UMTS Accessibilty
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Transcript of UMTS Accessibilty
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ACCESSABILITY ANALYSIS
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CONTENT
ACCESSIBILTYOBJECTIVE
ACCESSIBILTYKPI FORMULA
RRC & RAB ESTABLISHMENT FAILURE CAUSES TROUBLESHOOTING FLOW CHART
MAIN ACCESSIBILITY ISSUES
ADMISSION CONTROL FLOW CHART
DL POWER CONGESTION ANALYSIS
CHANNELISATION CODE CONGESTION ANALYSIS CE CONGESTION ANALYSIS ( UL & DL )
ASE CONGESTION ANALYSIS
HIGH PROCESSOR LOAD ANALYLSIS ( Mp LOAD )
CONNECTION LIMIT
HIGH UL NOISE
FAILED AFTER ADM ANALYSIS
SPECIAL ANALYSIS
CONCLUSION
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ACCESSABILITY Objective
Accessibility is defined as the ability of a user to access the UMTS network successfully
to utilize the available services. The metrics within Ericsson RNC and OSS provide
counters and KPIs that describe the behaviors and experience of the subscribers while
accessing the UMTS network.
This is divided up into a number of areas, CS and PS, as well as being divided on an RRC
and RAB basis.
The services which have counters for Accessibility are:
CS Voice
CS Data SRB
Video
PS Streaming & Interactive
HSDPA Streaming & Interactive
EUL (HSUPA)
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ACCESSABILITY KPI FORMULS
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RRC Setup Failure Causes
PLoad=pmNoRejRrcConnMpLoadC
DENIED_ADM=pmNoRrcReqDeniedAdm
FAIL_RADIO=pmTotNoRrcConnectReq - pmTotNoRrcConnectReqSucc pmTotNoUtranRejRrcConnReq
FAIL_AFT_ADM=pmTotNoUtranRejRrcConnReq - pmNoRejRrcConnMpLoadCpmNoRrcReqDeniedAdm
DEN_CS=pmNoRrcCsReqDeniedAdm
DEN_PS=pmNoRrcPsReqDeniedAdm
RL_DENIED_ADM=pmNoRlDeni edAdm
FAILURES_AFTER_ADM=pmNoFailedAfterAdm
ADMCONTROL_REQDEN=pmNoReqDeniedAdm
BLOCK_HW=pmNoFailedRrcConnectReqHw
BLOCK_HW_CS=pmNoFailedRrcConnectReqCsHw
BLOCK_HW_PS=pmNoFailedRrcConnectReqPsHw
BLOCK_NODE_CS=pmNoRrcCon nReqBlockNodeCs
BLOCK_NODE_PS=pmNoRrcConnReqBlockNodePs
BLOCK_HW_CS=pmNoFailedRrcConnectReqCsHw
BLOCK_HW_PS=pmNoFailedRrcConnectReqPsHw
BLOCK_NODE_CS=pmNoRrcConnReqBlockNodeCs BLOCK_NODE_PS=pmNoRrcConnReqBlockNodePs
REQDEN_CODES=pmNoRrcReqDeniedAdmDlChnlCode
REQDEN_ULHW=pmNoRrcReqDeniedAdmUlHw
REQDEN_DLHW=pmNoRrcReqDeniedAdmDlHw
REQDEN_DLPOWER=pmNoRrcReqDeniedAdmDlPwr
REQDEN_SPEECH=pmNoOfNonHoReqDeniedSpeech
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RAB Establishment Failure Causes
REQDEN_ULASE=100 * (pmNoFailedRabEstAttemptLackUlAse)/(pmNoRabEstablishAttempt)
REQDEN_DLASE=100 * (pmNoFailedRabEstAttemptLackDlAse)/(pmNoRabEstablishAttempt)
REQDEN_CODES=100 * (pmNoFailedRabEstAttemptLackDlChnlCode )/(pmNoRabEstablishAttempt))
REQDEN_DLPOWER=100 * ((pmNoFailedRabEstAttemptLackDlPwr )/(pmNoRabEstablishAttempt))
REQDEN_SFHYST=100 * ((pmNoFailedRabEstAttemptExceedConnLimit )/(pmNoRabEstablishAttempt))
REQDEN_ULHW=100 * ((pmNoFailedRabEstAttemptLackUlHwBest )/(pmNoRabEstablishAttempt))
REQDEN_DLHW=100 * ((pmNoFailedRabEstAttemptLackDlHwBest )/(pmNoRabEstablishAttempt))
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Troubleshooting Flowchart
The following flowchart may be useful for troubleshooting accessibility issues based onthe problem areas
Microsoft Of fice
PowerPoint 97-2003
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Main Accessibility issues
DL Transmitted Carrier Power Admission
DL Channelization Code Admission UL / DL HW (CE) Admission
ASE Admission
High MP load.
Connection limit.
