132794732-3G-Drop-Reason

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  • ALEX, COUNTERS AND PARAMETERS: ALEX, COUNTERS AND PARAMETERS ALPESH SHAH
  • OBJECTIVE: OBJECTIVE The purpose of this presentation is to give high level overview of counters, parameters and ALEX to new engineers to help them better understand the optimization process. The presentation also highlights flow diagrams for identifying accessibility and retainability degradation coupled with some real optimization examples.
  • AGENDA: AGENDA Post Launch KPI Composite Quality Index (CQI) Counters Parameters ALEX Accessibility and Retainability Flow diagrams Optimization examples
  • Post Launch KPIs: Post Launch KPIs
  • Composite quality index (CQI): Composite quality index (CQI) Key Components (current): UMTS Voice Accessibility Quality Distribution UMTS Voice Retainability Quality Distribution 3G IRAT to 2G (Handed down to 2G) 3G ISDR to 2G (Set up on 2G) 3G devices establishing calls on 2G within polygon Overall Composite Quality = 1 - [(1-Acc QD) + (1 - Ret QD) + (3G to 2G IRAT) + (3G to 2G Directed Retry) + (3G device setups on 2G in Polygon)] ATT interpretation: Improve Customer Perception in the Networks on majority of sites Keep more traffic on UMTS in UMTS polygon Ericsson Interpretation: Stricter KPI Targets Aggressive Optimization needed based on QDR and QDA
  • Composite quality index (CQI) contd.: Composite quality index (CQI) contd. Overall Composite Quality = 1 - [( 1-Acc QD ) + (1 - Ret QD ) + ( 3G to 2G IRAT ) + ( 3G to 2G Directed Retry ) + (3G device setups on 2G in Polygon)] Acc QD CS RAB Num - UtranCell.pmNoRabEstablishSuccessSpeech CS RAB Den - UtranCell.pmNoRabEstablishAttemptSpeech CS Directed Retry - UtranCell.pmNoDirRetrySuccess CS RRC Num - Utrancell.pmTotNoRrcConnectReqCsSucc CS RRC Den - (Utrancell.pmTotNoRrcConnectReqCs -pmNoLoadSharingRrcConnCs) CS RAN Acc Num = CS RAB Num + CS Directed Retry CS RAN Acc Den = CS RAB Den / (CS RRC Num / CS RRC Den) Acc QD Target per site CS RAN Acc Num / CS RAN Acc Den >= 97.5% Ret QD Drops - pmNoSystemRabReleaseSpeech Calls – pmNoRabEstablishSuccessSpeech Ret QD Target per site (Calls - Drops) / Calls >= 98.0% 3G to 2G Directed Retry pmNoDirRetrySuccess /pmNoRabEstablishAttemptSpeech 3G to 2G IRAT ((pmNoSuccessOutIratHoSpeech+ pmNoSuccessOutIratHoMulti)/ pmNoRabEstablishSuccessSpeech)) 3G device setups on 2G in Polygon Calculated by ATT from CDR live
  • Key performance Indicators (KPI): Key performance Indicators (KPI) The Key Performance Indicators (KPI) represents the End-user perception of a network on a macro level and are of typical interest for top-level management as well as others within an operator. These numbers are typically used to benchmark networks against each other and to detect areas of problem. The reliability, granularity and accuracy of this data are critical.
  • COUNTERS: COUNTERS WCDMA RAN generates performance data in network elements (NE) in the form of performance management (PM) statistics. Performance Statistics is continuously collected from the NE and stored persistently in the Operations Support System Radio and Core (OSS-RC). Statistics are mainly used for the detection of problem areas and for monitoring the performance of the network on a daily basis. Counter data from all active performance monitoring are written to an XML file for every measurement period. A measurement period, or Granularity Period (GP), is 15 minutes. The statistical file is collected by the OSS every 15 minutes. The name of all the counters created in NE begin with “pm”. There are two general classification of statistics counters. RNC counters RBS counters Grouping of counters in different NE is shown in the next slide
  • Managed Object Model: Managed Object Model The Managed Object Model (MOM) defines the information model with regard to node management. It presents a view of all the manageable resources in the node, and all the parameters and actions associated with these resources.
