SrchWinAThe earlyest

branch of active

The earlyest

branch of active

rc n

014 chips

4800

set


2880 6720

Neighbor Base Station

(PN 105)

Analyze network system parameterAnalyze network system parameter--Search WindowSearch Window


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Search Window of MobileSearch Window of MobileAnalyze network system parameter-Search WindowAnalyze network system parameter-Search Window

SRCH_WIN_A 20chips

SRCH_WIN_N 60chips

_ _ c ps

NGHBR_MAX_AGE

Search Window of BTSSearch Window of BTSMAXCELLR For BCCH UnitKi o metre

TCHSCHWSZFor TCH Unit64 chips


Analyze network system parameterAnalyze network system parameter--Neighbor CellNeighbor CellAnalyze network system parameterAnalyze network system parameter--Neighbor CellNeighbor Cell


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The improper setting of Neighbor Cell RelationshipThe improper setting of Neighbor Cell RelationshipThe improper setting of Neighbor Cell RelationshipThe improper setting of Neighbor Cell Relationship

Case one: Ne lect nei hbor cell confi uration

Check synchronization channel message and record PN used whenMS performs re-synchronization in case of call drop. If this PN

oes not e ong to act ve set, a t s to ne g or ce st.

Case two: Adjust neighbor cell priority

A opt EHDM or HDM to ca cu ate an o t me an t mes rom

source sector to target sector and list nerighbor cells with priority.

The blocks between adjacent cells disable sectors of adjacent cells

to be inter-matched because of terrain.


Analyze traffic measurement dataAnalyze traffic measurement data


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Understand general network performance to detect existing and potential

problems.

network resources rationally to enhance usage of current network equipment.

Main indexes

Successful call setup ratio

Call drop ratio

Successful soft handoff ratio

Soft handoff ratio

Traffic (exclude soft handoff)

Traffic channel con estion ratio

Successful hard handoff ratio


Analyze alarm dataAnalyze alarm data


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Grasp running condition of network to locate network equipment problems.

Exclude alarms to avoid potential problems and decrease complaints.

Collect and analyze major alarms.

Monitor parameter setting of each cell


Analyze alarm dataAnalyze alarm data -- System Equipment ProblemsSystem Equipment Problems


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System Equipment ProblemsSystem Equipment Problems Unqualified BTS standing wave, scaling and incorrect antenna

feeder installation lead to abnormal transmit power.

GPS satellite synchronization

BTS is out of Service BSC (clock and frame combination unit)

A interface

Others, such as power amplifier over prompting alarm.


Analyze customer complaint recordsAnalyze customer complaint records


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Worse signal coverage

Instable signal

Monolog

Echo

onversat on scont nu ty

Call drop

Cross-ta ing

Users detect mass network problems gradually in case of network

The statistical data from customer complaints are also important

data that locate network problems and reflect running conditions of

network. The data reflect current conditions and problem layout of

network specifically and visually.


Analyze signaling dataAnalyze signaling data


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Solve in-depth problems of network

er ec compre ens ve ne wor qua y.


Analysis and Example of Signaling DataAnalysis and Example of Signaling Data--------Pilot PollutePilot Pollute


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Case one: No Primary Pilot Check PSMM, the strength difference among 4 pilots is withinCheck PSMM, the strength difference among 4 pilots is within

1.5dB and all the pilots are within TADD1.5dB and all the pilots are within TADD1.5dB1.5dB

PSMM

23:50:40:881, FEB 08 2001, HANDOFF, PSMM,


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Clear Pilot Pollute:Clear Pilot Pollute:

Select the pilot with the best signal of all the pilots to adjust

antenna azimuth angle of relevant BTS, tilt angle and pilotower and decrease ilot stren ths of other ilots.

Change BTS configurations to decrease mounted height of

antenna.

Check whether some BTSs are over covered and adjust antenna

pitch angle of the BTS to reduce coverage area.

pollute area..Adopt micro cell to increase capacity in hotspot area and solve


pilot pollute.


