优化手册(MOTOROLA)

1、.gsm networkoptimization handbookgsgsm draft version1.0authors : song fenghua1999.8.6gsm network optimization handbook1 introduction52 gsm network structure52.1 gsm network structure and interface52.2 lac and ccch calculation62.2 link budget for mcell72.3 a-interface trunks claculation82.4 frequency

2、 planning83 gsm network signalling103.1 mo call setup103.2 mt call setup113.3 intra-bsc handover123.4 inter-bsc handover133.5 location updating143.6 efr signalling143.6.1 mo call143.6.2 mt call143.6.3 intra-bss153.6.4 inter-bss153.7 dualband signalling153.7.1 dualband bcch153.7.2 ms154 drivetest ana

3、lysis164.1 call setup failure analysis164.2 drop call analysis164.3 rxlev analysis164.4 rxqual analysis174.5 ms tx_power analysis175 gsm network performance statistics185.1 call setup statistics185.2 handover statistics205.3 neighbor statistics235.4 carrier statistics235.4.1 interference statistics2

4、35.4.2 carrier hw statistics245.5 efr statistics245.6 dualband statistics256 optimization for call_setup_suc_rate266.1 tch_blocking issue266.1.1 hardware check266.1.2 coverage issue266.1.3 db optimization266.1.4 reconfiguration276.2 non tch_ blocking issue276.2.1 hardware check286.2.2 antenna check2

5、86.2.3 interference check286.2.4 db optimization286.2.5 cic and msc check296.3 overall db optimization296.3.1 cell reselection optimization296.3.2 tch queuing306.3.3 db optimization307 optimization for drop_call_rate317.1 rf_loss issue317.1.1 hw check317.1.2 interference check317.1.3 coverage issue3

6、27.1.4 neighbor list issue327.1.5 neighbor blocking issue327.1.6 lower speed ho327.1.7 software issue337.2 ho_loss issue337.2.1 neighbor hw check337.2.2 neighbor interference check337.2.3 coverage issue337.2.4 first layer neighbor blocking issue347.2.5 faster speed ho347.3 overall db optimization347

7、.3.1 rf_loss vs ho_loss347.3.2 interference optimization357.3.3 handover cause optimization357.3.4 ho timer optimization358 optimization for msc respect378.1 msc call setup and ho timer378.2 no paging issue378.3 no inter_bsc handover issue378.4 long call_ setup time378.6 suggetion for msc connection

8、 rate optimization389 optimization for other respect399.1 no audio and one-way audio issue399.2 cerm feature3910 motorola gsm key solution4110.1 microcell pbgt ho4110.2 congestion relief4110.3 sfh f/p4210.4 dualband alm4411 omc tools4611.1 ctp4611.2 cat24711.3 ect4711.4 dgt4812 gsr4 new feature49gsm

9、 network optimization handbookgsm网络优化手册1 introduction 1 简介as we know, network optimization is a hard and complex work and every optimization engineer should be very familiar with all the gsm network respects. but unfortunately when we do optimization, we must have to look up too many kinds reference

10、 materials. so we often have the very strong desire for an optimization handbook. the following is a summarization of my optimization experience, i hope it can help you get some ideas in your work.如我们所知，网络优化是个复杂、艰巨的工作，每个优化工程师需对gsm网络的所有方面都非常熟悉。不幸的是，如此一来，我们做优化工作时，就得查找太多的参考资料。所以我们迫切需要得到一本优化手册。下面是我的优化经验

11、总结，我希望它能给你的优化工作带来一些思路。 2 gsm network structure2 gsm网络结构it is known we are all familiar with gsm network, so in this chapter i simply explain some respects which are very useful for our optimization and but neglected by our optimization.我们都对gsm网络非常熟悉了。所以在本章，我简单地介绍一些对我们的优化工作非常有用但又常常被忽略的方面。2.1 gsm netw

12、ork structure and interface2.1 gsm 网络结构和接口since we all know gsm interface, i focus on the interface and signaling structure in this section. during optimization we often just notice the layer3 signaling, actually the layer2, which is linker layer controlled by the protocols, is also very important,

13、it often help me to understand the layer3 well and resolve some issue which cant be explained on layer3. the protocols, which control gsm interfaces linking, can help us analyze the timing of link failure and can help us to optimize some timer. but these two respects often are ignored by our enginee

14、r.由于我们都很了解接口了，所以本节主要介绍接口和信令结构。在优化过程中，我们经常观察l3信息，实际上受协议控制的链路层l2也非常重要。它能更好地帮助我们理解l3消息，还能解决一些l3上不能解释的问题。这些控制gsm接口链路的协议能帮助我们分析链路失败的时间，帮助我们优化一些定时器的设置。但我们的工程师常常忽略这两方面。gsm interface tableair-interfaceabis-interfacea-interfacepathbts and msbts and bscbsc and mscsignalingumrslmtlprotocollapdmlapdc7gsm接口表空中接口

