279934373-6-GSM-Paging-Affecting-Factors-Check-Methods-and-Tools-and-Deliverables-20121031-ppt.ppt
- 1. HUAWEI TECHNOLOGIES CO., LTD. www.huawei.com Huawei Confidential Security Level: Affecting Factors Check Methods and Tools Deliverables GSM Paging
- 2. HUAWEI TECHNOLOGIES CO., LTD. Page 2 HUAWEI Confidential Topics in This Document Topic Description Paging Factors affecting GSM paging success rate Eight required actions to handle paging problems Eliminating factors causing GSM paging failures using top problem method and root cause method Required documents for submitting a paging problem, including a conclusion made by using these two methods Examples used here are typical.
- 3. HUAWEI TECHNOLOGIES CO., LTD. Page 3 HUAWEI Confidential Date Version Description Reviewer Author 2011-12-31 2011/12 1. Initial issue after review Caofei, Chen Ruiqun, Li Yugang, Liu Kuan, Ni Hongxiang, Xu Binbin, Xun Lijun, Zhu Kan, Zhang Liang, Du Jian, Wang Zhicheng, and Qi Haofeng Shen Jian, Wang Lu 2012-10-30 2012/10 1. Paging section updated Caofei, Liu Kuan, Ni Hongxiang, Xu Binbin, Xun Lijun, Zhu Kan, Zhang Liang, Du Jian, Wang Zhicheng, Qi Haofeng, Feng Zhenyan, Chen Jing, and Zhao Jinjin Shen Jian, Zhou Dong Change History
- 4. HUAWEI TECHNOLOGIES CO., LTD. Page 4 HUAWEI Confidential Technical Support Topic Name ID Paging Shen Jian 126759 Wang Lu 165414 We provide 7x24 training services. The following table lists engineers formulating this document:
- 5. HUAWEI TECHNOLOGIES CO., LTD. Page 5 HUAWEI Confidential Definition and Measurement Point of Paging Success Rate Cases Method for Optimizing Paging Success Rate General Method for Locating Problems Related to Paging Success Rate
- 6. HUAWEI TECHNOLOGIES CO., LTD. Page 6 HUAWEI Confidential Definition of Paging Success Rate The paging success rate is a counter on the core network. Therefore, this counter cannot be obtained from the BSS, and must be obtained from the core network. The measurement object of this counter is LAC. The specific definition is as follows: Paging success rate = (First paging response times on interface A + Repeated paging response times on interface A) /First paging request times on interface A
- 7. HUAWEI TECHNOLOGIES CO., LTD. Page 7 HUAWEI Confidential Measurement Point of Paging Success Rate The measurement statistics of paging success rate is measured on the core network. The following figure shows the paging process and measurement point on the BSS. A: Paging request times B: Paging response times
- 8. HUAWEI TECHNOLOGIES CO., LTD. Page 8 HUAWEI Confidential Definition and Measurement Point of Paging Success Rate Cases Method for Optimizing Paging Success Rate General Method for Locating Problems Related to Paging Success Rate
- 9. HUAWEI TECHNOLOGIES CO., LTD. Page 9 HUAWEI Confidential Classification of Paging Success Rate Problems Paging success rate problems Non-compliance of paging success rate on the replaced network The paging success rate is smaller than that of the original network after replacement. In this case, perform the following troubleshooting: 1. Check the power match (for details, see Guide to Power Matching During GSM Network replacement) . 2. Check parameters, including parameter mapping check and check of interconnection parameters between the MSC and BSC. For details, see intelligent parameter mapping document and Correlation Analysis of the GSM Wireless Network and Core Network Parameters. 3. Check whether the LAC division has any change before and after the replacement. After the confirmation of three preceding points, go to the normal optimization process. Non-compliance of paging success rate on the new network Go to the normal optimization process. Suddenly decrease of paging success rate on the maintenance network 1. Is there any version update? 2. Is there any parameters change? After the confirmation of two preceding points, go to the normal optimization process. Slowly decrease of paging success rate on the maintenance network 1. Rectifying Hardware and Transmission Faults 2. Confirm the season impact. After the confirmation of two preceding points, go to the normal optimization process. Range of Paging success rate problems Problem of the whole MSC Need to optimize the whole MSC. Problem of TOP LAC Optimize top LAC.