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Call Drop AnalysisCall Drop AnalysisCall Drop AnalysisCall Drop Analysis

Call Drop MechanismCall Drop Mechanism


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Drop Call Signature TemplatesDrop Call Signature Templates


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Access / Handoff Contention DropAccess / Handoff Contention Drop


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Forward Short Term Interference DropForward Short Term Interference Drop


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Imbalance DropImbalance Drop


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Coverage Drop Long Term Coverage OutageCoverage Drop Long Term Coverage Outage


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Coverage Drop Short Term Coverage OutageCoverage Drop Short Term Coverage Outage


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Constrained Traffic Channel Power DropConstrained Traffic Channel Power Drop


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Network OptimizationNetwork Optimization

ases na ys sases na ys s


ContentsContents


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apter ann ng ases


Chapter 1 Planning CasesChapter 1 Planning Cases


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Planning contents

Difficulties and emphases

Case review


Content of Project PlanningContent of Project Planning


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Project planning plays an important role in the project implementation, andhas a great impact on the network quality and optimization after projectcom letion. The content is as follows:

Project parameters: Latitude and longitude of BTS, mounted height, azimuth,

PN, adjacent cell and BTS power.Re ion arameters: location area code LAC REGZONE si nalin oints and

their coordination.

Network performance parameters: performance parameters

The arameters in this a e are not enumerated com letel . For thespecific parameters, refer to network planning parameters list.



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Problems:Problems:


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Due to 2 LACs and 1 REGZONE, terminal will not originate location registration

when performing handoff between LACs, which leads to terminal paging

failure before originating calls.

Two OPCs in every LAC will necessarily bring about a successful and a failed

ratio at BSC side.

Urban BTSs are distributed among frames and between the 2 signaling points,

which leads to a mass of soft handoffs between frames or between signaling

points. Large numbers of call drop will occur when CPU is overloaded.

Solutions:

Add REGZONE corresponding to each LAC.

Switch cross-regional BTSs to the same frame in the next cutover.


Think about:Think about:


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What should we concern about when planning location area and signaling points

during project planning?

The planning of BTSs must conform to the following rule: geographically adjacent BTSs,

especially the BTSs with frequent handoff, must be installed in the same module.

New office must reserve port numbers for BTS expansion. The reserved numbers are

decided by data setting center. The port numbers are not reserved currently. They are

added into new modules during each expansion.

One signaling point can be connected with one or more modules. One signaling point can

be connected with 15 modules at the most. (Each module with one FMR)

Each signaling point should correspond to one LAC. One signaling point may have several

LACs. But avoid the case that one LAC have several si nalin oints. It is not allowed

that BTSs in the same LAC are distributed in different modules and several LACs exist in

the same module in such configuration.


,

sparsely populated area.

Case 2Case 2


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Case: Two 3601 i-sites of V100R001B02D002 are added in an office expansion.

The call drop rate is considerable since the 2 i-sites are activated, which

kee s fluctuatin at 5%. The call dro s in one i-site even reaches 120 in a

single day.

Most of call drops in the 2 i-sites are caused by radio link according to trafficmeasurement result. All the indexes are normal except the considerable call

drops and high call drop rate. The drive test shows that indexes such as EC/IO,

RX and FFER are normal except TX of transmit power. TX in some area even

reaches +20 dBm, indicating a very poor reverse coverage.

e ng searc w n ow c ose y re a es o e coverage capa y o . ur ngon-site implementation, we should set the search window parameters

according to practical planning and avoid network failure due to incorrect

parameter setting.


Causes 2Causes 2


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Coverage causes: Forward coverage

s goo , w e e reverse one s poor.

PN planning causes: It is excluded

by check.

Hard handoff causes: It is excluded

since it is not involved.

Soft handoff causes: Since no call dro u on handoff is ca tured in on-sitedrive test, it can be excluded.

Data setting causes: We find that the reverse coverage of i-site is poor

according to the analysis of drive test and traffic measurement. Then

modify the parameters to improve the effect of the reverse coverage of i-

site.


SolutionsSolutions


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Increase the coverage radius of BTS from 20 km to 39 km and enlarge

search window from 1 to 5.

C ange t e ynamic a justment o searc win ow rom ENABLE into

DISABLE.

Result:

Call drop rate falls obviously, which decreases from about 5% to less

than 1%.

Sum-up: Setting search window closely relates to the coverage

. - ,search window parameters according to practical planning and avoid

network failure due to incorrect parameter setting.


Case Review 3Case Review 3

Case: The eq ipment aro nd site A is man fact red b M The c stomer


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Case: The equipment around site A is manufactured by M. The customerexpects the areas covered by Site A are distributed asymmetrically.

There are Blind Zones with short distance or long distance from site A in

some rec ons. ere are a so wea s gna areas n some rec ons.

access is difficult and call drop occurs frequently (34 out of 10 call

drops occur) before activating Huawei omni-directional i-site in site A.And MS access is still difficult and call dro occurs fre uentl 78 out of

10 call drops occur) after activating Huawei omni-directional i-site in

site A.