15、abis接口a接口位置bts和ms之间bts和bsc之间bsc和msc之间信令链路umrslmtl协议lapdmlapdc72.2 lac and ccch calculation2.2 lac 和 ccch 计算in our optimization , the location size is often considered very important for a gsm network. too large size will cause paging lose, too small means surplus numbers of location updating and inc

16、lude excessive signaling on a-interface. so it is necessary to properly calculate the location size. before determination of lac size, there are some information need to be known:在我们的优化中，对一个gsm网络中，lac分区的大小是很重要的。太大的分区会导致寻呼信息丢失，太小的lac分区会导致过多的位置更新，在a接口上会产生过多的信令流量。在确定lac分区大小时，需要知道以下的信息： no. of agch bloc

17、k are reserved of each cell in the lac(nag). no. of pages are sent for every mtc call setup(pr). the ratio of mtc to moc(1:k). the system erlang per subscriber(ems). the system call duration per subscriber(t) no. of subscriber within the network(nms). ccch utilization(uc). paging by type(peg, for im

18、si, peg=2, for tmsi, peg=4). 在lac中每个cell中保留的agch块（nag） 每次ms做被叫（mtc）的呼叫建立中送出的寻呼次数（pr） ms被叫与主叫的比例（1:k） 系统每用户忙时话务量（ems） 系统每用户呼叫时长（t） 网络中的用户数 （nms） ccch利用率（uc） 寻呼类型（peg，对imsi寻呼，peg=2；对tmsi寻呼，peg=4）the number of paging per secend in a lac :plac=(9-nag)*4.25*peq*uc/pr每秒内在lac中的寻呼次数：plac=（9-nag）*4.25*peg*uc

19、/prthe number of subscriber:nsub=plac*(1+k)*t/3600*3600=plac*(1+k)*tlac支持用户数：nsub=plac*（1+k）*t/3600*3600=plac*（1+k）*tthe number of lacnlac=nms/nsublac数：nlac=nms/nsubnumber of agch blocks require需要的agch块数目：the number of agch per second:ragch = (rcall + rlu + rsms)/3600where rcall = (e x 3600)/trlu =

20、(l x e x 3600)/trsms = (sms x e x 3600)/tsms = gsm sms messages per call in cell level(assume no change in sms) l = current gsm lus per call in cell level( assume the new lu border will be the current border)number of agch blocks requirenagch = ragch/(2 x 4.25)每秒agch的数目：ragch=（rcall+rlu+rsms）/3600其中

21、：rcall=（ex3600）/trlu=（lxex3600）/trsms=（smsxex3600）/tsms=在cell级别上每次通话中的gsm短消息数（假设sms没有改变）l=在cell级别上每次通话中的位置更新数（假设新的位置更新边界与现在的边界一致）需要的agch次数：nagch=ragch/（2x4.25）2.2 link budget for mcell 2.2 mcell的链路预算in hardware trouble shooting, the pathbalance is a very important stattistics, in a normal site its d

22、l and ul pathloss should be about equal to each other, the following link budget can serve as a checking reference.在硬件排障中，pathbalance是一个很重要的统计数据，在一个正常的基站中，其上行下行路径损耗应该大致相当，下面的链路预算可作为一个检查参考。for pgsmdownlink (bts to ms)uplink (ms to bts)bts tx power43dbmms tx power33dbmcombining loss3dbms antenna gain0

23、dbifeeder loss2dbtotal eirp33dbmbts antenna gain18dbitotal eirp56dbmbts antenna gain18dbifeeder loss4dbms rx sensitivity-100dbmdiversity gain5dbms antenna gain0dbibts rx sensitivity-104.00dbmfading margin6dbfading margin6dbinterference margin3dbinterference margin3dbantenna/body loss3dbantenna/body

24、loss3dbmax. allowed pathloss144.00dbmax. allowed pathloss144.00db对 pgsm下行 (bts to ms)上行 (ms to bts)bts 发射功率43dbmms发射功率33dbm合路损耗3dbms天线增益0dbi馈线损耗2db总有效射频功率33dbmbts 天线增益18dbi总有效射频功率56dbmbts天线增益18dbi馈线损耗4dbms接收灵敏度-100dbm分集接收增益5dbms天线增益0dbibts 接收灵敏度-104.00dbm衰落门限6db衰落门限6db干扰门限3db干扰门限3db天线/身体衰耗3db天线/身体衰耗

25、3db最大允许路径衰耗144.00db最大允许路径衰耗144.00dbfor dcsdownlink (bts to ms)uplink (ms to bts)bts tx power43dbmms tx power30dbmcombining loss3dbms antenna gain0dbifeeder loss2dbtotal eirp30dbmbts antenna gain17.5dbitotal eirp55.5dbmbts antenna gain17.5dbidiversity gain4dbms rx sensitivity-100dbmfeeder loss4dbms a

