3G Cell Optimisation_RevA

8/12/2019 3G Cell Optimisation_RevA

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counters. The /lannin( and pti$i2ation 3n(ineer $onitors and acts oncounters reflectin( the cell4s active perfor$ance.

5. It is possible to confi(ure alar$s to be (enerated for counters e6ceedin( specificvalues. These alar$s 'ould then be $onitored b! the N C.

#. For the Radio /lannin( 0 pti$isation 3n(ineer the focus is on $aintainin(ade uate cell perfor$ance in ter$s of Accessibilit! "call setup anal!sis%,Retainabilit! "drop call anal!sis% and Inte(rit! "speech ualit!*video ualit!*pac&etthrou(hput anal!sis%

ACCESSI"ILITY

7. If a cell has poor accessibilit! it is t!picall! due to either so$e for$ of con(estionor a hard'are*soft'are fault or a $isconfi(uration. It is also possible that there is

so$e e6ternal source of interference "such as a $icro'ave lin& on the sa$efre uenc!% affectin( the accessibilit!.

8. Accessibilit! should be $onitored independentl! for the different RAB t!pes "e.(.Speech, CS 9ideo, /S Interactive R::, /S Interactive +S /A, etc.% as in certainsituations onl! one of the RAB t!pes 'ill be affected. For e6a$ple, a disabled+S;TXB 'ill affect the accessibilit! of the /S Interactive +S /A RAB, but if theRBS also has a TXB "non;+S% installed then the other RABs $a! continue tohave an acceptable accessibilit!.


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E#! ple FACTS Report sho'in( a lo' CSSR Speech caused b! a hi(hp$NoRe eniedAd$. Note that p$NoRe eniedAd$ is not RAB specific so otherRABs 'ill $ost li&el! be affected in this case too.

A$ ission Control% DL Po&er

:. If Ad$ission Control re>ects a RAB establish$ent due to a lac& of po'er thenthe counter p No'!ile$R!bEstAtte ptL!c(DlP&r is incre$ented. Chec& thatthe feeder losses are confi(ured correctl! in the RBS and that the para$eter!#i ) Tr!ns issionPo&er is set correctl! "t!picall! to$a6 l/o'erCapabilit! $inus .)dB$%. The value of para$eter p&rA$ shouldalso be verified "t!picall! set to 8#D%. Also, chec& for C/A alar$s i.e.so$eti$es RBS -) ) sites 'ith hi(h feeder losses are confi(ured 'ith t'oC/As per sector and one of the C/As fails resultin( in a lar(e reduction inthe $a6 l/o'erCapabilit! of the sector and, hence, causin( a lac& of po'er.on( ter$ solutions are to increase the po'er capabilit! of the sector b! addin(or up(radin( an C/A "RBS -) -% or RE "RBS -) 7%, re;en(ineerin( the site toreduce feeder len(ths, or perhaps to chan(e the RBS t!pe to one usin( RREs"RBS -5 ) or RBS -51)% if this provides hi(her po'er at the reference point. Theshort ter$ solution is to reduce the traffic carried b! the site "See the ?Trafficffload@ sections%.


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E#! ple FACTS Report sho'in( a hi(h no of RAB establish$ent failures due to Ad$ission Control re>ections caused b! a lac& of po'er. In this situation the site hadonl! one of the t'o C/As in sector 1 functionin( correctl! causin( the po'ercon(estion. This is sho'n in the cabinet vie'er snapshot belo' "Red 3 on C/A%.There 'as also an alar$ in the RBS for the fault! C/A.


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A$ ission Control% DL C*!nnelis!tion Co$es

1 . If Ad$ission Control re>ects a RAB establish$ent due to a lac& of channelisation codes then the counterp$NoFailedRab3stAtte$pt ac& lChnlCode is incre$ented. This 'ill t!picall!affect the /S Interactive R:: " C+*FAC+% CSSR 'orse than the Speech CSSRas the /S Interactive R:: RAB re uires channelisation codes at a lo'erspreadin( factor "usin( $ore of the code tree%. In the /5 soft'are release a cellthat supports R:: and +S /A t!picall! has # spreadin( factor 17 channelisation codes reserved for +S /A. This $eans that appro6i$atel! -)Dof available codes are reserved for +S /A. =hen this is the case it is co$$onfor channelisation code con(estion too occur. Chec& the settin( of para$eter$lCo$eA$ "t!picall! set to


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E#! ple FACTS Reports sho'in( a hi(h no of RAB establish$ent failures due to Ad$ission Control re>ections caused b! a lac& of channelisation codes and thecorrespondin( decrease in CSSR for /ac&et Interactive. In this case a lar(e portion ofthe speech calls 'ere alread! redirected to GS so the R:: /ac&et Interactive RAB'as 'orst affected the re uired solution is sectorisation of the inbuildin( antenna

s!ste$ or i$ple$entation of a second carrier fre uenc!.


