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Knowledge sharing sessionsOverviewUsed ToolsTechnical Procedure                           SDCCH Drop RateFlow ChartExemple...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesOverview IntroductionSDCCHAssignment ...
Overview           Used Tool      Technical procedure         Flow Chart             ExamplesOverviewIntroduction SDCCHAss...
Overview            Used Tool     Technical procedure         Flow Chart     ExamplesOverview                    Request ...
Overview        Used Tool         Technical procedure            Flow Chart               Examples           MS           ...
Overview           Used Tool        Technical procedure         Flow Chart        ExamplesOverviewIntroductionSDCCHAssignm...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment o...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment o...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment o...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview           Used Tool     Technical procedure         Flow Chart     ExamplesOverviewIntroductionSDCCHAssignment on...
Overview   Used Tool   Technical procedure         Flow Chart     Examples                                   28/12/2010   ...
Overview            Used Tool       Technical procedure         Flow Chart     ExamplesUsed Tools Business Objects 6.5MCOM...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesUsed ToolsBusiness Objects 6.5 MCOM 4...
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesUsed ToolsBusiness Objects 6.5MCOM 4....
Overview           Used Tool      Technical procedure         Flow Chart     ExamplesUsed ToolsBusiness Objects 6.5MCOM 4....
Overview          Used Tool      Technical Procedure         Flow Chart     ExamplesTechnical Procedure  SDCCH Drop causes...
Overview           Used Tool      Technical Procedure         Flow Chart     ExamplesTechnical ProcedureSDCCH Drop causes ...
Overview           Used Tool       Technical Procedure         Flow Chart     ExamplesTechnical ProcedureSDCCH Drop types ...
Overview           Used Tool      Technical Procedure         Flow Chart     ExamplesTechnical ProcedureSDCCH Drop types  ...
Overview           Used Tool      Technical Procedure         Flow Chart     ExamplesTechnical ProcedureSDCCH Drop types  ...
Overview          Used Tool         Technical Procedure         Flow Chart     ExamplesTechnical ProcedureSDCCH Drop types...
Overview   Used Tool      Technical procedure         Flow Chart     ExamplesFlow Chart                   It is advised to...
Start           SDCCH          Drop Rate         high certain             cell         yes    No     Check         yes    ...
*                                 **   Is there     yes                      Open TT to BSS    LAPD  problem?             ...
***  Whether        yesfault exist in                               Trouble coverage                   shoot coverage     ...
Overview        Used Tool      Technical procedure         Flow Chart     ExamplesExemples                22685A: Hardwar ...
Overview       Used Tool      Technical procedure         Flow Chart     ExamplesExemples               03102A:Hardwar Pro...
Overview       Used Tool      Technical procedure         Flow Chart     ExamplesExemples               03663A:Hardwar Pro...
References listReference            [10] sjzl20062303-ZXG10-BSS (V2.97) Operation            Manual (Radio Parameters)   ...
28/12/2010   SDCCH Drop Rate
AppendixDRT/EDRTThe DRT/EDRT fulfills conversion between voice codes at the GSM radio interface and the PSTN A-law PCM voi...
Radio parametersRadio parameters setting                           Cell’s minimum access level: which causes SDCCH drop i...