26、ntenna gain0dbibts rx sensitivity-108.00dbmfading margin (90% coverage)6dbfading margin (90% coverage)6dbinterference margin3dbinterference margin3dbantenna/body loss3dbantenna/body loss3dbmax. allowed pathloss143.50dbmax. allowed pathloss143.50db2.3 a-interface trunks calculationon the a-interface

27、the cic number must be enough to support the number of tch on air interface. if the tch number is ntch, the cic number on the a interface should be ntch too. depending on the statistics we a can check if this cic number is enough. if the number of ma_req_from_ms is much less than the amount of ok_ac

28、c_proccm_service_call and ok_acc_proccm_restablish and ok_acc_procpage_response, it means the cic number is not enough.although this thing is very simple, it is often be ignored.2.4 frequency planningmotorola has three kinds of frequency planning methods: fixed and bbh and sfh. bbh and sfh can impro

29、ve system capacity and quality. for example, with 48 afrcn, the following table shows how the bbh and sfh improve the system capacity.fixedbbhsfhbcch4*34*34*3tch4*33*31*3*41*3*5capacity improvement1 1.251.251.50as for sfh, we can trade off f/p between capacity and quality. as shown in the above tabl

30、e, if we use 1*3*5 we can get larger capacity, if we use 1*3*4 we can get better quality. also we can mix the 1*3*4 and 1*3*5 or mix the loading between 4/12 and 4/11 and save some free frequency for microcell. it is very flexible.when sfh implement, the rxlev and rxqual window for pc should be beco

31、me sharper and the ho due to rxqual and rxlev should be more rapid. coverage optimization is primary necessity for sfh. if we use dtx and other features to reduce the interference, the sfh effect will be more positive.as for bbh, it is very important to fixed dri problems in time, otherwise the qual

32、ity will get worse and worse.3 gsm network signaling3.1 mo call setup 3.2 mt call setup3.3 intra-bsc handover 3.4 inter-bsc handover3.5 location updating3.6 efr signaling3.6.1 mo callwhen an efr mobile makes a call, it will notify msc it can support efr speech version through signaling of set up. if

33、 the msc has efr cics, it will assign an efr cic to bss and ask bss to use efr through assignment request signaling. then the bss will notify ms to use efr through assignment command signaling.3.6.2 mt callwhen an efr mobile receives a paging, it will notify msc it can support efr speech version thr

34、ough signaling of call confirmed. if the msc has efr cics, it will assign an efr cic to bss and ask bss to use efr through assignment request signaling. then the bss will notify ms to use efr through assignment command signaling.3.6.3 intra-bsswhen an efr mobile makes an intra-bss ho, the speech ver

35、sion it is using wont be changed.3.6.4 inter-bsswhen an efr mobile makes an inter-bss ho, the speech version may be changed. during the ho the bss will tell the msc it can support efr through ho required signaling and the msc notify the target bss through ho request. if the target bsc has efr cics,

36、it will answer msc it can support efr through ho request ack signaling. the ms will use efr speech version to contact the target cell.3.7 dualband signaling3.7.1 dualband bcch and sacchbts will broadcast the neighbors of the other band through system information type 2ter on bcch in idle mode and th

37、rough system information type 5ter on sacch in dedicated mode. and the mutiband reporting bits in the through system information type 5ter will tell ms how to report the neighbor measurement report.3.7.2 dualband mswhen a dualband ms starts a call it will notify bss it is a dualband mobile through c

38、m service request and classmark change complete signaling. this message will instruct bss to selection ho cell and peg some statistics.4 drivetest analysis4.1 call setup failure analysiswhen a call setup is failure, the bts usually sends the ms the disconnect signaling with a cause value. from the c

39、ause value we can induce the failure reason. according to our experience we list the following table.cause valuereason31bss or msc problem34(before assignment command)tch blocking34(after assignment complete)msc blocking41(after assignment command)bss problem, especially dri problem41(after assignme

40、nt complete)msc problem42msc congestion44bss problem, especially the cic blocking111bss or msc problem4.2 drop call analysis when call is dropped, please check the following case:1. if a neighbor signal is much higher than serving cell, please check the neighbor blocking.2. if all neighbor signal is

41、 lower than the serving cell and ta is large, please check the coverage and neighbor list.3. if the signal of serving cell is very lower and ta is very small, please check the dri power.4. if the signal is normal but rxqual is very bad, please check the interference5. if the serving cell signal is n

42、ormal and ta is large and rxqual is bad, please check whether coverage is overshooting.6. if dropped after ho failure, please check the target cell and ho timer.7. if dropped after ho complete, please check hardware and interference of the target cell4.3 rxlev analysisfrom fics tool we can get the r

