LTE空口信令流程详解以及相关优化案例汇总1、附着信令流程1.1 、Attach附着信令流程（统计时延：红色的为开始和结束信令）EPS MM Attach requestEPS MM Unknown(0x0734)UL CCCH rrcConnectionRequestDL CCCH rrcConnectionSetupUL DCCH rrcConnectionSetupCompleteDL DCCH rrcConnectionReconfigurationDL DCCH dlInformationTransferUL DCCH rrcConnectionReconfigurationCompleteEPS MM Security protected NAS messageEPS MM Authentication requestEPS MM Authentication responseEPS MM Unknown(0x077B)UL DCCH ulInformationTransferDL DCCH dlInformationTransferEPS MM Security protected NAS messageEPS MM Security mode commandEPS MM Security mode completeEPS MM Unknown(0x0790)UL DCCH ulInformationTransferDL DCCH ueCapabilityEnquiryUL DCCH ueCapabilityInformationDL DCCH securityModeCommandDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationCompleteEPS MM Security protected NAS messageEPS MM Attach acceptEPS SM Activate default EPS bearer context requestEPS SM Activate default EPS bearer context acceptEPS MM Attach completeEPS MM Unknown(0x072D)UL DCCH ulInformationTransferDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationCompleteattach.xlsAttach信令流程详解1.2、Detach去附着信令流程（统计时延：红色的为开始和结束信令）EPS MM Detach requestEPS MM Unknown(0x0734)UL DCCH ulInformationTransferDL DCCH dlInformationTransferEPS MM Security protected NAS messageEPS MM Detach acceptDL DCCH rrcConnectionReleaseEPS SM PDN connectivity requestdeatch.xlsDetach信令流程详解2、呼叫业务信令流程2.1、UE主叫信令流程（统计时延：红色的为开始和结束信令）EPS MM Extended service requestUL CCCH rrcConnectionRequestDL CCCH rrcConnectionSetupUL DCCH rrcConnectionSetupCompleteDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL DCCH securityModeCommandDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationCompleteUE 主叫信令.xlsUE主叫信令流程详解2.2、UE被叫信令流程（统计时延：红色的为开始和结束信令）DL PCCH PagingEPS MM Extended service requestUL CCCH rrcConnectionRequestDL CCCH rrcConnectionSetupUL DCCH rrcConnectionSetupCompleteDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL DCCH securityModeCommandDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationCompleteUE 被叫信令.xlsUE被叫信令流程详解3、重选与切换信令流程3.1、小区重选信令流程DL BCCH:DL SCH systemInformationBlockType1 DL BCCH:DL SCH systemInformationDL BCCH:DL SCH systemInformationBlockType1 DL BCCH:DL SCH systemInformationBlockType1 DL BCCH:DL SCH systemInformationDL BCCH:DL SCH systemInformationBlockType1 DL BCCH:DL SCH systemInformationBlockType1 DL BCCH:DL SCH systemInformationBlockType1重选.xls重选信令流程详解3.2、基站内同频切换信令流程（统计时延：红色的为开始和结束信令）UL DCCH measurementReportDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL BCCH:DL SCH systemInformationBlockType1DL BCCH:DL SCH systemInformationBlockType1DL BCCH:DL SCH systemInformationBlockType1DL BCCH:DL SCH systemInformationBlockType1DL BCCH:DL SCH systemInformation基站内同频切换信令流程详解基站内同频切换信令.xls3.3、基站间同频切换信令流程（统计时延：红色的为开始和结束信令）UL DCCH measurementReportDL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete DL BCCH:DL SCH systemInformationBlockType1DL DCCH rrcConnectionReconfigurationUL DCCH rrcConnectionReconfigurationComplete基站间同频切换信令流程详解基站间同频切换信令.xls4、跟踪区域更新信令流程4.1、新小区所属跟踪区域不在终端跟踪区域列表中信令流程4.2、周期性跟踪区域更新信令流程六、优化案例9.1、PUSCH BLER高案例问题现状：最近在上南路高青路做业务测试时发现PUSCH BLER较高，分别对Cell175进行了多次不同状态下的测试，分别为由其他小区切换至Cell175、处于定点状态下占用Cell175、处于移动状态下稳定占用Cell175进行测试，在这三种状态下，Cell175的PUSCH BLEW均很高，同时，在占用Cell175的时候，UE会多次出现重建的情况。

上南路高青路问题路段调整前测试情况：在切换占用上Cell175以后测试情况截图在定点状态下处于移动状态稳定占用Cell175调整措施：对Cell175进行了Lock&Unlock操作。

调整后复测情况说明：在对Cell175进行了相应的调整以后，在原问题路段及进行复测，复测过程中发现：原先切换至Cell175(Cell177切换至Cell175以及Cell174切换至Cell175)均会出现PUSCH BLEW偏高的问题已经得到了解决。

调整后，在切换占用上Cell175的时候，PUSCH BLEW值维持在10以下，原先在Cell175的过程中会频繁重建的问题也得到了解决。

调整后复测情况如下图所示：后续问题：已经抓取了UE侧和eNB侧的相关Trace，准备进一步分析定位问题。

9.2、天馈调整案例问题现状：在上南路永泰路路段附近进行业务测试时，UE在Cell183和Cell181之间切换的过程中会出现SNR突降，同时检测到许多奇怪的Cell ID的情况，导致切换失败事件频发。

怀疑是Cell181和Cell183小区之间的干扰所导致的，准备对Site61的天馈进行了相应的排查和调整。

Site61基站查勘情况1、Site61 Cell183 方位角由325度调整为355度，下倾角由0度调整为6度；Cell183方位角调整情况说明：如上图所示：由于Site61——PD125的实际位置与规划位置存在偏差，故对Cell183的天线方位角由325度调整为355度；同时，Cell183的电子下倾角由于工程的原因未进行下压，故今天将其由0度调整为6度。

2、Site61 Cell184 方位角保持160度不变，下倾角由0度调整为4度。

Cell184的电子下倾角由于工程原因未进行下压，故将其由0度调整为4度，Cell184的实际方位角为160度，已经处于最佳角度，故未进行调整。