- 10. HUAWEI TECHNOLOGIES CO., LTD. Page 10 HUAWEI Confidential Solution of PSR optimization Low paging success rate Check paging parameters NSS parameters: Paging policy (Paging times, paging duration, TMSI/IMSI flag, and All RAN paging flag) , Implicit IMSI detach timer (min) , Support pre-paging, Support release before pick-up, Support location update and optimization, Paging optimization control, and BSC Paging Threshold per Second. BSS parameters: Channel Type, CCCH Blocks Reserved for AGCH, Multi-Frames in a Cycle on the Paging CH, Random Access Error Threshold, CS RACH Min. Access Level, CS RACH Min. Access Level Offset, Minimum Access RXLEV, Paging Times, MS MAX Retrans, SDCCH Dynamic Allocation Allowed, T3212, A Interface Paging Co-ordination Switch, BSS Paging Co-ordination, and BTS Paging Lifetime. For details, see the parameter description on the following slide. Check the paging overload Find the top N cells with serious paging overload according to paging-related traffic statistics and flow control-related traffic statistics, and then perform the troubleshooting. For example, the paging overload can be avoided by adding extended BCCHs. If the paging overload of the entire network occurs, you are advised to restart the LAC division. Check the LAC planning In the process of dividing location areas, enlarge the LAC range to reduce the number of LACs under the prerequisite that the paging overload does not occur. In this way, the times of location updates can be minimized, and the decrease of unnecessary location updates has a positive impact on the paging success rate. Check hardware and transmission faults Find the cells with hardware faults by using the counter R373 Cell Out-of-Service Duration, and then perform the troubleshooting. If the ALM-21801 GSM Cell out of Service is reported, perform the troubleshooting according to the methods of clearing ALM-21801. Check the Interference and coverage problem Check and resolve the interference problem of TOP N cells. Check and resolve the poor coverage problem of TOP N cells. Check BSC/BTS Version According to the early warning, notification, release notes, and hitless upgrade tool, confirm whether the version variances or known problems of the current version affect the paging success rate. For known causes, take the preventive measures. Check for abrupt events Check whether there are abrupt events such as charging policy changes and mass gathering affecting the traffic model or Um interface environment. Check the long- term traffic trends Check whether the seasonal trend of changes in PSR, counters, and benchmark data vary with time segment and whether problems such as traffic change occur due to increasing subscribers.
- 11. HUAWEI TECHNOLOGIES CO., LTD. Page 11 HUAWEI Confidential Process of Handling Paging Success Rate Problems According to the preliminary analysis of the faulty LAC, determine main factors affecting the paging. LAC1: cell out of service LAC2: paging overload LAC3: a large number of poor coverage areas LAC4: improper parameter settings Perform the hardware and transmission fault troubleshooting according to the troubleshooting guide. Solve the paging overload problem by adjusting the parameter or LAC. Perform the following operations to solve the coverage problem: Locate the problem point by drive test, adjust the antenna, and add BTSs. Modify the improper parameters. According to the traffic statistics analysis of the paging success rate on the core network, locate the faulty LAC and the corresponding BSC. The common paging overload is BTS overload, that is, the Um interface overload. In the case of parameter adjustment, add the extended BCCH to solve the Um interface capacity problem. Focus on engineering adjustments and constructions with supplemented parameter optimization. In the case of parameter adjustment, adjust the access parameters to reduce the access restrictions.
- 12. HUAWEI TECHNOLOGIES CO., LTD. Page 12 HUAWEI Confidential Definition and Measurement Point of Paging Success Rate Cases Method for Optimizing Paging Success Rate General Method for Locating Problems Related to Paging Success Rate
- 13. HUAWEI TECHNOLOGIES CO., LTD. Page 13 HUAWEI Confidential Checking Paging–Related Parameters - NSS Paging–related parameters on the NSS are as follows: Paging times Paging duration TMSI/IMSI flag All RAN paging flag Implicit IMSI detach timer (min) Support pre-paging Support location update and optimization Support release before pick-up Paging optimization control The table on the right lists the parameter configuration of a certain office. Office SZS14 BSC SW02A BSC OPC 2739 LAC 46000255E Paging policy Paging Type = All paging types Priority = All priorities Paging times = 3 First paging duration = 6 Second paging duration = 8 Third paging duration = 6 Fourth paging duration = 4 Fifth paging duration = 4 TMSI/IMSI flag = Using TMSI for the first paging = Using IMSI for the second paging = Using TMSI for the third paging = Using TMSI for the fourth paging = Using TMSI for the fifth paging All RAN paging flag = The first paging delivered only to the current LAI = The second paging delivered only to the current LAI = The third paging delivered only to the current LAI = The fourth paging delivered only to the current LAI = The fifth paging delivered only to the current LAI Implicit IMSI detach timer (min) 66 Support pre-paging No Support location update and optimization Yes Support release before pick-up Yes