43、xlev distribution. according to this distribution we can do the following two things:1. estimate the coverage. if a very small fragment of rxlev is less than -90dbm, we can estimate the indoor coverage well.2. estimate the dl rxlev pc speed. if the distribution has no apperent peak, it means dl rxle

44、v pc speed is too slow. if the distribution peak isnt in the dl rxlev pc window, it means dl rxlev pc threshold is unfit.4.4 rxqual analysisfrom fics tool we can get the rxqual distribution. according to this distribution we can do the following three things:1. estimate the interference. if the frag

45、ment of bad rxqual is more than 10%, it means the interference of overall network is too large.2. estimate the dl rxqual pc speed. if the distribution has no apperent peak, it means dl rxqual pc speed is too slow. if the distribution peak isnt in the dl rxqual pc window, it means dl rxqua pc thresho

46、ld is unfit.3. estimate the dl rxqual ho speed. if the distribution peak is larger than the dl rxqual ho window, it means ho rxqual threshold and speed are unfit.4.5 ms tx_power analysisfrom fics tool we can get the ms tx_power distribution. according to this distribution we can estimate the ul pc e

47、ffect. if 20% of ms txpower are full power, it means the ul pc effect is not well and the ul pc optimization should been done.5 gsm network performance statistics5.1 call setup statisticscall_setup_success_rate: this statistic provides the percentage of calls that successfully access a tch when serv

48、ice is requested for regular calls, emergency calls, sms procedures, page responses, and calls that are reestablished. calls which do not require tch access are excluded.when a cell has lower call_setup_success_rate, the following statistics should be checked.5.1.1 sdcch performancesdcch_rf_loss_rat

49、e: this statistic compares the total number of rf losses (while using an sdcch), as a percentage of the total number of call attempts for sdcch channels. this statistic is intended to give an indication of how good the cell/system is at preserving calls. bad sdcch_rf_loss_rate often impacts cell cal

50、l_setup_success_rate. the following two statistics are not relation to call_setup_success_rate， but it also indicate the sdcch performance, so they are listed .sdcch_congestion_key: this statistic indicates the percentage of call set-ups refused due to congestion on the sdcchs.sdcch_accesses_rate: t

51、his statistic is the number of times a sdcch is successfully seized and a layer 2 sabm command is received from the ms.5.1.2 tch performancetch_congestion_key: this statistic indicates a percentage of call set-up and intra-cell handovers refused due to congestion on the tchs assign_failure_rate_lost

52、: this statistic is the percentage of assignment commands that are sent to the ms which fail and result in lost connectionsassign_failure_rate_recover: this statistic is the percentage of assignment commands which fail with the ms recovering to the source channel.all the three statistics affect the

53、call_setup_success_rate. when assign_failure_rate_recover is too high, the cell may have too more ma_fail_from_ms, it often indicates dri problem.ma_fail_from_ms: this statistic is the number of assignment failure messages received from mss. an assignment failure message can be received at call set-

54、up (traffic channel assignment) and at intra-cell handovers.5.1.3 cic and msc performancecic_alloc_suc_rate: this statistics is ourselves-defined statistic, which can indicate cic blocking or msc problem.when all the cells in a bsc have lower call_setup_success_rate, it is better to check its cic_al

55、loc_suc_rate. if this rate is too lower, it means the cic is blocking.when all the cells in a msc have lower call_setup_success_rate, it is better to check its cic_alloc_suc_rate. if this rate is too lower, it means the msc is in congestion or has some problems.5.2 drop call statisticsdrop_call_rate

56、: this statistic is the proportion of mss which, having successfully accessed the tch, subsequently experience an abnormal release, caused by either radio or equipment problems. this includes rf losses and losses during handovers.the value for this statistic may be calculated at the cell, bss, or ne

57、twork level. the following formula is for cell. when it is for network level, the handover section can be deleted from the common denominator.when a cell has too high drop_call_rate, the following two statistics should be checked.5.2.1 rf_losstch_rf_loss_rate: this statistic compares the total numbe

58、r of rf losses while using a tch as a percentage of the total number of call attempts for tch channels. the statistic is intended to show how good the cell/system is at preserving calls. the following formula is for cell. when it is for network level, the handover section can be deleted from the com

59、mon denominator.when the cell tch_rf_loss_rate is too high, the carrier statistic should be checked.5.2.2 ho_lossho_loss_rate: this statistic is the percentage of allocated calls that are lost during handover procedure. the following formula is for cell. when it is for network level, the handover se

60、ction can be deleted from the common denominator.when the cell ho_loss_rate is too high, the handover statistics should be checked.5.3 handover statisticsif a cell handover performance is not well, the following statistics should be checked.handover performance:handover_failure_rate: this statistic represents handovers that were attempted from the source cell (cell for which the statistic is presented) that failed to make it to the destination cell. this includes handovers t