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A$ ission Control% UL+DL ASE

11. If Ad$ission Control re>ects a RAB establish$ent due to a lac& of E or airspeech e uivalent "AS3% then the countersp No'!ile$R!bEstAtte ptL!c(UlAse orp No'!ile$R!bEstAtte ptL!c(DlAse are incre$ented. The AS3 $onitoraccounts for the air interface resource usa(e in a cell "separatel! for E and %b! $eans of an avera(e static load esti$ation of each radio lin& in the cell for$ore infor$ation refer to the ?Capacit! ana(e$ent@ docu$ent in the ?=C ARAN@ A 3X librar!. Because a R 4s AS3 is an esti$ation it is possible that incertain situations it is an over;esti$ation of the load in a cell e.(. for inbuildin(cells on a different carrier fre uenc! to the surroundin( $acro cells. In suchsituations it is possible to increase the E * AS3 ad$ission control li$it"para$eters aseElAd$*ase lAd$% in order to prevent unnecessar! ad$issioncontrol re>ections of RAB establish$ents. So, a short ter$ solution to relievesuch con(estion $a! be to increase aseElAd$*ase lAd$, but the effect onCR*CSSR should be closel! $onitored "Note that the aseElAd$ default valueon TN4s net'or& is alread! less strin(ent than the 3ricsson default%. Anothershort ter$ solution is to reduce the traffic carried b! the site "See the ?Trafficffload@ sections%. The lon( ter$ solution is to add another cell in the covera(earea to ta&e so$e of the traffic this $a! be achieved b! introducin( a secondcarrier, another sector, or another site.


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A$ ission Control% ,!r$&!re Us!-e .C*!nnel Ele ents/

1-. It is possible for Ad$ission Control to re>ect a RAB establish$ent atte$pt due toinsufficient E or RBS hard'are capacit! i.e. too fe' channel ele$entsavailable. The channel ele$ent capacit! of an RBS $a! be soft'are li$ited

"accordin( the soft'are license confi(ured for the RBS% or hard'are li$ited"accordin( to the TXBs and RAXBs installed in the RBS%. The t'o para$etersthat control the RBS hard'are ad$ission polic! are )l,&A$ and $l,&A$ .B! default these para$eters should be set to 1 D in 'hich case no hard'are isreserved for handovers and Ad$ission Control 'ill not bloc& RAB establish$entatte$pts for this reason "see ?Failure After Ad$ission +ard'are Esa(e@%. Insoft'are revision P0 t*ere is no specific co)nter to in$ic!te t*is t1pe ofA$ ission Control rejection2 so if p NoRe Denie$A$ is tri--ere$&it*o)t !n1 of t*e ot*er relev!nt co)nters in$ic!tin- ! re!son t*en it isli(el1 t*!t t*is is t*e c!)se !n$ t*!t )l,&A$ or $l,&A$ is incorrectl1confi-)re$ to ! v!l)e belo& 4556 . In the /# soft'are release there are ne'

counters that indicate 'hen lac& of hard'are capacit! causes RAB establish$entfailures in a cell p$NoFailedRab3stAtte$pt ac& l+',p$NoFailedRab3stAtte$pt ac& l+'Best,p$NoFailedRab3stAtte$pt ac&El+',p$NoFailedRab3stAtte$pt ac&El+'Best.


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E#! ple FACTS Reports sho'in( RAB establish$ent failures due to Ad$issionControl 'ith no counter sho'in( the reason "this is for /5%. In this case the +=ad$ission li$its 'ere suspected and found to be ul+'Ad$ 8 and dl+'Ad$ 8"instead of both bein( 1 %. After correctin( these settin(s the Ad$ission Controlre>ections disappeared and, as can be seen in the second plot belo', the /ac&et CSSR

i$proved. In the third plot belo' the E C3 Esa(e is seen to pea& around 5# C3s. ThisRBS had a capacit! of 75 E C3s 8 D of 75 C3s is 55.< C3s. In other'ords, the EC3 Esa(e and the Ad$ission Control li$it correlate to each other.


