08 GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manual.doc

8/11/2019 08 GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manual.doc

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GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manua IN!"RNA#

Product Name Confidentiality LevelGSM BSS INTERNALProduct Version Total ! "a#es

GSM BSS Net$or% &PI 'Immediate

Assi#nment Success Rate( )"timi*ationManual

'+or internal use only(

Pre"ared ,y GSM-.MTSNet$or% PerformanceResearc/ 0e"artment

1an# +ei

0ate2334536574

Revie$ed ,y 0ate Revie$ed ,y 0ate

Granted ,y 0ate

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Revision Record

Date RevisionVersion

Change Description Author

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ReferencesNumber References Author Date

7 GSM BSS Net$or% &PI 'Immediate Assi#nment Success Rate( Baseline Liu


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Content7 )vervie$ of t/e Immediate Assi#nment Success Rate99999999999999999999999999999999999999999999797 0efinition99999999999999999999999999999999999999999999999999999999999999999999999999792 Si#nalin# Procedure and Measurement Points99999999999999999999999999999999999999999999979 Sym"tom 0escri"tion99999999999999999999999999999999999999999999999999999999999999999

2 +actors Concernin# Immediate Assi#nment Success Rate999999999999999999999999999999999999999297 Si#nalin# +actors9999999999999999999999999999999999999999999999999999999999999999999292 +actor Analy*in# Accordin# to t/e 0efinition of t/e &PI999999999999999999999999999999999999929 +actors Analysis999999999999999999999999999999999999999999999999999999999999999999999

29 97 E>ui"ment +aults9999999999999999999999999999999999999999999999999999999999999999929 92 .m Interface Pro,lems9999999999999999999999999999999999999999999999999999999999999929 9 S0CC8 Con#estion999999999999999999999999999999999999999999999999999999999999999929 9! MS Pro,lems999999999999999999999999999999999999999999999999999999999999999999999Met/od of Analy*in# t/e Pro,lem of Lo$ Immediate Assi#nment Success Rate9999999999999999972

97 Process of Analy*in# t/e Pro,lem of Lo$ Immediate Assi#nment Success Rate99999999997292 Met/od of Solvin# t/e Pro,lem of Lo$ Immediate Assi#nment Success Rate9999999999999997!

9297 E>ui"ment +aults99999999999999999999999999999999999999999999999999999999999999999

9292 .m Interface Pro,lem999999999999999999999999999999999999999999999999999999999999999929 System Ca"acity 'Con#estion( Analysis9999999999999999999999999999999999999999999999999929! MS Pro,lem Analysis99999999999999999999999999999999999999999999999999999999999999

! Test Met/od9999999999999999999999999999999999999999999999999999999999999999999999999999? Cases of Immediate Assi#nment Success Rate )"timi*ation99999999999999999999999999999999999999?97 Case 7@ 0ecrease in Immediate Assi#nment Success Rate Because of S0CC8

Con#estion Caused ,y Incorrect LAC Settin#9999999999999999999999999999999999999999999999999?92 Case 2@ S0CC8 Con#estion Caused ,y a Burst of Location ."dates9999999999999999999999999992?9 Case @ Lo$ Assi#nment Success Rate Because t/e RAC8 Minimum Access Level Is

Set to 39999999999999999999999999999999999999999999999999999999999999999999999999999999?9! Case !@ Lo$ Immediate Assi#nment Success Rate in Some Cells Because of MS Error

36 )nsite Information t/at Needs to Be ),tained99999999999999999999999999999999999999999999999999

$%%&' %'$ All Ri#/ts Reserved Page , o* +,


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TablesTa,le 7 Ma""in# ,et$een formulae and factors9999999999999999999999999999999999999999999999999999

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GSGSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manua IN!"RNA#

GSM BSS Net$or% &PI 'Immediate Assi#nment

Success Rate( )"timi*ation Manual

AbstractKey Words: DCC!" immediate assignment success rate

Abstract: This document provides the procedure for analy#ing theproblems about immediate assignment success rate" describes the

troubleshooting procedure" and provides typical cases$Abbreviations:

Abbreviation %ull pelling

BSC Base Station Controller BTS Base Tranceiver StationS0CC8 Stand5alone 0edicated Control

C/annel

$% ,' %' + -uawei !ec.no ogies Proprietar/ Page 0 o* +,


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1 &vervie' of the (mmediate Assignment

uccess Rate

Immediate assi#nment success rate indicates t/e success rate of t/e MS accessin#t/e si#nalin# c/annel9 It concerns t/e "rocedure from t/e MS sendin# a c/annel re>uiredmessa#e to t/e BTS to t/e MS sendin# an esta,lis/ indication messa#e to t/e net$or%9

Immediate assi#nment success rate is a %ey access counter9 It directly reflects t/e

success rate of t/e MS accessin# t/e si#nalin# c/annel and affects t/e user e "erience9

T/e BSC versions concerned in t/is document are as follo$s@

BSC 2 G BSC 2V 33R33;C37B37?