M site b

M site a

M site D

M site c

Isitec 3601


Cause AnalysisCause Analysis

Th 4 il t i l ith i il t th i Sit A b f ti ti H i


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There are 4 pilot signals with similar strength in Site A before activating Huawei

omni-directional i-site. The 4 pilot signals will create pilot pollution, which

causes difficult MS access and fre uent call dro s. This is confirmed b the

test to network M)

Since the area where problem occurs is 3 km away from site A, and the signalstransmitted by the omni antenna are not strong, the activation of Huawei

omni-directional i-site equals to the addition of a new pilot signal with similar

strength. Therefore, the interference increases, aggravating the problem.


SolutionsSolutions

Replace omni antenna of Isitec3601 with directional antenna to make that the


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Replace omni antenna of Isitec3601 with directional antenna to make that the

main pilot to cover the area. Move the handoff band to the region without

residents and the call dro s in 90% of the covera e areas decrease.

Since the M network structure cannot be modified, we can modify the system

parameters of network M only. Faults in 95% of the area disappear, but theyremains in some small spot interference area, which can be removed by

adjusting network structure and increasing the tilt angle of BTS generating the

interference.


Suggestion and SumSuggestion and Sum--upup

Since the equipment around the site is from a third party manufacturer it is


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Since the equipment around the site is from a third-party manufacturer, it is

not suitable to install Huawei equipment in the blind zone. Since it is not

ossible to shift handoff band to the area without residents and even it is

some small interference areas in the coverage area cannot be controlled.

Since Huawei i-site is suitable for blind zone in belt shape or standalone site,the sites committed by market department should be monitored during

network planning.

If it is compulsory to install Huaweis BTS in similar environment, select the

directional antenna for adjustment instead of omni-directional antenna.


Cases SummarizerCases Summarizer

We should concern the following in planning according to the above three cases:


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We should concern the following in planning according to the above three cases:

BTS address (Avoid mixed networking)

ntenna ystem nc u ng az mut , t t ang e an antenna se ect on

Network parameters (Search window, carrier power and common channel power)

Region parameters (Location area parameters and signaling points)


ContentsContents


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apter ann ng ases


Chapter 2 Optimization CasesChapter 2 Optimization Cases


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Optimization Procedures

Difficulties and Emphases

Case Review


The optimization procedures are as followsThe optimization procedures are as follows

Preparation: Preparation of equipment, data and telephone directory of


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Preparation: Preparation of equipment, data and telephone directory of

personnel for optimization.

, ,

version information, user number and distribution.

Collecting traffic measurement and drive test data: The traffic measurementdata is the ma or criterion for o erator evaluation. The traffic measurement

and drive test data are important for analysis.

Data analysis: Analyze the collected data with various tools.

Ad ustin arameters: Ad ust corres ondin network arameters accordin toanalysis result.

Network optimization report: network optimization deliverables and work

achiev

ements. The report should be acknowledged.


Difficulties and EmphasesDifficulties and Emphases

The advantage of CDMA over 2G lies in the application of power control


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The advantage of CDMA over 2G lies in the application of power control

and soft handoff, which is the emphasis of the optimization. Besides,

,

focused on.

p m z ng power con ro parame er

Optimizing access parameters

Discover the roblems of al orithm and software.

Optimizing load control

Optimizing data service



Case: call setup success rate fluctuates at about 91.5% after the cutover


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Case: call setup success rate fluctuates at about 91.5% after the cutover

(R02B03) of project Z. 2% of the failures are caused by MSC rejection and call

early release. And 4.5% of the call setup failures are caused by capture failure

of traffic channel preamble and MS response expiration.

Call setup failure is generally caused by capture failure of traffic channel

preamble and MS response expiration, which exists in almost every cell, and it

is especially serious in some cells.

There is obvious interference in most of the BTSs with low call setup success

rate accordin to the anal sis of reverse RSSI. However the call dro rate of

these BTSs is not high, which is less than 5%. That indicates there are other

causes of call setup failure besides interference.



The signaling procedures of call origination and paging, together withi i f d l l l h i h


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g g p g p g g, gaction point of open and close loop power control are shown in the

followin fi ure:

BTS

Origination Msg

MS

ACCESS

Successful Access Attempt

start of open loop powercontrol

Base Sta. Acknlgmt. Order

TFC frames of 000s

ro ng

PAGING

FW TFC

anne ssnm . sg.

