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Internal
OMF000601 GSM RN
Optimization
ISSUE1.4
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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Concept of RN Optimization
Radio network optimization means network performance
improvement utilizing existing network resources.
Steps in general
Data collection and verification
Data analysis
Parameter and hardware adjustment
Optimization result confirm and reporting
The purpose is increasing the utilization of network resourcesand solving the existing and potential problem on the network,
identifying solutions for future network planning.
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Concept of RN Optimization
Capacity
CoverageQuality
Optimize
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Concept of RN Optimization
Due to the mobility of subscribers and complexity of radio wave
propagation, most of network problems are caused by
increasing subscribers and the changing environments.
RN Optimization is a continuous process that is required as the
network evolves
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Concept of RN Optimization
In the following case, the network should be optimized
New network or expansion on existing network
The network quality decreased seriously and there are
many complaints from subscribers.
An event occurs suddenly which affects the network
performance seriously.
The number of subscribers increased and affects the
network performance gradually.
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Concept of RN Optimization
TRAFFIC
STATISTICS
DRIVE
TEST
CUSTOMER
COMPLAINTS
OPTIMIZE
Input for Optimization
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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KPI of Radio Network
KPI (KEY PERFORMANCE INDICATORS)
Indicates overall performance of network over a period of time
Good way to monitor network trends and anticipate future
problems
Data obtained from drive test and traffic statistics
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KPI of Radio Network
Typical Radio Network KPI
BTS3
BTS4
BTS1
BTS2
KPI Parameter SourceCall Drop Rate OMC/Drive testCongestion Rate Drive test
Handover Success Rate OMC/Drive test
Busy Hour Traffic OMC
TCH Utilization OMC
Call Setup success rate OMC/Drive test
Coverage Drive test
Quality Drive test
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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Flow Chart of Network Optimization
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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Parameter Adjustment Principles
Parameter adjustment procedure
IDENTIFY
PROBLEM
MAKE
CHANGES
MONITOR
EFFECT
MAKE
CHANGES
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Parameter Adjustment Principles
Parameter Types
Radio Parameters Engineering Parameters
Handover
Parameters
Handover
Parameters
Handover
Parameters
Antenna
Orientation
Antenna
D-tilt
Antenna
Height
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Parameter Adjustment Principles
Adjustment of cell data parameters
Adjust the cell parameters according to the features of
actual radio channel traffic and signaling load. The
parameters are for cell select,cell reselect,call setup,
handover etc, so as to improve the overall network
performance and service quality to the end user.
Another basic principle of radio parameter adjustment is to
maximize the current network resource, traffic sharing in
the the whole network, increase the utilization of the
equipment, so as to increase the profit-investment ratio.
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Parameter Adjustment Principles
According to the feature of problem to be solved, there are two
types of radio parameter adjustment.
Solve static problems: Analyze the average traffic and
signaling flows of the network and solve the network
problems that existed long time
Solve traffic overload and congestion problems during
some special period caused by special events.
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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Driving Test Tools
The following are the frequently used drive test tools:
TEMS and GIMS
Ant Pilot and GSM 2000
SAFCO Walkabout & SAFCO OPAS
TS9951
NEPTUNE
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Driving Test Tools
Drive test Tool application
Identify specific problems in the network
Attend to customer complaints
Perform network benchmarking with other operators Collect periodic network data for reporting
Check coverage in new areas
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Driving Test Tools
Example: Drive test data
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Signaling Analyzer
Signaling analyzer
In real time, MA-10 signaling analyzer can trace A-bis
interface signaling message, A-G interface signaling
message, SS7 signaling message of ISUP, TUP and INAP,
and also bit error rate of transmission system.
For further analysis the signaling message files can be
saved during online tracing, then they can be opened for
analysis at anytime.
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Spectrum Analyzer
Spectrum analyzer
The spectrum analyzer is mainly used to test the
characteristics of frequency, including spectrum, power of
the adjacent channel, and frequency scanning etc.
