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

GSM GSM BSS BSS Netw Netwo ork KPI (Im (Immediat diatee Assig signme nment Su Success Rate Rate)) Op Optim timizati zatio on Ma Manua

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GSM GSM BSS BSS Netw Netwo ork KPI (Im (Immediat diatee Assig signme nment Su Success Rate Rate)) Op Optim timizati zatio on Ma Manua

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Author

GSM BSS Net$or% &PI 'Immediate Liu ui"ment +aults9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999997! 9292 .m Interface Pro,lem99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999997! 929 System Ca"acity 'Con#estion( Analysis99999999999999999999999999999999999999999999999999999999999999999999997= 929! MS Pro,lem Analysis9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999992! ! Test Met/od99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999926 ? Cases of Immediate Assi#nment Success Rate )"timi*ation999999999999999999999999999999999999999999999992; ?97 Case 7@ 0ecrease in Immediate Assi#nment Success Rate Because of S0CC8 Con#estion Caused ,y Incorrect LAC Settin#999999999999999999999999999999999999999999999999999999999999999999999992; ?92 Case 2@ S0CC8 Con#estion Caused ,y a Burst of Location ."dates99999999999999999999999999924 ?9 Case @ Lo$ Assi#nment Success Rate Because t/e RAC8 Minimum Access Level Is Set to 39999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999924 ?9! Case !@ Lo$ Immediate Assi#nment Success Rate in Some Cells Because of MS Error  3 6 )nsite Information t/at Needs to Be ),tained9999999999999999999999999999999999999999999999999999999999999999999999

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GSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manua

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Tables

Ta,le 7 Ma""in# ,et$een formulae and factors9999999999999999999999999999999999999999999999999999999999999999999999999973

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GSGSM BSS Network KPI (Immediate Assignment Success Rate) Optimization Manua

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GSM BSS Net$or% &PI 'Immediate Assi#nment Success Rate( )"timi*ation Manual Abstract Key Words: DCC!" immediate assignment success rate Abstract: This document provides the procedure for analy#ing the problems about immediate assignment success rate" describes the troubleshooting procedure" and provides typical cases$ Abbreviations: Abbreviation

BSC BTS S0CC8

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Base Station Controller   Base Tranceiver Station Stand5alone 0edicated Control C/annel

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1

&vervie'

of

the

(mmediate

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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>uired messa#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 BTS

MSC

BSC

Channel REQ Channl RQD A%

Channel ACT Channel ACT ACK IMM ASS CMD B%

first SABM UA EST IND(CM Service REQ)

C%

CR(CMP L inf!r"ati!n) CC CM Service Acce#te$

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

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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 sent9

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FF 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 immediate assi#nment success rate@ .m interface "ro,lems: S0CC8 con#estion: rece"tion of  $%,'%'+

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C8AN ACTIV NAC& ,ecause of e>ui"ment faults durin# S0CC8 activation: MS "ro,lems9 T/ese factors are related to t/e definition of t/e &PI9 T/ere are t/ree formulae t/at can define t/e immediate assi#nment success rate: t/e ma""in# ,et$een formulae and factors are as follo$s@ Ta,le 7 Ma""in# ,et$een formulae and factors

+ormula .m interface "ro,lems

Immediate Assi#nment Success Rate H  'Successful Immediate  Assi#nmentsDImmediate Assi#nment Re>uests(  733 Immediate Assi#nment Success Rate  'Successful Immediate Assi#nmentsD 'Immediate Assi#nment Re>uests 5 'Immediate Assi#nment Commands 5 Successful Immediate Assi#nments(((  733 Immediate Assi#nment Success Rate H  'Successful Immediate  Assi#nmentsDImmediate Assi#nment Commands(  733

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Affectin# +actor   Rece"tion S0CC8 of C8AN con#estion  ACTIV NAC& ,ecause of  e>ui"ment faults durin# S0CC8 activation H H

H

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MS "ro,lems

H

H

H

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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 TRui"men t faults

-C +evel

Cell +evel

BSC Measurement 5O Access measurement "er BSC 5O S0CC8 Availa,ility "er BSC Confi#ured S0CC8s "er BSC  Availa,le S0CC8s "er BSC

Call Measurement 5O C/annel Activation Measurement "er Cell 5O S0CC8 Connection Measurement "er Cell 5O C8AN ACTIV NAC& Messa#es Sent ,y BTS 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 $%,'%'+

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success rate9 Es"ecially in t/e areas $it/ a small s"ace ,et$een BTSs and dense BCC8 fre>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/e immediate assi#nment success rate and "a#in# success rate decrease: and t/e RAC8 may ,e overloaded9 ou can locate t/e "ro,lems ,y analy*in# t/e idle interference ,ands and 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

