Excellent Analysis of Call Setup
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Excellent Analysis of Call Setup Excellent Analysis of Call Setup Document Transcript

  • Wireless Network Planning Table of Contents Table of Contents Chapter 1 Traffic Statistics..........................................................................................................2 1.1 Brief Introduction to the Calling Flows...............................................................................3 1.1.1 Ultra-early TCH Assignment Flow...........................................................................3 1.1.2 Calling Flow (Calling Party)....................................................................................4 1.1.3 Handover Flow within the BSC...............................................................................5 1.1.4 Handover Flow between the BSCs.........................................................................6 1.1.5 Handover Flow between MSCs..............................................................................7 1.1.6 Subsequent Handover Flow (MS Roams from MSVb to MSCb').........................8 1.2 Analysis of Key Indexes of Traffic Statistics......................................................................9 1.2.1 TCH Drop-off Ratio.................................................................................................9 1.2.2 SDCCH Drop-off Ratio..........................................................................................11 1.2.3 Intercell Handover Success Ratio Within the BSC................................................11 1.2.4 Incoming BSC Handover Success Ratio..............................................................13 1.2.5 Outgoing BSC Handover Success Ratio..............................................................13 1.2.6 TCH Congestion Ratio..........................................................................................14 1.2.7 SDCCH Congestion Ratio....................................................................................17 1.2.8 Wireless Connection Ratio...................................................................................17 1.3 Description of Traffic Statistics Registration....................................................................17 1.3.1 Routine Performance Measurement Tasks Necessary to Be Registered.............17 1.3.2 Performance Measurement Tasks Used for Network Optimization and Location Problems.........................................................................................................................18 1
  • Wireless Network Planning Chapter 8 Traffic Statistics Chapter 1 Traffic Statistics Huawei BSC traffic statistics system provides perfect measurement types and rich counters, facilitating the network operators to learn about the BSC running status, to locate the network problems and to optimize the network. The BSC traffic statistics system consists of the BAM, the traffic statistics terminal, the OMC server, etc. The specific statistics flow is as follows: after registering on the traffic statistics terminal, the statistics task will be sent to the foreground host via the BAM for statistics, then the statistics result will be returned back to the BAM. Therefore we can view the statistics result on the traffic statistics terminal. In order to have an understanding of the statistics points of all indexes and to analyze problems, we will introduce some important calling flows first. 2
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1 Brief Introduction to the Calling Flows 1.1.1 Ultra-early TCH Assignment Flow Channel Request (RACH) BTSMS BSC MSC Channel Required Channel Activation (TCH) Channel Activation Acknowledge Immediate Assignment Command Immediate assignment (AGCH) CM-Service Request Complete layer 3 information£¨ CM-Service Req£© CM-Service Accept CM-Service Accept Assignment Request Mode modify Mode modify ACK Channel Mode modify Channel Mode modify ACK Assignment Complete 3
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1.2 Calling Flow (Calling Party) Channel_Active Channel_Active_Ack IMMEDIATE ASSIGN COMMAND BTS BSC MSCMS Channel_req First SABM Establish_IND( CM Service Req) CR(Complete_l3_information) CC Setup Call Proceeding Assignment_Req ASSIGNMENT COMMAND First SABM Establish_IND ASSIGNMENT CMP Assignment_CMP Alerting Connect Connect Ack Conversation Disconnect Release Release Complete Clear_CMD Clear_CMP CM Service Accepted Channel_Active Channel_Active_Ack Channel_Active Channel_Active_Ack IMMEDIATE ASSIGN COMMAND BTS BSC MSCMS Channel_req First SABM Establish_IND( CM Service Req) CR(Complete_l3_information) CC Setup Call Proceeding Assignment_Req ASSIGNMENT COMMAND First SABM Establish_IND ASSIGNMENT CMP Assignment_CMP Alerting Connect Connect Ack Conversation Disconnect Release Release Complete Clear_CMD Clear_CMP CM Service Accepted Channel_Active Channel_Active_Ack 4