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'!il)re After A$ ission% I)b Con-estion

15. If a ETRAN cell has a hi(h nu$ber of RRC*RAB establish$ent re uest failuresafter bein( ad$itted b! Ad$ission Control "p$NoFailedAfterAd$%, then aco$$on reason 'ould be due to Iub Con(estion. =hen considerin( the Iub

interface it is i$portant to re$e$ber that $ainl! RABs confi(ured to use strict AA ) HoS settin(s 'ill be bloc&ed at call setup b! AA ) CAC. T!picall! the R::RABs "i.e. all RABs e6cludin( +S /A and 3E RABs% are confi(ured to use

AA ) HoS class A or class B, 'ith both classes confi(ured to use a strict HoS.+S /A and 3E 'ill t!picall! use AA ) HoS class C and class , 'ith bothclasses confi(ured to use a best effort HoS. T!picall! the R:: /ac&et InteractiveRAB 'ill be the first RAB to sho' si(ns of AA ) con(estion 'ith a poor /ac&etInteractive CSSR and correspondin( hi(h p$NoFailedAfterAd$. The AA )Setup Success Rate statistics fro$ the relevant RXI to'ards the RBS $a! thenbe investi(ated. This should t!picall! be ::D and above, but if not and thecounter p UnS)ccO)tConnsLoc!l indicates that it is local re>ections "on the

RXI% b! CAC, then there is con(estion on the Iub interface.E#! ple FACTS Reports sho'in( hi(h p$NoFailedAfterAd$ "1 st plot%, lo' CSSR/ac&et Interactive ") nd plot%, and lo' AA ) Call Setup Success Rate 'ith correspondin(hi(h p$EnSucc utConns ocal "- rd plot%. Fro$ ) 7;11;)5 the proble$ disappears. Inthis case the solution 'as to activate irected Retr! to GS and to chan(e the AA )HoS class B traffic to use a best effort confi(uration thereb! allo'in( $ore /S75*1)or lin& to the RNC. It 'ould then be necessar! to loo& at the lin& utilisationin order to confir$ such lin& con(estion, but that is be!ond the scope of thisdocu$ent.

E#! ple FACTS Reports sho'in( poor CSSR Speech for CTRNC1 for t'o da!s andthen an i$prove$ent for the ne6t t'o da!s "1 st plot% and the correspondin( AA ) SetupSuccess Rate for the CT G=1;KRB G=1 ") nd plot% and RB G=1;KCT G=1 "- rd plot% lin&s for the sa$e da!s. The CT G=1J;KRB G=1 lin& had a hi(h utilisation"K< D% so the pea& cell rate "/CR% for the lin& 'as increased resultin( in the noticeablei$prove$ent.


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capacit! i.e. too fe' channel ele$ents available. The channel ele$ent capacit!of an RBS $a! be soft'are li$ited "accordin( the soft'are license confi(ured forthe RBS% or hard'are li$ited "accordin( to the TXBs and RAXBs installed in theRBS%. The t'o para$eters that control the RBS hard'are ad$ission polic! areul+'Ad$ and dl+'Ad$. If these para$eters are set to a value lo'er than 1 D

then Ad$ission Control should bloc& an! RRC*RAB setup atte$pts re uirin($ore than the available channel ele$ents "see ?Ad$ission Control +ard'areEsa(e@% ho'ever, b! default these para$eters should be set to 1 D in 'hichcase no hard'are is reserved for handovers and Ad$ission Control 'ill not bloc&RAB establish$ent atte$pts for this reason so the setup atte$pt fails afterad$ission. The RBS counters p$SetupFailureSfXX in the Eplin&Baseband/ool"E S3TE/FAI ER3SSFXX% and p$SetupFailureSfXX in theo'nlin&Baseband/ool " S3TE/FAI ER3SSFXX% indicate R "at SF XX%setup failures due to a lac& of E and hard'are capacit!. If this is the casethen a short ter$ solution $a! be to reduce the traffic carried b! the site "See the?Traffic ffload@ sections%. The lon( ter$ solution is to up(rade the E "RAXB% or

"TXB% channel ele$ent capacit! of the site. This $a! be achieved b!s'appin( the relevant board 'ith that of another site that has $ore capacit! thanit re uires, or b! sourcin( a ne' board. Note that it is possible for these countersto incre$ent even 'hen there should be sufficient channel ele$ent capacit! "fore6a$ple due to a soft'are bu( in the soft'are revision bein( used see ?Failure

After Ad$ission ther@% so it is i$portant to co$pare the channel ele$ent usa(eto the channel ele$ent capacit! of the RBS to $a&e sure that it $a&es sense forthis to be the root of the proble$.

E#! ple FACTS Reports sho'in( poor CSSR /ac&et Interactive "1 st plot% hi(hp$NoFailedAfterAd$ ") nd plot% and E setup failures due to a lac& of E baseband

hard'are capacit! "RAXB%. Note that this RBS had 75 E channel ele$ent capacit!until -1 st Au(ust 'hen it 'as up(raded to 1)< E channel ele$ents. The esti$ated EC3 Esa(e pea&s above 75 channel ele$ents even before the -1 st confir$in( that RAXBcon(estion is the source of the proble$, and then after the up(rade to 1)< channelele$ents the E C3 Esa(e starts pea&in( above 1 indicatin( ho' necessar! theup(rade 'as. The i$prove$ent to CSSR /ac&et Interactive and the decrease inp$NoFailedAfterAd$ after the RAXB up(rade is clearl! noticeable.


