GSM BSS Network KPI (Network Interference) Optimization Manual INTERN! Product Name Confidentiality Level G3BSC INTERNAL Product Version Total !a"es GSM BSS Network KPI (Network Interference) Optimization Manual ("or internal u#e onl$) Prepared by GSM%&MTS Network Performanc e Re#earc' epartment Su S'i Date **+,-,./ Reviewed by Date Reviewed by Date Approved by Date 0uawei Tec'nolo1ie# 2o34 !t53 ll ri1't# re#er6e5
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.3. S$mptom# of Network Interference33333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333338
.3 2la##ification of Interference Source# in t'e GSM S$#tem3333333333333333333333333333333333333333333333333333333333333333333333333333333:
2 Approaches to Finding nter!erence Prob"e#s...............................12
3. "in5in1 t'e Interference T'rou1' nal$#i# of OM2 Traffic Stati#tic#333333333333333333333333333333333333333333333333333333333333.
Interference i# one of t'e ke$ factor# t'at affect t'e network ;ualit$3 It 1reatl$ affect# t'e 6oice
;ualit$4 an5 cau#e# call 5rop#4 'an5o6er#4 an5 con1e#tion3 0ow to re5uce or eliminateinterference i# one of important ta#k# in network plannin1 an5 optimization3
T'e call i# 5i#connecte5 after t'e caller 'ear# a >eep (t'e prompt tone 6arie# wit'MS#)3
Coice 5i#continuit$4 noi#e4 or no au5io occur# 5urin1 t'e call3 In #eriou# ca#e#4 a call5rop ma$ occur3
3 &'en interference e(ists in a net$or+) t'e follo$in" sym!toms may %e found in t'e
traffic statistics*
T'e uplink interference i# reflecte5 in t'e traffic #tati#tic# for interference >an5#3 Doucan c'eck w'et'er interference eAi#t# >a#e5 on t'e #ettin1# of interference >an5t're#'ol5# an5 t'e actual application #cenario#3 If loo#e fre;uencie# are planne5 in ane51e network4 t'e fre;uenc$ reu#e 5en#it$ i# low3 In t'i# ca#e4 if interference >an5 i# 5i#pla$e5 in t'e traffic #tati#tic#4 interference ma$ occur3 "or an ur>an area wit''i1' fre;uenc$ reu#e 5en#it$4 if interference >an5 7 or 9 i# 5i#pla$e5 in t'e traffic#tati#tic#4 interference ma$ occur3
T'e num>er of faile5 S220 or T20 a##i1nment# i# 1reat3
T'e num>er of call 5rop# i# 1reat or t'e call 5rop rate i# 'i1'3
TR< fault If t'e performance of t'e TR< 5ecrea#e# >ecau#e of t'e pro5uction;ualit$ or lon1,term u#e4 t'e amplif$in1 circuit of t'e TR< ma$ >e #elf eAcite53 In
t'i# ca#e4 interference occur#3
2& or 5i6i5er fault F'en t'e acti6e amplifier in t'e 5i6i5er of t'e 2& or t'e5i6i5er mo5ule i# fault$4 #elf eAcitation ma$ occur3
Spuriou# emi##ion an5 intermo5ulation If t'e out>an5 #puriou# emi##ion of t'e TR<or power amplifier in a BTS eAcee5# t'e #pecifie5 t're#'ol54 or t'e R<@T< i#olationof t'e 5upleAer in t'e 2& i# too #mall4 t'e R< c'annel i# interfere53 "or pa##i6e5e6ice# #uc' a# antenna# an5 fee5er#4 t'e intermo5ulation interference ma$ al#ooccur3
Interference from #ur1e protector# F'en t'e #ur1e protector i# a1e5 or t'e #peec';ualit$ >ecome# poor4 intermo5ulation #i1nal# appear in t'e BTS3 In t'i# ca#e4 t'enormal fre;uenc$ plan i# affecte5 an5 t'e ra5io en6ironment i# 5eteriorate53
"re;uenc$ reu#e i# re;uire5 in t'e GSM #$#tem3 F'en t'e reu#e 5i#tance >etweentwo cell# t'at u#e t'e #ame fre;uenc$ or a5?acent fre;uencie# i# too #mall relati6e tot'e cell ra5iu#4 co,c'annel interference or a5?acent,c'annel interference ma$ occur3 Ina55ition4 t'e reflection of #urface feature# can al#o cau#e co,c'annel interference ora5?acent,c'annel interference3 F'en 2@I . 5B or 2@Ia H8 5B4 interferenceoccur#3
Interference from repeater#
In t'e initial p'a#e of network con#truction4 repeater# are u#e5 to eAten5 t'e co6era1eof t'e BTS3 If repeater# are u#e5 improperl$4 t'e BTS i# interfere53 T'e po##i>le
cau#e# for t'e interference from repeater# are a# follow# (.) Repeater# are in#talle5
#pecification# are muc' 1reater t'an t'o#e re;uire5 >$ t'e protocol3 If t'e power i#lar1e4 t'e intermo5ulation component i# lar1e3 In t'i# ca#e4 a5?acent BTS# areinterfere53 "or ca#ca5e5 repeater#4 a# t'e co,c'annel amplification i# performe5 fort'e repeater# an5 it take# a certain time for t'e repeater# to proce## #i1nal#4 5ela$eAi#t# >etween #i1nal#3 F'en t'e 5ela$ eAcee5# t'e time win5ow #ize #pecifie5 fort'e GSM #$#tem4 t'e co,c'annel interference occur#3
Intermo5ulation interference