BSC6333 BSC6333V=33R337

1 0efinition

T/e immediate assi#nment success rate is calculated from traffic statistics9 T/e

recommended formula is as follo$s@Immediate Assi#nment Success Rate 'Successful Immediate

Assi#nmentsDImmediate Assi#nment Re>uests( 733



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1$ Si#nalin# Procedure and Measurement Points

BSCBTS MSC

Channel REQ

Channl RQD

Channel ACT

Channel ACT ACK

IMM ASS CMD

first SABM

UAEST IND(CM Service REQ)

CR(CMP L inf!r"ati!n)

CC

CM Service Acce#te$

A%

C%

B%

Note@

A7@ Immediate Assi#nment Re>uests 'C/annel Re>uests 'Circuit Service((

B7@ Immediate Assi#nment Commands

C7@ Successful Immediate Assi#nments 'Call Setu" Indications 'Circuit Service((

1+ Sym"tom 0escri"tion

If t/e immediate assi#nment success rate decreases: t/e follo$in# sym"toms may

occur@

Call setu" success rate decreases9

$% ,' %' + -uawei !ec.no ogies Proprietar/ Page & o* +,


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Con#estion occurs fre>uently on t/e S0CC89

Traffic volume on t/e TC8 decreases9

S/ort messa#es cannot ,e successfully sent9FF

2 %actors Concerning (mmediate Assignment

uccess Rate

$1 Si#nalin# +actors

Accordin# to t/e si#nalin# flo$: t/e factors concernin# t/e immediate assi#nment

success rate durin# eac/ "/ase are as follo$s@

( ) Random access re>uest "/ase@ $/et/er t/e small interference si#nal on t/e .m

interface is re#arded as t/e random access re>uest ,y t/e BSC9 Affectin# factor@

.m interface "ro,lems

($) S0CC8 assi#nment "/ase@ $/et/er t/e S0CC8 is availa,le after t/e random

access re>uest is acce"ted9 Affectin# factor@ S0CC8 con#estion

(+) C/annel activation "/ase@ $/et/er t/e c/annel activation is successful after t/e

c/annel assi#nment succeeds9 Affectin# factor@ C8AN ACTIV NAC& messa#e is

received ,ecause of e>ui"ment faults durin# S0CC8 activation

(,) Immediate assi#nment command "/ase@ $/et/er t/e timer for t/e

ac%no$led#ment of t/e immediate assi#nment e "ires9 Affectin# factor@ .m

interface "ro,lems( ) Lin% esta,lis/ment "/ase@ $/et/er t/e lin% can ,e esta,lis/ed on t/e S0CC8

after t/e immediate assi#nment command is sent9 Affectin# factor@ MS features9

T/e follo$in# analysis is ,ased on t/ese factors9

$1$ +actor Analy*in# Accordin# to t/e 0efinition of t/e &PI

As s/o$n in t/e "revious section: t/e follo$in# four factors are related to immediateassi#nment success rate@ .m interface "ro,lems: S0CC8 con#estion: rece"tion of



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$1+ +actors Analysis

$1+1 E>ui"ment +aults

$1+1 1 Lo$ Immediate Assi#nment Success Rate Caused ,y TR< +aults

Generally: rece"tion of C8AN ACTIV NAC& durin# t/e S0CC8 activation is caused

,y e>ui"ment faults9 If one TR< fails in t/e cell confi#ured $it/ multi"le TR


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t/e ran#e in $/ic/ t/e "ro,lem e ists: and t/en find out t/e factors related to t/e "ro,lem

accordin# to &PI statistical formulae9 +or details: see section 292 +actor Analy*in#

Accordin# to t/e 0efinition of t/e &PI 9 In t/e case of recommended formula: t/e #eneral

