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
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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.
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Wireless Network Planning
Chapter 8 Traffic Statistics
1.1 Brief Introduction to the Calling Flows 1.1.1 Ultra-early TCH Assignment Flow
MS
BSC
BTS
MSC
Channel Request (RACH) 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
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Wireless Network Planning
Chapter 8 Traffic Statistics
1.1.2 Calling Flow (Calling Party)
BTS
MS
BSC
MSC
Channel_req Channel_Active Channel_Active_Ack IMMEDIATE ASSIGN COMMAND First SABM
Establish_IND( CM Service Req) CR(Complete_l3_information) CC CM Service Accepted Setup Call Proceeding Channel_Active
Assignment_Req
Channel_Active_Ack ASSIGNMENT COMMAND First SABM Establish_IND ASSIGNMENT CMP
Assignment_CMP
Alerting Connect Connect Ack
Conversation Disconnect Release Release Complete Clear_CMD Clear_CMP
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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.
BTS1
MS
BTS2
BSC
MS
Measure Report from MS Channel_Active Channel_Active_Ack HANDOVER COMMAND
Handover Access
Handover_Detect
PHY INFO PHY INFO
first SABM
Establish_IND
HANDOVER COMPLETE Handover_Performed
5
MSC
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.
MS
BTS1
BSC1
MSC
BSC2
BTS2
MS
Measure Report from MS Handover_Required Handover_Request
Channel_Active Channel_Active_Ack
HANDOVER COMMAND
Handover_CMD
Handover_Request_Ack Handover Access Handover_Detect Handover_Detect
PHY INFO PHY INFO first SABM Establish_IND HANDOVER COMPLETE
Handover_Cmp
Clear_CMD Clear_Cmp
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Wireless Network Planning
Chapter 8 Traffic Statistics
1.1.5 Handover Flow between MSCs Mobile
MS Um
BSS1 Measurement of radio transmissionsignal
A
MS E
MSCa
B
MSCb A
HANDOVER REQ.
Performhandover(MAP)
(Theglobal destinationcell table)
HANDOVER REQUEST HANDOVER REQUEST ACKNOWLEDGE
(Theglobal destination cell I Theglobal servicecell ID Channel type)
BSS2
Um
VLRb
(PCM&Channel type) (Including newTCHandhandover referencenumber )
Allocation handover number
(Assignhandover number ) Radio channel ack.(MAP)
Send handover report(HON.)
IncludingnewTCHand HON
(Sendhandover report)
Radio channel acknowledge
IAM ACM HANDOVER CMD
HANDOVER COMMAND
HANDOVER DETECT HANDOVER COMPLETE
Forward MS to new channel via original BSS
CLEAR COMMAND
Sendendsignal(MAP) ReleasePCM0
Sendendsignal
CLEAR COMPLETE ANS
~ ~ Release(TUP/ISUP) Endsignal
~ ~
Endsignal(MAP)
Disconnectthe physical link betweenMSCaandMSCb
Handover report Releasehandover report
7
BSS2selects anewTCHto connectto thePCMcircuit MS enters thedestinationcell
Wireless Network Planning
Chapter 8 Traffic Statistics
1.1.6 Subsequent Handover Flow (MS Roams from MSVb to MSCb') Roam
MS E
MSCa
MSCb
MS
MSCb'
VLRb' VLRb
BSS2 Measurement of radio transmission signal
HANDOVER REQUIRED (The destination cell table)
Performsubsequent handover (MAP) (The destination cell table , The destination cell ID ,MSC No.)
Performhandover
HANDOVER REQUEST (PCM&Channel type)
(The destination cell ID, The service cell ID, Channel type)
HANDOVER REQUEST ACKNOWLEDGE (Including newTCH number and handover number )
Allocate handover number(Assign handover number ) Radio channel acknowledge
Send handover report(HON) (Send handover report)
Radiochannnel ack. (MAP) (Include NewTCH and HON)
IAM ACM Subsequent handoverack. HANDOVER COMMAND
HANDOVER DETECT HANDOVER COMPLETE
Send end signal (MAP)
ANS End signal (MAP)
Release handover report
CLEAR COMMAND Release (TUP)
~~
Release HON
CLEAR COMPLETE End signal (MAP)
Release (TUP/ISUP)
~ ~
Disconnect the physical link betweenMSCaandMSCb Release handover report Disconnect the physical link betweenMSCaandMSCb’
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Release HON
BSS2'
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.
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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
SDCCH drop-off times(1)send out CLEAR_REQ, and
point of the original index
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
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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
BSC=Times
of
success
successful
ratio inter-cell
within
the
handover
within the BSC/ Times of Inter-cell handover attempts within the BSC. Analysis of the statistical
Times of successful inter-cell handovers within the
point of the original index
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 (intercell within the BSC)
Others
None
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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
Successful incoming BSC handover times
point of the original index
(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
Times of successful outgoing BSC handover:
point of the original index
(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
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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
Times of TCH call occupation failures
point of the original index
(1) Send out assignment failure message. Times of ultra-early assigned TCH Occupation Failures (1) Receive CH_ACT_NACK in the process of ultraearly 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 ultraearly 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
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Wireless Network Planning
Chapter 8 Traffic Statistics channel is of TCH type (for example, the emergency call).
Other
No.
None
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
Times of TCH call occupation failures:
point of the original index
(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
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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
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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
Times of all busy SDCCH occupation:
point of the original index
(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
The respective indexes in this formua are
point of the original index
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.
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