LTE系统事件简介一、LTE事件概述LTE切换时需要UE上报测量的结果（包括RSRP，RSRQ等），而上报又分为周期性上报和事件触发的上报。
➢周期性上报由基站配置，UE直接上报测量的结果。
➢事件触发的上报又分为系统内的事件和系统间的事件。
LTE系统内切换主要事件包括：➢A1事件，服务小区质量高于门限；这个事件可以用来关闭频间测量。
➢A2事件，服务小区质量低于门限；这个事件可以用来打开频间测量和系统间测量，因为这个事件发生后可能发生切换等操作。
➢A3事件，邻小区质量好于服务小区质量；这个事件一般用于频内/间基于覆盖的切换。
➢A4事件，邻小区质量好于门限；这个事件一般用于基于负荷的切换。
➢A5事件，服务小区质量低于一个门限并且邻小区质量高于一个门限；这个事件也可以用于频内/间基于覆盖的切换。
目前LTE同频切换都是基于A3/A5事件进行的切换（现网主要是基于A3事件的）二、切换流程举例三、切换流程简要说明- RRC Connection Reconfiguration（Measurement Control）测量控制，一般在初始接入或上一次切换命令中的重配消息里携带- Measurement Report测量报告，终端根据当前小区的测量控制信息，将符合切换门限的小区进行上报- HO Request源小区在收到测量报告后向目标小区申请资源及配置信息（站内切换的话为站内交互，站间切换会使用X2口或者S1口，优先使用X2口）- HO Request Ack目标小区将终端的接纳信息以及其它配置信息反馈给源小区- RRC Connection Reconfiguration（HO Command）将目标小区的接纳信息及配置信息发给终端，告知终端目标小区已准备好终端接入，重配消息里包含目标小区的测量控制- SN Status Transfer源小区将终端业务的缓存数据移至目标小区- Random Access Preamble终端收到第5步重配消息（切换命令）后使用重配消息里的接入信息进行接入- Random Access Response目标小区接入响应，收到此命令后可认为接入完成了，然后终端在RRC层上发重配完成消息（第9步）- RRC Connect Reconfiguration complete（HO Confirm）上报重配完成消息，切换完成- Release Resource当终端成功接入后，目标小区通知源小区删除终端的上下文信息四、协议对LTE事件的定义和说明4.1 A1事件定义Event A1 (Serving becomes better than threshold)The UE shall:1> consider the entering condition for this event to be satisfied when condition A1-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition A1-2, as specifiedbelow, is fulfilled;1> for this measurement, consider the primary or secondary cell that is configured on the frequencyindicated in the associated measObjectEUTRA to be the serving cell;Inequality A1-1 (Entering condition)-Ms>HysThreshInequality A1-2 (Leaving condition)Ms<+ThreshHysThe variables in the formula are defined as follows:Ms is the measurement result of the serving cell, not taking into account any offsets.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Thresh is the threshold parameter for this event (i.e. a1-Threshold as defined within reportConfigEUTRA for this event).Ms is expressed in dBm in case of RSRP, or in dB in case of RSRQ.Hys is expressed in dB.Thresh is expressed in the same unit as Ms.4.2 A2事件定义Event A2 (Serving becomes worse than threshold)The UE shall:1> consider the entering condition for this event to be satisfied when condition A2-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition A2-2, as specifiedbelow, is fulfilled;1> for this measurement, consider the primary or secondary cell that is configured on the frequencyindicated in the associated measObjectEUTRA to be the serving cell;Inequality A2-1 (Entering condition)+Ms<HysThreshInequality A2-2 (Leaving condition)Ms>-HysThreshThe variables in the formula are defined as follows:Ms is the measurement result of the serving cell, not taking into account any offsets.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Thresh is the threshold parameter for this event (i.e. a2-Threshold as defined within reportConfigEUTRA for this event).Ms is expressed in dBm in case of RSRP, or in dB in case of RSRQ.Hys is expressed in dB.Thresh is expressed in the same unit as Ms.4.3 A3事件定义Event A3 (Neighbour becomes offset better than PCell)The UE shall:1> consider the entering condition for this event to be satisfied when condition A3-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition A3-2, as specifiedbelow, is fulfilled;NOTE The cell(s) that triggers the event is on the frequency indicated in the associated measObject which may be different from the (primary) frequency used by the PCell.Inequality A3-1 (Entering condition)++>+Mn++-OcnOfpOcpMpHysOffOfnInequality A3-2 (Leaving condition)++<Mn++++MpOcpOfnOfpOffHysOcnThe variables in the formula are defined as follows:Mn is the measurement result of the neighbouring cell, not taking into account any offsets.Ofn is the frequency specific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell).Ocn is the cell specific offset of the neighbour cell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell), and set to zero if not configured for the neighbour cell.Mp is the measurement result of the PCell, not taking into account any offsets.Ofp is the frequency specific offset of the primary frequency (i.e. offsetFreq as defined within measObjectEUTRA corresponding to the primary frequency).Ocp is the cell specific offset of the PCell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the primary frequency), and is set to zero if not configured for the PCell.