TDLTE网络性能KPI切换成功率优化手册.doc

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TD-LTE网络性能KPI( 切换成功率) 优化手册

1 切换成功率定义说明
1.1 指标公式
指标名称
集团规范公式
NSN映射公式
切换成功率
( eNB间S1切换出成功次数+ eNB间X2切换出成功次数+ eNB内切换出成功次数) /( eNB间S1切换出请求次数+ eNB间X2切换出请求次数+ eNB内切换出请求次数) *100%
100* sum(M8009C7 + M8014C7 + M8014C19) / sum(M8009C6 + M8014C0 + M8014C14)

1.2 COUNTER定义
1.2.1 集团规范定义
1、 eNB间S1切换出请求次数:
源eNB向MME发送的”切换请求”消息( HANDOVER REQUIRED) ( 3GPP TS 36.413) , 指示eNB间经过S1接口的切换出准备请求。向不同小区发送的同一切换准备请求, 需要重复统计。
2、 eNB间S1切换出成功次数:
源eNB收到MME发送的”UE上下文释放命令”消息( UE CONTEXT RELEASE COMMAND) ( 3GPP TS 36.413) , 指示eNB间经过S1接口的切换出执行成功。

3、 eNB间X2切换出请求次数:
源eNB向目标eNB发送的”切换请求”消息( HANDOVER REQUEST) ( 3GPP TS 36.423) , 指示eNB间经过X2接口的切换出准备请求。向不同小区发送的同一切换准备请求, 重复统计。

4、 eNB间X2切换出成功次数:
源eNB收到目标eNB发送的”UE上下文释放”消息( UE CONTEXT RELEASE) ( 3GPP TS 36.423) , 指示eNB间经过X2接口的切换出执行成功。

5、 eNB内切换出请求次数:
eNB向UE发送携带mobilityControlInfo 的”RRC连接重配置”消息( RRCConnectionReconfiguration) , 指示eNB内小区间切换出请求。( 3GPP TS 36.331)

6、 eNB内切换出成功次数:
eNB收到UE发送的”RRC连接重配置完成”消息( RRCConnectionReconfigurationComplete) , 指示eNB内小区间切换出成功。( 3GPP TS 36.331)

1.2.2 NSN映射
1、 eNB间S1切换出请求次数:
M8014C14: INTER_ENB_S1_HO_PREP, The number of Inter eNB S1-based Handover preparations;

2、 eNB间S1切换出成功次数:
M8014C19: INTER_ENB_S1_HO_SUCC, The number of successful Inter eNB S1-based Handover completions;

3、 eNB间X2切换出请求次数:
M8014C0: INTER_ENB_HO_PREP, The number of Inter-eNB X2-based Handover preparations. The Mobility management (MM) receives a list with target cells from the RRM and decides to start an Inter-eNB X2-based Handover;

4、 eNB间X2切换出成功次数:
M8014C7: SUCC_INTER_ENB_HO, The number of successful Inter-eNB X2-based Handover completions;

5、 eNB内切换出请求次数:
M8009C6: ATT_INTRA_ENB_HO, The number of Intra-eNB Handover attempts;

6、 eNB内切换出成功次数:
M8009C7: SUCC_INTRA_ENB_HO, The number of successful Intra-eNB Handover completions;

1.3 信令统计点
1.3.1 eNB间S1切换
Counter
Counter ID
NetAct name
eNB间S1切换请求次数
M8014C14
INTER_ENB_S1_HO_PREP
eNB间S1切换目标小区准备失败次数
M8014C15
INTER_S1_HO_PREP_FAIL_TIME
M8014C16
INTER_S1_HO_PREP_FAIL_NORR
M8014C17
INTER_S1_HO_PREP_FAIL_OTHER
eNB间S1切换尝试次数
M8014C18
INTER_ENB_S1_HO_ATT
eNB间S1切换成功次数
M8014C19
INTER_ENB_S1_HO_SUCC
eNB间S1切换失败次数
M8014C20
INTER_ENB_S1_HO_FAIL

统计点关系: M8014C14 = M8014C15 + M8014C16 + M8014C17 + M8014C18
M8014C18 = M8014C19 + M8014C20( 注: 现网实际数据对不上)

1、 M8014C14: INTER_ENB_S1_HO_PREP
Updated: This counter is updated following the transmission of an S1AP:HANDOVER REQUIRED message from the source eNB to the MME if this message prepares an Inter eNB Handover.
2、 M8014C15: INTER_S1_HO_PREP_FAIL_TIME
Updated: This counter is updated at the expiry of the guarding timer TS1RELOCprep if the timer was started because of the preparation of an Inter eNB Handover.
3、 M8014C16: INTER_S1_HO_PREP_FAIL_NORR
Updated: This counter is updated following the reception of an S1AP: HANDOVER PREPARATION FAILURE message from MME to source eNB with cause "No Radio Resources Available in Target Cell" if this message is received in response to the preparation of an Inter eNB Handover.
4、 M8014C17: INTER_S1_HO_PREP_FAIL_OTHER
Updated: The number of failed Inter eNB S1-based Handover preparations due to the reception of an S1AP: HANDOVER PREPARATION FAILURE message with a cause other than "No Radio Resources Available in Target Cell."