- 14. HUAWEI TECHNOLOGIES CO., LTD. Page 14 HUAWEI Confidential Adjustment Policy of Paging–Related Parameters - NSS Parameter ID MO Parameter Name Version Adjustment Policy Priority LOCUPDT MOD VLRCFG Implicit IMSI detach timer (min) It specifies the time interval when the VLR sets the mobile subscribers to be in IMSI detach state. The unit is minute. The value of the parameter ranges from 1 to 10080. Implicit IMSI detach is originated by networks and explicit IMSI detach is originated by mobile stations. The value of the parameter should be greater than the time interval of periodic subscriber location update configured on the BSC. H PTMR MOD VLRCFG Subscriber purge timer (hr) It specifies the time period before the MSOFTX3000 (VLR) removes or marks the data of inactive mobile subscribers. The unit is hour. The value of the parameter ranges from 1 to 720. The value of the parameter should be greater than the time interval of periodic subscriber location update configured on the BSC. Generally, the value of this parameter is 24. L FIRSTD MOD PGCTRL First paging duration The parameter is set to a value greater than the BTS paging lifetime on the BSS. If the value is smaller than the BTS paging lifetime, the MSC delivers the second paging before the BTS delivers the paging in the paging process. This will increase load of the paging channel. (Refer to Case 1). H SECONDD MOD PGCTRL Second paging duration H THIRDD MOD PGCTRL Third paging duration H FOURTHD MOD PGCTRL Fourth paging duration H FIFTHD MOD PGCTRL Fifth paging duration H TIMES MOD PGCTRL Paging times It specifies the maximum number of paging times during a paging process. The value range is 1 to 5. A complete paging process refers to the process from initiating the paging to receiving the paging response or paging failure message. During a paging process, the maximum duration from initiating the paging to receiving the paging response or paging failure message is 20 seconds by default. When you set parameters, the summation of the valid duration values should be no more than 20 seconds. For example, if you set Paging times to 3, the summation of values of First paging duration, Second paging duration, and Third paging duration should be no more than 20 seconds. If you set both First paging duration and Second paging duration to 10, the system does not initiate the third paging regardless of the value of Third paging duration. Other cases are deduced in the same way. Two or three of them are required on the live network. H ALLRAN MOD PGCTRL All RAN paging flag It indicates whether the MSOFTX3000 sends paging messages to the specific location area or all the location areas served by the MSC. Enabling the pool-wide paging may have adverse impacts on the network. Therefore, you are advised to disable pool-wide paging. In a small scale network, the pool-wide paging can be used to improve the paging success rate under the condition that no paging overload occurs on the BSS. H IMSI MOD PGCTRL TMSI/IMSI flag It specifies whether the TMSI is contained in the paging messages sent by the MSOFTX3000 to the BSC or RNC. The default value is all empty, indicating that TMSI is used every time. If the Paging message sent from the MSC to the BSC contains only the IMSI of the MS, the BTS uses the IMSI in the paging message transmitted through the Um interface. If the MSC sends a Paging message that carries the IMSI and TMSI of the MS to the BSC, the BTS uses the TMSI in the paging message transmitted through the Um interface. The IMSI paging can be used to improve the paging success rate under the condition that no paging overload occurs on the BSS. H PTPS MOD BSC BSC Paging Threshold per Second It specifies the maximum paging times per second of a BSC. Its value ranges from 10 to 200. By default, the value is 65535, indicating that the MSOFTX3000 does not perform paging flow control on this BSC. If the value is set to be too small, the MSOFTX3000 performs paging flow control on this BSC. L Support pre-paging If the value of bit4 of P140 is set to 1, the pre-paging is enabled. If the value of bit4 of P140 is set to 0, the pre-paging is disabled. Pre-paging can improve the efficiency of the incoming call, and shorten the call delay. However, the occupied duration of the SDCCH increases. If the configuration is improper, the congestion may occur. As a result, the paging success rate decreases. L Support location update and optimization If the value of bit1 of P1100 is set to 0, the optimization is enabled. If the value of bit1 of P1100 is set to 1, the optimization is disabled. The default value is 1. Enabling this function can improve the paging success rate. After the function is enabled, the system effectively makes response to paging in the case of MS location update. H Support release before pick-up If the value of bit15 of P166 is set to 0, the function is enabled. If the value of bit15 of P166 is set to 1, the function is disabled. The default value is 1. This bit is used to control whether to make statistics of the PAGING RESP message in the case of early release. If this function is enabled, the paging response times increases in the case of the early release of the calling party. In this way, the paging success rate increases. H Paging optimization control If the value of the bit8 of P164 is set to 0, it indicates that the actual number of paging times is equal to the value of the paging times. If the value is set to 1, it indicates that the actual number of paging times is equal to the value of the paging times subtracted by 1. If the value of the paging times is 1, there is only one paging. The default value is 1. If the called party has no paging response in a certain call, the number of paging times is controlled by this parameter in the next call of this called party. The number of paging times is recovered to the original value when the called party has a paging response. This function is enabled to reduce times of delivering paging commands by the system when the called party cannot make a response to the paging. L