S0CC8 con#estion caused ,y interference

-C +evel

Cell +evel

TR, +evel

BSC Measurement 5O  Access measurement "er BSC 5O Random Access Success Ratio "er  BSC

Call Measurement 5O +lo$ Control Measurement "er  Cell 5O MSG CCC8 L)A0 IN0 'RAC8( Messa#es Sent on  A,is Interface

MR Measurement 5O  Analy*ed Measurement of Interference Band "er  TR< Receive Kuality Measurement "er TR<

%or the problem of mista.enly regarding interference as random access re/uests" you can locate the problem by performing signaling analysis on the Abis interface of the cell 'ith 'orst performance$

If t/e si#nalin# analysis result s/o$s t/at t/e random access si#nals are all from far  a$ay: for eam"le: t/e values of TA are /i#/er t/an 73: sometimes even /i#/er t/an 23: and t/e levels are lo$er t/an 5733 dBm: t/e random access success rate is /i#/ and t/e immediate assi#nment success rate is lo$: you can infer t/at t/e si#nals are interference9 To restrict t/e access of interference: reduce )A, TA  and increase RAC! )in Access +evel9

ou can c/ec% t/e follo$in# traffic statistics for reference@ Cause

Mista%enly  Access of  Interference on t/e $%,'%'+

-C +evel

Cell +evel

BSC Measurement 5O  Access measurement "er BSC 5O Random  Access Success Ratio

Call Measurement 5O Immediate  Assi#nment Measurement "er Cell 5O Immediate Assi#nment Analy*ed Measurement "er Cell 5O Call Setu"

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S0CC8

"er BSC

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Indications Timed )ut Call Measurement 5O Immediate  Assi#nment Measurement "er Cell 5O Immediate Assi#nment Analy*ed Measurement "er Cell 5O Success Rate of Random Access

+i#ure 2 s/o$s t/e contents of a c/annel re>uired messa#e9

+i#ure 2 C/annel re>uest si#nalin# Information element descri"tion@ 79 T/e meanin# of Random Access (nformation 01bits2  is as follo$s@ $%,'%'+

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Table 3$3456** T 78$71: C!ANN9+ R9;9T message content

MS codes ,its 4 9999 7

Accordin# to Esta,lis/ment cause@

737

Emer#ency call

773 Call re5esta,lis/ment TC8D+ $as in use: or  TC8D8 $as in use ,ut t/e net$or% does not set NECI ,it to 7 377373 Call re5esta,lis/ment TC8D8 $as in use and t/e net$or% sets NECI ,it to 7 377377 Call re5esta,lis/ment TC8D8  TC8D8 $as in use and t/e net$or% sets NECI ,it to 7 733 3373 3377 3337

Ans$er to "a#in# See ta,le =9=aDGPP TS 3!934

777 )ri#inatin# call and TC8D+ is needed: or ori#inatin# call and t/e net$or% does not set NECI ,it to 7: or  "rocedures t/at can ,e com"leted $it/ a S0CC8 and t/e net$or% does not set NECI ,it to 79 note 7 3733 )ri#inatin# s"eec/ call from dual5rate mo,ile station $/en TC8D8 is sufficient and su""orted ,y t/e MS for s"eec/ calls and t/e net$or% sets NECI ,it to 7 note ? 3737 )ri#inatin# data call from dual5rate mo,ile station $/en TC8D8 is sufficient and su""orted ,y t/e MS for data calls and t/e net$or% sets NECI ,it to 7 note ? 333

Location u"datin# and t/e net$or% does not set NECI ,it to 7

3333

Location u"datin# and t/e net$or% sets NECI ,it to 7

3337 )t/er "rocedures $/ic/ can ,e com"leted $it/ note 7 an S0CC8 and t/e net$or% sets NECI ,it to 7 377773 377773 377773

)ne "/ase "ac%et access $it/ re>uest for sin#le timeslot u"lin% transmission one P0C8 is needed9

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

377333 3773337 37733377

Reserved for future use

37777777

Reserved for future use9

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note 2

note 2a 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 is received ,y t/e net$or%: it may ,e i#nored9

29 T/e value of Access Delay indicates t/e TA9 9 Bits 7: 7!: 7?: and 76 indicate t/e RAC8 level and t/e num,er of error ,its in t/e trainin# 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 value of ,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@ ①