  • Basic Counter Types: Basic Counter Types Counter Types: Accumulator (ACC), Gauge (GAUGE), Peg (PEG), PDF, Scan (SCAN), TrigACC, or TrigSCAN. ACC:   An accumulator counter that is increased by the value of a sample. It indicates the total sum of all sample values taken during a certain time. The name of an accumulator counter begins either with pmSum or pmSumOfSamp . GAUGE:   A gauge counter that is increased or decreased depending on the activity in the system. PEG:   A peg counter that is increased by 1 at each occurrence of a specific activity. PDF:   A Probability Density Function (PDF) counter is a list of range values. A value is sampled (read) periodically. If the value falls within a certain range, the range counter for that range is increased. All range counter values are collected and stored in a Result Output Period (ROP) file at the end of each reporting period. SCAN:   A scan counter that is increased by 1 each time the corresponding accumulator counter is increased. It indicates how many samples have been read and added to the related accumulator counter. A scan counter can, therefore, be considered a type of peg counter. Due to these types of counters, it is possible to get the average value of all samples by dividing the accumulator counter by the scan counter. The name of a scan counter begins with pmSamples or pmNoOfSamp .
  • ALEX (Active Library Explorer) : ALEX (Active Library Explorer) ALEX is the encyclopedia for all the information pertaining to counters, parameters, alarms, call flows, etc for WCMDA/LTE. The link to ALEX is : http://cpistore.internal.ericsson.com/alex
  • Counter Reference in ALEX (RNC ): Counter Reference in ALEX (RNC )
  • Some Counter Examples : Some Counter Examples CS RAB Attempts - pmNoRabEstablishAttemptSpeech CS RAB Success - pmNoRabEstablishSuccessSpeech CS Directed Retry - pmNoDirRetrySuccess, pmNoDirRetryatt CS RRC Attempts - pmTotNoRrcConnectReqCs CS RRC Success - pmTotNoRrcConnectReqCsSucc Loadsharing - pmNoLoadSharingRrcConnCs CS Raw Drop Counts - pmNoSystemRabReleaseSpeech
  • Parameters: Parameters Counters are used to gauge network performance whereas parameters are used to tweak network performance. Commonly used parameters used in optimization are listed below:
  • Slide 15: Troubleshooting & Optimization Flowcharts
  • Accessibility and Retainability flow diagrams: Accessibility and Retainability flow diagrams Accessibility Flowchart Describe the possible causes of Access / Setup failures in CS and PS. Accessibility Analysis Basic checks to identity the cause of Access Failures (CS/PS) Retainability Flowchart Describe the possible causes of Dropped Calls Retainability Analysis Basic checks to identity the cause of Dropped Calls
  • Slide 17: CS/PS Accessibility RRC RAB
  • Slide 18: MP Load Admin Control License UTRAN Node Blocking Transport Blocking Check MP load for Main / extension sub racks: High ?? Check for core network ( Call Servers / SGSN outages) Re-module sites Virtual rebalance Implement FGA and ASU reduction parameters Re-home sites Check Parameter settings for: a) Feeder length/TMA b) OCNS c) Adm Control d) Check available resources (Downlink Tx power, Channelization codes) . RBS specific counter a) Verify /correct individual licensed capacity levels for the node. b) Check Channel elements usage trends Check for RRC rejections due to High MP Load, Admission control, failures due to DL channelization codes. Check for node configuration error, node limitations or transport network layer service unavailability. a) Check for congestion on user plane (AAL2)/ control plane (UniSaal /SCTP) for IuB resources. b) Expand TN bandwidth Check IuCs/IuPs CS/PS Accessibility (RRC)