- 15. HUAWEI TECHNOLOGIES CO., LTD. Page 15 HUAWEI Confidential Adjustment Policy of Paging–Related Parameters - BSS Parameter ID MO Parameter Name Version (R11/R12/R13/R14) Adjustment Policy Positive Impact Negative Impact Priority CHTYPE GTRXCHAN Channel Type R11, R12, R13, R14 If paging overload of a certain cell is serious, you can configure the extended BCCH to increase paging capacity. Set TS2 of BCCH TRX to BCH. If more BCHs need to be configured, you can set TS4 and TS6 of BCCH TRX to BCH. Paging capacity expansion of the Um interface can release paging overload of the Um interface. Decrease of other channels may cause congestion of the SD or the TCH. H BSAGBLKSRES GCELLIDLE BASIC CCCH Blocks Reserved for AGCH R11, R12, R13, R14 Huawei BTSs support the delivery priority of the immediate assignment messages. Therefore, the recommended value of this parameter is 1. As a result, more PCHs are reserved for the paging messages in the case of no immediate assignment messages. This increases paging channels and reduces paging overload probability. N/A H BSPAMFRAMS GCELLIDLE BASIC Multi-Frames in a Cycle on the Paging CH R11, R12, R13, R14 The recommended value of this parameter is 2. This has positive impacts on the delivery delay of the paging and the success rate. N/A L RANERRTHRED GCELLCCA CCESS Random Access Error Threshold R11, R12, R13, R14 The parameter is set to a small value to improve the paging success rate. However, this may affect the immediate assignment success rate and the congestion rate. Both the positive impacts and negative impacts must be considered. The paging success rate is improved. The immediate assignment success rate and the congestion rate are affected. H RACHACCLEV GCELLCCA CCESS CS RACH Min. Access Level R11, R12, R13, R14 RACHACCLEV and RACHACCLEVOFFSET determine the CS RACH minimum access level. The value of RACHACCLEVOFFSET ranges from 0 to 15. The value 0-14 is corresponding to -8 dB to 6 dB respectively. The default value 15 is corresponding to 0 dB. CS RACH Min. Access Level Offset is set to a small value to improve the paging success rate. However, this may affect the immediate assignment success rate and the call drop rate. Both the positive impacts and negative impacts must be considered. (Refer to Case 2 and 3) The paging success rate is improved. The immediate assignment success rate and the call drop rate are affected. H RACHACCLEVO FFSET GCELLSOFT CS RACH Min. Access Level Offset R11, R12, R13, R14 RXMIN GCELLBASI CPARA Minimum Access RXLEV R11, R12, R13, R14 The parameter is set to a small value to improve the paging success rate. However, this may affect the immediate assignment success rate, the call drop rate, and the congestion rate. Both the positive impacts and negative impacts must be considered. The paging success rate is improved. The immediate assignment success rate, the call drop rate and the congestion rate are affected. L PAGTIMES GCELLCCB ASIC Paging Times R11, R12, R13, R14 On the condition that no paging overload occurs in cells, the parameter is set to a large value to improve the paging success rate. The recommended value is 4. In the case of non-overload of the paging, setting of the parameter to a large value can improve the paging success rate. In the case of paging overload, setting of the parameter to a large value has negative impacts on the paging success rate. L MSMAXRETRAN GCELLCCB ASIC MS MAX Retrans R11, R12, R13, R14 On the condition that RACH overload does not occur in cells, the parameter is set to a large value to improve the paging success rate. In the case of non-overload of the RACH, setting of the parameter to a large value can improve the paging success rate. In the case of overload of the RACH, setting of the parameter to a large value has negative impacts on the paging success rate. L SDDYN GCELLBASI CPARA SDCCH Dynamic Allocation Allowed R11, R12, R13, R14 This parameter can be used to improve the low paging success rate due to SDCCH congestion. The paging success rate is improved. N/A L T3212 GCELLIDLE BASIC T3212 R11, R12, R13, R14 This parameter is set with the consideration of the implicit IMSI detach timer on the core network side. The value of the timer on the BSS must be smaller than the value of the timer on the NSS. In addition, value of the timer of the cells in the same LAC needs to be set to the same value. The paging success rate is improved. N/A H ACOOPERATPA GINGSWITCH BSCPSSOF TPARA A Interface Paging Co-ordination Switch R11 You are advised to turn on the two switches at the same time. In this way, the BSC with the built-in PCU can make response to CS paging of MSs when MSs implement PS services. The paging success rate is improved. The A interface paging co-ordination switch is deleted in versions later than R12 and only the BSS paging co-ordination switch is reserved. The paging success rate is improved. N/A H BSSPAGINGCO ORDINATION GCELLPSBA SE BSS Paging Co- ordination R11, R12, R13, R14 29 GCELLBTSS OFT BTS Paging Lifetime R11, R12, R13, R14 The value of the BTS software parameter 29 ranges from 0 to 255. The unit is 250 ms. By default, the value is 255, corresponding to 5s. When setting this parameter, consider the coordination with the first paging duration of the parameter on the core network. If this value needs to be smaller than the first paging duration on the core network, preferentially set the first paging duration on the core network to a large value. The paging success rate is improved. N/A H
- 16. HUAWEI TECHNOLOGIES CO., LTD. Page 16 HUAWEI Confidential Analyzing Paging Delay Distribution Prerequisite The Trace Analyzer on the core network must be based on Huawei MSC. Principle The Trace Analyzer on the core network exports the delay statistics according to the A interface signaling, and the setting of paging strategy parameters on the core network can be optimized. The principle is as follows: The sum of n times paging intervals on the core network must be larger than the most paging response delay (for example, 97%-98%). For the network in which the Um interface delivery capability becomes a bottleneck, the increase of the paging interval can reduce the repeated paging delivery. In this way, the impact of repeat paging delivery on the Um interface can be reduced. Note: This is a part of the parameter optimization, which serves as a reference for the paging duration optimization. For details, see Case 4 Core Network Tool Application. You can obtain the tool at the following website: http://support.huawei.com/support/pages/editionctrl/catalog/ShowSoftDetail. do?actionFlag=displaySoftInfo&node_id=000001505811&web_doc_id=SW0 000405465&colID=ROOTWEB|CO0000000065 GSM paging delay distribution Times Time (second)