TFC preamble of 000s

Base Sta. Acknlgmt. Order

RV TFC

FW FC

start of close loop powercontrol

. .

Service Connect Msg.

Svc. Connect Complete Msg

FW TFC

RV TFC


ase a. c n gm . r er

Call is Established!


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The offset power of both varies according to different radio configurations. The


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access channel in the case is IS95 access channel and the offset value is 73,

while the traffic channel is IS2000 traffic channel and the offset value is 81.5

therefore, 8.5 dB is reduced in transmit power when MS accesses traffic

channel. The difference can be compensated by RLGAIN_ADJ. The correction

rang is 015, which corresponds to 87dB. The value obtained through query, , .

Solution Case 2: call setup success rate rises when RLGIAN_ADJ is modified to15, which corresponds to 87dB.



From the viewpoint of BTS, most MSs in current network are in IS95A mode, so


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their forward power control mode conforms to slow power control mode

instead of fast power control that we are familiar with. In the slow forward

power control list, the maximum transmit power of forward channel is 215

and the initial value for transmit power of forward channel is 199, which is

much less than the pilot channel power (227). Since the loaded script after

upgrade does not involve the modification of slow forward power control, the

Solution:

Set the value of maximum transmit power of forward channel to 227 and the

initial value to 227 through dynamic data configuration.

After modification, the forward load is less than 70%, which has little effect on


,


Case: There is always way of optimization of CDMA MS access speed. Users oft i i l ffi l i th t it t k l ti f ll MS i th


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certain commercial office complain that it takes a long time for all MSs in the

network to be a ed when the are called. The roblem occurs in CDMA MSs

of many models.

Anal sis:

When BTS originates the first paging, MS does not receive the signal from BTS.

This indicates the BTS transmit power is so low that MS does not respond with

access probe.

When BTS originates first paging, MS receives the signal from BTS, but BTS does

not receive the response message from MS. MS will not stop sending access

probe until MS accesses the system or call drop occurs.

The key to locate the problem is to acknowledge whether MS sends the access

probe when BTS sends first paging.



Procedures


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Use the MS of other brands (or MS of China Mobile or China Unicom or PSTN of

na e ecom o or g na e a ca o e amsung

Click [View/statistics/access and paging statistics] in CAIT menu.

.

MS has to send 6 probes consecutively before accessing system during each

paging. The cause is that the initial reverse transmit power is low.

pwr_step=4, that is MS has to increase transmit power by 46=24dB before

accessing the system on the basis of open loop power control. The best access

,

increases access speed without affecting the capacity, so we need to increase

the transmit power by 4(62)=16dB.


All MSs can originate one paging to access system after parameter modification.


We need to optimize the timer parameter while call setup success rate remainslow even if the access speed is optimized


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low, even if the access speed is optimized.

- ,

affecting the call setup success rate are as follows;

Traffic channel preamble failure during BTS waiting for MS service- .

Further statistics show that the first cause accounts for 66%, and the last one

accounts for 34% of call setup failures.



Cause analysis: the two causes for call setup failure are that BTS fails tocapture reverse traffic channel preamble and timer expires during BTS


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capture reverse traffic channel preamble and timer expires during BTS

The following two timers implement control: CCM_T_WT_TCH_preamble and

CCM_T_WT_MS_ACK_ORD. The value of CCM_T_WT_TCH_preamble protocol

ranges from 1 to 4s, and so is the value range of the

CCM_T_WT_MS_ACK_ORD protocol.

.increasing time span of the waiting timer to raise call setup success rate.

Procedures: Change values of the two timers into 4s and 3s. After parameter

adjustment, the indexes of failures (BTS fails to capture reverse traffic

channel preamble, and failure of BTS waiting for response from MS) drop from

360 and 150 to 320 and 130 ever da res ectivel which decrease b 17%. It


is effective to adjust timer according to traffic measurement analysis.

Access optimization SumAccess optimization Sum--upup

S W h ld b f ili ith h t f MS lli


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Sum-up: We should be familiar with each stage of MS calling

proce ures so a we can ma c e s age w correspon ng

formula immediately.

Access rocess should be alwa s o timized durin s stem

optimization. Soft capacity of CDMA enables system capacity

to increase and access status to vary with it.


Case review 4Case review 4

Call drop during soft handoff remains a trouble for us. There are lots of causes.Take the following case for an example


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Take the following case for an example.

processing.

