LTE小区选择和小区重选(3

本节主要介绍小区重选过程，再次强调 重选过程发生在IDLE状态下

 

LTE小区重选分为同系统内的同频、异频重选以及异系统重选。

 

LTE小区同频重选没有优先级的概念。异频和异系统重选有高优先级的小区重选和低优先级的小区重选

 

向高优先级的小区重选时，只要高优先级的小区门限超过一定门限，不管本小区信号如何，终端都要向高优先小区进行重选

 

向低优先级的小区重选时，需要本小区的信号低于一定门限值，低优先级的小区高于一定门限值才能发生重选。

 

小区重选的步骤：启动测量->计算、评估->排序->重选

 

同频小区重选：

对于同频测量：主要参数在SIB1和SIB3中

启动测量：

      如果满足Srxlev > SIntraSearchP 且Squal >SIntraSearchQ时，UE可以选择不进行intra_freq测量

      否则开始进行测量同频小区

相关的参数有：

TreselectionRAT 测量时间

SIntraSearchP 用于启动同频测量的RSRP信号电平门限值

SIntraSearchQ 用于启动同频测量的RSRQ信号质量门限值

  

2011 Jul 22 14:27:32.497  [00] 0xB0C0  LTE RRC OTA Packet --  BCCH_DL_SCH

Pkt Version = 2

RRC Release Number.Major.minor = 9.3.0

Radio Bearer ID = 0, Physical Cell ID = 11

Freq = 5230

SysFrameNum = 990, SubFrameNum = 5

PDU Number = BCCH_DL_SCHMessage,    MsgLength = 22

 

Interpreted PDU:

 

value BCCH-DL-SCH-Message ::=

{

 message c1 : systemInformationBlockType1 :

     ============================================

       cellSelectionInfo

       {

         q-RxLevMin -60, //最小接入电平值-60*2=-120dBm

         q-RxLevMinOffset 4 //q-RxLevMinOffset=4*2=8dB

       },

      

         {

           si-Periodicity rf8,

           sib-MappingInfo

           {

             sibType3//--->SIB3消息

           }

         }

       },

     

 2011 Jul 22 14:27:32.533  [00] 0xB0C0  LTE RRC OTA Packet --  BCCH_DL_SCH

Pkt Version = 2

RRC Release Number.Major.minor = 9.3.0

Radio Bearer ID = 0, Physical Cell ID = 11

Freq = 5230

SysFrameNum = 994, SubFrameNum = 1

PDU Number = BCCH_DL_SCHMessage,    MsgLength = 7

 

Interpreted PDU:

 

value BCCH-DL-SCH-Message ::=

{

  message c1 : systemInformation:

     {

       criticalExtensions systemInformation-r8 :

         {

           sib-TypeAndInfo

           {

             sib3 :

               {

                 cellReselectionInfoCommon

                 {

                   q-Hyst dB2------------->=2dB

                 },

                 cellReselectionServingFreqInfo

                 {

                   s-NonIntraSearch 7,====SnonIntraSearchP”

                   threshServingLow 5,

                   cellReselectionPriority 5

                 },

                 intraFreqCellReselectionInfo ==同频测量信息

                 {

                   q-RxLevMin -60,

                   s-IntraSearch 31,//同频测量门限，SIntraSearchP

                   presenceAntennaPort1 TRUE,

                   neighCellConfig '01'B,

                   t-ReselectionEUTRA 2==时间 2s