Traffic statistic problem analysis recommended

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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

Traffic Statistic Problem Analysis

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Page1Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

Objectivesl 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


Contents1. 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 Analysisl 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 Analysisl 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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RRC Connection Failure Analysisl 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


RRC Connection Failure Analysisl 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


RRC Connection Failure Analysisl 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


RRC Connection Failure Analysisl 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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RAB Assignment Probleml 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


RAB Assignment Probleml 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


RAB Assignment Probleml 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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RAB Assignment Probleml 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


RAB Assignment Probleml 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


RAB Assignment Probleml 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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Call Drop Problem Analysisl 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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Call Drop Problem Analysisl 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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Call Drop Problem Analysisl 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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Soft Handover Problem Analysisl 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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Hard Handover Problem Analysisl 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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Hard Handover Problem Analysisl 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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Hard Handover Problem Analysisl 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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RAT Handover Problem Analysisl 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


RAT Handover Problem Analysisl 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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RAT Handover Problem Analysisl 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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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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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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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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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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Traffic statistic problem analysis recommended

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