2G Traffic Statistics Analysis ISSUE1.0

Revision Record
Course Code
Traffic Statistics Analysis
Foreword
Each traffic item is corresponding one feature of network.
Through the traffic statistics, can quickly settle the network problem.
Copyright © 2008 Huawei Technologies Co., Ltd. All rights reserved.
Objectives
Upon completion of this course, you will be able to:
Know the traffic statistics system structure of BSC6000
Understand some often-used traffic measurement items
Locate some problems through the traffic statistics system
Contents
Often-used Traffic Statistics Items Analysis
Locate Problem through Traffic Analysis
Measurement term
Counter WHAT
Customer counter
Object WHO
Period WHEN
Hierarchical Structure of Performance
Hierarchical Structure of Performance
Contents
Analysis Process
Systematical logic:
Integrality
Observe the change trend of the items for more than one week and the changing trend of each day.
Relativity
Analysis Process
Analysis process
First we shall analyze and compare the item of BSC measurement function to have a rough idea for the whole network.
During analyzing, if any important items (such as call drop rate or handover success rate) are abnormal, we shall do further detailed analysis for the corresponding items.
Analysis Process
There are 26 clusters in the BSC6000 traffic statistics, 4 of them are important for the optimization.
BSC Measurement
MR Measurement
Call Measurement
Channel Measurement
Traffic Analysis
The statistic items in BSC Measurement Function are used to measure the traffic volume of all the cells in the BSC, including the call drop, handover and assignment.
Traffic Analysis
MR measurement is some items about measurement report ,helping the user to optimization.
Traffic Analysis
Call measurement is the performance during the calling, such as Handover, call drop and assignment; measurement object includes cell, TRX and the LAPD link
Traffic Analysis
Channel measurement is about the channel allocated, channel conversion and the channel load
Often-used Items
In BSC6000, there are some traffic units are important for the analysis of interference, call drop and handover, more attention should be paid on those
Interference band measurement report per TRX
Power control messages per cell
Neighbor cell level measurement per cell
Uplink-and-downlink balance measurement per TRX
Radio link failure measurement per TRX
TCHF(H) receive level measurement per TRX
Often-used Items
In BSC6000, there are some traffic units are important for the analysis of interference, call drop and handover, more attention should be paid on those
KPI measurement per cell
Intra-cell Handover Measurement
CPU usage measurement
CPU Usage Measurement
Percentage of CPU occupation (%)
Peak percentage of CPU occupation (%)
The former one is the percentage of CPU in busy status during the measurement cycle. This item indicates the load of BSC. The latter one is the maximum CPU occupation within measurement cycle
It is recommended to register this task on any occasion
CPU Usage Measurement
KPI measurement is about the traffic statistics of each cell, it includes all the important items, helping the engineer analyze each cell performance
KPI Measurement
Interference Band Measurement Report
Interference band is the interference level contained in the RF RES IND message that the BTS reports to the BSC when the channel is idle. There are five levels. The level range of each band is set through the LMT. The higher rank suggests higher interference level. An idle channel at interference band 4 or 5 suggests the existence of interference.
Interference Band
Interference band 2
Interference band 3
Interference band 4
Interference band 5
Interference Band Measurement Report
TCHF(H) Receive Level Measurement
The valid MRs that the BSC receives contain the ranks of the uplink and downlink receive level and the ranks of the uplink and downlink receive quality
The receive level has eight ranks, and higher rank suggests greater receive level
The receive quality has eight ranks, and higher rank suggests worse receive quality
Rank of Receive Level
Neighbor Cell Level Measurement
Neighbor Cell Level Measurement per Cell refers to the measurement of mean receive level of neighbor cells. This measurement unit helps to determine whether to configure neighbor cells.
If “Number of MRs of Neighbor Cells” and “Strength of Signals in Neighbor Cells” are higher ,this cell should be configured as neighbor cell.
Neighbor Cell Level Measurement
Outgoing Inter-cell Handover Measurement
This measurement refers to performance of MS handover from target cell to the each neighbor cell, including Handover request times, handover success times, radio handover success rate
It also record the handover reason, such as receive level , bad quality, better cell, TA, receive level drop, enhance dual band cell.
Outgoing Inter-cell Handover Measurement
Incoming Inter-cell Handover Measurement
This measurement refers to performance of MS handover from each neighbor cell to this serving cell, including Handover request times, handover success times, radio handover success rate
From the incoming inter-cell handover measurement, can locate the neighbor cell which handover to this cell is not good.
Incoming Inter-cell Handover Measurement
It measures the intra-cell handover request times, success times.
This traffic unit also measure the reasons of intra-cell handover: interference intra-cell handover, TCHF-TCHH in the AMR calling, intra-cell handover during the channel conversion, overlaid/underlaid handover.
Uplink-and-Downlink Balance Measurement
Proper power estimation during network planning is a prerequisite for normal operation of the system. The uplink and downlink signals in the coverage area must be balanced.
The MR that the BSC receives contains the uplink receive level and the downlink receive level. The uplink and downlink balance level is determined by the following formula: Downlink receive level – uplink receive level – 6 .