Generation of intermo5ulation #i1nal# an5 t'eir impact on t'e GSM network mu#t >econ#i5ere5 in network plannin1 an5 optimization3 In nature4 w'en two R" #i1nal# areinput to a non linear component or pa## t'rou1' a 5i#continuou# tran#mi##ionme5ium4 a #erie# of new fre;uenc$ component# are 1enerate5 5ue to t'e non linearit$3T'e fre;uenc$ component# of new #i1nal# meet t'e followin1 fre;uenc$ relation3
##ume t'at t'e fre;uencie# of t'e two input #i1nal# are f. an5 f (a>#olutefre;uencie#)3 T'e formula# are a# follow#
"n J mf. nf an5 "n J mf. , nf
# t'e amplitu5e of t'e t'ir5 or5er an5 fift' or5er intermo5ulation pro5uct# i# 'i1'4t'e common component# are t'ir5 or5er an5 fift' or5er intermo5ulation component#3T'ir5 or5er intermo5ulation i# taken a# an eAample 'ere3
# t'e #pectrum component# of f.,f an5 f,f. are t'e clo#e#t to t'eir own #i1nal#4t'e #$#tem i# interfere5 mo#t po##i>l$ >$ t'e#e #pectrum component#3 "i1ure 3. #'ow# t'e #pectrum 5i#tri>ution3
8i"ure 491 Spectrum 5i#tri>ution of intermo5ulation #i1nal#
¡ ÷f ¡ ÷f ¡ ÷f
f1 f2
2f2-f12f1-f2
IM3
T'e amplitu5e of a new #i1nal 5epen5# on t'e non linearit$ of t'e component or t'e5i#continuit$ of microwa6e tran#mi##ion3 T'e t'ir5 or5er intermo5ulation in5eA (IM-) i#u#e5 for mea#urement3 IM- refer# to t'e 5ifference >etween t'e t'ir5 or5erintermo5ulation pro5uct 1enerate5 5ue to t'e non linearit$ of t'e #$#tem an5 t'e input#i1nal# w'en two e;ual,amplitu5e #i1nal# wit' a certain le6el are input3 Generall$4 a#IM- meet# t'e re;uirement#4 t'e fre;uencie# of t'ir5 or5er intermo5ulation are notcon#i5ere5 in fre;uenc$ plannin13 "or a 5ual,>an5 network (t'e antenna #$#tem i##'are5) or a wi5e>an5 network4 'owe6er4 t'e t'ir5 or5er intermo5ulation 1enerate5 on
#i1nal#4 an5 t'e po##i>le cau#e# of intermo5ulation 1eneration are a# follow# T'e input connector of t'e antenna i# unclean or mec'anicall$ 5ama1e54 t'e internal
#il6er la$er i# 5ama1e5 5ue to multiple in#ertion# an5 remo6al#4 or metal filin1# areleft in t'e connector3
T'e antenna connector i# not in#talle5 #ecurel$3
T'e antenna element# en6elope5 in t'e protection co6er are corro5e53
T'e fee5er part >etween t'e input connector of t'e antenna an5 t'e antenna elementi# corro5e53
T'e recei6er i# interfere5 >$ t'e intermo5ulation pro5uct w'en t'e followin1con5ition# are met
T'e intermo5ulation pro5uct fall# off in t'e R< >an53
T'e intermo5ulation pro5uct mu#t reac' a certain le6el3 ccor5in1 to t'ere;uirement# of t'e co,c'annel interference an5 BTS #en#iti6it$ H..* 5Bm4 t'emaAimum #i1nal le6el of t'e intermo5ulation pro5uct on t'e antenna port mu#t meett'e followin1 re;uirement H..* 5Bm H / 5B (#uppre##ion factor of t'e co,c'annelinterference) 8 5B (lo## of t'e 8* m fee5er ca>le) J H..- 5Bm3
"or t'e fir#t con5ition4 a##ume t'at t'e intermo5ulation pro5uct of two T< #i1nal# ofM/** fall# off in t'e R< >an53
T'e noi#e i# 6er$ o>6iou# w'en te#t call# are ma5e for cell of a BTS3 T'efre;uencie# in t'e cell are #e;uentiall$ .*/4 +:4 .+4 an5 /83 T'e 5ownlink a>#olutefre;uencie# of fre;uenc$ /8 an5 fre;uenc$ .+ are calculate5 a# follow#
2ompare5 wit' ot'er counter#4 t'e interference >an5 counter more 5irectl$ reflect# t'einterference of a cell (t'e mea#urement 6alue of interference #i1nal# in t'e ran1e of H..* 5Bm
to H.*9 5Bm i# inclu5e5 in interference >an5 .)3 T'e interference >an5 counter can onl$reflect w'et'er t'e uplink fre;uenc$ i# interfere53
If a lar1e num>er of interference #i1nal le6el# fall in interference >an5 7 an5 interference >an59 in a cell4 co,c'annel interference occur# in t'e cell3 If a lar1e num>er of interference #i1nalle6el# fall in interference >an5 . an5 interference >an5 4 interference ma$ not occur3 If alar1e num>er of interference #i1nal le6el# fall in interference >an5 -4 interference ma$ occur32on#i5erin1 5ifferent fre;uenc$ reu#e pattern#4 interference ma$ occur in an e51e networkwit' wi5e co6era1e e6en if t'e 6alue eAi#t# in interference >an5 3
T'e BTS #can# uplink fre;uencie# >$ i5le time#lot# to mea#ure interference >an5#3 If t'etraffic 6olume of a cell i# lar1e an5 t'e c'annel u#a1e i# 'i1'4 t'e mea#urement 6alue in t'einterference >an5 i# #mall3 In t'i# ca#e4 t'e interference cannot >e reflecte5 properl$3 To
5etermine w'et'er interference occur# on a TR<4 $ou nee5 to 6iew t'e mea#urement counter#relate5 to c'annel allocation3 T'e mea#urement o>?ect i# a TR<3
2.1.2 Finding the nter!erence *hrough Fre3uency&canning Per!or#ance 0easure#ent
