Traffic statistic problem analysis recommended

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Confidential Information of Huawei. No Spreading Without Permission
N-0
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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Traffic Statistic
Problem Analysis
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N-1
Page1Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
l Upon completion of this course, you will be able to:
p Know the basic reasons for traffic statistic problem

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N-2
Contents
1. Common Traffic Statistic Analysis
2. RRC Connection Failure Problem Analysis
3. RAB Assignment problem analysis
4. Call drop problem analysis
5. Handover problem analysis
6. Traffic problem analysis

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N-3
Coverage Problem Analysis
l Coverage problem
p If the traffic statistic shows most failure caused by “RF.RLCRst”
“RF.ULSync” or “UuNoReply”, RF problems should be
considered
p IOS tracing can help to analysis the poor coverage and
overshoot problem
p Pilot pollution can be analyzed by CHR (call history record)
analysis in Nastar
p Missing Neighbor cell list can also be analyzed by CHR
analysis in Nastar

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N-4
Interference Problem Analysis
l Interference problem
p Check the RTWP value
p if the mean RTWP value is over -100dBm, the interference
problem should be considered
p By Nastar interference analysis function, the internal and
external interference may be located
p By NodeB RTWP monitor, main and diversity antenna RTWP
value can help to analyze interference

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N-5
Contents

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N-6
RRC Connection Failure Analysis
l AAL2 failure
p Iub transmission broken
p Iub transmission congestion
n Check DL traffic to confirm the problem
l RL failure
p CE is not enough
n Check DL CE consumption to confirm the problem

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N-7
l Power congestion
p NodeB power is in congestion
n Check TCP value to confirm the problem
l CE congestion
p NodeB CE admission failure
n Check the CE consumption state to confirm the problem

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N-8
l Code congestion
p Due to code congestion, RRC connection failed
n Check the related counter to confirm the proble
– OVSF occupation efficiency
l Other congestion reason
p CPU consumption too high
p WFMR capability limitation

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N-9
l Coverage problem
p If the traffic statistic shows most failure caused by “RF.RLCRst”
“RF.ULSync” or “UuNoReply”, RF problems should be
considered
p IOS tracing can help to analysis the RF problem

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N-10
Contents

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N-11
RAB Assignment Problem
l TNL failure
p Transport network layer failure
p Check the transport network layer to confirm the problem
l Relocation failure
p When the RNC trigger relocation, CN sends RAN Assignment
Request. Then, RNC will not process it

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N-12
l Power congestion
p Check the RTWP and TCP to confirm the problem
l CE congestion
p Check the CE consumption
l Code congestion
p Check the code allocation efficiency
p If the code allocation efficiency should be higher than 30%

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N-13
l RIP failure
p Radio interface failure
n Related to coverage problem
l Unsupported failure
p Related to UE capability problem
n For example, trigger VP and high data rate service together

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N-14
l Invalid parameter
p RNC thinks the parameter from RAB Assignment is invalid
n For example, the MBR (maximum bit rate) or GBR (guaranteed bit
rate) is beyond the UE ability

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N-15
l Due to RB setup failure
p Physical channel failure
n Usually, it happens from Cell_FACH to Cell_DCH due to DCCC.
n In this case, RB setup failed due to synchronization failure
between UE and NodeB
p Cell update failure
n Usually, it happens from Cell_FACH to Cell_DCH due to DCCC
n In this case, RB setup failed when UE moves to another cell, and
trigger cell update

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N-16
l Due to RB setup failure
p Invalid configuration
n Related to UE problem. UE and network can not interpret the
parameter in the same way
n Or, the following case can also trigger the failure
– If subscriber find the dialed number is wrong, and terminate the call
immediately, this could be counted “invalid configuration”
p No reply
n Coverage problem
n UE can not receive RB setup from RNC

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N-17
Contents

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N-18
Call Drop Problem Analysis
l OM (operation & maintenance) intervention
p Call drop due to OM
n For example, Engineer executes “TRG RABRel”
l RAB pre-emption
p High priority UE is rejected in admission stage, and then pre-
empt other UE resource.
p Check the traffic state to confirm the problem

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N-19
l UTRAN generated reason
p Equipment abnormal
l SRB/TRB reset
p Coverage problem
n Poor coverage, pilot pollution, missing neighbor cell
n UE sends “cell update” in DCH due to RL failure
l Uplink synchronization failure
p RNC receives “Radio Link failure” from NodeB
p Coverage problem

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N-20
l No reply
p UE does not response the message of RNC, for example
n RB reconfiguration no reply
n Active set update no reply

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N-21
Contents

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N-22
Soft Handover Problem Analysis
l SHO percentage is high
p SHO percentage is over 40%
p Check the SHO parameters
p Special case
n CN does not send “Iu release” to RNC. Even the user plane is
release, the control plane is still connected.

