LTE无线网络优化切换优化手册

LTE无线网络优化切换优化手册1目录1概述....................................................................................................................42LTE切换原理....................................................................................................42.1Intra-eNodeB切换...................................................................................42.2基于X2接口的切换..............................................................................52.3基于S1接口的切换..............................................................................62.4异系统之间切换.....................................................................................62.4.1LTE到3G的切换........................................................................62.4.2LTE到2G的切换........................................................................82.4.33G到LTE的切换......................................................................102.4.42G到LTE的切换......................................................................123LTE切换问题优化方法及流程......................................................................143.1LTE主要切换问题................................................................................143.1.1邻区配置....................................................................................143.1.2参数设置....................................................................................153.1.3无线环境引起的切换异常........................................................163.2LTE切换问题优化流程........................................................................173.3LTE切换相关参数分析........................................................................183.3.1最小接收电平............................................................................183.3.2高优先级重选门限....................................................................193.3.3低优先级重选门限....................................................................193.3.4小区重选优先级........................................................................203.3.5B2事件基于RSRP触发门限2（3G）...................................213.3.6B2事件基于RSRP触发门限1................................................213.3.7B2事件基于接收电平触发门限2（2G）...............................223.4LTE切换相关参数分析........................................................................233.4.1A3事件触发偏置因子...............................................................233.4.2A3事件触发迟滞因子...............................................................243.4.3A3事件触发偏置因子小区分量...............................................2423.4.4A3事件触发持续时间...............................................................253.4.5A3事件触发类型.......................................................................263.4.6A1事件基于RSRP主触发门限...............................................273.4.7A2事件基于RSRP主触发门限...............................................273.4.8A4事件基于RSRP主触发门限...............................................283.4.9A5事件基于RSRP触发门限1................................................293.4.10A5事件基于RSRP触发门限2..............................................304LTE切换及互操作相关参数详表..................................................................30341概述本文主要从基本原理，信令流程，优化案例等各个方面介绍LTE系统内切换以及LTE跟其他系统互操作。2LTE切换原理2.1Intra-eNodeB切换触发事件：A3事件（同频切换），A5事件（异频切换）当UE从当前所处的服务小区切换到同一eNodeB下的另一小区时，会发生Intra-eNodeB切换。52.2基于X2接口的切换触发事件：A3事件（同频切换），A5事件（异频切换）当两个eNodeB之间存在X2接口时，UE从当前所驻留的服务小区切换到另一eNodeB时，可采用基于X2接口的切换:62.3基于S1接口的切换触发事件：A3事件（同频切换），A5事件（异频切换）当两个eNodeB之间不存在X2接口，或X2接口不可用时，UE从当前所驻留的服务小区切换到另一eNodeB时，可采用基于S1接口的切换。2.4异系统之间切换2.4.1LTE到3G的切换实现LTE到3G的切换首先需要满足几个前提：1.网络侧，LTE系统和3G系统均支持LTE到3G的PS切换2.UE侧，UE需要支持LTE到3G的PS切换，UE的FeatureGroupIndicatorbit位8和bit位22数值必须为1。LTE到3G切换的流程概述：1.LTE基站如果收到UE上报的A2测量报告，发现LTE的覆盖较差。2.LTE基站通过RRC重配置消息对UE配置B2事件的测量的相关参数。3.LTE基站收到B2事件的测量报告后，通过MobilityFromEutranCommand通知UE发起到3G的切换。74.LTE基站收到UE上发的MobilityToUtranComplete，切换成功。主要的LTERRC空口信令：UE上报B2测量报告：MeasurementReportUE在LTE小区收到往3G切换命令：MobilityFromEutranCommandUE向LTE小区反馈到3G切换成功：MobilityToUtranComplete具体的切换信令流程如下：1．切换准备信令流程（3GPP23.401）UESourceeNodeBTargetRNCSourceMMETargetSGSNServingGWHSS1.HandoverInitiation2.HandoverRequired3.ForwardRelocationRequest5.RelocationRequest5a.RelocationRequestAcknowledge8.CreateIndirectDataForwardingTunnelRequest7.ForwardRelocationResponsePDNGW8a.CreateIndirectDataForwardingTunnelResponseUplinkandDownlinkUserPlanePDUsTargetServingGW4.CreateSessionRequest4a.CreateSessionResponse6.CreateIndirectDataForwardingTunnelRequest6a.CreateIndirectDataForwardingTunnelResponse2．切换执行信令流程（3GPP23.401）8UESourceeNodeBTargetRNCSourceMMETargetSGSNServingGWHSSPDNGWUplinkandDownlinkUserPlanePDUs1.HandoverCommand2.HOfromE-UTRANCommand-Sendingofuplinkdatapossible4.UTRANIuAccessProcedures5.RelocationComplete6.ForwardRelocationComplete6a.ForwardRelocationCompleteAcknowledge7.ModifyBearerRequest8a.ModifyBearerResponse9.ModifyBearerResponseUplinkandDownlinkUserPlanePDUs(ViaTargetSGSNifDirectTunnelisnotused)4a.HandovertoUTRANCompleteDownlinkUserPlanePDUsIfDirectForwardingappliesIfIndirectForwardingapplies.TargetServingGW(A)8.ModifyBearerRequestViaTargetSGSNincaseDirectTunnelisnotused10.RouteingAreaUpdateprocedure11.DeleteSessi