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'!il)re After A$ ission% Ot*er

18. If none of the above reasons for a poor CSSR are apparent, then it is li&el! to bea $ore co$plicated proble$ to resolve often relatin( to a soft'are*hard'arefault, or perhaps an e6ternal source of interference in the area. At the ti$e of

'ritin(, the -G technolo(! is not as $ature as the current )G s!ste$ "as 'ouldbe e6pected% and hence there are still nu$erous i$prove$ents bein(i$ple$ented in ever! soft'are release, alon( 'ith the continued develop$ent ofne', $ore efficient and opti$ised hard'are (enerations for the various -Gnodes. The e6a$ple belo' illustrates one such proble$ of this t!pe encountered.

E#! ple FACTS Reports sho'in( poor CSSR Speech 'ith hi(h p$NoFailedAfterAd$"1st plot% and hi(h p$SetupFailuresSfXX indicatin( TXB con(estion. +o'ever, the C3 Esa(e is ver! lo', seldo$ pea&in( above 7 channel ele$ents so this doesn4t $a&esense. After investi(atin( nu$erous RBSs sho'in( these ?s!$pto$s@ it 'asestablished that the! all had a sin(le +S;TXB as opposed to the other RBSs 'hich all

had a TXB as 'ell as an +S;TXB. Both confi(urations are valid and have $ore thansufficient do'nlin& channel ele$ent capacit!. It 'as also noted that if the RBS isrestarted then the proble$ disappeared for a fe' da!s and then re;appeared this isclearl! visible in the plots 'here the restart occurred on ) Lanuar!. This turned out to bea soft'are fault for the sin(le TXB confi(uration "due to a failure to release so$eresources on the TXB%. The fi6 'as delivered fro$ soft'are release /5. .) "'hereasthe release installed on the nodes at the ti$e 'as /5. .1)%.


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site, a hard'are*soft'are fault or a $isconfi(uration. It is also possible that thereis so$e e6ternal source of interference "such as a $icro'ave lin& on the sa$efre uenc!% affectin( the retainabilit!.

1:. Retainabilit! should be $onitored independentl! for the different RAB t!pes "e.(.

Speech, CS 9ideo, /S Interactive R::, /S Interactive +S /A, etc.% as in certainsituations onl! one of the RAB t!pes 'ill be affected. For e6a$ple, a cell $a! beconfi(ured 'ith GS as the preferred + t!pe in 'hich case Speech calls 'illperfor$ IRAT handovers to GS rather than perfor$in( IF+ s, but CS 9ideocalls 'ill perfor$ IF+ s. In such a situation, $issin( inter;fre uenc! nei(hbourcell relation definitions 'ill i$pact the CR of CS 9ideo calls, but not Speechcalls.

) . +o'ever, in the $a>orit! of cases the factors that affect the Speech retainabilit!'ill also affect the retainabilit! of the other RABs. =hen a hi(h speech CR isdetected on a cell the first thin( to chec& is the t!pe of drops occurrin( as

indicated b! the counters p NoS1sRelSpeec*So,o2p NoS1sRelSpeec*Nei-*br2 p NoS1sRelSpeec*UlS1nc* !n$p NoOfTer Speec*Con- and then to anal!se the situation 'ith the follo'in(in $indM

Soft ,!n$over Drops

)1. T!picall! a cell that has a hi(h nu$ber of dropped calls due to S + failures"p$NoS!sRelSpeechSo+o% 'ill also have a hi(h nu$ber of drops due to $issin(nei(hbours "p$NoS!sRelSpeechNei(hbr% indictin( that the S + failures are

due to $issin( nei(hbour relations ho'ever, there are situations 'here S +failures happen for other reasons. T'o co$$on reasons are a nei(hbourin( cellthat is $isbehavin( "often due to fault! hard'are*soft'are% or a $isconfi(urationresultin( in a failure to perfor$ an inter;RNC S + across the Iur interface.These t'o situations are illustrated in the follo'in( e6a$plesM

E#! ple FACTS Reports sho'in( t'o cells in the sa$e area "1 st plot% 'ith a hi(hp$NoS!sRelSpeechSo+o and a $uch lo'er p$NoS!sRelSpeechNei(hbr indicatin(that the soft handover failures are not due to $issin( nei(hbours ") nd 0 - rd plot%. Afterfurther investi(ation it 'as discovered that the cells on the nei(hbourin( site E5##5'ere auto$aticall! loc&ed "5 th plot% and the ub interface to the site 'as do'n. Thesecells 'ere trans$ittin( C/IC+ !et there 'ere $ultiple channels "RAC+, FAC+, etc% that'ere disabled preventin( the site fro$ carr!in( an! traffic. +o'ever, E3s in thenei(hbourin( cells 'ere $easurin( the C/IC+ fro$ these cells and atte$ptin( toperfor$ S + to the$. Such S + atte$pts 'ere failin( leadin( to the S + drops.