"rocess of analy*in# t/e "ro,lem is as follo$s@

Start

Analysis of lo$immediate assi#nment

success rate

C/ec% num,er of S0CC8 activation

failuresDtimeout

C/ec%S0CC8

availa,lity

C/ec% TRuality

analysis

RAC8overload

times

SolveInterference "ro,lem

S0CC8 sei*uresuccess rate

'location u"date(

C/ec% timersrelated tolocationu"date

C/ec% S0CC8dynamic

confi#uration

Traffic volume"er S0CC8

e ceeds "aln

S0CC8 andTC8 traffic

volumeanalysis

Incomin# andout#oin#

/andovers of t/e cell

Re"lan t/elocationareas

No

Insufficient systemca"acityM

A,normal

Normal

8ard$aree "ansion

E>ui"ment fault

.m interfacefault

es

es

No

es

Pro,lemsolved

es

End

+ind cells $it/ lo$immediate assi#nment

success rate

MS fault Analy*e si#nalin# andtraffic statistics of cells

$it/ "ro,lem

Ena,le CBA

of t/e cell

+or s$a""ed net$or%:c/ec% $/et/er t/e

"ro,lem e ists inventorNs net$or%

No

Locate"ro,lem

and su,mitre"ort

$% ,' %' + -uawei !ec.no ogies Proprietar/ Page + o* +,


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4igure Process of analy*in# t/e "ro,lem of lo$ immediate assi#nment success rate

+1$Met/od of Solvin# t/e Pro,lem of Lo$ Immediate Assi#nment Success

Rate

Before analy*in# t/e cause of lo$ immediate assi#nment success rate: you s/ould

find out t/e difference ,et$een t/e actual immediate assi#nment success rate and t/e

e "ected value9 ou s/ould also find out t/e influence of t/e "ro,lem and t/e definition of

t/e s"ecific immediate assi#nment success rate &PI9

+1$1 E>ui"ment +aultsT/is "art aims to solve TR< or transmission "ro,lems9

+irstly: you s/ould c/ec% TR, Availability in - C )easurement and DCC!

Availability in DCC! )easurement 9 Secondly: you s/ould c/ec% t/e num,er of times

t/at a NAC& messa#e is received or t/e timer e "ires durin# t/e S0CC8 activation9 In

t/is $ay: you can determine $/et/er t/e "ro,lem is caused ,y ,oard faults9

ou can also c/ec% $/et/er /ard$are is faulty ,y vie$in# BTS alarms or ,y vie$in#t/e /ard$are state on ite Device *anel of t/e LMT9 ou can c/ec% t/e follo$in# trafficstatistics for reference@

Cause - C +evel Cell +evelE>ui"ment faults

BSC Measurement 5O Accessmeasurement "er BSC 5OS0CC8 Availa,ility "er BSCConfi#ured S0CC8s "er BSC Availa,le S0CC8s "er BSC

Call Measurement 5O C/annel ActivationMeasurement "er Cell 5O S0CC8Connection Measurement "er Cell 5OC8AN ACTIV NAC& Messa#es Sent ,yBTS in Immediate Assi#nment Procedure

'S0CC8(C/annel Activation Timeouts in Immediate Assi#nment Procedure 'S0CC8(&PI Measurement "er Cell 5O TC8 Availa,ility

+1$1$ .m Interface Pro,lem

+1$1$1 Mista%enly Re#ardin# Interference as Random Access Re>uests

Interference may cause S0CC8 con#estion: causin# lo$ immediate assi#nment$% ,' %' + -uawei !ec.no ogies Proprietar/ Page , o* +,


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success rate9 Es"ecially in t/e areas $it/ a small s"ace ,et$een BTSs and dense BCC8fre>uency "lannin#: t/e system allocates S0CC8 for eac/ si#nal if a lar#e num,er of interference si#nals are received9 T/us: t/e con#estion may occur9 In t/is situation: t/eimmediate assi#nment success rate and "a#in# success rate decrease: and t/e RAC8may ,e overloaded9 ou can locate t/e "ro,lems ,y analy*in# t/e idle interference ,andsand t/e TR< receive >uality durin# t/e call9

If t/e system mista%enly re#ards t/e interference as a random access si#nal and

sends an assi#nment command: t/e immediate assi#nment $ill fail9 ou can locate t/e

"ro,lem ,y analy*in# t/e C/an Re> messa#e9

+or t/e S0CC8 con#estion caused ,y interference: you can c/ec% t/e follo$in#

traffic statistics for reference@Cause - C +evel Cell +evel TR, +evelS0CC8con#estioncaused ,yinterference