T/e transmit "o$er of TRuired9 If t/e con#estion rate and traffic volume of t/e S0CC8 are /i#/: ,ut t/e traffic volume of t/e TC8 is normal: t/e S0CC8 con#estion may ,e caused ,y ,urst traffic9 +or  t/e sites alon# t/e rail$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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+or t/e confi#uration of related "arameters: see section 92992 Con#estion Caused ,y Ina""ro"riate Parameter Confi#uration9 ou can c/ec% t/e follo$in# traffic statistics for reference@ Cause

-C +evel

Cell +evel

Con#estion caused ,y /eavy traffic on t/e S0CC8

BSC Measurement 5O  Access measurement "er BSC 5O Con#estion Ratio on S0CC8 "er BSC

Call Measurement 5O Immediate Assi#nment Measurement "er Cell 5O C/annel Re>uests "er Cell 5O C/annel Re>uests 'M)C(: C/annel Re>uests 'MTC(: C/annel Re>uests 'Emer#ency Call(: C/annel Re>uests 'Call Re5esta,lis/ment(: C/annel Re>uests 'Location ."datin#(: C/annel Re>uests 'Pac%et Call(: C/annel Re>uests 'LM.Reserved(: C/annel Re>uests 'Protocol Incom"ati,le( &PI Measurement "er Cell 5O S0CC8 Traffic Volume: S0CC8 Sei*ure Re>uests: +ailed S0CC8 Sei*ures due to Busy S0CC8

 +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 /eavy@

+i#ure  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 /eavy

Con#estion Caused ,y Ina""ro"riate Parameter Confi#uration An inappropriate parameter configuration may lead to the DCC! congestion$ The parameters related to DCC! congestion and their configurations are as $%,'%'+

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follo's:

79  CR&: Generally: it is recommended t/at an MS s/ould not cam" on a cell $it/ /i#/ traffic volume or lo$ KoS9 T/e "arameters of suc/ cells s/ould ,e set as follo$s@ firstly: set PT to 7: so t/at T) ,ecomes invalid9 Secondly: set C2 to t/e same value as CR) su,tracted from C7 so t/a t t/e value of C2 is reduced and t/us t/e "ossi,ility of  reselectin# t/is cell is reduced9 In addition: net$or% o"erators can set t/e CR) accordin# to

t/e actual conditions9 T/e #reater t/e CR) is: t/e more difficult it is for an MS to access t/e cell9 29 Cell Reselection !ysteresis 0CR!2: T/is "arameter is used to determine $/et/er cell reselection is "erformed ,et$een different location areas9 T/is "arameter  can "revent fre>uent location u"date: t/us minimi*e t/e "ossi,ility of losin# "a#in# messa#es9 Generally: t/is "arameter is set to 6 dB9 +or dual5,and net$or%s in ur,an areas not s/arin# t/e location areas: t/is "arameter is set to 4Q73 dB9 

If t/e traffic volume in an area is /i#/: and si#nalin# overload occurs fre>uently: it is recommend t/at you set t/e CR8 of t/e nei#/,orin# cells ,elon# to different LACs under t/is area to a lar#er value9



If t/e overla""in# area of t/e nei#/,or cells under different location areas is lar#e: it is recommended t/at you set t/e CR8 of t/e cells to a lar#er value9



If some areas ,et$een t$o nei#/,or cells under different location areas /ave "oor covera#e: or if most of t/e MSs in t/e area 'suc/ as /i#/$ays( move at a /i#/ s"eed: it is recommended t/at you set t/e CR8 of t/e cells to 2Q6 dB9

9 et the parameters related to DCC! dynamic ad>ustment as follo's: *arameter

S0CC8 0ynamic  Allocation  Allo$ed Idle S0CC8 T/res/old N7 $%,'%'+

Description

If t/is "arameter is set to ES: t/e dynamic conversion ,et$een t/e S0CC8 and t/e TC8 is ena,led9

 Accordin# to t/e c/annel assi#nment al#orit/m: $/en t/e num,er of idle S0CC8s in t/e cell is smaller t/an or e>ual to t/e value of t/is "arameter: t/e system -uawei !ec.noogies Proprietar/

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Cell S0CC8 C/annel Maimum

TC8 Minimum Recovery Time's(

IN!"RNA#

tries to find a TC8+ t/at can ,e converted into an S0CC89 T/is "arameter is one of t/e conditions for  t/e dynamic conversion from TC8+ to S0CC89  Accordin# to t/e c/annel assi#nment al#orit/m: t/e system determines $/et/er t/e num,er of S0CC8s in t/e cell after t/e conversion eceeds t/e value of Cell S0CC8 C/annel Maimum ,efore initiatin# t/e dynamic conversion from TC8 to S0CC89 If yes: t/e conversion is not initiated9 T/is "arameter s"ecifies t/e minimum time for t/e recovery 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 CCC89