Incorrect BSC adjacent cell judgment: BSC takes No. 17 BTS 400 km away forthe current BTS servin the MSs in area A. When MS detects the incorrect

adjacent cell, it reports the message to BSC by PSMM. If there is PN

multiplexing in the system, BSC is unable to detect correct BTS from the PN

directly. There are two solutions:

Configure correct adjacent cell for BTS. BSC can detect correct BTS from PNaccording to adjacent cell relation.

BSC can detect PN by longitude and latitude of BTS provided by system. The

e au e ec on prec s on requ res a mu p ex ng s ance o over m

at least.



Some problems are impossible for us to solve except aforementioned casessolved by parameter modification. However, we cannot neglect them, and we


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solved by parameter modification. However, we cannot neglect them, and we

can take miti ation measures. We can take the data service and voice service

for an example to illustrate it.

Case: A CDMA 800M commercial office W receives complaints that users aredisconnected from network some time (several minutes later) after they

originate data service call through wireless network adapter And then they

have to redial to access network. Users express their great unsatisfaction with

this. The type of network adapter is Putian YM-1031K PCMCIA TYPE II/

.



Analysis: Recur the problemThe status transfer from Active to Dormant is normal


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The status transfer from Active to Dormant is normal

, .

Network side sends a paging request to terminal and it responds with paging

response. Then MSC send a clear command.

Check the value of service o tion is 0 in a in res onse.

Since the network adapter of the terminal is not consistent with the

requirement of protocol, the MSC releases the call directly. Though we require

manufacturer of the network card to make modification, it is urgent to solve

the problem immediately for the customer and reduce complaints. Change theduration of deactivating the timer from 20s to 180s to reduce the times that


.


Some problems can be mitigated during optimization of voice service


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Some problems can be mitigated during optimization of voice service.

ase: n o ce ran s ow n e ne wor qua y among e o ces n

the province because of low call drop rate at radio side. Large

number of erasure frames results in call drop, which can reach 310 inthe bus hour ever da . This kee s call dro rate of whole BSC under

140. Therefore we should focus on how to reduce the call drop

caused by excessive erasure frames.

Analysis: We should analyze the problem through csl to locate all the

possible problems



Processing Procedure:


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Processing Procedure:

e a arm s no genera e n e ce w g ca rop ra e an s

adjacent cell.

Check reverse RSSI through telnet, the status is normal.tart pr nt to ana yze t e ca rop cause y rames. e

value of threshold is 300 frames.

Set the threshold of module/frame erasure frame timer for urban BTS

.Reset threshold of all module timers



Sum-up:

Sometimes we cannot find the key to the problems in the network within a


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Sometimes we cannot find the key to the problems in the network within a

, .

corresponding mitigation measures on site. There is no substantial change

about the optimization of parameter adjustment in this case. The time before

call drop changes from 6s to 10s actually, which makes users hang up due to

impatience. Then it is recorded as a normal end in measurement result.

Viewed from the measurement result, the situation i



Load control is a field much researched by Huawei. But there is still a long wayto go.

Th f d l d f BTS f h 100% i 15 i ffi


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The forward load of a BTS sector often reaches 100% in a 15-minute traffic

measurement. The customer has a great doubt about the network load ability

due to the measurement result.

The f or war d l oad of a BTS

110

70

80

90

0

50

60

1 5 9 13 17 21 25 29 33 37 41 45 49 53

/ 15



Analysis of Alarm and its Cause

The o er e cited alarm of carrier po er occ rs freq entl


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The over excited alarm of carrier power occurs frequently.

The forward power is 43dBm at the end of a 15-minute period according to

traffic measurement. The power amplifier may transmit at the maximum.

Since users are distributed on the cell border, the sector has to consume more

power. As a result, the load of the sector is too high. Since the traffic of

adjacent BTS N is comparatively small and the traffic can be distributed

through load balancing. We can decrease the power of common channel in the

sector accordin to anal sis of drive test which will not affect s stem

performance, especially the coverage performance.



We do not give much research on data service optimization due to site problem,so the problems found in this aspect are not too much. The following is a case

of data service optimization


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of data service optimization.

Case: The mean download rate is too low and transmission gap is comparatively

large during test of data service optimization in area J.

The details are as follows: the mean download rate of serial port cable in

forward direction is 6 kbyte and the transmission gap is obvious.


QuestionsQuestions


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Documents

02 CDMA RNPRNO.pdf