BSC Measurement 5O Access measurement"er BSC 5ORandom AccessSuccess Ratio "er BSC

Call Measurement5O +lo$ ControlMeasurement "er Cell 5O MSG CCC8L)A0 IN0 'RAC8(Messa#es Sent on A,is Interface

MR Measurement 5O Analy*ed Measurementof Interference Band "er TRuest for sin#le timeslot u"lin%37777 3 transmission one P0C8 is needed937777 3

37773 Sin#le ,loc% "ac%et access one ,loc% "eriod on a P0C8 is

needed for t$o "/ase "ac%et access or ot/er RR si#nallin# "ur"ose9



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37733777 LM. esta,lis/ment note 2

37733 3 Reserved for future use37733 3737733377 note 2a

37777777 Reserved for future use9 note 2,

N)TE 7@ E am"les of t/ese "rocedures are@ IMSI detac/: S/ort Messa#e Service 'SMS(:Su""lementary Service mana#ement: Location Services9

N)TE 2@ If suc/ messa#es are received ,y a net$or%: an S0CC8 s/all ,e allocated9

N)TE 2a@ If suc/ messa#es are received ,y a net$or%: an S0CC8 may ,e allocated9

N)TE 2,@ T/is value s/all not ,e used ,y t/e mo,ile station on RAC89 If suc/ messa#e isreceived ,y t/e net$or%: it may ,e i#nored9

29 T/e value ofAccess Delay indicates t/e TA99 Bits 7 : 7!: 7?: and 76 indicate t/e RAC8 level and t/e num,er of error ,its in t/etrainin# se>uence9 In t/is e am"le: t/e value of ,it 7 is ! 9 T/is indicates t/at t/e,its follo$ed indicate t/e AB access level and t/e num,er of error ,its in t/e trainin#se>uence9 T/e value of ,it 7! is 29 T/is indicates t/at t/e follo$in# t$o ,its indicate

t/e AB access level and t/e num,er of error ,its in t/e trainin# se>uence9 T/e valueof ,it 7? indicates t/e RAC8 level ' = Q 723 Q47 dBm(9

+1$1$1$ Covera#e 0ifference

If t/e com,ination mode of t/e BCC8 TR< and t/e non5BCC8 TR< is different: or

t/e losses are inconsistent ,ecause of different transmit "o$er or ot/er "ro,lems: t/e

assi#nment on t/e non5BCC8 TR< may fail9

T/e causes can ,e classified into t/ree ty"es@ T/e transmit "o$er of TR


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antennae may cause assi#nment failure9 ou can solve t/is "ro,lem t/rou#/ en#ineerin#

adJustment9

T/e transmit and receive antennae are not on t/e same /ori*ontal "lane or t/eir

tilts are not t/e same9 ou can solve t/is "ro,lem ,y adJustin# t/e antennae9

+1$1+ System Ca"acity 'Con#estion( Analysis

+1$1+1 Con#estion Caused ,y 8eavy Traffic on t/e S0CC8

Generally: /eavy traffic on t/e S0CC8 is caused ,y fre>uent location u"dates9 ou

can c/ec% t/e rate of t/e S0CC8 ,ein# occu"ied ,y >ueryin# t/e counter Channel

Re/uests 0+ocation ;pdating2 and t/e total num,er of c/annel re>uests9 +i#ure

s/o$s t/e ratios of different %inds of S0CC8 re>uests to t/e total num,er of S0CC8

re>uests on S/an#/ai .nicom $/en t/e traffic is /eavy9 If t/e ratios are /i#/: c/ec% t/e

location area "lannin# and t/e drive test result9 If t/e ed#es of location areas are

confi#ured in t/e area $it/ /eavy traffic: reconfi#ure t/e location areas9 In addition: you

can adJust t/e C8R "arameters to reduce location u"dates9 +or details: see Case < 9If t/e S0CC8 con#estion rate is /i#/ '#reater t/an ? (: t/e traffic volume on eac/

S0CC8 may /ave e ceeded t/e limit as "lanned9 ou s/ould c/ec% t/e confi#uration of

t/e location u"date and S0CC8 dynamic confi#uration "arameters9 If t/e settin#s of