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OMC Traffic Statistics
OMC
Provides flexible means to record different information from
the network
Able to sample large amounts of data to give a better
picture of the network on a longer period of time
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OMC Traffic Statistics
Signalling test instrument
BSC performance measurement functions
TCH statistics Drop measure
Low HO suc rate
HO measurement
Incoming cell HO
Outgoing cell HO
List of alarm High block rate
Rx_q & Rx_l measure
Hardware Conk out
balance between UL & DL
List of alarmHigh drop rate
Drop call measure
Rx_q & Rx_l measure
List of alarm TCH statistics
List of alarm
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Chapter 1 Concept of RN optimization
Chapter 2 KPI of radio network
Chapter 3 Work flow of RN optimization
Chapter 4 Parameter adjustment principles
Chapter 5 RN optimization tools introduction
Chapter 6 Common problems of RN optimization
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Common Problems of RN Optimization
The three most important performance criterias are coverage,
capacity quality. they mainly correspond to the following
network problems:
Coverage
Congestion
Interference
Handover
TCH call drop
Dual-band network traffic distribution
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Common Problems --Coverage
Check and solve the coverage problem:
Power control measurement Function ( Statistics)
Receiving Level Measurement Function ( Statistics)
Cell Measurement Function ( Statistics)
Inter-cell Handover Measurement Function ( Statistics)
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Common Problems --Coverage
Check the coverage problem:
Call Drop Measurement Function ( Statistics)
Defined Adjacent Measurement Function (Statistics)
Undefined Adjacent Measurement Function ( Statistics)Outgoing Inter Cell Handover Measurement Function ( Statistics)
Rx Level data ( Drive test)
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Common Problems --Coverage
Coverage Problem Solution:
Adjust Radio parameters
Adjust antenna parameters
Use booster, low loss combiner and tower mount amplifierAdd new site (last resort)
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Common Problems --Capacity
CapacityTCH congestion
Check TCH congestion rate: attempted TCH seizers failure for all
(no radio resource available ) on OMC traffic statistics data, or
compare the busy hour traffic of each cell with the calculated
capacity in different GoS to judge the situation of traffic congestion .
Traffic balance
Adjust the antenna height, downtilt, and change the TX power of
BTS and MS.
Adjust parameters for cell selection, cell reselection and handover
Enable load handover and direct retry functions.
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Common Problems --Interference
How to locate the interference
Interference band in TCH Measurement Function
( Statistics)
Receiving Level Measurement Function ( Statistics)
Rx_Qual ( Drive test)
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Common Problems --Interference
How to locate the interference
Ratio of handovers for uplink/downlink quality ( Statistics)
Receiving Quality Measurement (Statistics)
Call drop measurement function ( Statistics)Too many handover failure and reestablishment failures ( Statistics)
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Common Problems --Interference
Check and solve the interference problems
Check the place with interference and conversation quality by drive test.
Use spectrum analyzer to find out the interference in the frequency band.
Enable frequency hopping, DTX and power control functions. Check and eliminate equipment problems (if any).
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Common Problems --Interference
Means to decrease the interference :
Increase the reuse distance between the co-frequency and
adjacent frequencies.
Decrease the transmitting power of BTS.
Adjust the antenna height, azimuth, down-tilt.
Use the anti-interference technologies, such as frequency
hopping, power control, DTX, and so on.
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Common Problems --Handover
Common handover problems:
Handover failure and handover delay lead to bad quality or
call drop.
Frequent handover decreases the conversation quality and
increases system signaling load.
Unreasonable proportion of outgoing inter-cell handover to
incoming inter-cell handover results in imbalanced traffic.
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Common Problems --Handover
Check and solve handover problems:
Check the handover parameters (OMC)
Inter-cell Handover Measurement Function (Statistics)
Undefined Adjacent Cell Measurement Function (Statistics)Outgoing Inter Cell Handover Measurement Function (Statistics)
Incoming Inter Cell Handover Measurement Function (Statistics)
TCH Measurement Function (Statistics)
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Common Problems --Handover
Causes of abnormal handover and solutions:
The outgoing inter cell handover threshold is too low.
The adjacent cells is congested.
There are undefined adjacent cells relationship.The handover hysteresis and handover priority are not reasonable.
The handover statistics times N and P are not set reasonable.
In HCS network coexisting with other vendors cells, the external
cells parameters (such as LAC, CI and BCCH) must be corrected.
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Common Problems Call Drop
TCH call drop
During the GSM network operation, call drop is the main reason
the subscribers complain. It usually refers to the call dropped after
TCH channel seized or conversation connected, which can be
located via traffic statistics or drive test.
There are many call drop causes. Such as poor signal strength,
interference and improper parameters.
There are two important counters related call drop, radio link
timeout (RLT downlink) and SACCH multi-frame number (uplink)sent in system information. These two counters should be set
properly according to the traffic and coverage.
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Common Problems Dual-band Network
Optimization for dual-band network
Take the following special approaches when optimize the dual-band
network, most of the approaches are same as single-band network
optimization:
When GSM 900M and GSM 1800M network belong to a same LAC
the features of two network are basically same. Parameters such as
CRO can be set flexibly according to the traffic, thus can balance the
traffic and avoid cell congestion.
When GSM 900M and GSM 1800M network has there own location
area code, CRH and CRO should be set properly to avoid frequentlocation update.
Adjust layer thresholds to balance traffic between GSM 900 and GSM
1800
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Common Problems Dual-band Network
Dual band network optimization elements
Dedicate mode
Idle mode Calling mode
Cell select Direct retry
Hand over
Cell reselect
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Exercise
Questions
Please write down KPI for normal network
Please write down the work flow for radio network
optimization
How to do for traffic balance
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