- 17. HUAWEI TECHNOLOGIES CO., LTD. Page 17 HUAWEI Confidential Impact The paging volume exceeds the processing capability of the BSC. As a result, the BSC discards the paging. Check Method BSC6000 check method (taking the CS paging as an example) A0300 + A0301 > A032, or A032 > ∑A330 (averaging the counters of cells in the same LAC and taking the sum of the averaged counters of several LACs) BSC6900 check method (taking the CS paging as an example) A0300 + A0301 > ∑A330 (averaging the counters of cells in the same LAC and taking the sum of the averaged counters of several LACs) Solution 1. The CPU load is heavy on the XPU board. If the value exceeds 85% of the standard load, the flow control starts. You are advised to adjust the BTS to balance the CPU usage. 2. Increase Max CS Paging Message Num in Period and Max PS Paging Message Num in Period. For details, see Case 5 BSC Discard. 3. The LAC is incorrectly configured on the core network. As a result, the paging messages are incorrectly delivered to this LAC. You are advised to check the configuration of the core network. 4. Perform the BSC capacity expansion and reduce the number of local areas in the BSC. Troubleshooting Paging Overload - BSC Discard
- 18. HUAWEI TECHNOLOGIES CO., LTD. Page 18 HUAWEI Confidential Impact The LAPD link between the BSC and BTS is congested or unavailable. As a result, the paging message is discarded. Check Method A531: CS Pagings Discarded on LAPD Link > 0 A532: PS Pagings Discarded on LAPD Link > 0 Solution 1. Enable the Cell Paging Package Switch (for the BTS version support, see "Paging Problems" on Slide 28). 2. When the delay of the Abis transmission is large, change RSL LAPD Window Size from 4 to 8. 3. For the large paging volume cell, change Multiplexing Mode of the corresponding site to 2:1 or 1:1. If this configuration cannot be performed successfully due to deficient transmission resource, you are advised to perform the transmission capacity expansion for the Abis interface. Troubleshooting Paging Overload - LAPD Discard In R11 and R12, these two counters are the internal counters which cannot be queried by PRS. In addition, the two counters can be exported by using the OMstar or performance browse tool.
- 19. HUAWEI TECHNOLOGIES CO., LTD. Page 19 HUAWEI Confidential Impact There are too many paging messages. They exceed the paging message transmitting threshold of the Um interface on the BTS. As a result, the BTS discards the paging message. Check Method A337: Number of Deletions of the Paging for CS Services on the PCH >> 0, or A338: Number of Expiries of the Paging for CS Services on the PCH >> 0 A339: Number of Deletions of the Paging for PS Services on the PCH >> 0, or A340: Number of Expiries of the Paging for PS Services on the PCH >> 0 For the Huawei network, the common paging processing capability of the Um interface is 200,000 times/hour (according to different traffic models, this value may be different). If the value exceeds 200,000 times/hour, check the paging overload condition immediately. Solution 1. Configure the extended BCCH. For details, see Case 6 BTS Discard. 2. Split the LAC area. Troubleshooting Paging Overload - BTS Discard
- 20. HUAWEI TECHNOLOGIES CO., LTD. Page 20 HUAWEI Confidential Troubleshooting Paging Overload - SDCCH Congestion Impact The paging has no response due to the SDCCH congestion. Check Method ZTR103A: Congestion Rate on SDCCH per BSC ZK3001: Failed SDCCH Seizures due to Busy SDCCH per BSC The preceding two counters are large. Solution 1. Filter the top N cells with continuous congestion according to the cell-level counter RR370 Congestion Rate on SDCCH per CELL (due to Busy). 2. Add static SDCCHs to handle the SDCCH congestion. 3. Expand the capacity of the TRX board and configure the SDCCH. 4. In versions later than R13, configure Num of TSs Convertible to SDCCHs per TRX to reduce the SDCCH congestion. 5. For the SDCCH congestion caused by a large number of location updates, the LAC border adjustment must be considered, instead of only adding SDCCHs.
- 21. HUAWEI TECHNOLOGIES CO., LTD. Page 21 HUAWEI Confidential Principle In the process of dividing location areas, enlarge the LAC range to reduce the number of LACs under the prerequisite that the paging overload does not occur. In this way, the times of location updates can be minimized, and the decrease of unnecessary location update has a positive impact on the paging success rate. LAC Area Assessment 1. Capacity: In the case of no extended BCCH, the paging load capability of a location area is 50 times/s (the peak of the paging volume cannot exceed this value in the LAC). In the case of extended BCCHs, the paging load capability of a location area can be calculated as follows: 50 times/s x (1 + Number of extended BCCHs). Reduce the number of LACs if only the capacity requirement can be met. 2. Border reasonableness: The LAC border should not be planned in areas with large passenger flow volume. The LAC crossed by the main traffic lines such as expressways and railways should be as few as possible; therefore, a large number of unnecessary location updates are avoided. For details, see Case 7 "Planning the LAC ". Planning the LAC
- 22. HUAWEI TECHNOLOGIES CO., LTD. Page 22 HUAWEI Confidential Impact The paging messages cannot be processed or delivered due to hardware or transmission faults. Check Method R373: Cell Out-of-Service > 0 CA306: Timeouts Waiting MSC's CC Message > 0 ALM-21801: GSM Cell out of Service Rectifying Hardware and Transmission Faults Solution To rectify the hardware and transmission faults, perform the troubleshooting according to the methods of alarm ALM-21801. You can obtain the alarm description from HEDEX.