As is clearl! visible in the FACTS Reports, 'hen the site E5##5 ca$e bac& on air on ))Lan the S + drops on the nei(hbourin( cells disappeared alon( 'ith a hu(e reductionin the CR e6perienced b! these cells.


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E#! ple Referin( to the three sites sho'n in the fi(ure belo' "1 st plot% E1-:- andE #58 are on CTRNC1 'hile E-:8 is on TBRNC1. The three FACTS Reports belo'") nd , - rd 0 5 th plots% sho' cells fro$ these sites 'ith a hi(h p$NoS!sRelSpeechSo+o.Note that althou(h there are so$e drops due to $issin( nei(hbours"p$NoS!sRelSpeechNei(hbr%, but $ost of the S + drops are for another reason. Inthis case the soft handover counters "p$RlAddAtte$ptBestCellSpeech andp$RlAddSuccessBestCellSpeech% indicated S + success bet'een -:8 C1 and1-:-B1*#58B1 ho'ever a G/3+ trace of eventINT3RNA S FT +AN 93R 3X3CETI N sho'ed that these handovers actuall!failed "see snapshot of slide in # th plot%. It 'as established that a $isconfi(uration of an

AA ) routin( case bet'een the t'o RNCs resulted in all S + atte$pts across the Iurinterface to fail. This 'as corrected on : Lan and fro$ the FACTS Reports thei$prove$ent is obvious.


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7issin- Nei-*bo)r Drops

)). A cell that has a hi(h nu$ber of dropped calls due to $issin( nei(hbour

relations 'ill have a hi(h p$NoS!sRelSpeechNei(hbr. A $issin( nei(hbourrelation 'ill onl! cause a dropped call if the RNC receives an 3vent 1a, 1c or 1deasure$ent Report fro$ the E3 re uestin( the addition of a SC to the AS "oran +S cell chan(e% for a SC that is not defined as a nei(hbour relation to an! ofthe cells in the AS and if the 3c*No reported for that SC is releaseConn ffsetabove the 3c*No of the best servin( cell in the AS 'here the RNC para$eterreleaseConn ffset is t!picall! set to 1)dB$. The reason for this s!ste$ releaseis to prevent e6cessive E interference in the net'or&. This t!pe of dropped callis relativel! eas! to solve usin( the General /erfor$ance 3vent +andler "G/3+%tool in SS;RC. =ith this tool all details on 3vent 1a, 1c or 1d easure$entReports containin( a SC not in the AS nei(hbour list $a! be captured and

anal!sed usin( the INT3RNA S + S ISSING N3IG+B ER event"includin( those easure$ent Reports that do not cause a s!ste$ release of thecall%. In this 'a! the $issin( nei(hbour or interferin( cell $a! be established andappropriate action ta&en e.(. addition of the nei(hbour relation and*or antennatiltin(, etc. For $ore infor$ation on the G/3+ tool refer to the relevantdocu$entation in the A 3X RNC and SS;RC libraries. Because $issin(nei(hbour drops are relativel! eas! to solve, it is reco$$ended to opti$ise thenei(hbour relations and antenna confi(uration until the percenta(e of drops dueto $issin( nei(hbour relations is less than 1 D of the total nu$ber of drops ineach RNC.

E#! ple FACTS Report sho'in( a hi(h CR Speech on cell 1-8:C1 'ith the $a>orit!of dropped calls due to $issin( nei(hbours as sho'n b! the counter

p$NoS!sRelSpeechNei(hbr "1 st plot%. A G/3+ trace 'ith eventINT3RNA S + S ISSING N3IG+B ER 'as e6ecuted on 5 Lan 'here it 'asfound that SC )5 and SC


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UL S1nc*ronis!tion Drops

)-. A connection is considered lost b! the Radio Connection Supervision "RCS%

function in the SRNC 'hen the last radio lin& set "R S% for the connection hasbeen out;of;s!nc for a ti$e (iven b! the para$eter $c*RcLostT "or*sDsc*RcLostT for an +S /A connection%. =hen this occurs for a connectioncontainin( a speech RAB "or a $ulti;RAB containin( speech% the counterp$NoS!sRelSpeechElS!nch is incre$ented. A cell that has a hi(h CR 'ith arelativel! hi(h nu$ber of dropped calls due to loss of E s!nchronisation $a!have various contributin( factors. These $a! include $issin( IRAT nei(hbourrelation definitions resultin( in the connection ?han(in( on@ to the -G net'or&until the call is dropped 'hen it 'ould be better served handin( the call over tothe )G net'or&. This $a! be especiall! true for cells on the border of the -Gcovera(e area 'here the -G si(nal $a! reach areas further a'a! fro$ the site

