LTE專(zhuān)項(xiàng)優(yōu)化-KPI優(yōu)化指導(dǎo)手冊(cè)-無(wú)線接通率

1、湖南移動(dòng)專(zhuān)項(xiàng)優(yōu)化KPI優(yōu)化指導(dǎo)手冊(cè)-無(wú)線接通率 2015/3/14目錄 TOC o 1-3 h z u HYPERLINK l _Toc416431188 1 概述 PAGEREF _Toc416431188 h 2 HYPERLINK l _Toc416431189 2 指標(biāo)定義 PAGEREF _Toc416431189 h 2 HYPERLINK l _Toc416431190 3 RRC建立成功率分析 PAGEREF _Toc416431190 h 2 HYPERLINK l _Toc416431191 3.1 理論介紹 PAGEREF _Toc416431191 h 2 HYPERL

2、INK l _Toc416431192 3.2 正常信令流程 PAGEREF _Toc416431192 h 2 HYPERLINK l _Toc416431193 3.3 指標(biāo)定義 PAGEREF _Toc416431193 h 3 HYPERLINK l _Toc416431194 3.4 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn) PAGEREF _Toc416431194 h 4 HYPERLINK l _Toc416431195 3.5 RRC接入成功率處理經(jīng)驗(yàn)及流程 PAGEREF _Toc416431195 h 7 HYPERLINK l _Toc416431196 4 S1 建立成功率 PAG

3、EREF _Toc416431196 h 9 HYPERLINK l _Toc416431197 4.1 正常信令流程 PAGEREF _Toc416431197 h 9 HYPERLINK l _Toc416431198 4.2 指標(biāo)定義 PAGEREF _Toc416431198 h 9 HYPERLINK l _Toc416431199 4.3 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn) PAGEREF _Toc416431199 h 9 HYPERLINK l _Toc416431200 4.4 S1建立成功率處理經(jīng)驗(yàn)及流程 PAGEREF _Toc416431200 h 11 HYPERLINK l

4、 _Toc416431201 5 ERAB建立成功率分析 PAGEREF _Toc416431201 h 11 HYPERLINK l _Toc416431202 5.1 正常信令流程 PAGEREF _Toc416431202 h 11 HYPERLINK l _Toc416431203 5.2 指標(biāo)定義 PAGEREF _Toc416431203 h 12 HYPERLINK l _Toc416431204 5.3 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn) PAGEREF _Toc416431204 h 12 HYPERLINK l _Toc416431205 5.4 ERAB建立成功率處理經(jīng)驗(yàn)及流程

5、PAGEREF _Toc416431205 h 14 HYPERLINK l _Toc416431206 6 相關(guān)案例 PAGEREF _Toc416431206 h 14 HYPERLINK l _Toc416431207 6.1 PRB資源受限 PAGEREF _Toc416431207 h 14 HYPERLINK l _Toc416431208 6.2 告警導(dǎo)致接入成功率低 PAGEREF _Toc416431208 h 16 HYPERLINK l _Toc416431209 6.3 GPS故障導(dǎo)致接入成功率低 PAGEREF _Toc416431209 h 17 HYPERLINK

6、 l _Toc416431210 6.4 天線接反導(dǎo)致模3干擾 PAGEREF _Toc416431210 h 18 HYPERLINK l _Toc416431211 7KPI指標(biāo)相關(guān)counter PAGEREF _Toc416431211 h 201 概述無(wú)線接通率可以統(tǒng)計(jì)UE成功接入LTE網(wǎng)絡(luò)的性能。無(wú)線接入主要發(fā)生在開(kāi)機(jī)附著、異系統(tǒng)重選回LTE、位置更新、收到pagging等過(guò)程中，無(wú)線接入是用戶使用LTE網(wǎng)絡(luò)的前提。無(wú)線接通率由RRC建立成功率、S1建立成功率和ERAB建立成功率3部分構(gòu)成。2 指標(biāo)定義無(wú)線接通率= RRC建立成功率*ERAB建立成功率*100%。RRC建立成功率=