- 23. HUAWEI TECHNOLOGIES CO., LTD. Page 23 HUAWEI Confidential Definition and Measurement Point of Paging Success Rate Cases Method for Optimizing Paging Success Rate General Method for Locating Problems Related to Paging Success Rate
- 24. HUAWEI TECHNOLOGIES CO., LTD. Page 24 HUAWEI Confidential Adjust the paging duration of the core network on the Erdos entire network, and the paging success rate is improved by 0.4%. Promotion in phase 1: At 11:00, change the paging duration of 14 LACs from 6/5/4 to 6/6/5. Promotion in phase 2: At 4:00, change the paging duration of 14 LACs from 6/6/5 to 6/6/6. Conclusion: By modifying the paging duration of the core network, the paging success rate is improved by 0.4%. Phase 1: The whole paging success rate is improved by 0.3%. Case 1 Parameter Optimization Phase 2: The whole paging success rate is improved by 0.1%.
- 25. HUAWEI TECHNOLOGIES CO., LTD. Page 25 HUAWEI Confidential Paging success rate tendency July 25 July 26 July 27 July 28 July 29 July 30 July 31 August 1 August 2 August 3 August 4 August 5 August 6 August 7 August 8 August 9 August 10 August 11 August 12 August 13 August 14 August 15 August 16 August 17 August 18 August 19 August 20 August 21 August 22 August 23 August 24 August 25 August 26 August 27 August 28 August 29 August 30 August 31 September 1 September 2 September 3 September 4 September 5 September 6 September 7 September 8 September 9 September 10 September 11 September 12 September 13 September 14 September 19 September 16 September 15 September 18 September 17 September 20 September 21 Entire network Adjust the access parameters on the Erdos entire network, and the paging success rate is improved by 0.3%–0.4%. Random Access Error Threshold: Change the value larger than 180 to 180. CS RACH Min. Access Level: For GSM900 cells, set this value to –109. For GSM1800 cells, set this value to –105. Minum Access RXLEV: For GSM900 cells, set this value to 10. For GSM1800 cells, set this value to 15. Conclusion: After the whole wireless access parameter optimization, the paging success rate of the entire network is improved by 0.3%–0.4%. The TCH call drop rate increases by 0.01%, and other KPIs have no change. Case 2 Parameter Optimization
- 26. HUAWEI TECHNOLOGIES CO., LTD. Page 26 HUAWEI Confidential CMCC adjusts parameters related to the BSS and NSS. The paging success rate is improved by 2%. Conclusion: The paging success rate is improved by 2% after the paging parameter optimization on both the BSS and NSS. Case 3 Parameter Optimization Parameter Name Current Value Recommended Value Modification Reason Send System Information 2ter No Yes The system 2ter message is not sent, which affects the MS reselection between the 900 MB cell and 1800 MB cell in idle state. Minimum Access RXLEV 10 8 Because the coverage of BSC 3B1 is not the main urban area and the distance between BTSs is 5 Km, you are advised to set this parameter to a small value and widen the restriction of MS camping on the cell. According to the preceding experience, a small value of this parameter has a positive impact on the paging success rate. RACH Min. Access Level -109 -112 Because the coverage of the BSC is not the main urban area and the distance between BTSs is 5 Km, you are advised to set this parameter to a small value and widen the restriction of MS access. According to the preceding experience, a small value of this parameter has a positive impact on the paging success rate. Paging times 2 6 Some paging messages on the BTS are deleted currently by querying the traffic statistics. The hardware fault occurs in cell 7 and cell 79, and no paging is deleted in the other site. Therefore, to increase the paging retransmissions can improve the paging success rate. MS MAX Retrans 4 7 Because the BTS Paging Lifetime is set to a large value of 7s, and no paging overload of the uplink RACH occurs, you are advised to set MS MAX Retrans to a large value to improve the paging success rate. Paging times (MSC side) 2 3 (first paging TMSI+LAC, second paging IMSI+LAC, third paging IMSI+LAC) Enable three times paging to improve the paging success rate under the condition that no paging overload occurs. First paging duration (MSC side) 6s 8s The BTS software parameter is 29, that is, BTS Paging Lifetime. To optimize the TBF setup success rate, set the software parameter from 255 to 28, that is, from 5s to 7s. However, the interval between first paging and second paging on the core network is set to 6s. According to the recommended configuration, BTS Paging Lifetime should be smaller than the paging interval of the core network. Otherwise, the paging queue resources on the BTS are wasted. The paging interval of the core network is set to (6, 8). That is, the first paging duration is 6s, and the second paging duration is 8s. Set the first paging duration to a large value that is greater than BTS Paging Lifetime. In this way, the first paging success rate can be improved, and the paging overload probability on the BSS is reduced.