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1.3 Handover Flow within the BSC The handover process within the BSC is controlled and implemented by the BSC. After the completion of a handover, the BCS will inform the MSC of this handover in a piece of Handover_performed message. Channel_Active Channel_Active_Ack HANDOVER COMMAND BTS1 BSC BTS2MS f i r s t S A B M Establish_IND Handover Access Handover_Detect PHY INFO PHY INFO HANDOVER COMPLETE MSC Handover_Performed MS Measure Report from MS 5
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1.4 Handover Flow between the BSCs When realized through the A interface, the handover between the BSCs goes like this: an originating BSC originates Handover_Request to the destination BSC, and MSC requests the destination BSC for handover and gets Handover-Request_Ack, then it sends the handover command “Handover_CMD” to the originating BSC. When realized through the A-bis interface, the originating BSC sends the handover command to the original BTS, and the n0w BTS will report Hand_Detect on detecting the handover and access of MS, and then report HANDOVER COMPLETE after establishing a link with MS. And the old A-bis interface will disconnect the link to release the resource. Channel_Active Channel_Active_Ack BTS1 BSC1 BTS2MS f i r s t S A B M Establish_IND Handover Access Handover_Detect PHY INFO PHY INFO HANDOVER COMPLETE MSC BSC2 MS Measure Report from MS HANDOVER COMMAND Handover_Required Handover_Request Handover_Request_Ack Handover_CMD Handover_Detect Handover_Cmp Clear_CMD Clear_Cmp 6
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1.5 Handover Flow between MSCs ~ ~~ ~ MS MS BSS1 MSCa MSCb BSS2 VLRb Measurementofradio transmissionsignal HANDOVERREQ. Performhandover(MAP)(Theglobaldestinationcelltable) (TheglobaldestinationcellI TheglobalservicecellID Channeltype) HANDOVERREQUEST (PCM&Channeltype) HANDOVERREQUEST ACKNOWLEDGE (IncludingnewTCHandhandoverreferencenumber) Allocationhandover number(Assignhandovernumber) Send handover report(HON.) (Sendhandoverreport) Radio channelack.(MAP) IncludingnewTCHandHON Radiochannelacknowledge IAM ACM HANDOVERCOMMAND HANDOVERCMD ForwardMStonew channelviaoriginalBSS HANDOVERDETECT HANDOVERCOMPLETE BSS2selectsanewTCHtoconnecttothePCMcircuit MSentersthedestinationcell Sendendsignal Sendendsignal(MAP) CLEARCOMMAND ReleasePCM0 CLEARCOMPLETE ANS Release(TUP/ISUP) Endsignal(MAP)Endsignal Disconnectthephysicallink betweenMSCaandMSCb Handoverreport Releasehandoverreport Mobile Um A E B A Um ~ ~~ ~ MS MS BSS1 MSCa MSCb BSS2 VLRb Measurementofradio transmissionsignal HANDOVERREQ. Performhandover(MAP)(Theglobaldestinationcelltable) (TheglobaldestinationcellI TheglobalservicecellID Channeltype) HANDOVERREQUEST (PCM&Channeltype) HANDOVERREQUEST ACKNOWLEDGE (IncludingnewTCHandhandoverreferencenumber) Allocationhandover number(Assignhandovernumber) Send handover report(HON.) (Sendhandoverreport) Radio channelack.(MAP) IncludingnewTCHandHON Radiochannelacknowledge IAM ACM HANDOVERCOMMAND HANDOVERCMD ForwardMStonew channelviaoriginalBSS HANDOVERDETECT HANDOVERCOMPLETE BSS2selectsanewTCHtoconnecttothePCMcircuit MSentersthedestinationcell Sendendsignal Sendendsignal(MAP) CLEARCOMMAND ReleasePCM0 CLEARCOMPLETE ANS Release(TUP/ISUP) Endsignal(MAP)Endsignal Disconnectthephysicallink betweenMSCaandMSCb Handoverreport Releasehandoverreport Mobile Um A E B A Um 7
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.1.6 Subsequent Handover Flow (MS Roams from MSVb to MSCb') Roam E MS MSCa MSCb MSCb' VLRb VLRb' BSS2 BSS2' Measurementofradio transmissionsignal HANDOVERREQUIRED(Thedestinationcelltable) Performsubsequenthandover(MAP) (Thedestinationcelltable,ThedestinationcellID,MSCNo.) Performhandover (ThedestinationcellID,TheservicecellID,Channel type) HANDOVER REQUEST (PCM&Channel type) HANDOVERREQUESTACKNOWLEDGE (IncludingnewTCHnumberandhandovernumber) Allocatehandover number(Assignhandovernumber) Sendhandoverreport(HON)(Sendhandoverreport) Radiochannnel ack.