7、RRC接入成功率次數(shù)/RRC接入嘗試次數(shù)*100% =pmRrcConnEstabSucc/pmRrcConnEstabSucc*100%ERAB建立成功率=ERAB建立成功率次數(shù)/ERAB建立嘗試次數(shù)*100% =(PmErabEstabSuccInit+PmErabEstabSuccAdded)/(PmErabEstabAttInit+PmErabEstabAttAdded)*100%3 RRC建立成功率分析3.1 理論介紹RRC連接建立過(guò)程分為兩個(gè)階段：準(zhǔn)備階段和實(shí)施階段。在準(zhǔn)備階段中，UE會(huì)根據(jù)NAS 層的觸發(fā)原因和系統(tǒng)廣播中的接入限制信息，通過(guò)一系列檢查來(lái)判斷自己是否被允許進(jìn)行接入過(guò)

8、程，如果可以，則執(zhí)行后續(xù)的實(shí)施階段；否則UE的RRC將啟動(dòng)相應(yīng)的定時(shí)器，在該定時(shí)器超時(shí)前UE無(wú)法發(fā)起任何接入過(guò)程。上述機(jī)制的目的是負(fù)荷擁塞控制，當(dāng)網(wǎng)絡(luò)負(fù)荷較重時(shí)限制某些UE進(jìn)行接入3.2 正常信令流程RRC建立流程如下圖所示，其中紅點(diǎn)處為RRC建立重要counter（PmRrcConnEstabAtt和pmRrcConnEstabSucc）統(tǒng)計(jì)節(jié)點(diǎn)。RRC 建立觸發(fā)原因：IDLE態(tài)UE需變?yōu)檫B接態(tài)時(shí)發(fā)起該過(guò)程，如呼叫、響應(yīng)尋呼、TAU（跟蹤區(qū)）、Attach(附著)等。RRC連接建立成功流程RRC連接請(qǐng)求：UE通過(guò)UL_CCCH在SRB0上發(fā)送，攜帶UE的初始（NAS）標(biāo)識(shí)和建立原因等，該消息

9、對(duì)應(yīng)于隨機(jī)接入過(guò)程的Msg3RRC連接建立：eNB通過(guò)DL_CCCH在SRB0上發(fā)送，攜帶SRB1的完整配置信息，該消息對(duì)應(yīng)隨機(jī)接入過(guò)程的Msg4RRC連接建立完成：UE通過(guò)UL-DCCH在SRB1上發(fā)送，攜帶上行方向NAS消息，如Attach Request、TAU Request、Service Request、Detach Request等，eNB根據(jù)這些消息進(jìn)行S1口建立RRC連接重建立拒絕流程第二步中，如果eNB中沒(méi)有UE的上下文信息，則拒絕為UE重建RRC連接，則通過(guò)DL_CCCH在SRB0上回復(fù)一條RRC連接重建立拒絕消息3.3 指標(biāo)定義RRC連接建立是指處于空閑狀態(tài)的UE或待開(kāi)

10、機(jī)的UE準(zhǔn)備發(fā)起一個(gè)呼叫或響應(yīng)尋呼時(shí)發(fā)起的過(guò)程。處于降低接入時(shí)延的考慮，LTE系統(tǒng)將RRC連接建立過(guò)程設(shè)計(jì)發(fā)生在ENB和MME之間的S1連接建立前，也就是在ENB尚未從MME獲得任何UE上下文前，ENB需要將RRC連接建立完畢，因此該過(guò)程主要建立最基本的SRB1。RRC連接建立成功意味著UE與網(wǎng)絡(luò)建立了信令連接，是進(jìn)行其他業(yè)務(wù)的基礎(chǔ)。RRC建立成功率公式：RRC建立成功率=RRC接入成功率次數(shù)/RRC接入嘗試次數(shù)*100% =pmRrcConnEstabSucc/pmRrcConnEstabSucc*100%指標(biāo)指標(biāo)描述RRC連接請(qǐng)求次數(shù)小區(qū)接收UE的RRC Connection Reques