High UL NOISE [RSSI]
FAILURE AFTER ADM
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Admission Control Workflow
Check if the requested
ASE UL + estimated ASE UL
>
aseUlAdm
Check if the requestedASE DL + estimated ASE UL
>
aseDlAdm
Check if the requested
DL PWR + estimated PWR
>
pwrAdm
Check if the requested
code usage + estimated code usage
>
dlCodeAdm
Check if the requestedDL SF + estimated DL SF
>
sfXAdm
Check if the requested +
estimated # compressed mode RL
>
compModeAdm
Is admission blocked
by Congestion Control
Resource request Yes, then block
Yes,
then
block
Yes,
then
block
Yes,then
block
Yes,then
block
Yes,
then
block
Yes,
then
block
No
No
No
No
No
No
No, then
accept
X=8, 16 or 32
Only checked if
BE-service requests
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DL POWER
WCDMA Networks TCP (Tx Carrier Power) is always an important resource. Available RBS
Downlink TCP is limited by MCPA capability (20W, 30W & 40 W)
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DL POWER COUNTERS
FAILURE Counters:
RRC : pmNoRrcReqDeniedAdmDlPwr
RAB : pmNoFailedRabEstAttemptLackDlPwr
CRITERIA
ADMISSION REJECTION : Power > pwradm
CONGESTION REJECTION : Power > pwradm+pwroffset
Action: Check and align the Power parameters & DL attenuation parameters.
Increase the value for pwrAdm + pwrOffset and could be less than 100%
Optimize the parametrs minPwrRl, minPwrMax, interPwrMax, maxPwrMax, maximumTransmissionPower.
If 2nd carrier cell is not congested then share traffic by Qoffset (Idle mode)
If 2nd carrier is congestion also, then check neighbor cells and try to off load traffic by reducing cpich (-1 db)
and adjust Qoffset values Do physical optimization incase of overshooting
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DL Transmitted Carrier Power Admission
Non-HS DL Power > pwrAdm, block start
Non-HS DL Power
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DL Power Congestion
The threshold for detection of downlink congestion is determined by theparameters pwrAdm + pwrOffset and the hysteresis time pwrHyst.
When non-HS DL power + HS-required DL power > 100% utilization for a hysteresis
time maxPowerOverloadHystTime, then DL HSDPA-overload happens.
DL Overload DL HS Overload
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DL CHANNELISATION CODE
WCDMA Code tree is considered as one of the important Resource
Below picture will clearly explain the code tree usage
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DL CHANNELISATION CODE Lack of DL CODE
FAILURE Counters: RRC : pmNoRrcReqDeniedAdmDlChnlCode
RAB : pmNoFailedRabEstAttemptLackDlChnlCode
CRITERIA ADMISSION REJECTION : code > dlcodeadm
Action: Increase dlCodeAdm from 90 to as high as 95
Decrease pwrLoadThresholdDlSpeech.amr12200 from 50 to possibly as low as 0
Reduce NumHsScchCode
Reduce NumHsPdschCode
Reduce the values for sf4Adm, sf8Adm, sf16Adm to free some codes for other uses
Carrier addition
SPECIAL CHECK (for Hybrid & IP Nodes) UlCreditUsage != AvgULCEUsage ACTION: IUB Reset
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UL/DL HARDWARE CHANNEL ELEMENT
Ericsson RBS Hardware consumption is measured in terms of CE.
RNC allocates CE resources based
on the Credit usage
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Lack of UL HW
FAILURE Counters:
RRC : pmNoFailedRabEstAttemptLackUlHwBest
RAB : pmNoFailedRabEstAttemptLackUlHW
CRITERIA
ADMISSION REJECTION : CE Usage > Available CEs in DUW
Action:
Check availableRbsChannelElementsUplink & licenseCapacityRbsChannelElementsUplink Rejection in only one DUW (out of available two DUWs) - Tune the ulLicFractBbPool2
Recommend for CE addtion.
Reduce the values for sf4AdmUl, sf8AdmUl, sf16AdmUl,
Switch off the 2ms TTI for EUL eulServingCellUsersAdmTti2
Send more traffic to GSM if GSM is not congested Change
Directed Retry to GSM loadSharingGsmThreshold Increase UlHwAdm
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Lack of UL HW
SPECIAL CHECK (for Hybrid & IP Nodes)
CRITERIA
CE FREEZE : UlCreditUsage != AvgULCEUsage
ACTION:
IUB ResetCE FREEZE
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Lack of DL HW
FAILURE Counters:
RRC : pmNoFailedRabEstAttemptLackDlHwBest
RAB : pmNoFailedRabEstAttemptLackDlHW
CRITERIA
ADMISSION REJECTION : CE Usage > Available CEs in DUW
Action:
Check availableRbsChannelElementsDownlink & licenseCapacityRbsChannelElementsDownlink
Rejection in only one DUW (out of available two DUWs) - Tune the dlLicFractBbPool2
Recommend for CE addtion.