5、 M8014C18: INTER_ENB_S1_HO_ATT
Updated: This counter is updated following the reception of an S1AP: HANDOVER COMMAND message from the MME to the source eNB in case that this message is received in response to the preparation of an Inter eNB Handover.

6、 M8014C19: INTER_ENB_S1_HO_SUCC
Updated: This counter is updated following the reception of an S1AP: UE CONTEXT RELEASE COMMAND message from the MME to the source eNB with the cause value Radio Network Layer (Successful Handover) in case that this message is received for an Inter eNB Handover.

7、 M8014C20: INTER_ENB_S1_HO_FAIL
Updated: This counter is updated following the expiry of the guarding timer TS1RELOCoverall in case that this timer was started because of an Inter eNB Handover.

1.3.2 eNB间X2切换
Counter
Counter ID
NetAct name
eNB间X2切换请求次数
M8014C0
INTER_ENB_HO_PREP
eNB间X2切换目标小区准备失败次数
M8014C2
FAIL_ENB_HO_PREP_TIME
M8014C3
FAIL_ENB_HO_PREP_AC
M8014C5
FAIL_ENB_HO_PREP_OTHER
eNB间X2切换尝试次数
M8014C6
ATT_INTER_ENB_HO
eNB间X2切换成功次数
M8014C7
SUCC_INTER_ENB_HO
eNB间X2切换失败次数
M8014C8
INTER_ENB_HO_FAIL

统计点关系: M8014C0 = M8014C2 + M8014C3 + M8014C5 + M8014C6
M8014C6 = M8014C7 + M8014C8( 注: 现网实际数据对不上)

1、 M8014C0: INTER_ENB_HO_PREP
Updated: This counter is updated following the transmission of an X2AP: Handover Request to the target eNB.

2、 M8014C2: FAIL_ENB_HO_PREP_TIME
Updated: This counter is updated following the expiry of the guarding timer TX2RELOCprep.
3、 M8014C3: FAIL_ENB_HO_PREP_AC
Updated: This counter is updated following the reception of an X2AP: Handover Preparation Failure message from the target eNB.
4、 M8014C5: FAIL_ENB_HO_PREP_OTHER
Updated: The counter is updated if the failure detected does not match any other failure counter.

5、 M8014C6: ATT_INTER_ENB_HO
Updated: This counter is updated following the reception of an X2AP: Handover Request Acknowledge message from the target eNB.

6、 M8014C7 : SUCC_INTER_ENB_HO
Updated: This counter is updated following the reception of an X2AP:Release Resource message sent by the target eNB.
7、 M8014C8: INTER_ENB_HO_FAIL
Updated: This counter is updated following the expiry of the guarding timer TX2RELOCoverall.

1.3.3 eNB内切换
Counter
Counter ID
NetAct name
eNB内收到MR次数
M8009C0
TOT_NOT_START_HO_PREP
eNB内切换决断次数
M8009C1
TOT_HO_DECISION
eNB内切换请求次数
M8009C2
INTRA_ENB_HO_PREP
eNB内切换准备失败次数
M8009C3
FAIL_ENB_HO_PREP_AC
M8009C5
FAIL_ENB_HO_PREP_OTH
eNB内切换尝试次数
M8009C6
ATT_INTRA_ENB_HO
eNB内切换成功次数
M8009C7
SUCC_INTRA_ENB_HO
eNB内切换执行失败次数
M8009C8
ENB_INTRA_HO_FAIL

统计点关系: M8009C1 > M8014C2
M8014C2 = M8014C3 + M8014C5 + M8014C6
M8014C6 = M8014C7 + M8014C8( 注: 现网实际数据对不上)

1、 M8009C0: TOT_NOT_START_HO_PREP
Updated: The reception of an RRC Measurement Report message sent by the UE to eNB and of the RRM decision not to execute a handover. Updated to the source cell.

2、 M8009C1: TOT_HO_DECISION
Updated: The reception of an RRC Measurement Report message sent by the UE to eNB and of an RRM decision to execute a handover. Updated to the source cell.
3、 M8009C2: INTRA_ENB_HO_PREP
Updated: An internal eNB trigger. The eNB MM receives a list with the target cells from RRM and decides on an Intra-eNB Handover. Updated to the source cell.
4、 M8009C6: ATT_INTRA_ENB_HO
Updated: The transmission of an RRC Connection Reconfiguration message sent by the eNB to UE, which indicates a Handover Command to the UE. Updated to the source cell.
5、 M8009C7: SUCC_INTRA_ENB_HO
Updated: The reception of an internal UE Context Release Request for the handover on the source side. Updated to the source cell.