"arameters are reasona,le: a /ard$are ca"acity e "ansion is re>uired9

If t/e con#estion rate and traffic volume of t/e S0CC8 are /i#/: ,ut t/e traffic

volume of t/e TC8 is normal: t/e S0CC8 con#estion may ,e caused ,y ,urst traffic9 +or

t/e sites alon# t/e rail$ay: es"ecially for t/ese near t/e tunnel "ortal: t/e ca"acity

confi#ured is #enerally small9 1/en a train "asses t/rou#/ or sto"s: a lar#e num,er of

location u"dates occur: $/ic/ finally lead to S0CC8 con#estion9 In addition: durin# t/e

"eriod $/en t/e volume of s/ort messa#es is lar#e: S0CC8 con#estion may occur9 T/is

"ro,lem cannot ,e com"letely solved: ,ut you can ta%e some measures to alleviate t/e

con#estion9 +or e am"le: confi#ure more S0CC8s: or ena,le t/e dynamic conversion

,et$een t/e S0CC8 and TC89 +or details: see Case = 9



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tries to find a TC8+ t/at can ,e converted into anS0CC89 T/is "arameter is one of t/e conditions for t/e dynamic conversion from TC8+ to S0CC89

CellS0CC8C/annelMa imum

Accordin# to t/e c/annel assi#nment al#orit/m: t/esystem determines $/et/er t/e num,er of S0CC8s int/e cell after t/e conversion e ceeds t/e value of CellS0CC8 C/annel Ma imum ,efore initiatin# t/edynamic conversion from TC8 to S0CC89 If yes: t/econversion is not initiated9

TC8MinimumRecovery

Time's(

T/is "arameter s"ecifies t/e minimum time for t/erecovery of a TC8 from t/e S0CC89

!9 Related timers and their recommended configurations are as follo's:

T 737@ T/is timer is used for immediate assi#nment "rocedure monitorin#9

Reduce t/e value of t/is "arameter "ro"erly to minimi*e t/e con#estion caused

,y dual assi#nment of t/e S0CC89 If t/e len#t/ of t/is timer is too lon#: t/e

invalid usa#e of si#nalin# resources is increased9 To en/ance t/e usa#e of t/e

si#nalin# resources: you s/ould s/orten t/e len#t/ of t/is timer: es"ecially $/en

t/e >ueuin# function is ena,led9

T 722@ T/is timer is started ,y t/e MS $/en t/e MS receives t/e IMME0IATE

ASSIGN RE ECT messa#e9 T/e MS can send a ne$ c/annel re>uest messa#e

only after T 722 e "ires9 If t/e len#t/ of T 722 is too s/ort: t/e MS may send

t/e c/annel re>uest messa#e fre>uently $/en no system resources are

availa,le9 T/is increases t/e load on t/e RAC8 and CCC89T 272@ T/is timer is used for t/e "eriodic location u"date9 Increase t/e len#t/ of

t/is timer "ro"erly to reduce t/e load on t/e S0CC8 ,rou#/t ,y "eriodic

location u"date9

T 777@ T/is timer delays t/e deactivation of c/annels after main si#nalin# lin%s

are disconnected to reserve time for re"eated lin% disconnection9 T 777 is

started durin# t/e disconnection of ,ot/ TC8 and S0CC89 T/e value of T 777

must ,e t/e same as t/e value of T 773 at t/e MS side9 Generally: t/ey are set

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739Cell -ar ualify 0C- 2 @ C- ta%es effect durin# cell selection rat/er t/an cell

reselection9+1$1, MS Pro,lem Analysis

+1$1,1 C/ec%in# t/e Pro,lem Sym"toms

),Jective@ to c/ec% t/e "ro,lems t/at e ist on site and solve t/e "ro,lems caused ,y

"oor air interface >uality and incorrect "arameter settin#s9

T/e sym"toms are listed as follo$s@

Sym"tom 7@ T/e num,er of failed S0CC8 sei*ures due to timeout is almost e>ual to

t/e num,er of location u"datin# re>uests minus t/e num,er of lin% esta,lis/ment

indications for location u"datin#9

Sym"tom 2@ T/e "ro,lem /a""ens discontinuously durin# ,ot/ ,usy /ours and idle/ours9

Sym"tom @ T/e call service is normal9 E ce"t for lo$ immediate assi#nment

success rate in a fe$ cells durin# certain "eriods: t/e &PIs and drive test result are

normal: and no call dro" com"laint is received9 Because $/en an MS fails in location

u"date: it may try to access ot/er cells or try to access t/e cell a#ain "eriodically9