Reduce the values for sf4Adm, sf8Adm, sf16Adm,
Send more traffic to GSM if GSM is not congested Change
Directed Retry to GSM loadSharingGsmThreshold Increase DlHwAdm
SPECIAL CHECK (for Hybrid & IP Nodes)
DlCreditUsage != AvgDLCEUsage
RECOMMENDATION: IUB Reset
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ASE AIR SPEECH EQUIVALENT
ASE is a Virtual capacity resource of air interface in WCDMA Network. It is a measure of
how much of user of this service load the air interface.
ASE is equated to Speech RAB ASE (sum of DCH-SPEECH + DCH-SRB)
ASE calculation for Speech RAB
ASE for different RABs are
shown in the picture
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Lack of ASE
FAILURE Counters:
RAB : pmNoFailedRabEstAttemptLackUlAse & pmNoFailedRabEstAttemptLackDlAse
CRITERIA
UL ADMISSION REJECTION : ASE Usage > aseUlAdm
DL ADMISSION REJECTION : ASE Usage > aseDlAdm
Calculation of Actual ASEs:
ASEs are cacluated by using the following counters
Action:
Generally ASE rejections will not be pegged due to higher value setting of aseUlAdm & aseDlAdm
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High Processor Load
Calculation: pmSumMeasuredLoad / pmSamplesMeasuredLoad
pmprocessorload
Action Terminate MRR Recording
Turn off unnecessary traces
change reportingRange1a from 6 to 4,
reportingRange1b from 10 to 8, and
timeToTrigger1c from 11 to 12
Incase of IUB congestion, Check and upgrade IUB
PROCESSOR LOAD TOUCHING
PEAK LOAD OF 94% in DUW1.Leading to Fluctuation for both
carrier in DUW1 (FDD10 & FDD
7)
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Connection limit
FAILURE Counters:
EUL : pmNoOfNonHoReqDeniedEul
HS : pmNoOfNonHoReqDeniedHs
CRITERIA
ADMISSION REJECTION EUL : EUL Serv Users > eulServingCellUsersAdm
ADMISSION REJECTION HSDPA : HSL Serv Users > hsdpaUsersAdm
Action:
Need to recommend the increase in the license limit for HS and
EUL users
Increase hsdpaUsersAdm but need to leave scope for HS users
needing access while in handover in connected mode.
Increase maxNumHsdpaUsers
Increase eulServingCellUsersAdm
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High UL Noises
FAILURE Counters:
RSSI : pmAverageRssi
[Low RSSI-95]
RESONS
Defective TMA and antenna
Faulty Hardware
Increase in traffic manly EUL traffic
Action:
Reduce OwnUuload and RotCoverage (if EUL throughput is currently good,
otherewise we will be reducing EUL thp to an unacceptable level) to 80 and 100
respectively
Reduce aseUlAdm
Set Sf4AdminUl to 0, set sf8AdmUl to 0 (if (not already done)
reduce compModeAdm in outdoor cells
Consider increasing CPICH of indoor sites
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FAIL AFTER ADM
Description : Number of Radio Resource Control (RRC) or Radio Access Bearer (RAB)
establishment requests failed after being admitted by admission control.
RRC and RAB establishment failures which occur after admission control can be due to
Iub transport Network blocking Node blocking
NBAP RL setup failure (RAX or TXB congestion)
Channel Code Allocation Failure (code not available)
Core transport network congestion or failures
timeout in the UE, RNC or RBS
invalid parameter settings
Formulas
Failures due to RAXB congestion= (pmSetupFailuresSf128 + pmSetupFailuresSf16 + pmSetupFailuresSf256 +
pmSetupFailuresSf32 + pmSetupFailuresSf4 + pmSetupFailuresSf64 + pmSetupFailuresSf8)
Failures due to TXB congestion= (pmSetupFailuresSf128 + pmSetupFailuresSf16 + pmSetupFailuresSf256 +
pmSetupFailuresSf32 + pmSetupFailuresSf4 + pmSetupFailuresSf64 + pmSetupFailuresSf8)
DL Channel code alloc Failure = (pmNoDlChCodeAllocFailureSf8 + pmNoDlChCodeAllocFailureSf16 +
pmNoDlChCodeAllocFailureSf32 + pmNoDlChCodeAllocFailureSf64 + pmNoDlChCodeAllocFailureSf128 +
pmNoDlChCodeAllocFailureSf256)
Action:
Check and remove TAX/RAX Board congestion
Check and upgrade IUB link in case of congestion
Check and clear Hardware issues
Check and clear Iub Link outages.
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SPECIAL ANALYSIS
NODE B BLOCKING ANALYSIS
ATM UTILIZATION CHECKUPs
IUR DISCREPANCY CHECK
VC QoS Mapping Issue
UL CE Credits
STEPS /Commands To CHECK ATM Discrepancy
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CONCLUSION
This Presentation gives a complete analysis for Accessibility Failure reasons, Methods to
analyse and solutions to solve the same.
Analysis is also provided for Node-B Blocking, ATM Iub Utilisation, IURDiscrepancy
Check, VC QoS Mapping Issue, RAB Blocking due to DL CE Credits & DL CE usage.
Using this presentation, any Resource can start the delivery of the AccessibilityKPI
Monitoring.