T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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to 2 seconds9 If t/e len#t/ of T777 is too lon#: t/e S0CC8 con#estion rate is increased9

?9  RAC! )in Access +evel @ If t/e value of t/is "arameter is too small: muc/ interference may access t/e net$or%: t/us leadin# to S0CC8 con#estion9 If t/e value of  t/is "arameter is too lar#e: it is "ro,a,le t/at MSs cannot ma%e t/e call even t/ou#/ t/e si#nal level is /i#/9 T/is "arameter s/ould ,e set on t/e ,asis of t/e actual receiver  sensitivity of t/e BTS: t/e minimum access level of t/e MS: and t/e interference condition9 69 +ate assignment@ T/is function is set at t/e MSC side9 If t/is function is ena,led: t/e call is on t/e S0CC8 ,efore t/e called MS ans$ers9 T/is "rolon#s t/e time $/en t/e S0CC8 is occu"ied and t/us may cause S0CC8 con#estion9 ;9 R,+9V?ACC9?)(N@ If t/is level is too lo$: a lar#e num,er of MSs may access t/e net$or%: and S0CC8 con#estion may occur durin# call initiation or location u"date9 In addition: interference si#nal may ,e mista%enly re#arded as t/e random access si#nals9 +or details: see Case 59 49 T@integer @ 1/en t/e net$or% traffic is /eavy: t/e success rate of immediate assi#nment is lo$ if t/e sum of S and T is small9 T/us: t/e value of T s/ould ,e "ro"erly adJusted to ma%e t/e sum of S and T #reater9 +or details a,out t/e value of S: see t/e descri"tion of T@integer 9 =9 Cell -ar Access 0C-A2@ 3@ cell access allo$ed 7@ cell access "ro/i,ited9 To#et/er $it/ C-: C-A determines t/e "riority of a cell9 +or details: see t/e GSM 3!934 "rotocol9 C-

3 3 7 7 $%,'%'+

C-A

3 7 3 7

Cell

election

Cell Reselection

*riority

*riority

Normal Pro/i,ited Lo$ Lo$

Normal Pro/i,ited Normal Normal

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739 Cell -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$s t/at t/e num,er of re>uest retransmissions and t/e retransmission interval of t/e failed location u"dates meet t/e confi#uration re>uirements9 If all t/e "revious sym"toms eist: you can infer t/at t/e "ro,lem is lo$ 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$or% side currently9 To im"rove t/e user satisfaction: do as follo$s@ $%,'%'+

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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(9





Increase t/e len#t/ of t/e follo$in# timers@ T5uests '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 description

T/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 Cause analysis and handling

'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/at four 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



1/en Random Access 9rror Threshold and RAC! )in Access +evel are set to 233 and 3 res"ectively: t/e mean immediate assi#nment success rate of  all t/e cells is =79=2 an /our later



1/en Random Access 9rror Threshold and RAC! )in Access +evel are set to 743 and 7 res"ectively: t/e mean immediate assi#nment success rate of  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 Cause analysis and handling

'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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small and t/e level is /i#/9 T/is indicates t/at t/e "ro,lem is not caused ,y interference9 But after t/e BSS sends t/e immediate assi#nment command and $aits for t/e MS to access: t/e u"lin% si#nal stren#t/ detected ,y t/e BTS is al$ays lo$er t/an Q773 dBm9 T/is indicates t/at t/e MS does not re"ort t/e lin% esta,lis/in# indication and t/us causin# t/e immediate assi#nment failure9

In addition: $e c/ec% $/et/er location u"dates are initiated ,y a same MS and $/et/er t/e num,er of location u"dates is in com"liance $it/ t/e net$or% settin#9 T/e follo$in# fi#ure s/o$s t/e si#nalin# ca"tured in t/e local net$or%9 As can ,e seen: t/e location u"dates are mainly initiated ,y a same MS and t/e maimum num,er of  retransmissions of t/e location u"date re>uest set on t/e net$or% is five9

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T/e "arameters associated to c/annel re>uest are confi#ured as follo$s@

'!( Cell ,ar access 'CBA( status modification test9  After t/e CBA of a cell is ena,led: t/e system information of t/e cell $ill carry a fla# ,it9 T/e MSs t/at receive suc/ system information $ill not consider t/at cell durin# cell reselection: and t/e num,er of location u"date re>uests to t/e nei#/,orin# cells increases9  After t/e CBA is ena,led: t/e immediate assi#nment &PIs ,ecome ,etter: as s/o$n $%,'%'+

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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