T'i# function i# u#e5 to #can t'e uplink R< le6el# of all fre;uencie# on t'e GSM/**fre;uenc$ >an5 (+/* M0z to /.9 M0z)4 GSM.+** fre;uenc$ >an5 (.+*9 M0z to .++*M0z)4 E,GSM eAten5e5 fre;uenc$ >an5 (++* M0z to +/* M0z)4 an5 R,GSM eAten5e5fre;uenc$ >an5 (+:8 M0z to ++* M0z)3 T'at i#4 t'e interference #i1nal #tren1t' on t'efre;uenc$ >an5# +:8 M0z to /.9 M0z an5 .+*9 M0z to .++* M0z i# #canne53 T'e uplinkfre;uenc$ #cannin1 function i# u#e5 to te#t t'e interference3 T'at i#4 t'e function i# u#e5 to te#tt'e uplink le6el3 T'e mea#urement re#ult reflect# t'e #i1nal #tren1t' of mea#urementfre;uencie# recei6e5 in t'e cell to pro6i5e a reference for en1ineer# to #elect properfre;uencie#3
2.1.$ Finding the nter!erence *hrough R4 5ua"ityand %eve" Per!or#ance 0easure#ent
Ba#e5 on t'e R< le6el mea#urement re#ult an5 R< ;ualit$ mea#urement re#ult4 $ou cananal$ze t'e co6era1e an5 interference of ra5io #i1nal# in a cell3 If t'e le6el i# 'i1' an5 t'e;ualit$ i# poor4 interference ma$ occur3 If t'e le6el i# low an5 t'e ;ualit$ i# poor4 t'e co6era1ema$ >e in#ufficient3 T'e mea#urement counter# can >e u#e5 to locate t'e fault# t'at occur on
interference an5 a5?acent,c'annel interference3 T'e mea#urement o>?ect# relate5 to t'e R<;ualit$ an5 le6el mea#urement counter# are TR<#3
2.2 O0C A"ar#s and &ubscriber Co#p"aintsT'e OM2 alarm con#ole can report 'ar5ware fault# on t'e BTS #i5e in time3 Before #tartin1to locate an interference #ource4 $ou mu#t anal$ze t'e alarm information3 Before t'eoptimization4 it i# nece##ar$ to rectif$ 'ar5ware fault#3
Dou cannot c'eck t'e potential interference from t'e MS or ot'er BTS# accor5in1 to t'e alarminformation on t'e alarm con#ole3
Dou can fin5 t'e potential interference accor5in1 to #u>#cri>er complaint#3 T'e informationrelate5 to #u>#cri>er complaint# inclu5e# t'e mo>ile num>er4 mo>ile mo5el4 calle5 num>er4fault #$mptom# on t'e callin1 #i5e4 fault #$mptom# on t'e calle5 #i5e4 an5 #pecific locationw'en t'e fault occur#3 If t'e 5etaile5 complaint information i# collecte54 $ou can ea#il$ fin5network pro>lem#3
Generall$4 t'e complaint information i# incomplete3 T'i# i# >ecau#e a #u>#cri>er ma$ notun5er#tan5 t'e cellular network completel$ or #pecif$ t'e interference #ource3 F'eninterference occur# on a network4 t'e #u>#cri>er 1enerall$ complain# a>out t'e followin1con5ition# (.) T'e noi#e i# 'i1' () T'e peer 6oice i# unclear (-) T'e local 6oice i# unclear(7) T'e call 5rop# (9) 2all# cannot >e ma5e3 T'erefore4 w'en man$ #u>#cri>er# complaina>out t'e #ame pro>lem in an area4 $ou nee5 to c'eck w'et'er interference occur# in t'e area3
2.$ Finding the nter!erence *hrough D* andC5*
T'e T i# t'e mo#t common approac' to fin5in1 interference3 Dou nee5 to c'eck w'et'er t'einterference foun5 t'rou1' anal$#i# of t'e prece5in1 counter# an5 #u>#cri>er complaint# eAi#t# >$ con5uctin1 t'e T (T can >e u#e5 to c'eck onl$ t'e 5ownlink interference)3 Generall$4two t$pe# of T# are a6aila>le i5le mo5e te#t an5 5e5icate5 mo5e te#t3
In an i5le mo5e te#t4 $ou can u#e te#t 5e6ice# to te#t t'e #i1nal le6el of t'e #er6in1 cell an5t'o#e of t'e nei1'>orin1 cell#3 Dou can al#o u#e a fre;uenc$ #canner to te#t t'e #pecifie5fre;uencie# or fre;uenc$ >an5#3 T'e roun5,trip te#t# mu#t >e performe5 aroun5 t'e BTS3
In a 5e5icate5 mo5e te#t4 $ou can u#e te#t 5e6ice# to te#t t'e #i1nal le6el4 R< ;ualit$4 powercontrol le6el4 an5 timin1 a56ance (T) of t'e #er6in1 cell an5 t'o#e of t'e nei1'>orin1 cell#3If t'e continuou# 'i1' le6el ( -*) an5 poor R< ;ualit$ (RA=ual 9) are 5etecte5 in an area4it in5icate# t'at t'e ! interference eAi#t# in t'e area3 Some te#t 5e6ice# can 5i#pla$ t'e frameerror rate ("ER)3 F'en t'e "ER i# 1reater t'an 94 6oice 5i#continuit$ occur#3 T'at i#4interference eAi#t# in t'e area3 Note t'at t'e mea#ure5 "ER of NT i# inaccurate3
T'e #peec' ;ualit$ te#t (2=T) mean# t'at te#t call# are ma5e in #ome important place# or t'earea wit' #u>#cri>er complaint# to #u>?ecti6el$ c'eck w'et'er 6oice 5i#continuit$4 metal#oun54 or acce## failure occur#3 T'e #i1nal le6el of t'e #electe5 te#t point mu#t >e 'i1'er t'an H/* 5Bm3
2.( Finding the nter!erence *hrough &igna"ing*racing
F'en performin1 t'e T for a cell4 $ou can al#o trace >i# #i1nalin1 of t'e cell3 Ba#e5 on t'emea#urement report4 $ou can c'eck w'et'er t'e uplink interference occur#3
2.+ Finding the nter!erence by *rans#ittingd"e ursts on the *R4
