ACCESSIBILITY

 

ACCESSIBILITY 1. Poor coverage  Check inter site distance with neighbors site.  Check value of pmBadCovEvalR  pmBadCovEvalReport eport (if MCPC enabled, need to check pmCriticalBord  pmCriticalBorderEvalReport  erEvalReport ). ). If this counter is pegging high in respect to RRC attempts, then we can say that more number of UEs are falling in bad coverage.  Check counter pmCriticalBorderEv  pmCriticalBorderEvalReport alReport (this means there is no LTE coverage, and UE will do release with redirect_(RWR) with any Technology) & pmRadioTbs  pmRadioTbsPwrRestricted PwrRestricted (If this counter is more (>70%), then for that sector, the UE is using more power to reach EnodeB, in that case pdcchutil is also high)  Change qrxlevmin (In Sprint the parameter value is changed from -120dBm to -110dBm), so as to discard d iscard bad coverage / cell edge UEs. 2. Alarms 

Through OSS commands “ alt ” (Current / Active site alarms can be checked) & “ lga ” (n is an integer value) (Site alarms present for n days can be checked) 3. High Load (High Traffic)  Check pmRrcConnEsta  pmRrcConnEstabFailHighLoad bFailHighLoad & pmRrcConnEstab  pmRrcConnEstabFailOverload FailOverload counters If any sector is having high traffic. These counters could be high due to high traffic and impacting CFR.  The command “ue print -admitted ” is used to find the no. of UEs c urrently latched to the site sector-wise ROP-wise & the counters “ pmRrcConnMax (max)” & “ pmRrcConnMax (sum)” are used to find out ‘max. active users/ day’ and ‘sum of all active users/day’, respectively. Sometimes, due to MOs are not synchronized properly,  pmRrcConnEsta  pmRrcConnEstabFailOverload bFailOverload is pegged high. In this case, the ServiceUnavailable (S1 Connection failure) alarm is observed in sites, even though RRC Conn Users remain to be same. 4. H/W issue (Hard Reset on site / RRU Replacement, if required)  If RRUs RRUs are disabled, in that case “HW fault” alarm is observed in sites.  Command “st . aux” shows that the operational state of the auxiliary unit/ RRUs is DISABLED.  Command “lgd

5. High UL interference  High UL N+I is impacting to all KPIs. UL NI values {-119 {- 119 …….. -110 dBm} is considered to be good.  The cause may be Internal Sources (Check Tx & Rx antenna ports, fiber cables and connectors. All connection should be proper) and External Sources ( like repeaters, airport, power plant etc. sources resulting in high EMWin the neighborhood).   pmRadiorecInterferenc  pmRadiorecInterferencePwr ePwr is checked for UL N+I values.  Use pmr -m 72 -r 6 -f | egrep -i 'Interference|Res_ 'Interference|Res_AvgNrOfRrcConnected AvgNrOfRrcConnectedUsers Users’ command to find out ROP-wise ROP -wise UL NI status of last 72 hours, along with corresponding no. of average users. 6. PCI conflict

 

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Two types of PCI conflict:  PCI confusion, i.e., UE is confused if it is getting two or more target cells having same PCI.  PCI collision, i.e., UE is collision due to source and target having same PCI.  Impacts all KPIs.  Use “EUtranCellFDD . pciconflict ” to find out PCI conflict of site. 7. RACH Root Sequence Index plan need to be reviewed  Based on ‘Zero Correlation Zero Configuration‘ parameter RACH root Sequence index need to be planned. For Ncs = 12, difference of 10 is recommended for RACH root Sequence index per cell. 8. UE camping in the wrong cell. c ell. Cell Reselection Parameters need to be tuned  When UE is doing cell reselection if priorities are wrongly defined, in that case, UE will connect with wrong technology.  In Sprint, cell reselection priority are defined based on capacity and technology whose range varies {0 .. 7} ( cell reselection priority for LTE 2.5GHz is 7, LTE1900 is 5, LTE800 is 4, CDMA2000 is 2 and CDMA20001xRtt is 0)  The command cellreselectionpriority is used to find out technology-wise priority for cell re-selection. 9. Wrong System constant setting(SC-556)  We can set SC-556 from 10, 25, 35 & 45, based on traffic. 10. VSWR over threshold  The cabx command provides VSWR status for RL1 & RL2 (for 2T2R). Both, RL1 and RL2 should be more than 14 with a difference of less than 5. 11. Cell availability  Cell availability should be 100%, if availability is less than 100%, then the site might be having transmission issue and also, the site may not be taking traffic.

 

 

Solution :Failure at RRC Setup Stage :  pmRrcConnEstabFail is to be checked.  pmRrcConnEstabFail contributes to poor RRC Setup Success Rate. The triggering issues for  pmRrcConnEstabFail are as follows : 1. pmRrcConnEstabFailLic: The total number of failed RRC Connection establishments due to lack of connected users license. Probable Solutions: Upgrade the LKF (License Key File) by Upgrading Software. E.g.- From L12A to L12B and L13A to L13B.L14A having License of 2000 Connected user per EnodeB. (License/Software up-gradation activity governs as per the agreement with customer).