6、 M8009C3: FAIL_ENB_HO_PREP_AC
Updated: An internal eNB trigger. The eNB MM receives a list with the target cells from the RRM. The MM or RRM AC decides not to execute an Intra-eNB Handover Updated to the source cell.
7、 M8009C5: FAIL_ENB_HO_PREP_OTH
Updated: An internal eNB trigger. The eNB MM receives a list with the target cells from RRM. The MM or RRM AC decides not to execute an Intra-eNB Handover. The counter is updated if the failure detected does not match any other failure counter. Updated to the source cell.

8、 M8009C8: ENB_INTRA_HO_FAIL
Updated: The counter is updated to the source cell when timer THOoverall expires.

2 影响切换成功率的因素
2.1 从信令流程角度分析
( 注: 个别流程能够会有不同, 但大致相当, 此处仅以X2切换为例。eNB内切换流程更少, eNB间S1切换仅多了有线侧的信令, 如果丢失均属于传输侧问题)
2.1.1 切换判决阶段
( 注: 此阶段不会影响后台统计切换成功率指标)
1) 现象: eNB未收到测量报告
Ø 覆盖、 干扰等无线环境问题
因PDCCH问题导致UE上发测量报告的UL GRANT没有收到;
因PUSCH问题导致eNB未收到或收到CRC校验出错)
Ø UE内部处理问题
2) 现象: eNB未发送切换请求
Ø 参数问题: 如触发事件门限过晚等, 未及时触发测量报告
Ø 邻区漏配
Ø 黑名单
2.1.2 切换准备阶段
1) 现象: 切换请求发出, 对方未收到
Ø 传输丢包
2) 现象: 目标小区拒绝
Ø 目标小区准入控制、 容量问题
3) 现象: 目标小区回准备失败
Ø 已知的有unknown-MME-Code
Ø 其余的需要跟着LOG确定具体原因值
4) 现象: TX2RELOCprep准备超时
Ø 目标小区故障、 告警
Ø 目标小区休眠
2.1.3 切换执行阶段
1) 现象: 切换命令( RRC连接重配) 丢失
Ø 覆盖、 干扰等无线环境问题
UE下行PDCCH解析失败, 下行PDCCH受限
UE下行PDSCH解析失败, 下行PDSCH受限
2) 现象: 切换完成信令( RRC连接重配完成) 丢失
Ø 覆盖、 干扰等无线环境问题
UE在目标小区的PREAMBLE, eNB没有收到, 上行PRACH受限
UE下行接收RAR失败, 下行PDSCH受限
UE上发切换完成, eNB没有收到, 上行PUSCH受限
3) 现象: 在非真正的目标小区接入失败
Ø PCI混淆
4) 现象: 目标小区非最优小区
Ø 邻区混乱、 漏配
5) 现象: 源eNB发起Handover Cancel
Ø 覆盖、 干扰等无线环境问题
切换过程中失步, 重建回源小区
Ø 目标小区休眠
当前主要是室分小区休眠问题
2.1.4 路径转换阶段
1) 现象: 各S1AP信令丢失
Ø 各网元内部处理信令失败
Ø S1口传输异常, 如传输丢包
2) 现象: X2AP: UE CONTEXT REL丢失
Ø 各网元内部处理信令失败
Ø X2口传输异常, 如传输丢包

2.2 按原因分类汇总分析

3 切换成功率分析流程和优化方法
3.1 整体分析流程图

3.2 从COUNTER指标确定优先排查方向
3.2.1 切换准备阶段
阶段
COUNTER
COUNTER NAME
最可能原因
eNB间S1切换目标小区准备失败次数
M8014C15
INTER_S1_HO_PREP_FAIL_TIME
目标小区故障告警、 传输丢包
M8014C16
INTER_S1_HO_PREP_FAIL_NORR
目标小区容量
M8014C17
INTER_S1_HO_PREP_FAIL_OTHER

需跟踪LOG确认
eNB间X2切换目标小区准备失败次数
M8014C2
FAIL_ENB_HO_PREP_TIME
目标小区故障告警、 传输丢包
M8014C3
FAIL_ENB_HO_PREP_AC
目标小区容量
M8014C5
FAIL_ENB_HO_PREP_OTHER
需跟踪LOG确认
eNB内切换准备失败次数
M8009C3
FAIL_ENB_HO_PREP_AC
目标小区容量
M8009C5
FAIL_ENB_HO_PREP_OTH
需跟踪LOG确认
3.2.2 切换执行阶段
当前仅有HO_FAIL统计, 此统计项的原因值为TX2RELOCoverall、 TS1RELOCoverall、 THOoverall超时。
还有其它原因, 需要跟踪LOG确认。
( 注: 建议诺基亚厂家后期开发切换执行阶段失败原因值相关COUNTER, 方便快速定位问题)

3.3 从关联指标定位问题根因
切换失败分类
关联指标
故障告警
告警信息
容量问题
RRC准入拒绝
传输问题
链路闪断; 传输误码超限
无线环境
RSRP、 SINR、 IBLER、 MCS、 CQI等
配置问题
邻区漏配、 鉴权开关
产品问题
所有指标为"0"或"-"

4 切换成功率优化案例