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LTE Accessibility Problem cause & solution a-z step Prepared by- Rajesh Kumar.

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Presentation on theme: "LTE Accessibility Problem cause & solution a-z step Prepared by- Rajesh Kumar."— Presentation transcript:

1 LTE Accessibility Problem cause & solution a-z step Prepared by- Rajesh Kumar

2 Definition: Ability of a user to Obtain an E-RAB from the System. Point:-Accessibility/SSSR is combination of 3 Phase. 1.RRC Phase. 2.S1 Signaling Phase. 3.E-RAB Phase. Definition based on Counter:- SSSR =[(PmRrcConnEstabSucc/PmRrcConnEstabAtt)*(Pms1SigConnEstabSucc/PmS1SigConnEsta bAtt)*(PmErabEstabSuccInit/PmErabEstabAttInit)]*100 SSSR Phase based on Counter:- 1.RRC Setup:-Following counter are Responsible- a> PmRrcConnEstabAtt. b> PmRrcConnEstabAttReAtt C> PmRrcConnEstabSucc Accessibility/SSSR(Session setup success Rate):-

3 2.S1-Signalling Setup: Following Counter are Responsible- a> PmS1SigConnEstabAtt. b> PmS1SigConnEstabSucc. 3. E-RAB Establishment: Following Counter are Responsible- A> PmErabEstabAttInit B> PmErabEstabSuccInit. C> PmErabEstabAttAdded. D> PmErabEstabSuccAdded.

4 Accessibility/SSSR(Session setup success Rate):- Step for Find out the Problem with Counter:- 1.RRC Failure(PmRrcConnEstabFail):-Following issue need to be verified- A> pmRrcConnEstabFailLic:The total number of failed RRC Connection Establishments due to lack of connected users license. Soln:- Upgrade the LKF(License Key File) by Upgrading Software.Ex- From L12A to L12B And L13A to L13B.L13B having License of 2000 Connected user per ENB.(License/Software upgradation activity depends as per Agreement with customer).For this Customer pay to Ericsson. Soln:- Offload the Traffic: 1> Shared the Traffic by Changing Azimuth,By Tilt,By Implementing Hi-Cap Parameter.If still Traffic load is more,planned new site to offload. B>pmRrcConnEstabFailHighLoad:The total number of failed RRC Connection Establishments due to high load. Soln: There are many ways to Offload the Traffic: 1> Shared the Traffic by Changing Azimuth,By Tilt,By Implementing Hi-Cap Parameter. Following are the List of Hi-Cap Parameter which can be tune as per N/W requirement.

5 Accessibility/SSSR(Session setup success Rate):- MOCParameter NameParameter Type Parameter - High Cap Site System ConstantulInterferenceForgettingFactor (system constant 70)Site Level Parameter5 System ConstantdeltaPsdRs2Tx (system constant 872)Site Level Parameter0 System ConstantSpdcchLaGinrMargin (system constant 220)Site Level Parameter30 System ConstantnumInitialAccessAndIncomingHo (system constant 556)Site Level Parameter10 Hidden ParametertPollRetransmitUl - DataRadioBearerSite Level Parameter160 Hidden ParametertPollRetransmitUl - SignallingRadioBearerSite Level Parameter160 Hidden ParametertPollRetransmitDl - DataRadioBearerSite Level Parameter160 Hidden ParametertPollRetransmitDl - SignallingRadioBearerSite Level Parameter160 Hidden ParameterdlMaxRetxThreshold - DataRadioBearerSite Level Parameter8 Hidden ParameterulMaxRetxThreshold - DataRadioBearerSite Level Parameter8 EUtranCellFDDnoOfPucchCqiUsersSector Level Parameter640 EUtranCellFDDnoOfPucchSrUsersSector Level Parameter590 EUtranCellFDDpdcchCfiModeSector Level ParameterCF_Static_3 (3) EUtranCellFDDulSrsEnableSector Level ParameterTRUE UlFssfeatureStateUlFssSite Level Parameter1 EUtranCellFDDpZeroNominalPucch Sector Level Parameter-120 EUtranCellFDDpZeroNominalPuschSector Level Parameter-102 QciProfilePredefinedschedulingAlgorithm - defaultSite Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 1Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 2Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 3Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 4Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 5Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefined schedulingAlgorithm - qci 6 Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 7Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 8Site Level ParameterRESOURCE_FAIR (0) QciProfilePredefinedschedulingAlgorithm - qci 9Site Level ParameterRESOURCE_FAIR (0)

6 Accessibility/SSSR(Session setup success Rate):- C> pmRrcConnEstabFailOverload:The total number of failed RRC Connection Establishments due to overload. Soln: Same as Above. d>> pmRrcConnEstabFailActiveUserLicenseExceeded:The number of failed RRC establishments due to more active users than what license allows. Soln:1. Check Active user per cell through counter PmActiveUserDlSum, PmActiveUserUlsum. 2. Try to Offload traffic if possible by changing Azimuth,Tilt or Loading Hi- Cap Parameter. Earlier we have discussed abt Hi-Cap. 3.Also check distance of UE from ENB,if connected from far distance,Can change parameter RxlevAccmin to Protect access.