(MAP)(IncludeNewTCHandHON) Radiochannelacknowledge IAM ACM Subsequenthandoverack. HANDOVER COMMAND HANDOVER DETECT HANDOVERCOMPLETE Send end signal (MAP) ANS End signal (MAP) Releasehandoverreport ReleaseHON CLEAR COMMAND CLEAR COMPLETE Release(TUP) DisconnectthephysicallinkbetweenMSCaandMSCb End signal (MAP) Release (TUP/ISUP) Releasehandoverreport ReleaseHON Disconnectthephysical linkbetweenMSCaandMSCb’ ~~ ~~ MS Roam E MS MSCa MSCb MSCb' VLRb VLRb' BSS2 BSS2' Measurementofradio transmissionsignal HANDOVERREQUIRED(Thedestinationcelltable) Performsubsequenthandover(MAP) (Thedestinationcelltable,ThedestinationcellID,MSCNo.) Performhandover (ThedestinationcellID,TheservicecellID,Channel type) HANDOVER REQUEST (PCM&Channel type) HANDOVERREQUESTACKNOWLEDGE (IncludingnewTCHnumberandhandovernumber) Allocatehandover number(Assignhandovernumber) Sendhandoverreport(HON)(Sendhandoverreport) Radiochannnel ack.(MAP)(IncludeNewTCHandHON) Radiochannelacknowledge IAM ACM Subsequenthandoverack. HANDOVER COMMAND HANDOVER DETECT HANDOVERCOMPLETE Send end signal (MAP) ANS End signal (MAP) Releasehandoverreport ReleaseHON CLEAR COMMAND CLEAR COMPLETE Release(TUP) DisconnectthephysicallinkbetweenMSCaandMSCb End signal (MAP) Release (TUP/ISUP) Releasehandoverreport ReleaseHON Disconnectthephysical linkbetweenMSCaandMSCb’ ~~ ~~ MS 8
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.2 Analysis of Key Indexes of Traffic Statistics 1.2.1 TCH Drop-off Ratio No 001 Index name TCH drop-off ratio (%) Measurement type General BSC performance measurement/cell performance measurement Formula description TCH drop-off ratio=TCH drop-off times /TCH occupation success ratio Analysis of the statistical point of the original index TCH drop-off times: (1) When the message CLEAR REQ is sent to MSC, the current occupied channel is of TCH type. Successful TCH occupation times: (1) Receive the message CH_ACT_ACK during the immediate assignment, if the channel is of TCH type. (2) Receive the message CH_ACT_ACK in the state of CS_WAIT_RR_EST, and the current channel is of TCH type.; (3) The message of the completion of assignment is sent in the process of assignment (4) Receive the message MSG_ABIS_HO_DETECT during incoming BSC for handover. At this time the handover is not of SDCCH type. (5) Receive the message MSG_ABIS_HO_DETECT during handover within the BSC. At this time, the handover is not of SDCCH type. Others 1. In the “General BSC performance measurement” The calculating formula of the “call loss ratio” in the former version: Call loss ratio (%) =Drop-off times after conversation/(Successful connection times + Successful incoming BSC handover times) * 100% The calculating formula of “TCH drop-off ratio” in the updated version: TCH drop-off ratio (%) =TCH drop-off times / Successful TCH occupation times *100% Configuration of the parameters that affect the drop-off ratio: 9
  • Wireless Network Planning Chapter 8 Traffic Statistics (1) “Number of SACCH multiframes”, “Maximum retransmission times of physical information”, “Timer for wireless link connection” in the Cell Attribute Table. (2) “Counter for wireless link failure” in the Cell System Message Table. 10
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.2.2 SDCCH Drop-off Ratio No 002 Index name SDCCH drop-off ratio (%) Measurement type Cell performance measurement Formula description SDCCH drop-off ratio=SDCCH drop-off Times / SDCCH occupation success times (All) Analysis of the statistical point of the original index SDCCH drop-off times(1)send out CLEAR_REQ, and the channel is of SDCCH type; (2) When receiving ERROR_IND, the channel is of SDCCH type; With respect to (1) there are following cases: Incoming SDCCH handover the message HO_DETECT is illegal. Incoming SDCCH handover the message HO_CMP is illegal. Incoming SDCCH handover sending the message HO_CMP fails TN_WAIT_HO_DETECT, TN_WAIT_HO_CMP (SDCCH handover) Time out TN_WAIT_INTER_HO_CMP (SDCCH handover) time out TN_T8 (Outgoing BSC handover is completed) time out Internal clearance resulted from other various reasons. SDCCH occupation success times (All): (1) When receiving CH_ACT_ACK in the process of assignment, the channel is SDCCH. (2) When receiving the message CH_ACT_ACK in the state of CS_WAIT_RR_EST, the current channel is SDCCH. (3) Incoming SDCCH handover receives HO_DETECT. (4) In the BSC SDCCH handover receives HO_DETECT. Others None 1.2.3 Intercell Handover Success Ratio Within the BSC The factors which affect the handover success ratio include:(1) Base station clock, BSC clock and MSC clock and judge if these clocks are out of frame; For MSC: Δf/f (frequency offset) ≤ 1E-8; For BSC/BTS: Δf/f(frequency offset) ≤5E-8. (2) The 11