11、t消息次數(shù)（不包括重發(fā)）RRC連接建立完成次數(shù)小區(qū)接收UE返回的RRC Connection Setup Complete消息次數(shù)RRC建立失敗次數(shù)資源分配失敗而導(dǎo)致連接建立失敗的次數(shù)UE無(wú)應(yīng)答而導(dǎo)致連接建立失敗的次數(shù)小區(qū)發(fā)送RRC Connection Reject消息次數(shù)3.4 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn)RRC建立成功率相關(guān)主要counter統(tǒng)計(jì)節(jié)點(diǎn)如下圖所示：Random accessRRC connection setup is triggered byUERRC connectionRBSRRC connection request messagerequestpmRrcConnEs

12、tabAtt +RRC connectionYessetup already ongoingfor the sameS-TMSI or RandomValue?NopmRrcConnEstabAttEmstep for cause EmergencypmRrcConnEstabAttHpapmRrcConnEstabAttEm +step for cause High Prio AccesspmRrcConnEstabAttHpa +pmRrcConnEstabAttMtapmRrcConnEstabAttMta +step for cause Mobile Terminating Acces

13、spmRrcConnEstabAttMos +pmRrcConnEstabAttMospmRrcConnEstabAttMod +step for cause Mobile Originating SignalingpmRrcConnEstabAttModstep for cause Mobile Originating DatapmRrcConnEstabAttreattEmpmRrcConnEstabAttReatt +step for cause EmergencypmRrcConnEstabAttReattHpastep for cause High Prio AccesspmRrcC

14、onnEstabAttReattEm +pmRrcConnEstabAttReattMtapmRrcConnEstabAttReattHpa +step for cause Mobile Terminating AccesspmRrcConnEstabAttReattMta +pmRrcConnEstabAttReattMospmRrcConnEstabAttReattMos +step for cause Mobile Originating SignalingpmRrcConnEstabAttReattMod +pmRrcConnEstabAttReattModstep for cause

15、 Mobile Originating DataAL0000311GA Check with license control(number of connected users)pmRrcConnEstabFailLic +Successful license control? No Yes UE RRC connection RBSpmRrcConnEstabFailHighLoad + or pmRrcConnEstabFailOverload +High load or Overload? Yes reject NoAll UEs bearers rejected during bear

16、e admission?pmRrcConnEstabFailBeareAdmissionRej+ YesRRC connrequest rejecte? No UE RRC connection RBSreject UE RRC connection RBS No stup UE RRC connection RBSpmRrcConnEstabSucc+ Stup complete pmRrcConnEstabSuccEm +pmRrcConnEstabSuccHpa +pmRrcConnEstabSuccMta +pmRrcConnEstabSuccMos +pmRrcConnEstabSu

17、ccMod +pmRrcConnEstabSuccDta +pmRrcConnEstabSuccGummeiNative + pmRrcConnEstabSuccEm + step for cause ”Emergency” pmRrcConnEstabSuccHpa + step for cause ”High Prio Access” pmRrcConnEstabSuccMta + step for cause ”Mobile Terminating Access” pmRrcConnEstabSuccMos + step for cause ”Mobile Originating Sig

18、naling pmRrcConnEstabSuccMod + step for cause ”Mobile Originating Data” pmRrcConnEstabSuccDta+ step for cause “Delay Tolerant Access” pmRrcConnEstabSuccGummeiNativeEnd RRC connection setup step when indicating “GUmmei type equal to native 3.5 RRC接入成功率處理經(jīng)驗(yàn)及流程根據(jù)之前處理RRC接入成功率的經(jīng)驗(yàn)，RRC接入成功率主要從ENB問(wèn)題、弱覆蓋、干擾、