  • Slide 19: Congestion UTRAN Node Blocking Transport Blocking Check for RRC rejections due to High MP Load, Admission control, failures due to DL channelization codes. Check for node configuration error, node limitations or transport network layer service unavailability. a) Check for congestion on user plane (AAL2)/ control plane (UniSaal /SCTP) for IuB resources. b) Expand TN bandwidth Check T1 Errors Check Locked T1s Check Iub/TD ( Vc/Vp ) Mismatches Share Traffic with Nbr or Escalate for expansion Reduce CPICH or Tilt to take less traffic Increase Directed Retry to Offload to GSM CS/PS Accessibility (RAB) Node Blocking Transport Blocking Check for node configuration error, node limitations or transport network layer service unavailability. a) Check for congestion on user plane (AAL2)/ control plane (UniSaal /SCTP) for IuB resources. b) Expand TN bandwidth Check T1 Errors Check Locked T1s Check Iub/TD (Vc/Vp) Mismatches Share Traffic with Nbr or Escalate for expansion Reduce CPICH or Tilt to take less traffic Increase Directed Retry to Offload to GSM Hardware Fault
  • Slide 20: Congestion CS/PS Accessibility (RAB) ASE Hardware Resource Connection Limit DL Power Code Check if Maximum Transmission Power is aligned with MaxDlCapability Check Maximum Transmission Power and CPICH ratio Increase PwrAdm, Reduce PwrOffset Explore IFLS with other Carrier Enable or Increase Directed Retry to GSM Reduce sf16Adm/sf8Adm Consider changing to 60W RU Add another Carrier Check dlCodeAdm values if adjustment is still possible Reduce 384k Users on DL (sf8Adm) Reduce HS-PDSCH Codes Reduce HS-SCCH Codes Check Locked Tx/Rax Boards Check hanging CE (restart) Check HS/EUL resource allocation ul/dlHwAdm FIRS 16kbps Channel Type DCH to FACH eulServing/NonServingAdm Replace RAX/TX Boards a) Verify settings for “dlASEAdm b) Check for traffic load on the cell. c) Optimize radio network to reduce interference / pilot pollution. Verify Admission settings /Usage trends for different SF RAB. Fine tune parameter settings to maintain balance between Accessibility & throughput.
  • Slide 21: Hardware Fault Escalate Escalate Restart Board Cold Restart Node Verify SW on node Swap Cards/Boards Replace Cards/Boards Attenuation/Losses TMA Check Verify RFDS External Interference CS/PS Accessibility (RAB) Errors/Crashes Alarms RSSI T1 Errors
  • ACCESSIBILITY ANALYSIS: ACCESSIBILITY ANALYSIS BASIC CHECKS TO IDENTIFY THE CAUSE OF ACCESS FAILURE
  • Accessibility Lack of Power: Accessibility Lack of Power If > 1 carrier, then try to load balance between the carriers (qOffset1sn/qOffset2sn) in idle mode. Original settings between carriers are as follows: qOffset1sn = 0 (UMTS <-> UMTS); qoffset1sn = 7 (UMTS -> GSM); qOffset2sn = 0 (UMTS <-> UMTS). Increase pwrAdm (but make sure that pwrAdm + pwrOffset is less than 100%) Con: Less power available for SHO Reduce CPICH Con: Reduced coverage Add another carrier Reduce DL attenuation (e.g. better/shorter cables, Main-Remote) Overshooter (propagationDelay/WNCS)? => Down-tilt Con: Reduced coverage
  • ACCESSIBILITY ANALYSIS: ACCESSIBILITY ANALYSIS Admission Congestion Check most used parameters (RNC – MO Utrancell ) pwrAdm, pwrOffset, dlCodeAdm, sf8Adm, sf16Adm, dlHwAdm, ulHwAdm Cell designation/Layer Management settings (RNC – MO Utrancell ): hoType, qQualMin, qRxLevMin, usedFreqThresh2dEcno, usedFreqThresh2dRscp Check Propagation Delay in order to detect overshooter cells: RBS: pmx . pmpropagationdelay -m 72 -a * Note: 72 is the time window that you want to analyze, expressed in hours. You can set the time that best suits your analysis
  • Accessibility Lack of Codes: Accessibility Lack of Codes Increase dlCodeAdm Con: Less codes reserved for SHO Reduce number of reserved (SF16) HS codes (numHsPdschCodes) Increase the amount of AMR 5.9 if possible (pwrLoadThresholdDlSpeech) Con: Decreased speech quality Increased usage of SF256 for AMR5.9 (codeLoadThresholdDlSf128)
  • Accessability minPwrMax: Accessability minPwrMax A setting of -15 for minPwrMax has been recommended by the trial performed in Lafayette; This setting improves accessibility at a slight expense to retainability.