  • Wireless Network Planning Chapter 8 Traffic Statistics handover-related data configuration; Check Tables BA1, BA2 and the handover data table under the handover menu see whether the data configuration are correct and handover threshold settings are reasonable. For the handover involved between the MSCs, it is necessary to check or confirm if the opposite MSC has been configured with the handover data of the local MSC. If not, then there is handover request, but the successful handover is not available. No. 003 Index name Inter-cell handover success ratio within the BSC (%) Measurement type General BSC performance measurement Formula description Inter-cell handover success ratio within the BSC=Times of successful inter-cell handover within the BSC/ Times of Inter-cell handover attempts within the BSC. Analysis of the statistical point of the original index Times of successful inter-cell handovers within the BSC: (1) The completion of handover in the BSC. Times of the inter-cell handover attempts within the BSC. (1) When receiving the handover requests (inter- cell within the BSC) Others None 12
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.2.4 Incoming BSC Handover Success Ratio No 004 Index name Incoming BSC handover success ratio (%) Measurement type General BSC performance measurement Formula description Incoming BSC handover success ratio =Incoming BSC handover success ratio/ Incoming BSC handover attempts Analysis of the statistical point of the original index Successful incoming BSC handover times (1) When HO_CMP is sent to MSC successfully Times of successful handover within the BSC: (1) When the incoming handover request message from MSC is received. Others 1.2.5 Outgoing BSC Handover Success Ratio No. 005 Index name Outgoing BSC handover success ratio (%) Measurement type General BSC performance measurement Formula description Outgoing BSC handover success ratio =Times of successful outgoing BSC handovers/ Times of outgoing BSC handover attempts Analysis of the statistical point of the original index Times of successful outgoing BSC handover: (1) For outgoing handover CLEAR_CMD is received because of HO_SUCC. Times of outgoing BSC handover attempts: (1) Statistics begins when the message HO_REQ is sent to MSC (including direct operation retry) Other 13
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.2.6 TCH Congestion Ratio TCH congestion ratio (handover excluded)=Times of TCH occupation failures (handover excluded)/Times of TCH occupation requests (handover excluded)*100% TCH congestion ratio (handover included) =Times of TCH occupation failures (handover included)/ Times of TCH Occupation requests (handover included)*100% 100 No. 007 Index name TCH congestion ratio (handover excluded)(%) Measurement type Cell performance measurement Formula description TCH congestion ratio (handover excluded)=(Times of TCH call occupation Failures + ultra-early assigned TCH occupation failures) / (Times of TCH call occupation requests + Times of ultra-early assigned TCH occupation requests Analysis of the statistical point of the original index Times of TCH call occupation failures (1) Send out assignment failure message. Times of ultra-early assigned TCH Occupation Failures (1) Receive CH_ACT_NACK in the process of ultra- early assignment (including receiving CH_ACT_NACK when the satellite transmission state is WAIT_RR_EST. (2) CVI_INTERNAL_ERR (internal error) is the return cause when channels are distributed in the process of ultra-early assignment (3) CVI_NO_ACCEPT (illegal channel request) is the return cause when the channels are distributed in the process of ultra-early assignment (4) Channel has not been assigned when the channels are distributed in the process of ultra- early assignment (5) TN_WAIT_CH_ACT timed out in the process of ultra-early assignment Times of TCH call occupation requests: (1) Receiving MSC assignment request message. Times of ultra-early assigned TCH occupation requests: (1) No resource is available and the immediate assignment is allowed when distributing SDCCH; (2) When the channel request is received, the 14
