umts accessibilty

8/10/2019 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


DL PWR + estimated PWR

>

pwrAdm


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.

umts accessibilty

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