CSFB时延优化方案验证报告
CSFB时延优化方案验证报告
一RNC178
CSFB时延优化方案
优化措施 方案原理 T300定时器为UE接入3G网络时发送RRC Connection Request后等待RRC 降低T300定时器长度 Connection Setup的时间。由于无线环境、对于这种情况，缩短该Timer的设置，有助于缩短RRC建链过程的时延，以减少CSFB端到端时延 CSFB回落至WCDMA后，需要同步进行RAU推迟CSFB用户的RAU流程 流程，RNC可以控制推迟该流程，以降低CSFB时延 备注：此功能需要RNC识别用户为CSFB用户，目前仅iPhone5s和三星Note3支持 打开RRC建立消息瘦身优化开关 F1载波关闭SIB4/12系统消息 对RRC建立消息进行瘦身，改善CSFB接入时延 在CSFB过程中没有必要侦听SIB4/12，关闭有助于缩短侦听系统消息的时间，改善CSFB接入时延 开启该功能，标明将SIB3的下发周期缩短SIB3调度优化 至160ms，有助于缩短侦听系统消息的时间，改善CSFB接入时延 IMEI查询可以在CN和RNC/BSC侧进行，目CSFB流程中IMEI查询优化 关闭IMSI查询 的是为了获取UE的标识，从而进行特定目的的控制。但是该流程会增加UE在CSFB回落UMTS的时延，建议在非必要的情况下，关闭该流程查询的开关 打开RB建立消息瘦身优化开关 打开DMCR（延迟测量控制读取） 存在CS域IU连接且CS未建立完成时PS RB建立DRD（直接重试）开关 RB建立消息长度会影响到RB建立的时延，通过缩短RB消息长度，可以改善CSFB接入的时延 打开DMCR，推迟UE读取SIB11等消息，缩短CSFB接入时延 关闭该功能，RNC收到CN下发的PS RAB指派消息时，先判断是否存在CS域的初始直传或直传消息，初始直传或直传消息原因值是cm service request(主叫)或paging 避免PSDRD失败影响CS接通率 无 缩短CSFB时延约20ms 缩短CSFB时延约200ms 缩短CSFB时延约100ms 缩短SIN3调度周期至160ms 缩短CSFB时延 无 缩短CSFB时延约30ms 无 缩短CSFB时延<100ms 无 对于RRC Connection 的情况，可以节约600ms时延 上行RACH负荷可能增加，下行FACH负荷可能增加，RTWP可能抬升，RRC接入成功率可能降低 优化增益 负面影响 瞬间链路拥塞等可能导致第一次接入失败， Request无响应无 开启该功能，则网络侧无法获取UE的TAC信息，不影响业务。建议只在保障测试前配置 无 无 CSFB时延优化方案验证报告
response(被叫)，且CS语音业务未建立完成，如果条件满足，则PS RB建立不允许做DRD CSFB时延改善效果评估
方案执行后，CSFB主叫建立时延（ExtendedServiceRequest-Alerting）由7274ms缩短至6482ms，改善约800ms，达到预期效果。具体如下：
CSFB时延（毫秒） 修改前 修改后 改善幅度 ExtendedServiceRequest-Alerting 7274 6482 793 ExtendedServiceRequest-RRCConnectionRelease 78 73 5 RRCConnectionRelease-CM Service Request 1761 1243 517 CM Service Request-Setup 716 710 5 Setup-Call Proceeding 214 226 -13 Call Proceeding-Alerting 4506 4228 278 时延改善与方案子项的匹配关系如下：
系统消息下发策略变更评估
由方案执行前后UE接收的系统消息集对比确认方案生效： ? 方案执行后延迟下发SIB11
? 方案执行后SIB3的下发周期缩短至160ms ? 确认T300修改为400ms生效 方案执行前-主叫：
22:43:36.317
22:43:36.319 22:43:36.349 22:43:36.816 22:43:36.816 22:43:36.856 22:43:36.876 22:43:36.896 22:43:36.896 22:43:36.916 22:43:36.916 22:43:36.976 22:43:36.976 22:43:36.996 22:43:37.056 22:43:37.056 22:43:37.136 22:43:37.136 22:43:37.176 22:43:37.176 22:43:37.196 22:43:37.292 22:43:37.492
ExtendedServiceRequest ULInformationTransfer RRCConnectionRelease
System Information Block Type7 Master Information Block Extension Type
System Information Block Type1 System Information Block Type7 Master Information Block Scheduling Block1
System Information Block Type2 System Information Block Type7 Master Information Block
System Information Block Type5 System Information Block Type7 Master Information Block
System Information Block Type7 Master Information Block Extension Type
System Information Block Type11 System Information Block Type3 RRC Connection Request RRC Connection Setup
CSFB时延优化方案验证报告
22:43:37.592 22:43:37.597 22:43:37.597 22:43:37.597
RRC Connection Setup Complete Initial Direct Transfer Initial Direct Transfer CM Service Request
方案执行前-被叫：
22:38:06.385 22:38:06.386 22:38:06.403 22:38:06.869 22:38:06.869 22:38:06.929 22:38:06.949 22:38:06.949 22:38:06.969 22:38:06.969 22:38:07.029 22:38:07.029 22:38:07.049 22:38:07.109 22:38:07.109 22:38:07.189 22:38:07.189 22:38:07.229 22:38:07.229 22:38:07.249 22:38:07.396 22:38:07.604 22:38:07.701 22:38:07.706 22:38:07.706 22:38:07.706
ExtendedServiceRequest ULInformationTransfer RRCConnectionRelease
System Information Block Type7 Master Information Block
System Information Block Type3 System Information Block Type7 Master Information Block Scheduling Block1
System Information Block Type2 System Information Block Type7 Master Information Block
System Information Block Type5 System Information Block Type7 Master Information Block
System Information Block Type7 Master Information Block Extension Type
System Information Block Type11 System Information Block Type1 RRC Connection Request RRC Connection Setup