than e6pected. B! identif!in( such areas an! $issin( )G nei(hbour relations$a! be added or perhaps a $isconfi(uration discovered, such as havin( anIRAT nei(hbour relation defined in an RNC to'ards a )G cell that is not definedas an outer cell in the -G SC Server "see e6a$ple belo'%. Bear in $ind that a$a6i$u$ of 1 to 1) GS nei(hbours is reco$$ended for each -G cell in orderto avoid nei(hbour list truncation issues. Another $eans to i$prove the situation$a! be to lo'er the thresholds used to tri((er IRAT + s "refer to the settin(s forpara$eters usedFre Thres)d3cno, utranRelThresh-a3cno,usedFre Thresh)dRscp and utranRelThresh-aRscp%. For e6a$ple, tri((erin(co$pressed $ode at 3c*No ;11dB$ instead of ;1)dB$ $a! prevent drops ascalls are handed earlier to the GS net'or& that t!picall! has better covera(e

than the -G net'or&. If the po'er of a R is ver! lo' then that R 'ill be $oresensitive to sudden interference chan(es, so a cell that has a hi(h nu$ber of Es!nchronisation drops $a! cover a radio environ$ent 'ith a relativel! hi(hnu$ber of E3s e6periencin( sudden interference chan(es "(enerall! caused b!brid(es, buildin(s, tunnels, steep hill! terrain, etc%. In order to prevent the /o'erControl function fro$ decreasin( the po'er too $uch due to te$porar! (oodradio conditions, a $ini$u$ code po'er $a! be confi(ured usin( theEtranCell para$eter $in/'rRl. Note that this para$eter has an effect on the po'er capacit! of the cell so should onl! be used if reall! necessar!. An e6ternalinterference source $a! also be the cause of E s!nc drops refer to the sectionO ther Reasons for rops4 for an e6a$ple of this. It is reco$$ended to resolvean! S + and $issin( nei(hbour drop proble$s before atte$ptin( to resolveE s!nc drops as often the cause of such drops 'ill resolve E s!nchronisationdrops too.

E#! ple FACTS Report sho'in( a hi(h CR Speech on cell 551)A1 'ith the $a>orit!of dropped calls due to loss of E s!nchronisation as sho'n b! the counterp$NoS!sRelSpeechElS!nch "1 st plot%. It 'as discovered that the IRAT + s to'ards the)G net'or& stopped functionin( as sho'n in the ) nd plot belo'. After further


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chan(ed to fro$ ;1# ";1#dB$% to ;15 "15dB$% and t'o additional GS nei(hbourrelations 'ere added. This cell 'as on the border of the -G covera(e area.

Rele!se $)e to Con-estion Resolve Action

)5. =hen Con(estion Control detects do'nlin& cell con(estion, besides li$itin(ad$ission to the con(ested cell con(estion resolve actions are also initiated inthe cell. Initiall! non;(uaranteed services are tar(eted 'hich t!picall! results inR:: pac&et interactive connections bein( channel s'itched to use theRAC+*FAC+ co$$on channels 'ith the counter p$No fS' o'nN(Con( bein(incre$ented. If do'nlin& cell con(estion persists then RABs belon(in( to theother service classes "(uaranteed and (uaranteed;hs% $a! also be release 'iththe follo'in( counters bein( incre$ented accordin(l!p$No fTer$SpeechCon(, p$No fTer$CsCon( and p$No fTer$+sCon(."Note that at the ti$e of 'ritin( not all of these counters 'ere available inFACTS%. =hen such s!ste$ releases are detected then the solution is to solvethe con(estion proble$s as described in the Accessibilit! section of this

docu$ent. Nor$all! the con(estion should be detected and resolved throu(h Accessibilit! $onitorin( before the CR is si(nificantl! affected due tocon(estion resolve actions. Refer to the OCapacit! ana(e$ent4 docu$ent in the=C A RAN A 3X librar! for $ore infor$ation on the Con(estion Controlfunctionalit!.


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E#! ple At the ti$e of 'ritin( onl! the follo'in( counters related to Con(estionResolve Actions 'ere available in FACTS. Note that in this e6a$ple onl! the counterp$No fS' o'nN(Ad$ has been incre$entin( but this counter actuall! sho's thenu$ber of channel rate do'ns'itches "/S75*-


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E#! ple FACTS Reports sho'in( all three sectors of site E171: suddenl!e6periencin( a hi(h CR of around < D. The counters (ive no indication as to thereason for the drop i.e. the! are not S + , or $issin( nei(hbour or E s!nch drops.

After restartin( the RBS, the CR returns to ?nor$al@ on all three sectors as can beseen in the plots belo' 'here the RBS 'as restarted at around 1< on ): Au(. This

t!pe of situation appeared rando$l! on sites throu(hout the net'or& and turned out tobe a soft'are fault in the soft'are release i$ple$ented on the RBSs at the ti$e.