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N-23
Hard Handover Problem Analysis
l Hard handover preparation failure
p NoResAvail
n No radio resources available in target cell, which means target cell
is in congestion
p Expired
n No response message from CN
n Due to transmission problem or improper parameters of CN
l 硬切换伴随迁移出准备失败
l 目标小区无可用无线网络资源
l 目标系统迁移超时
l 在目标CN/RNC或系统中迁移失败在目标CN/RNC或系统中迁移不知支持迁移目标
不允许OM 干预无可用资源未定义原因其他原因

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N-24
l Hard handover preparation failure
p Relocation Failure in Target CN/RNC or Target System
n Improper CN parameter configuration
p Relocation not supported in Target RNC or Target system
n Some handover parameters can not be supported by RNC
p Relocation Target not allowed
n Improper MSC parameter configuration
p OM intervention
l 硬切换伴随迁移出准备失败
l 目标小区无可用无线网络资源
l 目标系统迁移超时
l 在目标CN/RNC或系统中迁移失败在目标CN/RNC或系统中迁移不知支持迁移目标
不允许OM 干预无可用资源未定义原因其他原因

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N-25
l Hard handover execution failure
p Configuration Unsupported
n UE compatible problem
p Physical Channel Failure
n Coverage problem or high interference
p Incompatible simultaneous reconfiguration
l UE认为硬切换伴随迁移出小区的命令不支持，一般为手机兼容性问题
l 硬切换伴随迁移出失败
l 配置不支持
l 物理信道失败
l 同步重配置不兼容
l 非法配置
l 配置未完成
l 其他原因

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N-26
RAT Handover Problem Analysis
l Inter-RAT handover preparation failure
p Relocation Cancelled
n RNC request relocation to CN, then CN send relocation cancelled
n UE terminate the call when the RNC send the relocation to CN.
Then CN send relocation cancelled.
p TRELOCalloc Expiry
n CN does not response the relocation request
n CN network parameters and transmission problem
– Tracing can be followed to do further analysis
l RAT系统间切换准备失败

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N-27
l Inter-RAT handover preparation failure
p Unknown Target RNC
n In proper MSC parameters, for example
– Target cell without LAC
p No Resource Available
n 2G network is in congestion
l RAT系统间切换准备失败

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N-28
l Inter-RAT handover execution failure
p Configuration Unsupported
p Physical Channel Failure
n 2G poor coverage or high interference
n The 2G parameters from CN is not compatible with BSC
n 1、2G信号比较弱或者干扰比较严重导致UE接入失败；
2、是网络发给UE的加密方式等信道参数与BSC的不一致，这个需要
进行终端和BSC的参数对比确认，一般发生在CN为友商的设备的网
络中，需检查MSC和SGSN的加密算法配置

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N-29
Contents

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N-30
Traffic Problem Analysis
l Uplink CE
p Check the uplink mean and maximum CE consumption
n Close to the maximum configuration of NodeB or not
l Downlink CE
p Check the downlink mean and maximum CE consumption
n Close to the maximum configuration of NodeB or not

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N-31
l Mean TCP
p Close to the maximum the TCP or not
p Other traffic counter indicate high traffic or not
l Maximum TCP
p Close to the maximum the TCP or not

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N-32
l Mean RTWP
p Uplink RTWP value is higher than -100dBm or not
l Maximum RTWP
p Analysis this value with mean RTWP

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N-33
l Allocated Spreading Factors
p Check the spreading code efficiency
l Cell Unavailability Duration
p Transmission interruption
n Most cases happened due to microwave transmission in bad
weather

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N-34
Thank you
www.huawei.com

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