Sym"tom !@ No interference and no cells $it/ t/e same BCC8 fre>uency and BSIC

e ist9

Sym"tom ?@ No a,normality suc/ as u"lin%5do$nlin% im,alance e ists9

Sym"tom 6@ T/e result of si#nalin# analysis on t/e A,is interface s/o$s t/at t/e

num,er of re>uest retransmissions and t/e retransmission interval of t/e failed location

u"dates meet t/e confi#uration re>uirements9If all t/e "revious sym"toms e ist: you can infer t/at t/e "ro,lem is lo$ immediate

assi#nment success rate caused ,y a,normal location u"date9

+1$1,1$ Pro,lem 8andlin#

As t/e "ro,lem of lo$ immediate assi#nment success rate is caused ,y some MSs:

and t/e MSs cannot ,e located ,ecause no layer5 information is "rovided in location

u"date "rocedure: t/is "ro,lem cannot ,e solved on t/e net$or% side currently9To im"rove t/e user satisfaction: do as follo$s@

$% ,' %' + -uawei !ec.no ogies Proprietar/ Page $, o* +,


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'7( Reduce t/e im"act of a,normal MS location u"dates on t/e net$or% &PIs9

'2( Communicate t/orou#/ly $it/ customers9

*roblem handling:

If any of t/e "revious si sym"toms does not e ist: initiate t/e "rocedures for

net$or% o"timi*ation and trou,les/ootin#9

To "erform net$or% o"timi*ation accordin# to t/e RSL si#nalin#: do as follo$s@79 If t/e value of TA in t/e location u"date si#nalin# is /i#/ and t/e access level is

lo$ durin# t/e time $/en t/e "ro,lem e ists: do as follo$s@

AdJust t/e follo$in# "arameters@)a@ TA : RAC! )in Access +evel : and T@

integer 'increase S and T(9Increase t/e len#t/ of t/e follo$in# timers@T5uests received $/en t/e

"ro,lem occurred $ere sent ,y some a,normal MSs: and t/e BTS res"onded and

/andled t/e re>uests correctly9 T/e analysis is ,ased on t/e u"lin% and do$nlin%9 T/e

details are descri,ed as follo$s@

29 ."lin% Q c/annel re>uests from t/e MS

'7( 1/en t/e cell access is "ro/i,ited: t/e immediate assi#nment success rate of t/e

cell ,ecomes normal9 T/is indicates t/at t/e a,normal location u"dates are caused ,y

t/e MS rat/er t/an t/e interference9'2( T/e location u"date re>uests are $it/ /i#/ level: lo$ error rate: and small TA

$% ,' %' + -uawei !ec.no ogies Proprietar/ Page $ o* +,


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'e ce"t for some sites $it/ $ide covera#e area(9 T/is indicates t/at t/e a,normal

location u"dates are initiated ,y t/e MS9

' ( T/e num,er of location u"date re>uests sent ,y an MS com"lies $it/ t/e settin#s

of net$or% "arameters9 T/is also indicates t/at t/e a,normal location u"dates are

initiated ,y t/e MS9

9 0o$nlin% Q immediate assi#nment

'7( T/e immediate assi#nment commands are sent correctly: ,ecause t/e values of

T7: T2: and T are t/e same as t/ose in t/e c/annel re>uests9

'2( Call access and t/e su""lementary services suc/ as s/ort messa#e are all

normal9 T/e "ro,lem only e ists in t/e S0CC8 access related to location u"date9 T/is

indicates t/at t/e immediate assi#nment commands are sent correctly9

!9 Net$or% data com"arison 'for t/e s$a""ed offices and t/e offices $it/ se#mental

net$or%in#(

By com"arin# t/e data ,efore and after s$a""in# 'for s$a""ed offices( and t/e data

of t/e surroundin# cells 'for t/e offices $it/ se#mental net$or%in#(: $e find t/at t/e

"ro,lem also e ists in t/e net$or%s of ot/er com"anies9

4 Test )ethod

Immediate assi#nment success rate is a traffic measurement counter9

As t/e formulae of t/is counter in different manufacturers and o"erators are different

currently: you s/ould record t/e value of ot/er related counters and c/oose a "ro"er formula accordin# to t/e actual conditions9

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5Cases of (mmediate Assignment uccessRate &ptimi#ation