E#! ple FACTS Reports sho'in( poor CR perfor$ance 'ith al$ost all drops bein(due to loss of E s!nchronisation "1 st plot%. Fro$ the counters it is evident that the RRCconnection setup success rate is lo'er than it should be "p$TotNoRrcConnecReversus p$TotNoRrcConnecRe Success in ) nd plot% ho'ever, fro$ drive tests it 'asonl! possible to establish a call if the E3 'as less than 1 $ fro$ the site and 'ith line


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of site to the antenna. After chec&in( all confi(urations and e uip$ent no cause for theproble$ could be established. It 'as noted fro$ the drive tests that 'hen a call 'asestablished the E3 TX po'er 'as constantl! at $a6i$u$ "or ver! close there too%.

Also, fro$ the RBS counter p$Avera(eRSSI "not available in FACTS at the ti$e of'ritin(% it 'as established that the uplin& RSSI 'as constantl! (reater than ;< dB$.

These t'o facts indicate the presence of hi(h E interference. A spectru$ anal!ser 'asused to establish that there 'as another si(nal in the area bein( trans$itted on thesa$e fre uenc! and, as it turned out, Transtel had a $icro'ave lin& usin( thisfre uenc! that 'ent strai(ht throu(h the site "- rd plot%.


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,SDPA .7AC;,S/ T*ro)-*p)t .Cell Level/

- . The +S /A service is $ar&eted as a broadband $obile data service 'ithsuperior perfor$ance to standard -G "or R::% $obile pac&et data. f course this$eans that it is i$portant to ensure that an +S /A user actuall! e6periencessuperior perfor$ance to an R:: -G user and 'hile the +S /ac&et Interactive

RAB is capable of $uch hi(her throu(hputs than the R:: /ac&et InteractiveRAB, one has to bear in $ind that +S /A uses a shared channel "+S; SC+%'hereas in R:: the channel is dedicated " C+% to the user. The total AC;+Scell throu(hput before re;trans$issions "+SC3 ATARAT3% and after re;trans$issions "+SC3 T+R EG+/ET%, as 'ell as the avera(e AC;+Sthrou(hput per user before re;trans$issions "+SES3R ATARAT3% and after re;trans$issions "+SES3RT+R EG+/ET% are available fro$ RBS counters andi$ple$ented in FACTS. Note that this reflects the throu(hput over the radiointerface and (enerall! does not reflect proble$s in the transport net'or& "See?Considerations for +S /A Iub Band'idth@%. As 'ould be e6pected, there arerelationships bet'een the CHI value reported b! the E3, the retrans$ission rate,

and the cell throu(hput. o' CHI values reflect a poor radio environ$ent andhence a lo'er throu(hput 'ith hi(her retrans$ission rate. Bear in $ind that this$a! be due to a sin(le user that is in a poor covera(e area, 'hereas the celldoes provide (ood throu(hputs in other areas. In such a situation so$e antennaad>ust$ents $a! i$prove perfor$ance other'ise an additional site $a! bere uired to fill the covera(e (ap. Note too that for reliable throu(hput statistics areasonable data volu$e is re uired.


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E#! ple FACTS Reports sho'in( (ood AC;+S Throu(hputs 'ell above 1 bps forthe cell althou(h droppin( belo' # &bps 'hen the data volu$e drops belo' # PB!teper 1# $inute interval "1 st plot% (ood avera(e reported CHI values $ostl! above ) 'iththe avera(e used CHI value noticeabl! hi(her sho'in( that the AC;+S scheduler isschedulin( the users in the better instantaneous radio environ$ent ") nd plot%

retrans$ission ratio and NACP ratio $ostl! belo' .1 "or 1 D% correlatin( to the (oodradio environ$ent reflected b! the CHI values "- rd plot% a noticeable split bet'een thecell throu(hput and user throu(hput as the avera(e nu$ber of E3s 'ith data buffered inthe RBS increases "5 th plot%.


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E#! ple FACTS Reports sho'in( poor AC;+S Throu(hputs belo' - &bps "1 st plot% correspondin( poor avera(e reported CHI values of around < 'ith the avera(eused CHI belo' the avera(e reported CHI possibl! due to the poor ACP*NACPdetection success rate and the fact that there is onl! one user in the cell ") nd plot% ver!poor retrans$ission ratio "above .#% and NACP ratio "above .5% reflectin( the poor

radio environ$ent reported b! the CHI values "-rd

plot%.