Mapping between the uplink/downlink balance rank and the receive level.
Uplink-and-Downlink Balance Rank
1
–14 dB, –13 dB, –12 dB, –11 dB, –10 dB
3
4
5
6
9
10
10 dB, 11 dB, 12 dB, 13 dB, 14 dB
11
15 dB, 16 dB, 17 dB, 18 dB, 19 dB, 20 dB
Power Control Messages
Power Control Messages per Cell refers to the measurement of the transmission power and the receive level between the BTS and the MS. It can measure the coverage of cell and the receive level or quality average.
Power Control Messages
Radio Link Failure Measurement
Radio Link Failure Measurement per TRX refers to the measurement of level, quality, and TA in the MR during call drops. From this unit can check is there any interference or coverage too low. Judge the call drop position from “Radio link failure measurement based on TA”
Call Drop Measurement
Call drop measurement classify all the call drop by reasons and the channel type
According this traffic , can get the detail reason of call drop ,helping locate the call drop problem
Call Drop Measurement
AMR Measurement
The BSC measures these counters when receiving the SETUP or CALL CONFIRMED message that contains the speech version.
It indicates penetration of AMR MS.
AMR Measurement
Contents
Call Drop Analysis
drop due to the Abis interface
drop due to the equipment
drop due to forced H.O
alarmhardware
Interference band
Up-down link balance
Find out the high call drop rate cell in the “KPI measurement”
Check those cell’s traffic and the call drop times, exclude the low traffic high call drop rate cell
Find out the call drop reason in “call drop measurement ”
Check the receive level ,quality and the TA in “radio link failure measurement”
“Interference band” “Up-down link balance “ and the alarm system also will help to locate the high call drop reason
Call Drop Analysis
Call drop in stable state: call drop during the calling, the major reasons are “error indication” and “connect failure”.
Call drop in handover state: call drop during handover, in other word , handover failure and reset-up also failure.
Call drop due to Abis terrestrial link failure: normally the reason is Abis transmission, also can check alarm system to find out this problem.
Call drop due to equipment failure: the call drop reason is related to hardware fault.
Call drop due to force handover: during the calling, system force the MS handover and handover failure , call drop occur.
Radio Link Failure Measurement
Check receive level, quality and TA in “radio link failure measurement” to analysis the call drop type:
Edge call drop: low receiving signaling strength, large TA.
Short distance call drop: low receiving signal strength and small TA.
BQ call drop: high receiving signal strength and poor quality.
Edge Call Drop
Causes
MS is out of cell’s effective coverage area, “Island” phenomenon caused by over shooting or missing neighbor, Isolated site.
Solutions
Add the necessary neighbor;
Adjust antenna height and antenna downtilt, use high gain antenna;
Modify some parameters
Modify some parameters: “SACCH multi-frames”, “Radio link timeout counter”, “handover threshold”, “handover statistic time”, etc
Short Distance Call Drop
Poor coverage caused by complicated terrain or high dense building
Solutions
Increase EIRP
Adjust antenna direction and downtilt, make the main lobe point to high traffic area
Adjust parameters related to call drop
Interference Call Drop
Analysis interference band to monitor uplink interference, judging inter network or intra network interference according the relationship between interference and traffic
Monitor uplink and downlink interference via “TCHF(H) receive level measurement”. If most M.R receive level high and the quality bad, the interference will be serious
In “BTS maintenance”-”maintain cell”-”configure frequency scan” , can monitor which frequency is interfered
Solutions
Drive test in the suspected area, check the receive level and the quality; using the spectrum equipment to find out the interference resource.
Active frequency hopping, DTX and the Power control to reduce the interference.
Up-down Link Balance
Analyze “up-down link balance measurement function” statistics result and confirm whether the uplink and downlink are balanced.
In call drop measurement function, analyze the average receiving signal strength and quality for both the uplink and downlink .
In power control measurement function, analyze the average receiving signal strength for both the uplink and downlink .
Handover Analysis Process
Handover Analysis
Handover problem direction:
Outgoing or incoming
Handover failure object:
Handover to all the neighbor cells or just handover to certain cell has problem
Handover Analysis
Analysis the major handover failure is in outgoing or incoming
Check “Incoming and outgoing handover measurement” to find out it is just related to certain cell or to all the neighbor cells
From “neighbor cell revel” to decide deleting or adding neighbor cell
Check “Intra-cell handover measurement” to monitor AMR, overlaid/underlaid performance
Handover Analysis
Monitor transmission and board alarms
Analysis “Up-down link balance measurement” to make sure that cell unbalance or not
Interference also will make the handover success rate lower, so should pay more attend to “interference band” “TCHF(TCHH) receive level measurement”
Handover Parameters
Locate and solution
Check whether the handover threshold such as TA, BQ and handover function switch are suitable or not.
Check whether the successful TCH seizures for handover are much more than successful TCH seizures for call. If handover times divided by call times is larger than 3, then it indicates that there may be ping-pong handover. Check the parameter settings and adjust them (layer setting, layer handover hysteresis, inter cell handover hysteresis, PBGT threshold, etc.).
Check whether the average signal strength is low when the handover happens. If so, it indicates the edge handover threshold is too low.
Summary

2G Traffic Statistics Analysis ISSUE1.0

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