Current licenseCapacityConnectedUsers as per WLA for Sprint is 100 Users per site.  By changing qRxLevMin (Default Value -120dBm); can be modified to -110 dBm  By implementing Hi-Cap Parameter, if Max RRC Conn Users is more than 150/sector and pdcchutil>70%. Detailed parameters for Hi-Cap parameter implementation have been shared later  If traffic load is still high after implementation of above solutions, plan for new site to offload or change LKF from 1000 to 2000 . (L12A- ;L12B-; L13A-; L13B-L14A ) is submitted. 2. pmRrcConnEstabFailHighLoad: The total number of failed RRC Connection Establishments due to high load. Probable Solutions: - Same as above.

3. pmRrcConnEstabFailOverload: The total number of failed RRC Connection Establishments due to overload. Probable Solutions: - Same as above. 4. pmRrcConnEstabFailActiveUserLicenseEx pmRrcConnEstabFailActiveUserLicenseExceeded: ceeded: The number of failed RRC establishments due to more active users than what license allows. Probable Solutions:  Check Active user per cell through counter  pmActiveUserDlSum, pmActiveUserUlsum .  Try to offload traffic, if possible, by changing Azimuth/ Tilt or Loading Hi-Cap parameter or Load Sharing (In Sprint traffic load sharing b/w LTE1900 & LTE800 co-located site is activated).  Check distance of UE from EnodeB. If UE is connected to far away EnodeB, RxlevAccmin parameter can be changed to protect access. 

If Enhanced cell ID feature is enabled in N/W Timing Advance, then  pmTimingAdvance counter can be used to check the TA value. 5. pmRrcConnEstabFailFailureInRadioProcedure: pmRrc ConnEstabFailFailureInRadioProcedure: The number of failed RRC establishments due to failed radio procedure. Probable Solutions: - Same as above.

 

6. 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 control. Probable Solutions:  Implement Hi-Cap Parameter to allow more users.  Also PDCCH Admission control Threshold can be changed. Before modifying this parameter, PDCCH CCE Utilization need to be checked via the counter- pmPdcchCceUtil (it should be more than 70%) 7. pmRrcConnReestFailLicMtReest: The number of RRC Connection Reestablishments attempts that failed due to feature "Multi-Target RRC Connection Reestablishment" not being enabled.

Probable Solutions: - Not included in any predefined scanner. So you have to activate Scanner. 8. pmRrcConnEstabFailLackOfResources: The number of failed RRC establishments due to lack of resources. Probable Solutions:  Check the cell utilization and try to offload by Implementing Hi-Cap Parameter; shift traffic on the less utilized cells using tilt and load balancing feature. 9. pmRrcConnEstabFailUnspecified: The number of failed RRC establishments due to unspecified

Retainability 1. Poor coverage* 2. Alarms* 3. High Load (high traffic)* 4. H/W issue (Re-set first) if required replace RRU* 5. VSWR over threshold* 6. HO failure : If a sector is having high HO Execution fail, it results in poor retainability. Probable Solutions: The counter pmErabRelAbnormalEnbActHo is checked. If this counter is pegging high, it implies poor retainability and resolution of sector HOSR is required.

 

  Solution :-

1. pmErabRelAbnormalEnbActCdt  – The total number of abnormal ERAB releases by the eNB per cell due cell down time (manual intervention) with the pre-condition that the Initial Context Establishment procedure must first have been successfully completed and that there was data in either the UL or DL buffer (i.e. active). Probable Solutions : - Check Outage report or Fluctuation Report. 2. pmErabRelAbnormalEnbActHo  – The total number of abnormal ERAB releases per cell by the eNB due to handover execution failure and that there was data in either the UL or DL buffer (i.e. active). Probable Solutions: Check PCI Planning is correct or not, to avoid PCI collision issue. There should not be any PCI re-use in nearby cells (Tier 1, Tier 2 neighbours). Coverage issue(make Any PCI Dominant which should be based on Clutter as per Common sense). Make EDT, Change Azimuth High UL Interference issue on Target cell (PmRadiorecInterferencePwr). Check Connection b/w Antenna Connector & RRU Connector.  Also Repeater is responsible sometimes for Hi-UL Interference. Might be due to Power Leakage. 3. pmErabRelAbnormalEnbActUeLos pmErabRelAbnormalEnbActUeLostt  – The total number of abnormal ERAB releases by the eNB per cell due that the contact with the UE is lost with the pre-condition that the Initial Context Establishment procedure must first have been successfully completed and that there was data in either the UL or DL buffer (i.e. active). Probable Solutions: Solve the Poor Coverage issue by changing tilt / azimuth or appropriate parameter value setting, E.g. : - partOfSectorPower, ENB Power, P0NominalPucch / P0NominalPusch (for uplink Coverage).  High UL NI Issue(As per earlier mentioned. Also make sure Nominal power Should not set very high otherwise it will create interference in neighbour cell). 4. pmErabRelAbnormalEnbLic  – The total number of abnormal E-RAB Releases initiated by the RBS due to license reject (per cell). 5. pmErabRelAbnormalEnbActTnFail  – The total number of abnormal ERAB releases per cell due to S1 interface down, "X2 interface down" or "Transport Resource Unavailable", with the pre-condition that the Initial Context Establishment procedure must first have been successfully completed and that there was data in either the UL or DL buffer (i.e. active). Probable Solutions : - Issue can be resolved with the help of NOC / IM Team by raising the required tickets. 4. pmErabRelAbnormalEnbActHpr – The total number of abnormal ERAB releases by the eNB per cell due to handover preparation and that there was data in either the UL or DL buffer (i.e. active).

 

Probable Solutions:MME missing issue or MME might be disabled. Transport issue suspected. License issue suspected. Site Configuration issue.