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E#! ple FACTS Reports sho'in( the i$prove$ent to p$CapAlloclub+s i$itin(Ratioand the disappearance of lost +S data fra$es 'hen the Iub interface 'as up(radedfro$ one 31 to t'o 31s. In the second fi(ure, notice that there is no obviousi$prove$ent to the +S /A Throu(hput as these counters $easure the throu(hputacross the radio interface "at the AC;+S la!er% 'hereas the Iub 'as con(ested.


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Consi$er!tions for ,SDPA% T*ro)-*p)ts Above 3;45 UEs/

--. To support +S /A throu(hputs above -.7 bps "'hich is possible fro$ the /#soft'are release throu(h support of $ore that five +S /A codes per cell% it is

li&el! that $an! cells 'ill re uired the introduction of a second carrier fre uenc!in order to prevent do'nlin& channelisation code con(estion. Also, the Iubband'idth 'ill need to be up(raded to $a&e such throu(hputs possible and thee6istin( channel ele$ent capacit! "TXB*+S;TXB co$binations% 'ill need tobe revie'ed in order to cater for $ore than five +S /A codes per cell.

Consi$er!tions for ,SDPA% C*!nnel Ele ent Us!-e

-5. Another consideration 'ith the introduction of +S /A is the channel ele$entcapacit! re uired in the RBS to support the +S do'nlin& channels and the A;

C+ in the uplin&. Because +S /A is broadband in the do'nlin& onl! thetendenc! is to provide sufficient channel ele$ent capacit! in the do'nlin& 'ithoutproperl! considerin( the uplin& channel ele$ent re uire$ents for the A; C+.This is especiall! evident 'hen the optional E -


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E#! ple FACTS Reports sho'in( ho' the SF 5 E setup failures"E S3TE/FAI ER3SSF5% increased rapidl! after the introduction of +S /A, and thendisappeared 'hen the E -


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Offlo!$in- Tr!ffic% Directe$ Retr1 to GS7

-#. =hen a ETRAN cell is con(estin(, for 'hatever reason, one possibilit! to

provide te$porar! "and often onl! partial% relief is to enable irected Retr! toGS on that cell. In the /5 soft'are release this is the best option ho'ever forthe /# soft'are release refer to the section ? ffloadin( Traffic Service Based+andover@ belo'. nl! speech calls $a! be re;directed to the GS net'or& andonl! one directed retr! tar(et GS cell $a! be specified "t!picall! the co;sitedcell%. It is a blind redirection so it is i$portant that the tar(et GS cell has thesa$e "or better% covera(e area as the ETRAN cell. It is also ver! i$portant toensure that the GS cell has the capacit! to handle the additional speech traffic.The redirection is tri((ered b! a trans$itted po'er threshold 'hich is notideal for situations 'here po'er is not the cause of con(estion ho'ever asuitable po'er threshold $a! be established for other for$s of cell

con(estion.E#! ple T'o slides sho'in( an e6a$ple calculation to esti$ate the po'er thresholdto use i.e. the settin( for para$eter loadSharin(Gs$Threshold.


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E#! ple FACTS Reports sho'in( ho' the nu$ber of directed retries to GSincreased as the threshold specified b! loadSharin(Gs$Threshold 'as chan(ed to1#D, 15D, 1-D and finall! &ept on 1)D "1 st plot% the correspondin( i$prove$ent toCSSR Speech and the decline in p$NoRe eniedAd$ "Ad$ission Control 'asre>ectin( due to a lac& of channelisation codes% ") nd plot% the correspondin(

i$prove$ent to CSSR +S "-rd

/lot%.


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CSSR Call Setup Success Rate6C: 6edicated Channel *!ransport Channel+6CR 6rop Call Rate6 C: 6edicated hysical Channel * hysical Channel+6( 6ownlink

G ): General erformance ) ent :andler :S$6SC: :i%h$Speed 6ownlink Shared Channel *!ransport Channel+:S$ 6SC: :i%h$Speed hysical 6ownlink Shared Channel * hysical Channel+:S$SCC: :i%h$Speed Shared Control Channel * hysical Channel+:S6 & :i%h$Speed 6ownlink acket &ccessI9:< Inter$9re;uency :ando er IR&! Inter$Radio &ccess !echnolo%y Iu Interface "etween an RNC and a CN Iu" Interface "etween an RNC and an RBSIur Interface "etween two RNCs2C & 2ulti$Channel ower &mplifier *"oard in RBS 31 1+

2G5 2edia Gateway 2u" 2ana%ement *uality of Ser iceR&B Radio &ccess Bearer R&N&G Radio &ccess Network &%%re%ator R&XB Random &ccess and Recei er Board RBS Radio Base StationR( Radio (ink R(S Radio (ink Set RNC Radio Network Controller RRC Radio Resource Control R7 Radio 7nit *"oard in RBS 31 4+RXI roduct instance of R&N&GSC Scram"lin% CodeS9 Spreadin% 9actor S

Documents

3G Cell Optimisation_RevA