19、資源受限、license受限等方面來(lái)分析處理。總結(jié)處理經(jīng)驗(yàn)及流程如下表：失敗階段原因查找失敗原因優(yōu)化建議RRC失敗檢查告警、小區(qū)可用性、RRU的狀態(tài)及VSWRENB問(wèn)題根據(jù)告警原因解決告警RRC失敗通過(guò)地圖信息檢查周邊環(huán)境及站點(diǎn)分布弱覆蓋調(diào)整工參或者增加新站加強(qiáng)周邊覆蓋RRC失敗根據(jù)工參信息檢查受周邊小區(qū)干擾模3干擾調(diào)整工參或者PCI解決模3干擾RRC失敗檢查上行RSSI是否偏高上行干擾解決干擾問(wèn)題RRC失敗檢查上行PRB的利用率PRB資源受限增加noOfPucchSrUsers，noOfPucchcqiUsers配置RRC失敗檢查connected user的license數(shù)量license

20、受限建議客戶進(jìn)行l(wèi)icense擴(kuò)容RRC接入成功率優(yōu)化詳細(xì)流程及counter如下如： 4 S1 建立成功率4.1 正常信令流程S1建立流程：UE完成SRB1承載和無(wú)線資源配置，向eNB發(fā)送RRCConnectionSetupComplete消息，包含NAS層Attach request信息，Arrach request信息中攜帶了PLMN等信息。eNB選擇MME，向MME發(fā)送INITIAL UE MESSAGE消息，此信息攜帶了UE標(biāo)示GUTI 或 IMSI。MME向HSS發(fā)送鑒權(quán)請(qǐng)求后HSS回復(fù)鑒權(quán)需要的向量（Kasme, RAND, AUTN, XRES）。MME通過(guò)DL Informa

21、tion Transfer向UE發(fā)起鑒權(quán)請(qǐng)求。 4.2 指標(biāo)定義S1建立成功率是指UE完成RRC連接后NAS層信令建立的成功率。S1建立成功率=S1建立成功率次數(shù)/S1建立請(qǐng)求次數(shù)*100%=pmS1SigConnEstabSucc/pmS1SigConnEstabAtt*100%4.3 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn)Signalling connection setup triggered by initial UE message UE Initial UE RBSmessageppmS1SigConnEstabAttEm +pmS1SigConnEstabAtt +step for caus

22、e ”Emergency”pmS1SigConnEstabAttHpa +pmS1SigConnEstabAttEm +pmS1SigConnEstabAttHpa +pmS1SigConnEstabAttMod +pmS1SigConnEstabAttMta +pmS1SigConnEstabAttMos +pmS1SigConnEstabAttDta +step for cause ”High Prio Access”pmS1SigConnEstabAttMod +step for cause ”Mobile Originating Data”pmS1SigConnEstabAttMta

23、+step for cause ”Mobile Terminating Access”pmS1SigConnEstabAttMos +step for cause ”Mobile Originating Signalling”pmS1SigConnEstabAttDta +RBS timeout on initial context setup request from MME?step for cause ”Delay Tolerant Access” yesEnd signallingconnection setup NoMME sends initial context setup re

24、quest to RBSRBS Initial context MMESetup request(E-RABs, Sec keys)Any message received on the S1 logical connection? NO Stepped for any of the following pmS1SigConnEstabSucc +messages: Yes pmS1SigConnEstabSuccEm +S1 downlink NAS transport step for cause ”Emergency” S1 UE context release command pmS1

25、SigConnEstabSuccHpa +pmS1SigConnEstabAttEm +pmS1SigConnEstabAttHpa +pmS1SigConnEstabAttMod +pmS1SigConnEstabAttMta +pmS1SigConnEstabAttMos +pmS1SigConnEstabAttDta +S1 initial context setup request step for cause ”High Prio Access”S1 reset pmS1SigConnEstabSuccMod + step for cause ”Mobile Originating