F'en t'e traffic 6olume i# #mall4 $ou can mea#ure t'e interference >an5 in a cell an5 t'entran#mit i5le >ur#t# on all t'e TR<# of t'e cell3 In t'i# ca#e4 if t'e le6el of t'e interference >an5 increa#e# (for eAample4 interference >an5 . >ecome# interference >an5 or a 'i1'er
Mo#t OM2 alarm# are relate5 to 'ar5ware fault#4 (for eAample4 no power i# tran#mitte5 5ue to completelo## of t'e TR<) performance 5e1ra5e4 an5 #elf eAcitation3 "or #ome potential fault#4 for eAample4 t'eR< performance of t'e TR< or 2& fall#4 no alarm information i# reporte53
$.1.$ Chec,ing Fre3uency P"anning
Dou can c'eck t'e fre;uenc$ plannin1 of a cell an5 it# nei1'>orin1 cell# to 5etermine w'et'er t'e cell i# interfere53 It i# recommen5e5 t'at $ou u#e a fre;uenc$ plannin1 c'eck tool (for
If t'e 2RO i# #et to a lar1e 6alue4 t'e MS 1ain# acce## to an i5le cell w'o#e R< le6el i# lowert'an t'o#e of t'e nei1'>orin1 cell#3 F'en t'e call i# ma5e an5 t'e 2@I 6alue i# #maller t'an .5B4 interference occur#3
If a nei1'>orin1 cell i# not confi1ure54 t'e MS cannot >e 'an5e5 o6er to a cell wit' 'i1'#i1nal le6el an5 1oo5 ;ualit$3 In t'i# ca#e4 interference occur#3 If t'e 'an5o6er t're#'ol5 or t'eP@N criterion i# #et to a lar1e 6alue4 'an5o6er# cannot >e ea#il$ performe5 >etween cell#3 In
If t'e "0 parameter# (#uc' a# MIO4 0SN4 an5 M) are confi1ure5 improperl$4 #tron1fre;uenc$ interference occur#3
$.1.+ D*
T'e T i# an effecti6e approac' to locatin1 interference pro>lem#3 T'e location approac' i##imilar to t'at 5e#cri>e5 in #ection 3-3 T'e 5ifference i# t'at t'e interfere5 cell i# te#te5 in t'elocation p'a#e3
$.1.6 %ocating the nter!erence *hrough a &pectru#Ana"y7er
Before 5eterminin1 t'e location of an inter,network interference #ource4 $ou can performfre;uenc$ #cannin1 te#t# for t'e interfere5 area# >$ t'e BTS antenna (t'at i#4 fre;uenc$#cannin1 te#t# for t'e local BTS)3
8i"ure 191 2onnection te#t of t'e local BTS t'rou1' t'e #pectrum anal$zer
Dou can u#e MS@T<,Te#t an5 0!,O&T port# on t'e BTS 2& to locate eAternal interference3T'e two port# can >e u#e5 to te#t R< #i1nal# of t'e antenna wit'out affectin1 t'e runnin1 of
t'e BTS30sT;7Test !ort T'i# port i# locate5 at t'e front en5 of t'e 2&3 Dou can connect t'e portto t'e #pectrum anal$zer to 6iew all #i1nal #pectrum# recei6e5 >$ t'e antenna3 2on#i5erin1 t'e >an5wi5t' of t'e antenna4 t'e #i1nal #pectrum# 5i#tri>ute5 in t'e ran1e of +** M0z to .***M0z can >e normall$ te#te53 # t'ere i# a couplin1 5e1ree of -* 5B >etween t'e antenna an5t'e M#@T<,Te#t port4 an5 t'e >ack1roun5 noi#e eAi#t# on t'e #pectrum anal$zer4 #mall #i1nal#pectrum# cannot >e te#te53 Generall$4 t'e te#t port i# u#e5 w'en lar1e #i1nal# an5 GSM R<out>an5 fre;uenc$ #cannin1 are te#te53
In t'e formula4 in5icate# t'e #i1nal amplitu5e te#te5 on t'e M#@T<,Te#t port an5 in5icate#t'e #i1nal amplitu5e on t'e top R" port of t'e BTS ca>inet3
C-< 6L7=<T !ort Dou can connect t'e 2& 0!,O&T port to t'e #pectrum anal$zer wit'a ca>le to locate eAternal interference3 T'e connection 'a# t'e followin1 a56anta1e#
T'e #er6ice# on t'e BTS are not 5i#rupte5 an5 t'e #i1nal #pectrum# recei6e5 >$ t'e BTS
antenna can >e monitore5 w'en t'e BTS work#3
T'e recei6e5 #mall #i1nal# can >e amplifie5 to re5uce t'e >ack1roun5 noi#e of t'e
#pectrum anal$zer3
# t'e 1ain of t'e tri>utar$ from t'e T<@R< NT to 0!,O&T port i# 5B on t'e R<fre;uenc$ >an54 t'e 6alue 5B i# 5e5ucte5 from t'e #i1nal amplitu5e te#te5 on t'e 2&0!,O&T port to o>tain t'e #i1nal amplitu5e te#te5 on t'e top R" port of t'e BTS ca>inet3 T'eamplitu5e of te#t #i1nal# i# calculate5 a# follow#
'a# t'ree cell#3 Dou can connect t'e #pectrum anal$zer to t'e te#t port# of t'e 2&# int'e t'ree cell# to capture t'e interference #i1nal an5 recor5 t'e fre;uenc$4 amplitu5e4#pectrum 1rap'ic#4 an5 #i1nal c'aracteri#tic# of t'e interference #i1nal3 In a55ition4 $oucan 5etermine t'e cell 5irection of t'e interference #ource >$ anal$zin1 t'e amplitu5ean5 fre;uenc$ of t'e interference #i1nal recei6e5 >$ t'e t'ree cell#3
fter 5eterminin1 t'e interfere5 cell4 $ou nee5 to te#t it# nei1'>orin1 cell#4 e#peciall$ t'enei1'>orin1 cell# pointin1 to t'e interfere5 cell3 T'e te#t met'o5 i# a# follow# 2onnectt'e #pectrum anal$zer to t'e te#t port of t'e 2& in t'e cell4 an5 t'en recor5 t'efre;uenc$4 amplitu5e4 #pectrum 1rap'ic#4 an5 #i1nal c'aracteri#tic# of t'e interference#i1nal3 If multiple #pectrum anal$zer# are u#e5 to #imultaneou#l$ te#t multiple cell#4 t'eefficienc$ of capturin1 t'e interference #i1nal #ource i# 'i1'3