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Off is the offset parameter for this event (i.e. a3-Offset as defined within reportConfigEUTRA for this event).Mn, Mp are expressed in dBm in case of RSRP, or in dB in case of RSRQ.Ofn, Ocn, Ofp, Ocp, Hys, Off are expressed in dB.4.4 A4事件定义Event A4 (Neighbour becomes better than threshold)The UE shall:1> consider the entering condition for this event to be satisfied when condition A4-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition A4-2, as specifiedbelow, is fulfilled;Inequality A4-1 (Entering condition)-+Mn>+HysThreshOcnOfnInequality A4-2 (Leaving condition)Mn<+++ThreshOfnHysOcnThe variables in the formula are defined as follows:Mn is the measurement result of the neighbouring cell, not taking into account any offsets.Ofn is the frequency specific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell).Ocn is the cell specific offset of the neighbour cell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell), and set to zero if not configured for the neighbour cell.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Thresh is the threshold parameter for this event (i.e. a4-Threshold as defined within reportConfigEUTRA for this event).Mn is expressed in dBm in case of RSRP, or in dB in case of RSRQ.Ofn, Ocn, Hys are expressed in dB.Thresh is expressed in the same unit as Mn.4.5 A5事件定义Event A5 (PCell becomes worse than threshold1 and neighbour becomes better than threshold2)The UE shall:1> consider the entering condition for this event to be satisfied when both condition A5-1 andcondition A5-2, as specified below, are fulfilled;1> consider the leaving condition for this event to be satisfied when condition A5-3 or condition A5-4, i.e. at least one of the two, as specified below, is fulfilled;NOTE: The cell(s) that triggers the event is on the frequency indicated in the associatedmeasObject which may be different from the (primary) frequency used by the PCell.Inequality A5-1 (Entering condition 1)1Thresh Hys Mp <+Inequality A5-2 (Entering condition 2)2Thresh Hys Ocn Ofn Mn >-++Inequality A5-3 (Leaving condition 1)1Thresh Hys Mp >-Inequality A5-4 (Leaving condition 2)2Thresh Hys Ocn Ofn Mn <+++The variables in the formula are defined as follows:Mp is the measurement result of the PCell, not taking into account any offsets.Mn is the measurement result of the neighbouring cell, not taking into account any offsets.Ofn is the frequency specific offset of the frequency of the neighbour cell (i.e. offsetFreq as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell).Ocn is the cell specific offset of the neighbour cell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell), and set to zero if not configured for the neighbour cell.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Thresh1 is the threshold parameter for this event (i.e. a5-Threshold1 as defined within reportConfigEUTRA for this event).Thresh2 is the threshold parameter for this event (i.e. a5-Threshold2 as defined within reportConfigEUTRA for this event).Mn, Mp are expressed in dBm in case of RSRP, or in dB in case of RSRQ.Ofn, Ocn, Hys are expressed in dB.Thresh1 is expressed in the same unit as Mp .Thresh2 is expressed in the same unit as Mn .Event A6 (Neighbour becomes offset better than SCell)The UE shall:1> consider the entering condition for this event to be satisfied when condition A6-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition A6-2, as specifiedbelow, is fulfilled;1> for this measurement, consider the (secondary) cell that is configured on the frequency indicatedin the associated measObjectEUTRA to be the serving cell;NOTE: The neighbour(s) is on the same frequency as the SCell i.e. both are on the frequency indicated in the associated measObject.Inequality A6-1 (Entering condition)+>Mn++-MsOcsOffHysOcnInequality A6-2 (Leaving condition)+<+Mn++OcsOffMsHysOcnThe variables in the formula are defined as follows:Mn is the measurement result of the neighbouring cell, not taking into account any offsets.Ocn is the cell specific offset of the neighbour cell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the frequency of the neighbour cell), and set to zero if not configured for the neighbour cell.Ms is the measurement result of the serving cell, not taking into account any offsets.Ocs is the cell specific offset of the serving cell (i.e. cellIndividualOffset as defined within measObjectEUTRA corresponding to the serving frequency), and is set to zero if not configured for the serving cell.Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within reportConfigEUTRA for this event).Off is the offset parameter for this event (i.e. a6-Offset as defined within reportConfigEUTRA for this event).Mn, Ms are expressed in dBm in case of RSRP, or in dB in case of RSRQ.Ocn, Ocs, Hys, Off are expressed in dB.Event B1 (Inter RAT neighbour becomes better than threshold)The UE shall:1> for UTRA and CDMA2000, only trigger the event for cells included in the correspondingmeasurement object;1> consider the entering condition for this event to be satisfied when condition B1-1, as specifiedbelow, is fulfilled;1> consider the leaving condition for this event to be satisfied when condition B1-2, as specifiedbelow, is fulfilled;Inequality B1-1 (Entering condition)Thresh+Mn>-HysOfnInequality B1-2 (Leaving condition)++Mn<ThreshHysOfnThe variables in the formula are defined as follows:Mn is the measurement result of the inter-RAT neighbour cell, not taking into account any offsets.For CDMA 2000 measurement result, pilotStrength is divided by -2.Ofn is the frequency specific offset of the frequency of the inter-RAT neighbour cell (i.e. offsetFreq as defined within the measObject corresponding to the frequency of the neighbour inter-RAT cell).Hys is the hysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigInterRAT for this event).Thresh is the threshold parameter for this event (i.e. b1-Threshold as defined within reportConfigInterRAT for this event). For CDMA2000, b1-Threshold is divided by -2.Mn is expressed in dBm or in dB, depending on the measurement quantity of the inter-RAT neighbour cell.Ofn, Hys are expressed in dB.Thresh is expressed in the same unit as Mn.4.8 B2事件定义Event B2 (PCell becomes worse than threshold1 and inter RAT neighbour becomes better than threshold2)The UE shall:1> for UTRA and CDMA2000, only trigger the event for cells included in the correspondingmeasurement object;1> consider the entering condition for this event to be satisfied when both condition B2-1 andcondition B2-2, as specified below, are fulfilled;1> consider the leaving condition for this event to be satisfied when condition B2-3 or conditionB2-4, i.e. at least one of the two, as specified below, is fulfilled;Inequality B2-1 (Entering condition 1)+HysMp<Thresh1Inequality B2-2 (Entering condition 2)-+Mn>Ofn2ThreshHysInequality B2-3 (Leaving condition 1)Hys-Mp>1ThreshInequality B2-4 (Leaving condition 2)Mn<++OfnHys2ThreshThe variables in the formula are defined as follows:Mp is the measurement result of the PCell, not taking into account any offsets.Mn is the measurement result of the inter-RAT neighbour cell, not taking into account any offsets.For CDMA2000 measurement result, pilotStrength is divided by -2.Ofn is the frequency specific offset of the frequency of the inter-RAT neighbour cell (i.e. offsetFreq as defined within the measObject corresponding to the frequency of the inter-RAT neighbourcell).Hys is the hysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigInterRAT for this event).Thresh1 is the threshold parameter for this event (i.e. b2-Threshold1 as defined within reportConfigInterRAT for this event).Thresh2 is the threshold parameter for this event (i.e. b2-Threshold2 as defined within reportConfigInterRAT for this event). For CDMA2000, b2-Threshold2 is divided by -2.Mp is expressed in dBm in case of RSRP, or in dB in case of RSRQ.Mn is expressed in dBm or dB, depending on the measurement quantity of the inter-RAT neighbour cell.Ofn, Hys are expressed in dB.修正版Thresh1 is expressed in the same unit as Mp. Thresh2 is expressed in the same unit as Mn.。
