Presentation on theme: "Accessibility/SSSR(Session setup success Rate):-"— Presentation transcript:
1LTE Accessibility Problem cause & solution a-z step Prepared by- Rajesh Kumar
2Accessibility/SSSR(Session setup success Rate):- Definition: Ability of a user to Obtain an E-RAB from the System.Point:-Accessibility/SSSR is combination of 3 Phase.RRC Phase.S1 Signaling Phase.E-RAB Phase.Definition based on Counter:-SSSR=[(PmRrcConnEstabSucc/PmRrcConnEstabAtt)*(Pms1SigConnEstabSucc/PmS1SigConnEstabAtt)*(PmErabEstabSuccInit/PmErabEstabAttInit)]*100SSSR Phase based on Counter:-RRC Setup:-Following counter are Responsible-a> PmRrcConnEstabAtt.b> PmRrcConnEstabAttReAttC> PmRrcConnEstabSucc
3Accessibility/SSSR(Session setup success Rate):- 2.S1-Signalling Setup: Following Counter are Responsible-a> PmS1SigConnEstabAtt.b> PmS1SigConnEstabSucc.3. E-RAB Establishment: Following Counter are Responsible-A> PmErabEstabAttInitB> PmErabEstabSuccInit.C> PmErabEstabAttAdded.D> PmErabEstabSuccAdded.
4Accessibility/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.
6Accessibility/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.
7Accessibility/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- PmPdcchCceUtilg> pmRrcConnReestFailLicMtReest:The number of RRC Connection Reestablishments attempts that failed due to feature "Multi-Target RRC Connection Reestablishment" not being OPERABLESoln: Not included in any predefined scanner.So U have to activate Scanner.
8Accessibility/SSSR(Session setup success Rate):- h>pmRrcConnEstabFailLackOfResources:The number of failed RRC establishments due to lack of resourcesSoln: 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.
9Accessibility/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.
10Accessibility/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, dlTransNwBandwidthb> 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, ,ulTransNwBandwidthc>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).
11Accessibility/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.RRC Degradation due to RRC Reject.Parameter: no of Pucch CQI user-160no of Pucch Sr user-160Here RRC Conn max user is>160Hence 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 KPIImproved after DUL Restart.
12Accessibility/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.