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  1. 1. Knowledge sharing sessionsOverviewUsed ToolsTechnical Procedure SDCCH Drop RateFlow ChartExemples BENAIAD Abdellah
  2. 2. Overview Used Tool Technical procedure Flow Chart ExamplesOverview IntroductionSDCCHAssignment on SDCCHSDCCH Drop Rate This chapter is designed to provide an overview of root cause analysis for SDCCH drop rate KPI. It addresses the SDCCH drop rate analysis, investigation procedures and troubleshooting techniques to degrade the effect of this issue. 28/12/2010 SDCCH Drop Rate
  3. 3. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroduction SDCCHAssignment on SDCCHSDCCH Drop Rate SDCCH is a bidirectional logical channel used in different ways: -Registration: periodic location update, IMSI attach/detach. -Call setup: immediate assignment. -SMS to/from MS in dedicated mode. 28/12/2010 SDCCH Drop Rate
  4. 4. Overview Used Tool Technical procedure Flow Chart ExamplesOverview Request and allocation of SDCCH:IntroductionSDCCH Assignment on SDCCHSDCCH Drop Rate 28/12/2010 SDCCH Drop Rate
  5. 5. Overview Used Tool Technical procedure Flow Chart Examples MS BSC Paging BTS Paging MS C Paging command request PCH Channel required Channel request RACH Channel Activation Ch Activation Acknowledge Immediate assignment command Immediate assignment 28/12/2010 SDCCH Drop Rate
  6. 6. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate SDCCH Drop Rate is a KPI which largely decides the subscriber service quality , the existing KPI formula is listed below: (C10602+C10604+C10605+C10646+C10653+C10601+C10603+C10606)*100 (C11644+C11646) 28/12/2010 SDCCH Drop Rate
  7. 7. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10603 It represents the number of call drops due to contact C10604 C10604 loss between RMM and Service Management Module C10605 C10605 (SMM) on SDCCH. C10606 C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  8. 8. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10603 C10604 C10604 It represents the number of call drops due to radio link C10605 C10605 failure on SDCCH. C10606 C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  9. 9. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 It represents the number of call drops due to LAPD link C10605 failure on SDCCH. C10606 C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  10. 10. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 It represents the number of call drops due to SDCCH C10605 forced C10606 release. C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  11. 11. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 It represents the number of call drops due to force C10604 C10605 release from high priority calls on SDCCH. BSC C10606 receives force release message from BTS for high C10646 priority calls and counter increments. C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  12. 12. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 C10605 It represents the number of call drops on SDCCH due C10606 to other causes. C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  13. 13. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 It represents the total number of call drops due to C10605 handover C10606 failure on SDCCH, this counter is not allowed. C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  14. 14. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 It represents the total number of SDCCH call drops C10605 (short C10606 message). C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  15. 15. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 C10605 Number of successful SDCCH assignments. C10606 C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  16. 16. Overview Used Tool Technical procedure Flow Chart ExamplesOverviewIntroductionSDCCHAssignment on SDCCH SDCCH Drop Rate C10601 C10602 C10603 C10604 C10605 Number of successful SDCCH handovers. C10606 C10646 C10653 C11644 C11646 28/12/2010 SDCCH Drop Rate
  17. 17. Overview Used Tool Technical procedure Flow Chart Examples 28/12/2010 SDCCH Drop Rate
  18. 18. Overview Used Tool Technical procedure Flow Chart ExamplesUsed Tools Business Objects 6.5MCOM 4.2ZXG10 OMCRTEMS Investigation which can be used for accessing different performance statistics, creating queries, setting up reports, creating variables and using the Business Objects functions to analyze the data in the reports. 28/12/2010 SDCCH Drop Rate
  19. 19. Overview Used Tool Technical procedure Flow Chart ExamplesUsed ToolsBusiness Objects 6.5 MCOM 4.2ZXG10 OMCRTEMS Investigation This tool is used to know the type of interference (Co- channel interference or adjacent interference) between cells; and the value of tilt, azimuth and height of the cell. 28/12/2010 SDCCH Drop Rate