  • Wireless Network Planning Chapter 8 Traffic Statistics channel is of TCH type (for example, the emergency call). Other None No. 008 Index name TCH congestion ratio (handover included)(%) Measurement type Cell performance measurement Formula description TCH congestion ratio (handover included)=(Times of TCH call occupation Failures +Times of ultra-early assigned TCH occupation failures +Times of incoming cell handover within the BSC TCH Occupation Failures (due to congestion)+ Times of between BSCs incoming cell handover TCH occupation failures (due to congestion) / (Times of TCH call occupation requests +Times of ultra-early assigned TCH occupation requests + Times of within the BSC Incoming cell handover TCH occupation requests +Times of between BSCs incoming cell handover TCH occupation requests) Analysis of the statistical point of the original index Times of TCH call occupation failures: (1) Times of ultra-early assigned TCH occupation failures Times of TCH call occupation requests: (1) Times of Ultra-early Assigned TCH occupation requests The above indexes please refer to the analysis of No.008 indexes Times of within the BSC incoming cell handover TCH occupation failures (due to congestion) 1) TCH channel assignment fails during incoming cell handover within the BSC. Times of between BSCs incoming cell handover TCH occupation failures (due to congestion): (1) The reason for sending handover failure message when incoming cell handover between BSCs is that the TCH channel has not been assigned. Times of incoming cell handover TCH occupation requests in BSC: (1) When receiving inter-cell incoming cell 15
  • Wireless Network Planning Chapter 8 Traffic Statistics handover request message within the BSC. (TCH handover) Times of incoming cell handover TCH occupation requests between BSCs: (1) When receiving incoming handover request message (TCH handover). Others None 16
  • Wireless Network Planning Chapter 8 Traffic Statistics 1.2.7 SDCCH Congestion Ratio No 006 Index name SDCCH congestion ratio %) Measurement type Cell performance measurement Formula description SDCCH congestion ratio (%)=Times of All Busy SDCCH occupation / Times of SDCCH occupation requests (All) Analysis of the statistical point of the original index Times of all busy SDCCH occupation: (1) When SDCCH channel has not been assigned Times of SDCCH occupation requests (all) (1) Receiving the channel request message (the channel is SDCCH) (2)Once receiving the channel request message,immediately assign TCH. And SDCCH can be assigned when there is no TCH (3) SDCCH handover within the BSC (4) Incoming BSC handover,the handover is of SDCCH type Other None 1.2.8 Wireless Connection Ratio No 009 Index name Wireless connection ratio Measurement type Formula description Wireless connection ratio=(1-SDCCH congestion ratio)*(1-TCH congestion ratio)*100% Analysis of the statistical point of the original index The respective indexes in this formua are illustrated as follows: For calculation of SDCCH congestion ratio and TCH congestion ratio please refer to Sections 8.2.6 and 8.2.7. Others This index is specified in the report of the mobile office. 1.3 Description of Traffic Statistics Registration 1.3.1 Routine Performance Measurement Tasks Necessary to Be Registered 1. The general BSC performance measurement task is compulsory. All the indexes under this statistics function type should be registered as much as possible either at the beginning of the deployment or at the stable system running stage. It is suggested that the statistics circle be 60 minutes, and the statistics time period be 17
  • Wireless Network Planning Chapter 8 Traffic Statistics 00:00~24:00 2. Cell performance measurement task is compulsory. It is suggested that the statistics circle be 60 minutes, and the statistics time period be 00:00~24:00 1.3.2 Performance Measurement Tasks Used for Network Optimization and Location Problems Incoming and outgoing cell handover performance measurement, defined and undefined adjacent cells performance measurement, receiving quality, receiving level performance measurement, drop-off performance measurement, power control performance measurement, uplink and downlink balance performance measurement, uplink frequency band scanning statistics, and interference band statistics after sending idle Burst, are all the good instruments both for checking whether the data configuration is reasonable and for network optimization. At the beginning of deployment, this kind of tasks should be registered as many as possible, and in the stable system running stage they could be deleted. SCCP protocol performance measurement and MTP link performance measurement can be used to detect whether NO.7 link and the A interface are normal. LAPD protocol performance measurement is used to monitor whether LAPD link and Abis interface are normal. This task could be deleted in the stable system running stage. Except the SCCP protocol performance measurement, the tasks of the above types consume subtask numbers extremely. Therefore the tasks of these types should be registered with pertinence in case of the subtask numbers being inadequate for use. 18