1 Case 7@ 0ecrease in Immediate Assi#nment Success Rate Because of

S0CC8 Con#estion Caused ,y Incorrect LAC Settin#

*roblem description

T/e S0CC8 con#estion rate of cell 2 in S7D7D7 confi#uration $as /i#/er t/an 4 :

and t/e immediate assi#nment success rate of t/at cell $as =3 9

Cause analysis and handling

'7( T/e m easurement counters of t/e TC8 and S0CC8 s/o$s t/at t/e traffic volume on

t/e TC8 is lo$: and t /e traffic volume "er cell in ,usy /ours is lo$er t/an 292 Erl /o$ever:

t/ere are many S0CC8 sei*ure re>uests ' 3 2 in ,usy /ours(: t/e traffic volume on t/e

S0CC8 is 7946 Erl: and t/e con#estion rate is /i#/er t/an 4 9

'2( T/e S0CC8 is mainly occu"ied ,y t/e si#nalin# ,efore t/e call is esta,lis/ed:t/e si#nalin# durin# /andover: t/e si#nalin# for location u"date in idle mode: and t/e

s/ort messa#es9

' ( As t/e traffic volume on t/e TC8: t/e num,er of TC8 sei*ure re>uests ' 74(: and

t/e num,er of /andover re>uests '7!6( are all normal: $e infer t/at t/e /i#/ S0CC8

sei*ure rate may ,e caused ,y too fre>uent location u"dates or too many s/ort

messa#es9

'!( T/e LAC of t/e cell is 3?33: ,ut t/e LACs of ot/er cells around t/is cell are all

3?239 After t/e LAC of t/e cell is c/an#ed to 3?23: t/e num,er of S0CC8 sei*ure

re>uests ,ecomes 2=4: t/e traffic volume on t/e S0CC8 ,ecomes 392; Erl: t/e

con#estion rate decreases to 3: and t/e immediate assi#nment success rate reac/es u"

to =? 9



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1$ Case 2@ S0CC8 Con#estion Caused ,y a Burst of Location ."dates

*roblem descriptionT/e immediate assi#nment success rate $as lo$ in a local net$or%9 Traffic statistics

s/o$ed t/at t/e "ro,lem $as mainly caused ,y S0CC8 con#estion on some sites9


'7( Traffic statistics s/o$s t/at t/e S0CC8 is occu"ied for 33 to !33 times in ,usy

/ours9 T/e con#ested cells are all in S7D7D7 confi#uration and eac/ cell is confi#ured $it/

ei#/t S0CC8sD49 In normal conditions: 33 to !33 times of S0CC8 sei*ures are

acce"ta,le: ,ut S0CC8 con#estion /a""ens for tens of times in eac/ cell9

'2( Traffic statistics s/o$ t/at most of t/e S0CC8 sei*ures are caused ,y location

u"date9 As most of t/e con#ested BTSs are located in t/e intersection areas of t$o

location areas alon# t/e rail$ay: $e dou,t t/at t/e S0CC8 con#estion may ,e caused ,y

a ,urst of location u"dates9

' ( After c/ec%in# t/e five5minute traffic statistics: $e find t/at most of t/e location

u"dates /a""ened $it/in a certain "eriod of five minutes9 T/e train timeta,le s/o$s t/atfour or five trains /ad "assed $it/in t/at five minutes9 1/en t/e trains "assed: a ,urst of

location u"dates $ere "erformed durin# a s/ort "eriod of time: t/us: t/e con#estion

/a""ened9

'!( +or t/e BTSs located in t/e intersection areas of t$o location areas alon# t/e

rail$ay: it is recommended t/at t/e S0CC8 dynamic assi#nment function ,e ena,led

and ade>uate S0CC8s ,e confi#ured9

1+ Case @ Lo$ Assi#nment Success Rate Because t/e RAC8 Minimum

Access Level Is Set to 3

*roblem description

Su,scri,ers of t/e cells controlled ,y a certain BSC com"lained t/at t/e success

rate of random access $as lo$9

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Cause analysis and handling:

'7( T/e cloc% status of t/e BTSs are normal9

'2( T/e value of "arameter T@ integer 0RAC! Timeslot2 is normal9 By analy*in#t/e data and traffic statistics: $e find t/at t/e "arameter RAC! )in Access +evel

of all t/e cells $it/ lo$ assi#nment success rate is set to 39 T/e immediate

assi#nment success rates of cells $/ose RAC! )in Access +evel are set to 7: :

or ?: /o$ever: are around == 9 Accordin# to t/e "revious data: $e infer t/at t/e

"ro,lem is caused ,y mista%en access9

' ( If RAC! )in Access +evel is set to 3: t/ere is no restriction on t/e random

access If RAC! )in Access +evel is set to 7: a call can access t/e cell only

$/en t/e level is /i#/er t/an Q73= dBm9

In S/antou .nicom: t/e RAC! )in Access +evel of most of t/e cells is set to 3 to

im"rove t/e "a#in# success rate9 T/is causes a #reat num,er of mista%en access

and finally causes lo$ assi#nment access rate9

In addition: t/e "arameter Random Access 9rror Threshold also /as error

restrictions on t/e access si#nals9'!( 1/en RAC! )in Access +evel and Random Access 9rror Threshold of all

t/e cells in module 7 of t/e BSC in S/antou .nicom are set to different values: t/e

results are as follo$s@

1/en Random Access 9rror Threshold and RAC! )in Access +evel are

set to 233 and 7 res"ectively: t/e mean immediate assi#nment success rate of

all t/e cells is =;9= an /our later



all t/e cells is =79=2 an /our later



all t/e cells is =;92! t/ree /ours later9

After discussin# $it/ t/e customer: $e decide to set Random Access 9rror



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Threshold and RAC! )in Access +evel of all t/e cells to 743 and

res"ectively9 In t/is $ay: mean immediate assi#nment success rate of all t/e

cells is /i#/er t/an =496 9

1, Case !@ Lo$ Immediate Assi#nment Success Rate in Some Cells

Because of MS Error

*roblem description

T/e "ersonnel on site re"orted t/at t/e immediate assi#nment success rate of some

cells $as lo$9


'7( As t/e "ro,lem e ists only in some cells: it may ,e caused ,y t/e MS error9

'2( Traffic statistics of t/e cells $it/ t/e "ro,lem s/o$ t/at t/e num,er of lin%

esta,lis/in# failures durin# location u"dates is a""ro imately e>ual to t/e num,er of

times t/at t/e setu" indication timer e "ires: as s/o$n in t/e follo$in# fi#ure9 T/is

indicates t/at t/e S0CC8 setu" failure is mainly caused ,y location u"dates9

' ( T/e si#nalin# of t/e cells $it/ "ro,lem s/o$s t/at #enerally t/e value of TA is

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in t/e follo$in# fi#ure9

'?( +or a s$a""in# "roJect: c/ec% $/et/er t/e "ro,lem e ists in t/e net$or% ,efore

s$a""in#9 If t/e "ro,lem e isted: t/en $e can infer t/at t/e "ro,lem is mainly

related to t/e MS9

6 &nsite (nformation that Needs to -e

&btained

79 Traffic statistics of t/e net$or% durin# one $ee% ,efore and after t/e "ro,lem

occurred9

- C5=:

'7( All t/e counters of t/e Access Capability )easurement < and Access

Capability )easurement = in - C &verall *erformance )easurement

'2( All t/e counters of Receive uality *erformance )easurement

' ( All t/e counters of t/e DCC! Assignment *erformance )easurement

and TC! Assignment *erformance )easurement in Channel Assignment

*erformance )easurement

'!( All t/e counters of DCC! *erformance )easurement : TC! *erformance

)easurement : and Random Access *erformance )easurement in Cell

*erformance )easurement 9

- CB777:

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'7( All t/e counters of Access )easurement per - C in - C )easurement

'2( All t/e counters of (nterference -and )easurement per TR, and Receive

uality )easurement per TR, in )R )easurement

' ( All t/e counters of Channel Configuration )easurement per Cell in

Channel )easurement

'!( All t/e counters of K*( )easurement per Cell : (mmediate Assignment

)easurement per Cell : and %lo' Control )easurement per Cell in Call

)easurement 9

29 0ata confi#uration and )MC data o"eration lo#s ,efore and after t/e "ro,lem

occurred9

9 0ata confi#uration file and en#ineerin# "arameters ta,le9

!9 1/et/er t/e net$or% o"timi*ation o"erations: suc/ as antenna adJustment:

fre>uency adJustment: and location area adJustment: are "erformed after t/e "ro,lem

occurred9

?9 Alarms #enerated ,efore and after t/e "ro,lem occurred: includin# commissionin#

alarms9

08 GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manual.doc

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