RRC Connection Setup Complete Initial Direct Transfer Initial Direct Transfer Paging Response
方案执行后-主叫：
00:39:29.619 00:39:29.646 00:39:30.056 00:39:30.076 00:39:30.076 00:39:30.096 00:39:30.096 00:39:30.116 00:39:30.116 00:39:30.211 00:39:30.421 00:39:30.519 00:39:30.524 00:39:30.524 00:39:30.524
ExtendedServiceRequest RRCConnectionRelease
System Information Block Type1 Extension Type Scheduling Block1
System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 RRC Connection Request RRC Connection Setup
RRC Connection Setup Complete Initial Direct Transfer Initial Direct Transfer CM Service Request
方案执行后-被叫：
00:36:09.429 00:36:09.430 00:36:09.449 00:36:09.831 00:36:09.831 00:36:09.851 00:36:09.851 00:36:09.871 00:36:09.871 00:36:09.976 00:36:10.186 00:36:10.275 00:36:10.279 00:36:10.279 00:36:10.279
ExtendedServiceRequest ULInformationTransfer RRCConnectionRelease Extension Type Scheduling Block1
System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 RRC Connection Request RRC Connection Setup
RRC Connection Setup Complete Initial Direct Transfer Initial Direct Transfer Paging Response
CSFB时延优化方案验证报告
方案执行后-SIB3下发间隔：
00:36:51.424 00:36:51.424 00:36:51.484 00:36:51.484 00:36:51.564 00:36:51.564 00:36:51.584 00:36:51.584 00:36:51.644 00:36:51.644 00:36:51.664 00:36:51.684 00:36:51.704 00:36:51.704 00:36:51.724 00:36:51.724 00:36:51.744 00:36:51.744 00:36:51.804 00:36:51.804 00:36:51.884 00:36:51.884 00:36:51.904 00:36:51.904 00:36:51.964 00:36:51.964 00:36:51.984 00:36:52.004 00:36:52.024 00:36:52.024 00:36:52.044 00:36:52.044 00:36:52.064 00:36:52.064 00:36:52.104
System Information Block Type2 System Information Block Type3 System Information Block Type7 Master Information Block System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 System Information Block Type7 Master Information Block System Information Block Type5 System Information Block Type1 Extension Type Scheduling Block1
System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 System Information Block Type7 Master Information Block System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 System Information Block Type7 Master Information Block System Information Block Type5 System Information Block Type1 Extension Type Scheduling Block1
System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 System Information Block Type11
方案执行后-T300修改为400ms：
01:18:55.045 01:18:55.065 01:18:55.065 01:18:55.125 01:18:55.125 01:18:55.184 01:18:55.205 01:18:55.205 01:18:55.285 01:18:55.285 01:18:55.345 01:18:55.345 01:18:55.365 01:18:55.365 01:18:55.385 01:18:55.385 01:18:55.554 01:18:55.760 01:18:55.849 01:18:55.853 01:18:55.853 01:18:55.853
Master Information Block System Information Block Type2 System Information Block Type3 System Information Block Type7 Master Information Block RRC Connection Request
System Information Block Type7 Master Information Block System Information Block Type7 Master Information Block Extension Type Scheduling Block1
System Information Block Type7 Master Information Block System Information Block Type2 System Information Block Type3 RRC Connection Request RRC Connection Setup
RRC Connection Setup Complete Initial Direct Transfer Initial Direct Transfer Paging Response
WCDMA指标评估
前台指标评估
关键指标正常波动，未见异常：
CSFB时延优化方案验证报告
话音端到端建立时延 平均值 4.42 4.32 最大值 WCDMA指标评估 FTP下话音接通 载建立成功率 99.09% 99.06% 100% 100% FTP上传建立成功率 100% 100% MOS值 MOS均值 MOS值分布 TotalRSCP(SC) Ec/Io≥-12dB比例 88.32% 89.48% TotalRSCP≥-80dBm 64.14% 56.48% TotalRSCP≥-95dBm 94.73% 92.08% 实施前 实施后 11.69 3.98 2.43% 10.81 4.04 1.83% 后台指标评估
关键指标正常波动，未见异常：
WCDMA后台指标监控
后续计划
经验证，CSFB时延优化方案实施后，CSFB主叫建立时延（ExtendedServiceRequest- Alerting）由7274ms缩短至6482ms，改善约800ms，达到预期效果。并且WCDMA网络指标正常波动，无负面影响。
后续建议逐步扩大修改/验证范围，全网推广。
LTE CSFB时延优化方案验证报告