26、Data” pmS1SigConnEstabSuccMta + step for cause ”Mobile Terminating Access” pmS1SigConnEstabSuccMos + step for cause ”Mobile Originating Signalling” pmS1SigConnEstabSuccDta + step for cause Delay Tolerant Access”4.4 S1建立成功率處理經(jīng)驗(yàn)及流程失敗階段原因查找失敗原因優(yōu)化建議S1失敗檢查小區(qū)可用性、告警等，可能多個(gè)站點(diǎn)出現(xiàn)類(lèi)似問(wèn)題傳輸問(wèn)題解決傳輸問(wèn)題S1失敗檢查T(mén)AC在MME上的配置

27、TAC配置問(wèn)題修復(fù)TAC配置S1失敗檢查T(mén)AC與LAC在MME映射關(guān)系LAC-TAC映射問(wèn)題重選規(guī)劃并配置問(wèn)題TAC-LAC映射關(guān)系5 ERAB建立成功率分析5.1 正常信令流程ERAB建立信令流程及重要counter統(tǒng)計(jì)節(jié)點(diǎn)如下圖：ERAB建立信令流程：Initial Context Setup過(guò)程通過(guò)MME向ENB下發(fā)的INITIAL CONTEXT SETUP REQUEST信令觸發(fā)。此條信令包含了初始ERAB建立請(qǐng)求信息、并包含安全算法和安全密匙。RBS通過(guò)SECURITY MODE COMMAND信令要求UE使用安全模式。UE回復(fù)SECURITY MODE COMPLETE后UE與R

28、BS間的通信將進(jìn)行加密和完整性保護(hù)。安全模式激活后，RBS通過(guò)向UE下發(fā)RRC CONNECTION RECONFIGURATION為數(shù)據(jù)承載分配資源。UE上發(fā)RRC CONNECTION RECONFIGURATION COMPLETE，ENB上發(fā)INITIAL CONTEXT SETUP RESPONSE。5.2 指標(biāo)定義E-RAB建立成功是成功為用戶分配了用戶平面的連接比例。E-RAB建立成功率用E-RAB建立請(qǐng)求個(gè)數(shù)和E-RAB建立成功個(gè)數(shù)的比表示，E-RAB建立請(qǐng)求（E-RAB SETUP REQUEST）用于E-RAB建立；在初始上下文建立請(qǐng)求（Initial Context Se

29、tup Request）消息中含有E-RAB to Be Setup List IE，也可以用于E-RAB建立。ERAB建立成功率= E-RAB建立成功數(shù)/E-RAB建立請(qǐng)求數(shù)*100%=(pmErabEstabSuccInit+pmErabEstabSuccAdded)/(pmErabEstabAttInit+pmErabEstabAttAdded)*100%5.3 詳細(xì)counter統(tǒng)計(jì)節(jié)點(diǎn)S1cnnSuccNote:Corresponding counter per QCI pmErabEstabAttlnitQcipmUeCtxtEstabAtt+pmErabEstabAttlnit+

30、pmErabEstabAttlnitArp+ Stepped for each E-RAB that has the given ARP Priority LevelpmErabEstabAttlnitPa+ Stepped for attempted setup of bearer No With priviliged accessLicense for number ofE-RABs per user/License for RLC UM OK ? UE RRC connection RBS reconfiguration pmErabEstabFailLlinitLic+ UE RRC

31、connection RBS Reconfiguration complete Yes DL/UL GBR resource overload?UE Linitial context RBS Setup failure YespmErabEstabFailGbrDIEnb+or pmErabEstabGbrUlENB+RBS sends initial context setup response to MME No RBS Initial context MME Setup responseUE Initial context RBS Note:Corresponding counter p

32、er QCI pmErabEstabSucclnitQcipmUeCtxtEstabSucc + pmErabEstabSuccInit + Setup failurepmErabEstabSuccInitArp + Stepped for each successfully setup E-RAB that has the given ARP Prionity LevepmErabEstabSuccInitPa + Stepped for successfully setup of bearer with privileged accessEnd signaling connection s