fter multiple te#t# >$ t'i# met'o54 $ou can anal$ze te#t recor5# in eac' cell an5 t'enfin5 t'e cell# w'ere t'e amplitu5e an5 fre;uenc$ of t'e interference #i1nal are 'i1'3fter fin5in1 t'e o6erlappe5 area of t'e cell#4 $ou can 5etermine t'e approAimate areaw'ere interference occur#3
3 Locatin" e(ternal interference sources
Set t'e #pectrum anal$zer to work in a proper #tate3 T'e parameter #ettin1# of t'e /**M0z BTS are a# follow# f* J /* M0z4 SPN J -* M0z4 TT J *4 RBF J -* k0z4an5 CBF J -* k0z3 T'e parameter #ettin1# of t'e .+** M0z BTS are a# follow# f*J .:.9 M0z4 SPN J .* M0z4 TT J *4 RBF J -* k0z4 an5 CBF J -* k0z3
Select t'e output port of t'e 5i6i5er in t'e interfere5 cell3 To en#ure t'at t'e BTSwork#4 $ou mu#t #elect an i5le output port connecte5 to t'e loa5 (eit'er main or5i6er#it$ i# a6aila>le)3
!oo#en t'e #electe5 connector4 an5 t'en intro5uce t'e output #i1nal of t'e 5i6i5er tot'e #pectrum anal$zer wit' a coaAial ca>le3 Dou mu#t pre6ent a lar1e input powerfrom 5ama1in1 t'e meter3
2'eck t'e #pectrum 5i#tri>ution on t'e #pectrum anal$zer4 an5 t'en fin5 t'e a>normalinterference #i1nal3 T'e le6el of t'e interference #i1nal i# calculate5 a# follow#Interference le6el on t'e antenna port J Interference le6el te#te5 >$ t'e #pectrumanal$zer H 5B - 5B of ca>le lo##
"or eAample Interference le6el on t'e antenna port J H89 5Bm H .9 - H : J H+75Bm3 Note T'e ca>le lo## 6arie# wit' 5ifferent ca>le len1t'#3 Dou can c'eck w'et'er t'e interference le6el affect# t'e #$#tem >$ t'e followin1 #tan5ar5#
(.) F'en MaAimum interference le6el on t'e antenna port J H.*+ 5Bm (a##ume5
#en#iti6it$) H / 5B of co,c'annel interference J H..: 5Bm4 t'e #$#tem i# not affecte53
() F'en MaAimum interference le6el on t'e output port of t'e 5i6i5er J H..: 5Bm .9 H - : J H/+ 5Bm4 t'e #$#tem i# not affecte53
-3 Searc'in" e(ternal interference sources
Dou can 5etermine t'e approAimate 5irection of t'e interference #ource >$ t'e output port of t'e BTS 5i6i5er3 To locate t'e interference #ource4 $ou nee5 to u#e a 5irectionalantenna for #earc'3 T'e operation proce5ure i# a# follow#
.) Select a te#t point t'at i# not >locke5 >$ >uil5in1# in t'e interfere5 cell3 Set t'e#pectrum anal$zer an5 in#tall t'e 5irectional antenna properl$3
) Place t'e antenna on a rotar$ platform if a6aila>le wit' t'e >eam of t'e antenna pointin1 to t'e front 5irection an5 6ertical polarization u#e53
8i"ure 194 !ocation of t'e Da1i,&5a 5irectional antenna
-) # #'own in t'e prece5in1 fi1ure4 if t'e polarization mo5e of t'e interference#ource i# 5ifferent from t'at of t'e monitorin1 antenna4 t'e recei6e5 #i1nal i# weakan5 t'e interference cannot >e foun5 ea#il$3 In t'i# ca#e4 $ou mu#t turn t'e Da1i,&5aantenna >$ /* 5e1ree# (t'e antenna 5irection remain# unc'an1e5)3
7) nal$ze t'e 5i#tri>ution of #i1nal #pectrum# to 5etermine t'e interference #i1nalan5 recor5 t'e #i1nal #tren1t' an5 t'e azimut' an5 pitc' an1le of t'e 5irectionalantenna >eam3
9) Searc' for a new te#t point alon1 t'e 5irection of t'e antenna >eam4 an5 t'en return#tep for te#tin1 until t'e interference #ource i# foun53
8) If t'e 5irection# of t'e interference #ource are te#te5 in t'e two te#t point#4 t'einter#ection of t'e two 5irection# i# t'e approAimate location of t'e interference#ource3 Dou can #earc' for t'e interference #ource aroun5 t'e inter#ection3
Generall$4 a #tron1 interference #i1nal can >e te#te5 >$ t'e DBT9* near t'e interference
#ource3 Dou nee5 to c'eck w'et'er t'ere i# a #c'ool4 a 1o6ernmental or1an4 or aconfi5ential unit t'at ma$ u#e interference e;uipment3
If interference i# foun54 $ou mu#t re;ue#t t'e cu#tomer to eliminate t'e interference3
$.1.8 9p"in, Fre3uency &canner !or d"e *R4s
If t'e time w'en t'e inter,network interference occur# i# 5etermine54 $ou can u#e a #pectrumanal$zer for timel$ te#t >a#e5 on t'e time3 F'en c'eckin1 t'e inter,network interference4'owe6er4 $ou cannot ea#il$ 5etermine t'e time rule of interference #i1nal#3 fter performin1te#t# for a lon1 time >$ t'e #pectrum anal$zer4 $ou ma$ i1nore or not fin5 interference #i1nal#3T'e #cannin1 time of t'e #pectrum anal$zer (for eAample4 DBT9*) u#e5 in a pro?ect cannot >e 5ecrea#e5 to a #mall 6alue (t'e 6alue i# 9* m# 1enerall$4 t'at i#4 it take# 9* m# for t'e