7 Accessibility/SSSR(Session setup success Rate):-.e> pmRrcConnEstabFailFailureInRadioProcedure:The number of failed RRC establishments due to failed radio procedure. f> pmRrcConnEstabFailBearerAdmissionRej:The total number of failed establishment of RRC Connection due to the fact that all the UE's bearers are rejected during bearer admission. Soln: Implement hi-Cap Parameter to allow more user.Also PDCCH Adm control Th can be changed.Befor change Check PDCCH CCE Utilization by Counter- PmPdcchCceUtil g> pmRrcConnReestFailLicMtReest:The number of RRC Connection Reestablishments attempts that failed due to feature "Multi-Target RRC Connection Reestablishment" not being OPERABLE Soln: Not included in any predefined scanner.So U have to activate Scanner.

8 Accessibility/SSSR(Session setup success Rate):- h>pmRrcConnEstabFailLackOfResources:The number of failed RRC establishments due to lack of resources Soln: check the Utilization of Cell and try to Offload by Implementing Hi- Cap Parameter,Shift traffic on some less utilized cell. i> pmRrcConnEstabFailUnspecified:The number of failed RRC establishments due to unspecified cause. Apart from that Please check Coverage issue,UL Interference issue,Alarm issue,H/W issue(Re-set first) if required replace RRU.

9 Accessibility/SSSR(Session setup success Rate):- 2. S1-signalling Failure(PmS1SigConnEstabFail):-There is no any Specific Secondary counter I have found.But Following could be the reason : a> TN(Transport issue): Need to check Fiber issue from IPBH Team. b> TAC Wrong Configure: Configure Correct TAC as Per Design. c> LAC-TAC mapping: Validate the LAC-TAC mapping is correct as per Design. d> Message mismatch: The message flow b/w UE to MME is found any Mismatch,will laid S1-Signalling Failure.

10 Accessibility/SSSR(Session setup success Rate):- 3. E-RAB Failure(PmErabEstabFailInit)- a> pmErabEstabFailGbrDlEnb(The total number of failed E-RAB setup attempts due to downlink GBR overload for resources common to the eNodeB). Soln: Parameter which is Responsible:dlNonGbrRatio, dlTransNwBandwidth b> pmErabEstabFailGbrUlEnb(The total number of failed E-RAB setup attempts due to uplink GBR overload for resources common to the eNodeB). Soln: Parameter Which is Responsible :ulNonGbrRatio,,ulTransNwBandwidth c>pmErabEstabFailAddedLic(The total number of failed establishment of added E-RABs due to license rejects (Multiple Radio Bearer per user or RLC UM). Added E-RABs are all E-RABs present in S1 message E-RAB Setup Request). d>pmErabEstabFailInitLic(The total number of failed establishment of initial E- RABs due to license rejects (Multiple Radio Bearer per user or RLC UM). Initial E- RABs are all E-RABs present in the S1 message Initial Context Setup Request).

11 Accessibility/SSSR(Session setup success Rate):- Apart from that Following Could be checked: 1> Security update Fail. 2> Vendor specific issue. 3> TN(Transport issue). Note: Some case study based Problem & Solution. 1.RRC Degradation due to RRC Reject. Parameter: no of Pucch CQI user-160 no of Pucch Sr user-160 Here RRC Conn max user is>160 Hence due to CQI resource Congestion RRC Conn was rejected. 2. SSSR degrade due to Low S1 Succ rate: Sometimes it has been Observed that S1 Succ rate degraded due to Software upgradation.Cell KPI Improved after DUL Restart.

12 Accessibility/SSSR(Session setup success Rate):- 3. SSSR Degraded due to H/W issue: Once RRU was replace SSSR improved. Accessibility can also be improved by tunning these parameter. Change dlMaxRetxTh &ULMaxRetxTh of SRB-1(1,2,4,8,16,32) Note: Any Suggestion/Feedback will be Highly Appreciable to Improve This Presentation.

13 THANK YOU


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