  20. 20. Overview Used Tool Technical procedure Flow Chart ExamplesUsed ToolsBusiness Objects 6.5MCOM 4.2ZXG10 OMCRTEMS Investigation which can be used to provide access to all the available support activities for Operations and Maintenance in the radio and core networks, besides, the accessibility to Configuration Management, Fault management and Performance management 28/12/2010 SDCCH Drop Rate
  21. 21. Overview Used Tool Technical procedure Flow Chart ExamplesUsed ToolsBusiness Objects 6.5MCOM 4.2ZXG10 OMCR TEMS Investigation Ericsson’s tool which is used to analyze drive tests on the downlink level. 28/12/2010 SDCCH Drop Rate
  22. 22. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical Procedure SDCCH Drop causesSDCCH Drop Reasonstroubleshooting The following are main causes for SDCCH drop rate: SDCCH Drops Due connection loss RMM SMM. SDCCH Drops Due Radio Failure. SDCCH Drops Due LAPD Failure. SDCCH Drops Due OMC Forced release SDCCH Drops Due Preemption. SDCCH Drops Due Others . SDCCH Drops Due Handover Failure. SDCCH Drops SMS (according to the formula of SDCCH Drop Rate). 28/12/2010 SDCCH Drop Rate
  23. 23. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical ProcedureSDCCH Drop causes SDCCH Drop Reasonstroubleshooting The following are main causes for SDCCH drop rate: SDCCH Drops Due connection loss RMM SMM. SDCCH Drops Due Radio Failure. SDCCH Drops Due LAPD Failure. SDCCH Drops Due OMC Forced release . SDCCH Drops Due Preemption . SDCCH Drops Due Others . SDCCH Drops Due Handover Failure. SDCCH Drops SMS. 28/12/2010 SDCCH Drop Rate
  24. 24. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical ProcedureSDCCH Drop types SDCCH Drop Reasons The following are reasons of Radio SDCCH drop: RADIO link loss 1. There exists weak coverage area, and radio signal LAPD SDDCH Drop is weak too.troubleshooting 2.There exists interference, such as intra-network interference due to unreasonable frequency planning, and other external interference, etc. 3.Unreasonable radio parameter setting 4.Equipment hardware fault, such as low output power of the power amplifier, large difference among different carrier transmission power, carrier transmitter fault, combiner fault, etc. 28/12/2010 SDCCH Drop Rate
  25. 25. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical ProcedureSDCCH Drop types SDCCH Drop Reasons RADIO link loss LAPD SDDCH Droptroubleshooting 5.Antenna feeder system fault. For example, VSWR of antenna feeder is big; antenna is too high or lower inclination is unreasonable, which causes too big the coverage range or cross-cell coverage, and forms the remote isolated island effect; etc. 28/12/2010 SDCCH Drop Rate
  26. 26. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical ProcedureSDCCH Drop types SDCCH Drop Reasons RADIO link loss LAPD SDDCH Droptroubleshooting The following are reasons of LAPD SDCCH drop: 1.Site transmission problems, such as transmission interruption or unstable transmission . 2.Site hardware fault, such as unreliable E1 cable, CMM fault, etc. 3.BSC hardware fault. 28/12/2010 SDCCH Drop Rate
  27. 27. Overview Used Tool Technical Procedure Flow Chart ExamplesTechnical ProcedureSDCCH Drop typesSDCCH Drop Reasons troubleshooting SDCCH Drop rate analysis troubleshooting procedure: 1. SDCCH availability. 2. SDCCH Drop causes. 3. Basic NMS to know which TRX might be faulty. 4. Alarms. 5. BTS measurement and cell measurement. 6. Data base parameter. 7. Drive testing and site audit. 28/12/2010 SDCCH Drop Rate
  28. 28. Overview Used Tool Technical procedure Flow Chart ExamplesFlow Chart It is advised to locate the problem by checking radio parameters together with hardware troubleshooting. The flow of handling SDCCH drop is shown below: 28/12/2010 SDCCH Drop Rate
  29. 29. Start SDCCH Drop Rate high certain cell yes No Check yes SDCCH availability yes Is there Open TT to BSS team LAPD problem? No Is there HW Open TT to yes problem BSS team (cell/TRX/TS )? No* Reset cell
  30. 30. * ** Is there yes Open TT to BSS LAPD problem? team NoRF problems Whether radio yes Modify parameter unreasonable are set parameters reasonably No Whether yes Trouble interference shoot exist interference No
  31. 31. *** Whether yesfault exist in Trouble coverage shoot coverage No Whether yesfault exist in Troubleshoot equipment equipment fault HW No Whetherfault exist in yes Trouble antenna shoot antenna feeder feeder fault system No Whether the No yes SDCCH Drop Rate persist restart the investigation END
  32. 32. Overview Used Tool Technical procedure Flow Chart ExamplesExemples 22685A: Hardwar Problem by checking data base stat, we notice a high SDCCHRadio ProblemLAPD Problem Drop Rate on the site. Problem Description: using ZXG10 OMCR tool, the problem is a PA power alarm (hardware problem). Action Taken: open TT to BSS team to solve the PA power alarm. 28/12/2010 SDCCH Drop Rate