#pectrum anal$zer to #can t'e entire #pectrum)3 T'erefore4 if $ou 5o not 1ra#p t'e time rule ortime 5omain c'aracteri#tic# of interference #i1nal#4 t'e efficienc$ of t'e #pectrum anal$zer i#low3
T'e #canner can #can uplink fre;uencie# on t'e local i5le TR<#4 an5 t'e #cannin1 re#ult5i#pla$# t'e uplink interference of t'e TR<# in t'e form of 5ata an5 1rap'ic#3 In a55ition4 t'e#cannin1 re#ult al#o 5i#pla$# t'e peak le6el an5 1eneration time of interference on eac'fre;uenc$ 5urin1 t'e te#t3 Dou can u#e t'e #pectrum anal$zer to #can t'e entire fre;uenc$ >an5(fre;uenc$ * to fre;uenc$ .7) or a #in1le fre;uenc$ to monitor t'e interference w'en eac'time#lot recei6e# t'e #i1nal# from t'e fre;uenc$3
T'e late#t 6er#ion of t'e #canner i# 63*3 "or 5etail#4
See ppen5iA Operation Guide to Uplink Frequency Scanner for Local T! 3
$.2 %ocating nter!erence Prob"e#sGenerall$4 interference i# 5i6i5e5 into t'ree t$pe# interference from 'ar5ware e;uipment4intra,network interference4 an5 inter,network interference3 If interference occur# in a cell4 $oumu#t c'eck w'et'er t'e BTS of t'e cell run# normall$3 t t'e remote en54 $ou mu#t c'eckw'et'er an$ alarm relate5 to t'e antenna #$#tem4 TR<4 or BTS clock i# 1enerate53 t t'e localen54 $ou mu#t c'eck w'et'er (.) t'e antenna i# 5ama1e5 or immer#e5 in t'e water () t'efee5er (inclu5in1 ?umper) i# 5ama1e5 or immer#e5 in t'e water (-) t'e 2& or TR< i#fault$ (7) t'e BTS ?umper i# connecte5 improperl$ or t'e clock i# unlocke53 T'en4 $ou mu#tc'eck w'et'er intra,network co,c'annel or a5?acent,c'annel interference occur# 5ue toimproper fre;uenc$ plannin1 or 5ata confi1uration3 "inall$4 $ou mu#t 5etermine w'et'erinter,network interference occur#3
T'e !recedin" c'ec+ !rocedure is !erformed in t'e follo$in" se:uence* intra7net$or+interference 7> 'ard$are !ro%lems 7> inter7net$or+ interference9 T'e !recedin" !rocedure is forreference only9 In !ractice) you can fle(i%ly ad?ust t'e ste!s to c'ec+ t'e interference9
3 2'eck t'e connection >etween t'e output port on t'e ca>inet top an5 t'e ?umper an5 t'econnection >etween t'e ?umper an5 t'e fee5er3 If t'e port connection# are improper4 t'efront,en5 circuit of t'e BTS ma$ >e in un#ta>le #tate3 In t'i# ca#e4 t'e #elf,eAcitationo#cillation of t'e circuit cau#e# wi5e>an5 interference in t'e R< >an53
&tep 1 Make preparation# an5 fin5 potential pro>lem#3
Before c'eckin1 interfere5 cell#4 $ou mu#t 5i#a>le 5ownlink power control in all t'e cell# oft'e BTS an5 #en5 i5le >ur#t# on all t'e TR<# to eApo#e all t'e cell# wit' potential pro>lem# in >u#$ 'our#3
If t'e connector i# not fiAe54 intermo5ulation occur# in t'e BTS3 T'i# pro>lem can >e ea#il$c'ecke5 an5 #ol6e53 ccor5in1 to t'e eAperience from t'e Tielin1 pro?ect4 t'e loo#ene5connector can >e #crewe5 manuall$3
T'e connector# to >e c'ecke5 on t'e BTS #i5e inclu5e t'e ?umper connector4 fee5erconnector4 #ur1e protector connector4 an5 repeater connector3 T'at i#4 $ou nee5 to c'eckconnector B4 connector 2 (#ee t'e followin1 fi1ure)4 an5 all connector# in t'e in5oor antenna#$#tem3 If a connector i# loo#e4 $ou can #crew it >$ 'an5 an5 t'en #ecure it wit' a #panner (noteAcee5in1 *39 circle)3
If a filter eAi#t# in t'e 2M network4 $ou nee5 to replace it3 Ot'erwi#e4 #kip t'e #tep3
If t'e interference pro>lem i# #ol6e5 after t'e operation# are complete4 $ou can 1o to #tep +3Ot'erwi#e4 1o to t'e neAt #tep3
&tep 6 2'eck w'et'er t'e intermo5ulation of main e;uipment or antenna intermo5ulation occur#3
T'e main e;uipment of t'e BTS refer# to t'e "2& an5 P& (or PM for t'e -**82)3 Ift'e interference occur# in c'annel or c'annel B4 $ou nee5 to c'eck w'et'er to replace t'emain e;uipment w'en t'e pro>lem cannot >e #ol6e5 >$ t'e prece5in1 #tep#3
Dou can c'eck w'et'er to replace t'e "2& in t'e followin1 wa$#
.3 If a lar1e,power4 low,intermo5ulation loa5 i# a6aila>le4 it i# more accurate for $ou toc'eck w'et'er to replace t'e "2&3 2onnect c'annel of t'e main e;uipment to t'elow,intermo5ulation loa54 an5 t'en #en5 i5le >ur#t# on all TR<# of t'e c'annel3 O>#er6e
t'e interference >an5# for two minute#3 If interference >an5 or a 'i1'er le6el i# foun54$ou nee5 to replace t'e "2& or P& in c'annel 3 &#e t'e #ame met'o5 to te#tc'annel B3 If interference >an5 or 'i1'er le6el i# foun54 $ou nee5 to replace t'e "2&or P& in c'annel B3 If onl$ interference >an5 . eAi#t#4 it in5icate# t'at t'e "2& or P& work#3