  • Accessibility: ASE UL, UL HW and DL HW : Accessibility: ASE UL, UL HW and DL HW ASE UL Disable ASE UL admission (set aseUlAdm to 500) UL HW Increase ulHwAdm Con: Less resources available for SHO Add RAX card(s) DL HW Increase dlHwAdm Con: Less resources available for SHO Add or replace TX card(s) with higher capacity card(s)
  • Accessibility pmCounters: Accessibility pmCounters Admision Control: DL Channelization Code Admission Policy pmNoFailedRabEstAttemptLackDlChnlCode DL Tx Carrier Power Admission Policy pmNoFailedRabEstAttemptLackDlPwr DL / UL ASE Admission Policy pmNoFailedRabEstAttemptLackDlAse pmNoFailedRabEstAttemptLackUlAse DL / UL Spreading Factor Admission Policy pmNoFailedRabEstAttemptExceedConnLimit Compressed Mode Admission Policy pmSumCompMode / pmSamplesCompMode (Number of CM Users per Cell) Serving HS Admission Policy pmNoOfNonHoReqDeniedHs Serving/non-serving E-UL Admission Policy pmNoServingCellReqDeniedEul pmNoNonServingCellReqDeniedEul DL / UL RBS Hardware Admission Policy pmNoFailedRabEstAttemptLackDlHwBest pmNoFailedRabEstAttemptLackUlHwBest
  • ACCESSIBILITY ANALYSIS: ACCESSIBILITY ANALYSIS Hardware Resources Check available CE the RBS (UL/DL): lget . channelelements Check CE usage in the RNC (UL/DL): cedhr (it lists the CE usage per Iub link) Others Check T1 / IMA errors RBS: pmx . pmes|pmses|pmuas –m 72 –a pmxh . pmes|pmses|pmuas –m 72 –a * Note: 72 is the time window that you want to analyze, expressed in hours. You can set the time that best suits your analysis.
  • ACCESSIBILITY ANALYSIS: ACCESSIBILITY ANALYSIS Others (Cont.) Check AAL2 failures RNC: pmxh -m 24 . pmUnSuccInConnsLocal|pmUnSuccInConnsRemote|pmUnsuccessfulConnsInternal -a * Note: 24 is the time window that you want to analyze, expressed in hours. You can set the time that best suits your analysis. Check RBS/RNC faults Check alarms through al, ala, alt, alk, etc. Check hardware faults through lhsh commands MP Load RNC: pmr
  • RETAINABILITY FLOWCHART: RETAINABILITY FLOWCHART CS DROP CAUSES
  • Slide 32: Add suggested Neighbors with WNCS/GPEH/Drive Test data Analyze existing neighbors with 3G-3G radio link attempts, distance and location Analyze cell coverage by RF Planning tool /Drive Test data/PRACH Plots Down tilts or other physical optimization  Counter pegged: pmNoSysRelSpeechNeighbr Check RBS HW Alarms Check T1 Errors or bouncing IP Check Cell Availability Determine if the issue affects only one cell or a RBS or cluster Verify for SC Clashes Counter pegged: pmNoSysRelSpeechSoHo   Investigating the UE TxPwr by using Drive test data or WMRR Analyze cell coverage by RF Planning tool/ Drive test data/PRACH/WMRR Use of GPEH to determine the number of Event 6a or number of Event 2d Check Cells for RSSI Issues Counter pegged: pmNoSysRelSpeechUlSync Neighbor List cleaning/ deletion GSM coverage area verification for IRAT neighbors Re-prioritization the neighbor list based on usage Check down switch counter for congestion reason. Investigate the RRC Access failure due to lack of DL power & codes Perform analysis of coverage area and reduce overshooting Verify CE usage and HW allocation and dimensioning Counter pegged: pmNoOfTermSpeechCong Transport Issue RBS / RNC HW issue RF issues outside of available counters UE issues Co-PSC issues Counter pegged: pmNoSystemRabReleaseSpeech – (other drop reasons) Missing Neighbour Soft Handover Uplink Sync IRAT Congestion Others CS/PS Retainability
  • RETAINABILITY ANALYSIS: RETAINABILITY ANALYSIS BASIC CHECKS TO IDENTIFY DROP CAUSES