- 27. HUAWEI TECHNOLOGIES CO., LTD. Page 27 HUAWEI Confidential GSM paging delay distribution Times Time (second) The paging interval of the original core network (3, 3): The summation of two paging intervals is small. As a result, some of them send paging response messages. If the interval exceeds the paging lifetime of the core network, the measure fails. A large number of second paging messages are retransmitted. Actual network conditions: The delivery capability is a bottleneck, and the paging overload occurs. The paging interval of the core network after optimization (10, 3): Most of paging responses are measured. The paging retransmission and paging flow control are reduced. Actual network conditions: The paging success rate is improved from 50% to 90%. Case 4 Core Network Tool Application The paging success rate of a certain office in Philippines is improved by adjusting the paging interval. Typical LAC: 41022 2011-11-2 2011-11-3 2011-11-23 2011-11-24 First paging delivery times 10:00 109427 103110 76127 74887 19:00 180343 182447 151361 156693 Paging success rate 10:00 83.30% 82.70% 92.20% 92.10% 19:00 75.40% 68.30% 90.00% 90.00% First paging success rate 10:00 78.50% 78.30% 90.00% 89.80% 19:00 60.40% 47.60% 87.00% 86.80% Total paging delivery times 10:00 132860 125487 83735 82479 19:00 252229 280329 170971 177261 GSM paging delay distribution Times Time (second)
- 28. HUAWEI TECHNOLOGIES CO., LTD. Page 28 HUAWEI Confidential Low paging success rate The paging volume delivered by A interface exceeds the threshold of the BSC due to traffic increase, and a large number of paging messages are discarded by the BSC. As a result, the paging success rate is low and the retransmitted paging messages increase abruptly. Case 5 BSC Discard BSC version: BSC6000V9R8C12SP25 CS paging received by the A interface: A0300 = 2071150 A0301 = 0 CS paging delivered by the Abis interface: ∑A330 = 1101831 Average BSC discarding CS paging is equal to 969319. Solution: Change Max CS Paging Message Num in Period from 160 to 330, and the BSC discarding paging disappears. BSC configuration: Max CS Paging Message Num in Period is 160. The following figure shows the configuration of signaling link 7 on the A interface. Two signaling links 7 on the A interface are in subrack 0 (BM) to subrack 6 (TC) and subrack 3 (BM) to subrack 7 (TC) respectively. Note: The paging message arrival rate is configured based on the CPU. As shown in the following figure, two A interface signaling links are bound in different subracks. Therefore, they do not share the same CPU. Each CPU allows 160 paging messages per second. The maximum paging volume allowed by a BSC in an hour is 1152000 (160 x 3600 x 2 = 1152000). The following table lists parameter values of two networks. Office BSC Name CS Paging Volume on the A Interface Average Paging Volume Delivered by the Abis Interface: ∑A330 Average BSC Discard: A0300+A0301- ∑A330 Paging Success Rate of the Core Network A0300 A0301 Indonesia XL BLMP7 2071150 0 1101831 969319 38.23% Erdos BSC17 105625 0 105620 5 98.30%
- 29. HUAWEI TECHNOLOGIES CO., LTD. Page 29 HUAWEI Confidential Low paging success rate in XXX network After a new BTS is configured for a BSC, the paging volume exceeds the paging capacity limitation of the Um interface, and a large number of paging messages are discarded by the BTS. As a result, the paging success rate is low and the retransmitted paging messages increase abruptly. Case 6 BTS Discard BSC version: BSC6900V900R011C00SPH732 CS paging delivered by the Abis interface: Average A330 = 361797 The paging volume delivered by the Abis interface exceeds the paging capacity limitation of the Um interface. Paging discarded by the BTS: A337 = 69626 A338 = 118319 A339 = 1001 A340 = 105 Solution: Configure the extended BCCH for all cells. The paging success rate is recovered rapidly. The following table lists parameter values of two networks. Office BSC Name Paging Volume Discarded by the BTS Paging Success Rate of the Core Network A337 A338 A339 A340 Uganda —— 69626 118319 1001 105 43.36% Erdos BSC17 0 0 0 0 98.30%
- 30. HUAWEI TECHNOLOGIES CO., LTD. Page 30 HUAWEI Confidential XXX network LAC area planning assessment Select top N cells of the location update by filtering cells in the LAC borders. Green circle: This circle covers three LACs at the provincial road border. This symptom is abnormal. The preliminary adjustment plan is required. Brown circle: This circle covers the urban area or the Banner and county centers with a high density of population. There are many location updates in this circle, and this is normal. Blue circle: This circle covers the border between the LAC area and Baomao Expressway. The expressway is close to the LAC border, and this configuration must be optimized later. Case 7 Planning the LAC
- 31. HUAWEI TECHNOLOGIES CO., LTD. Page 31 HUAWEI Confidential In XXX network, some BSCs have low PSR due to MSC SPF board overload. Case 8 MSC SPF board overload Time GBSC Integrity CA306: Timeouts Waiting MSC's CC Message 09/07/2012 20:00 BSC_Cirebon_2 100% 446680 09/07/2012 20:00 BSC_Indramayu 100% 244420 We can monitor the counter CA306 to find out if the SPF board with high load. After the expansion of SPF board, PSR became normal.