3 If a low,intermo5ulation loa5 i# una6aila>le4 $ou nee5 to >lock all TR<# in c'annel B of t'e cell an5 5i#connect c'annel B of t'e main e;uipment from t'e connector of t'e lower ?umper3 Sen5 i5le >ur#t# on all TR<# in c'annel 4 an5 t'en o>#er6e t'e cell for fi6eminute#3 If t'e interference pro>lem per#i#t#4 $ou nee5 to replace t'e "2& or P& inc'annel 3 &#e t'e #ame met'o5 to te#t c'annel B3 If t'e interference pro>lem per#i#t#4$ou nee5 to replace t'e "2& or P& in c'annel B3
-3 If a low,intermo5ulation loa5 i# una6aila>le4 $ou can al#o u#e t'e followin1 met'o5 for c'eckin13 Remo6e one ?umper in a normal cell an5 fault$ cell re#pecti6el$3 2onnect t'e ?umper in t'e normal cell to t'e main e;uipment in t'e fault$ cell an5 t'e ?umper in t'efault$ cell to t'e main e;uipment in t'e normal cell4 an5 t'en 5i#connect ot'er two ?umper#3 O>#er6e t'e cell for fi6e minute#3 If t'e interference per#i#t# in t'e fault$ cell4 itin5icate# t'at t'e main e;uipment in t'e c'annel of t'e cell i# fault$3 In t'i# ca#e4 $ounee5 to replace t'e main e;uipment3 If t'e interference occur# in t'e normal cell4 itin5icate# t'at t'e antenna intermo5ulation occur# in t'e fault$ cell3 In t'i# ca#e4 $ou nee5to replace t'e antenna3 If no interference occur# in t'e two cell#4 it in5icate# t'at t'eantenna an5 t'e main e;uipment in t'e c'annel work properl$3 In t'i# ca#e4 $ou nee5 toc'eck t'e main e;uipment in t'e ot'er c'annel3
If t'e interference #$mptom# in c'annel an5 c'annel B are con#i#tent4 t'e antenna
intermo5ulation ma$ occur3
fter replacin1 t'e fault$ main e;uipment4 o>#er6e t'e interference >an5# for two minute#3 Ift'e interference #till occur# in t'e cell4 $ou nee5 to procee5 wit' t'e neAt #tep3 If t'einterference pro>lem i# #ol6e54 $ou can 1o to #tep +3
low,intermo5ulation loa5 i# re;uire5 in t'e fir#t met'o54 an5 two man$ operation# are performe5 int'e #econ5 met'o53 T'e t'ir5 met'o5 i# #imple4 >ut t'e 5ownlink interference occur# in t'e a5?acentBTS#3 It i# recommen5e5 t'at $ou u#e t'e t'ir5 met'o5 to c'eck w'et'er t'e main e;uipment an5antenna are fault$3
Generall$4 t'e 'ar5ware fault can >e locate5 >$ >oar5 #witc'in1 or traffic mea#urement 5ata3If a #pectrum anal$zer i# a6aila>le4 $ou can fa#t locate t'e pro>lem3 F'en t'e interferenceoccur# in a cell w'ere no 5ata i# mo5ifie54 $ou mu#t c'eck w'et'er t'e 'ar5ware i# fault$3T'e prece5in1 interference relate5 to t'e BTS i# t'e uplink interference t'at can >e reflecte5in t'e interference >an53
$.( ntra)-etwor, nter!erenceGenerall$4 t'e intra,network interference in t'e GSM #$#tem refer# to t'e co,c'annelinterference an5 a5?acent,c'annel interference3 Dou can c'eck co,c'annel an5 a5?acent,c'annel reu#e to 5etermine w'et'er t'e fre;uenc$ plan i# rea#ona>le3 "or 5etail#4 #ee t'efre;uenc$ plannin1 1ui5e3 To o>tain t'e fre;uenc$ plannin1 1ui5e4 6i#it'ttp@@#upport3'uawei3com an5 t'en c'oo#e -ocumentation 0o%ile Communication
En"ineer -ocument Net$or+ Plannin" and =!timi/ation GS0 Net$or+ Plannin"
and =!timi/ation Guide3
F'en a5?u#tin1 t'e fre;uenc$ plan4 $ou mu#t control t'e co6era1e of eac' cell a# re;uire53"or a network wit' few fre;uenc$ re#ource# an5 'i1' traffic4 it i# 6er$ important to control t'e
co6era1e an5 en#ure proper co,c'annel an5 a5?acent,c'annel reu#e3 F'en t'e traffic 6olumei# 'i1'4 t'e intra,network interference increa#e#3 F'en t'e interference occur#4 $ou mu#tc'eck t'e topolo1$ of t'e BTS an5 fre;uenc$ plan map (t'e operation i# t'e ea#ie#t an5 'a#t'e minimum effect) to fin5 t'e fre;uencie# w'ere t'e co,c'annel or a5?acent,c'annelinterference occur#3 T'en4 $ou nee5 to mo5if$ #ome fre;uencie# to c'eck w'et'er t'einterference 5ecrea#e# or c'an1e#3 In a55ition4 #ome improper parameter confi1uration# al#ocau#e fre;uenc$ colli#ion an5 interference3 In t'i# ca#e4 t'e interference ma$ occur3
$.(.1 Co)Channe" or Ad<acent)Channe" nter!erence
"re;uenc$ reu#e i# re;uire5 in t'e GSM #$#tem3 F'en t'e reu#e 5i#tance >etween two cell#t'at u#e t'e #ame fre;uenc$ or a5?acent fre;uencie# i# #mall relati6e to t'e cell ra5iu#4 co,
c'annel interference or a5?acent,c'annel interference ma$ occur3 In a55ition4 t'e reflection of#urface feature# can al#o cau#e co,c'annel interference or a5?acent,c'annel interference3