  33. 33. Overview Used Tool Technical procedure Flow Chart ExamplesExemples 03102A:Hardwar Problem Problem Description: Co-channel interference on the Radio ProblemLAPD Problem BCCH of 03102A Action Taken: Changing the BCCH frequency from:108-->89 22685A: Problem Description: 22685A of BSCSBA2 (BSC04) is having PA Output Power alarm on TRX1 Action Taken: Replacing the faulty TRX 28/12/2010 SDCCH Drop Rate
  34. 34. Overview Used Tool Technical procedure Flow Chart ExamplesExemples 03663A:Hardwar Problem Problem Description: Transmission disconnectionRadio Problem LAPD Problem problem on the A-bis interface Action Taken: Fixing the TXM problem 28/12/2010 SDCCH Drop Rate
  35. 35. References listReference [10] sjzl20062303-ZXG10-BSS (V2.97) Operation Manual (Radio Parameters) GBO_014_E1_0 Special Topic of Radio Network Optimization-82 GBC_004_E1_0 Radio parameters -50 ZTE Statistics 28/12/2010 SDCCH Drop Rate
  36. 36. 28/12/2010 SDCCH Drop Rate
  37. 37. AppendixDRT/EDRTThe DRT/EDRT fulfills conversion between voice codes at the GSM radio interface and the PSTN A-law PCM voice codes in the BSC, and implements rate adaptation (including dataservices rate adaptation) between them.DRT: Dual-rate transcoder, realizing the transcoding service processing. It can process 126 FRs or 32 EFRs at most.EDRT (C62): Enhanced dual-rate transcoder, an enhanced version of the DRT board. It can process 126 FRs or 126 EFRs at most.EDRT (C64): Enhanced dual-rate transcoder, an enhanced version of the DRT board. It can process 126 FRs, 126 EFRs or 126 HRs at most.Functions and PrinciplesThe board has the following functions. Performs the transcoding and rate adaptation function: It converts the 260-bit vocoder block into one hundred and sixty 8-bit A-law PCM sample signals, and viceversa. Performs framing and vocoder block synchronization, detect voice activation, regulate the block phase in the downlink direction to minimize delay, send alarms to BSC bypassing through BTS through in-band signaling, processes data blocks in compliance with the protocol standard rate adaptation and re-assorting them following the A interfacerequirements. Provide physical-layer functions of the digital trunk interface. Separates signals, SS7 links pass transparently, and the service channels pass through the DSP for processing. Has the HDLC channels communicating directly with the, facilitating O & M Center.Fig 3.18-1 shows the DRT/EDRT board organizational diagram. DRT uses eight DSPs, EDRT (C62) uses six, and EDRT (C64) uses two. In the given figure, n = 8, 6, 2 respectively.The DRT/EDRT comprises the DSP, CPU, and switching circuits. The DSP is responsible for mass calculations, implementing the conversion between radio service channels andground service channels. It is the core of the DRT/EDRT board.Fig 3.18-1 DRT/EDRT Board Organizational Diagram HDLC i t c u i r c n g h i t c i w S DSPn . . A .. .. CPU DSP4 DSP3 Abis HPI DSP 2 DSP 1DRT/EDRT Board FaultFault SymptomDSP is faulty or communication with the corresponding TCPP is disconnected.Fault Cause AnalysisCommunication between TCPP and DRT/EDRT is faulty. Hardware of the TCPP board is faulty. DSP on the DRT/EDRT board is faulty.TroubleshootingPerform the following steps to troubleshoot the fault:1. Check whether the corresponding TCPP board is faulty. If it is faulty, troubleshoot the TCPP board fault first.2. If the DSP is faulty, then go to step 6.3. Check whether there is any clock loss alarm from this board. If there is, then reset and unplug/plug the relevant board.4. Check whether the backplane connection cable is loose or modified.5. Check whether the foreground and background data are consistent and whether relevant data are configured.6. Download the DRT and EDRT versions again and reset the board.7. Replace the DRT/EDRT board. If the fault still remains, plug the board to another slot.PrecautionsBe sure to wear an antistatic wrist strap when touching a board or component. 28/12/2010 SDCCH Drop Rate
  38. 38. Radio parametersRadio parameters setting Cell’s minimum access level: which causes SDCCH drop in weak coverage area. Unreasonable BSIC setting Unreasonable power control setting, such as unreasonable level, quality power control threshold, which will cause MS to reduce power even in the case of weak signal and poor call quality. () Unreasonable FH parameter setting: parameter setting Unreasonable MAIO configuration will cause co-channel interference and adjacent-channel interference within one site. Incomplete adjacent-cell data definition or configuration error Congestion exists in adjacent cell 28/12/2010 SDCCH Drop Rate
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