33、etup5.4 ERAB建立成功率處理經(jīng)驗(yàn)及流程失敗階段原因查找失敗原因優(yōu)化建議ERAB失敗通過(guò)UETR信令消息查看原因值Security update failures問(wèn)題解決SIM，UE，ENB或MME安全性參數(shù)問(wèn)題ERAB失敗通過(guò)UETR信令消息查看原因值vendor/UE specific issues問(wèn)題解決SIM，UE，ENB或MME參數(shù)配置問(wèn)題ERAB失敗檢查MME容量licens容量問(wèn)題增加MME容量ERAB失敗通過(guò)地圖信息檢查周邊環(huán)境及站點(diǎn)分布弱覆蓋問(wèn)題調(diào)整工參或者增加新站增強(qiáng)周邊覆蓋ERAB失敗檢查小區(qū)可用性、告警等，可能多個(gè)站點(diǎn)出現(xiàn)類(lèi)似問(wèn)題傳輸問(wèn)題解決傳輸問(wèn)題6 相關(guān)案例

34、6.1 PRB資源受限一、問(wèn)題描述在岳陽(yáng)武廣火車(chē)站3小區(qū)接通率偏低為91.05%，且發(fā)現(xiàn)該小區(qū)Erab接通率正常為99.39%，可RRC接通率只有91.05%，RRC建立失敗了4263次。二、原因分析PRB資源受限。下圖可以看出Pucch請(qǐng)求CQI和SR資源未響應(yīng)次數(shù)較高，說(shuō)明該小區(qū)有業(yè)務(wù)需求但是資源無(wú)法滿足分配。pmPucchSrCqiResCongSr ：The number of times a PUCCH allocation request for SR resource(s) could not be granted.pmPucchSrCqiResCongCqi ：The numb

35、er of times a PUCCH allocation request for CQI resource(s) could not be granted進(jìn)一步分析發(fā)現(xiàn)，該小區(qū)RRC最大連接數(shù)超過(guò)設(shè)定上限。 該站覆蓋岳陽(yáng)高鐵站，元旦假日臨近人流量增大用戶數(shù)增多，資源分配不足，導(dǎo)致RRC建立成功率不高。三、解決措施確定PRB資源受限，因此需要增加no0fPucchCqiUsers和no0fPucchSrUsers配置。令后臺(tái)更改參數(shù)如下：MO Class AttributeRecommendedEUtranCellTDDnoOfPucchSrUsers200EUtranCellTDDnoOf

36、PucchCqiUsers0EUtranCellTDDcommonSrPeriodicity 20四、處理結(jié)果參數(shù)更改后，該站現(xiàn)網(wǎng)配置如下：RRC接通率恢復(fù)為：6.2 告警導(dǎo)致接入成功率低一、問(wèn)題描述岳陽(yáng)市漁光社區(qū)2、3小區(qū)接通率變差分別為52.49%、48.24%。該站接通變差主要由于RRC建立成功率變差引起，RRC接通率分別只有52.58%和48.37%，兩個(gè)小區(qū)RRC建立都失敗了四千余次。二、原因分析基站電源故障。當(dāng)時(shí)查得該站并無(wú)強(qiáng)干擾，也未出現(xiàn)業(yè)務(wù)量激增的情況。登錄后臺(tái)查詢(xún)告警情況時(shí)，也未發(fā)現(xiàn)實(shí)時(shí)告警產(chǎn)生。后進(jìn)一步查詢(xún)?cè)撜镜臍v史告警，發(fā)現(xiàn)該站曾短時(shí)間內(nèi)頻繁的出現(xiàn)了電源告警。三、解決措施查得告警將該情況反饋給工程部，并令后臺(tái)將該站暫時(shí)鎖住，以免KPI指標(biāo)繼續(xù)下滑。工程組實(shí)地勘察得知，該站近日新開(kāi)了2G站點(diǎn)與之共站，共用電源。而電源額定功率不足，無(wú)法負(fù)荷兩個(gè)基站，于是導(dǎo)致我4G站點(diǎn)頻繁電源告警，基站處于通而未通斷而未斷