T'e GSM #$#tem i# a 5upleA #$#tem4 an5 t'e uplink an5 5ownlink fre;uencie# ma$ >einterfere53 F'en t'e 5ownlink fre;uencie# are interfere54 $ou can u#e t'e eAi#tin1 Te;uipment to 5etermine w'et'er co,c'annel interference occur# >$ t'e in5irect mea#urement3If t'e 'i1' R< #i1nal le6el ( H+* 5Bm) an5 poor R< ;ualit$ (RA=ual 9) are 5etecte5 in anarea4 it in5icate# t'at co,c'annel or a5?acent,c'annel interference ma$ occur on t'e fre;uenc$3T'e T e;uipment can >e u#e5 to te#t onl$ 5ownlink fre;uencie#3 F'en t'e uplink fre;uenc$i# interfere54 $ou can trace #u>#cri>er #i1nalin1 on t'e >i# interface to #$nc'ronou#l$ te#t t'euplink an5 5ownlink3 In a55ition4 $ou can furt'er anal$ze t'e uplink interference >$ t'einterference >an5 5ata in t'e traffic #tati#tic#3
.3 "re;uenc$ 87 (B220 fre;uenc$) an5 fre;uenc$ / are allocate5 to t'e BTS3
3 &#e a te#t MS to make a call an5 retain t'e call4 an5 t'en u#e anot'er MS to perform afre;uenc$ #cannin1 te#t for fre;uenc$ 873 F'en t'e MS i# clo#e to t'e ur>an area4 t'e#i1nal #tren1t' of fre;uenc$ 87 i# #maller t'an H.** 5Bm an5 t'e call 5rop#3 F'en t'eMS i# in t'e ur>an area4 t'e #i1nal #tren1t' of fre;uenc$ 87 #u55enl$ ri#e# to H89 5Bman5 5i#appear# after a>out .** #econ5#3 In t'i# ca#e4 $ou can infer t'at t'e co,c'annelinterference ma$ >e from t'e T20 fre;uenc$ of t'e nei1'>orin1 cell3
-3 T'e neAt 5a$4 u#e a #pectrum anal$zer to te#t t'e location w'ere t'e #i1nal #tren1t' of t'efre;uenc$ i# t'e #tron1e#t3 Meanw'ile4 u#e anot'er MS to perform t'e i5le mo5e te#t3ccor5in1 to t'e #$#tem information4 fre;uenc$ 87 i# in t'e cell 2 ta>le of B220 79an5 allocate5 to t'e T20 TR<4 an5 t'e call i# e#ta>li#'e5 on fre;uenc$ 873
73 fter c'an1in1 t'e fre;uenc$4 rete#t t'e place w'ere t'e co,c'annel interference occur#3ccor5in1 to t'e te#t re#ult4 no call 5rop occur# an5 t'e #peec' ;ualit$ i# 1oo5 (RA=ual
BTS la$out pla$# an important role in t'e earlier network plannin13 BTS# mu#t >e rea#ona>l$5i#tri>ute5 on t'e >a#i# of t'e re;uirement# of co6era1e4 capacit$4 network ;ualit$4 an5 totalcon#truction in6e#tment4 re1ar5le## of an$ fre;uenc$ plannin1 tec'nolo1$3 2apacit$contra5ict# ;ualit$3 In #ome ca#e#4 t'e ti1't fre;uenc$ reu#e tec'nolo1$ mu#t >e u#e5 to meet
t'e re;uirement# of capacit$ w'en ;ualit$ i# #acrifice53
If BTS# are 5i#tri>ute5 improperl$4 an5 t'e ti1't fre;uenc$ reu#e tec'nolo1$ i# u#e54 t'e co,c'annel an5 a5?acent,c'annel colli#ion occur#3 In t'i# ca#e4 $ou mu#t optimize t'e networkcarefull$4 e#peciall$ cro## co6era1e3 In t'e plannin1 5e#i1n p'a#e4 $ou mu#t en#ure rea#ona>lela$out of a network4 BTS# 5i#tri>ute5 in re1ular me#'e#4 an5 #imilar antenna 'ei1't3 In t'eoptimization p'a#e4 $ou mu#t control cro## co6era1e4 re5uce co6era1e o6erlappin14 rai#e'an5o6er #en#iti6it$4 an5 lower a5?acent,c'annel colli#ion3
T'e mea#ure# relate5 to GSM anti,interference inclu5e "04 5$namic power control4 an5 T<3In a55ition4 $ou can a5?u#t t'e tilt4 azimut'4 an5 'ei1't of t'e antenna to re5uce networkinterference3 In t'i# wa$4 t'e actual #er6in1 ran1e of eac' cell approAimate# to t'e 5e#i1ne5#er6in1 ran1e an5 t'u# cro## co6era1e can >e a6oi5e53 "or 5etail# on antenna a5?u#tment4 #eet'e Guide to "lannin# and $d%u&tin# Tilt $n#le& of the $ntenna3 T'e anti,interferencemea#ure# appl$ to intra,network interference3
1.1 Channe" A""ocation A"gorith# T'e c'annel allocation al1orit'm II of 0uawei applie# to t'e allocation of T20# an5
S220#3 T'e principle of t'e al1orit'm i# a# follow# Before allocatin1 a T20 or anS2204 t'e al1orit'm u#e# t'e preferential #election mec'ani#m to #elect t'e c'annel# fromall alloca>le c'annel# in a cell >a#e5 on t'e factor# #uc' a# interference4 preferential #electionle6el of t'e TR<4 'i#tor$ #eizure recor5#4 an5 loa5 >alancin13 T'e al1orit'm en#ure# t'at t'e#electe5 c'annel# are preferentiall$ allocate5 wit'out affectin1 t'e efficienc$ of t'e #$#tem3
Similar to t'e c'annel allocation al1orit'm II of 0uawei4 t'e i5le c'annel mea#urement(I2MSTTE) tec'nolo1$ of Eric##on4 t'e automatic cell la$erin1 tec'nolo1$ of Nortel4 an5t'e a5apti6e fre;uenc$ allocation tec'nolo1$ of Nokia preferentiall$ allocate optimumc'annel#3
(.2 RCT'e interference re?ection com>inin1 (IR2) tec'nolo1$ of Eric##on an5 t'e interferencecancellation (I"2) tec'nolo1$ of Nortel are u#e5 to cancel t'e co,c'annel interference w'ent'e fre;uencie# are ti1'tl$ reu#e53 Fit' t'e tec'nolo1ie#4 $ou can impro6e t'e #peec' ;ualit$4increa#e t'e capacit$4 an5 impro6e t'e fre;uenc$ u#a1e3 2urrentl$4 0uawei e;uipment 5oe#not #upport t'e tec'nolo1ie#3 T'e relate5 re#earc'4 'owe6er4 i# #tarte53