- 32. HUAWEI TECHNOLOGIES CO., LTD. Page 32 HUAWEI Confidential Problem Cause Solution The power is not matched after network replacement in Philippines with the high SD traffic volume and occurrence of paging overload. 1. The replacement power is not matched. As a result, the LAC paging volume is larger than that of the original network, and the paging request is replaced by the immediate assignment command. The paging overload occurs. 2. Other factors: SD congestion, interference from an external source, interference of engineering intermodulation, and paging flow control 1. Power matching 2. Paging policy matching: disabling AGCH priority 3. Performing configuration according to the new SD configuration rules 4. Replacement analysis, large paging volume LACs configurable with the extended BCH and AGCH 5. Sufficient expansion of transmission resources AGCH Mapping SD Reconfigure and Traffic Balance Paging Duration Extend In the large traffic volume environment in XXX network, the paging overload occurs because the paging volume exceeds the Um interface capacity after replacement. Case 9 Paging Overload in XXX network
- 33. HUAWEI TECHNOLOGIES CO., LTD. Page 33 HUAWEI Confidential In XXX network, it is MSC pool scenario, some BSCs with 0% PSR due to wrong NRI configuration: Case 10 configuration problem in MSC pool In MSC pool scenario, the NRI configuration of BSS should be the same with NSS. BSC SWLD2 & SWWV3 with 0% PSR
- 34. HUAWEI TECHNOLOGIES CO., LTD. Page 34 HUAWEI Confidential Attachment 1 Analysis Report on Paging Problems
- 35. HUAWEI TECHNOLOGIES CO., LTD. Page 35 HUAWEI Confidential Attachment 2 Required Actions Related to Paging Problems Required Actions Related to Paging Problems checklist Operation Range Description Application Scenario Operation Analysis Classifying problems related to paging success rate Entire network Specify the current paging problem. Specify current problems, for example, non-compliance of network paging success rate, degradation of NE paging success rate after upgrade, increase of live network paging success rate. Checking power matching (applicable to non-compliance of network paging success rate) Entire network Check power matching by using the power matching tool. replacement Check the power matching before and after the upgrade according to contents in the Power Matching Guide and the Power Matching Tool. Checking parameters (applicable to non-compliance of network paging success rate) Entire network Check the parameter mapping before and after the upgrade and checking parameters related to interconnection of NSS and BSS. replacement Check parameter mapping results of the live network and the original network according to the intelligent parameter mapping tool and verify parameters related to interconnection of MSC and BSC according to Correlation Analysis of the GSM Wireless Network and Core Network Parameters. Checking parameter inheritance (applicable to degradation of NE paging success rate after upgrade) Entire network Compare parameters before and after the upgrade. Upgrade Compare MML script files before and after the upgrade by using the PFMStudio to find different parameter setting. Comparing different versions (applicable to degradation of NE paging success rate after upgrade) Entire network Verify the existing information to confirm the version variances before and after the upgrade. Upgrade Confirm whether the version variances or known problems of the current version affect the paging success rate according to the early warning, notification, release notes, and hitless upgrade tool. For known causes, take the preventive measures. Troubleshooting hardware and transmission faults Entire network Find out and rectify hardware and transmission faults according to analysis of traffic statistics and alarms. Deployment, replacement, upgrade, and inventory Analyze traffic statistics (R373: Cell Out-of-Service Duration) and the alarm (ALM- 21801: GSM Cell out of Service) to find out cells with hardware or transmission faults and then analyze the cell according to the methods of clearing alarms. Troubleshooting paging overload Entire network and top N cells Analyze paging overload of the BSC according to the traffic statistics. Deployment, replacement, upgrade, and inventory Analyze related traffic statistics to find out bottleneck of the paging overload and then perform corresponding operations to solve the problem. Planning the LAC area Entire network Analyze capacity of the LAC and the LAC border. Deployment, replacement, upgrade, and inventory 1. Use the LACs to reduce the number of LACs if the paging volume is low. 2. Analyze the LAC border based on the engineering parameters and the digital map. The LAC border should not be planned in areas with large passenger flow volume. The LAC crossed by the main traffic lines such as expressways and railways should be as few as possible; therefore, a large number of unnecessary location updates are avoided. Analyzing cells with poor coverage and paging black holes Entire network and top N cells The core network tool searches the cells which have activities such as short messages, call, location update, and paging in the recent several minutes according to the IMSI of no paging response in the call logging to find the black hole cells. The analysis can be implemented manually combined with the coverage diagram output by OMstar. Deployment, replacement, upgrade, and inventory 1. Use the Trace Analyzer tool to filter the paging black hole cells. 2. Use the OMstar tool to output the coverage diagram. 3. Use the two tools to find the poor coverage points of paging black hole cells, pass the test of border roads, and investigate the on-site wireless environment. Based on the different reasons, you can optimize the cells. Checking paging-related parameters Entire network Troubleshoot parameters that may affect paging, including parameters on the BSS and parameters on the core network. Deployment, replacement, upgrade, and inventory Provide settings of paging-related parameters on the live network, including parameters on the BSS and parameters on the core network, and then optimize and adjust the parameters according to contents in the slide. Troubleshooting known version problems Entire network Troubleshoot known version problems. Deployment, replacement, upgrade, and inventory Troubleshoot the known version problems mentioned in the slide.