  • RETAINABILITY ANALYSIS – 1/5: RETAINABILITY ANALYSIS – 1/5 Missing Neighbor Drop WNCS Analysis; Check Neighbor cell availability (RNC – MO Utrancell): administrativestate and operationalstate; pmCellDowntimeMan and pmCellDowntimeAuto; Check Propagation Delay in order to detect overshooter cells: RBS: pmx . pmpropagationdelay -m 72 -a * Note: 72 is the time window that you want to analyze, expressed in hours. You can set the time that best suits your analysis
  • Retainability CPICH Setting at Reference Point: Retainability CPICH Setting at Reference Point A brief guideline has been provided by the Ericsson team on assignment of CPICH powers; As a rough rule of thumb, the ideal case is to have the same CPICH power setting at the reference point to balance the UL and DL handover regions; In general, the CPICH power assigned should be approximately 8-10% of the Total Power of the cell.
  • Retainability Drops due to others: Retainability Drops due to others With the drops due to others, it has been found that in many cases, it is an RF related issue; Tilts and parameter changes have been able to reduce the drops as per the examples attached.
  • Retainability individualOffset: Retainability individualOffset The parameter individualOffset can help reducing the number of drops caused by fast moving UEs A good starting point is to set the individualOffset parameter to 50 on the target cell, then adjust the parameter further to optimize the SHO success rate At least 3-5 days are needed for each step to fully assess the impact on performance by each change
  • Retainability CPICH and minPwrRl: Retainability CPICH and minPwrRl 25 dB power difference rule of thumb Minimum Downlink Transmitted Code Power If the power of a radio link is very low, it is very sensitive to various interference. To avoid that the Power Control function decreases the power too much due to temporary good radio conditions, a minimum downlink transmitted code power value is configured. The parameter that sets this value per cell is minPwrRl (dBm) and it is relative to primary CPICH power in a cell. Minimum Downlink Transmitted Code Power The minimum downlink transmitted code power, minPwrRl, must be set in such a way that the risk for downlink power rushes in transmitted downlink power is reduced. Field tests have shown that if minimum downlink transmitted code power is set to a too low level, there is the risk (depending on the mobile vendor) that UEs cause a sudden rush in downlink power behavior, which can result in downlink cell congestion being unnecessarily detected. A value set too low can also lead to uplink interference peaks, as the Power Control function may have problems receiving the control information. As a rule of thumb, the minimum power for each radio link should be set 25 dB below the maximum power allowed maxDlPowerCapability in the RBS .
  • Retainability VSWR: Retainability VSWR 10.14.11.193> lh ru fui get vswr : : =================================================================================== $ lhsh 001200/port_0_dev_5 fui get vswr 0012p0d5: vswr: 20.3[dB] =================================================================================== $ lhsh 001200/port_2_dev_19 fui get vswr 0012p2d19: vswr: 20.7[dB] =================================================================================== $ lhsh 001200/port_4_dev_6 fui get vswr 0012p4d6: vswr: 20.0[dB] =================================================================================== $ lhsh 001200/port_6_dev_20 fui get vswr 0012p6d20: vswr: 18.9[dB] =================================================================================== $ lhsh 001200/port_8_dev_7 fui get vswr 0012p8d7: vswr: 20.4[dB] =================================================================================== $ lhsh 001200/port_10_dev_21 fui get vswr 0012p10d21: vswr: 24.2[dB] ======================================
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