Omf000501 Gsm Rn Optimization Issue1.4
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OMF000501 GSM RN
Optimization ISSUE1.4
Wireless Training Department
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Course ContentsCourse Contents
Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
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Concept of RN OptimizationConcept 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 resources
and solving the existing and potential problem on the network,
identifying solutions for future network planning.
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Concept of RN OptimizationConcept of RN Optimization
Capacity
CoverageQuality
Optimize
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Concept of RN OptimizationConcept of RN Optimization
! Due to the mobility of subscribers and complexity of radio
wave propagation, most of network problems are caused byincreasing 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 OptimizationConcept 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 networkperformance seriously.
" The number of subscribers increased and affects the network
performance gradually.
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Concept of RN OptimizationConcept of RN Optimization
TRAFFIC
STATISTICS
DRIVE
TEST
CUSTOMER
COMPLAINTS
OPTIMIZE
Input for Optimization
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Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Course ContentsCourse Contents
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KPI of Radio NetworkKPI 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 NetworkKPI of Radio Network
! Typical Radio Network KPI
BTS3
BTS4
BTS1
BTS2
Drive testQuality
Drive testCoverage
OMC/Drive testCall Setup success rate
OMCTCH Utilization
OMCBusy Hour Traffic
OMC/Drive testHandover Success Rate
Drive testCongestion Rate
OMC/Drive testCall Drop Rate
SourceKPI Parameter
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Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Course ContentsCourse Contents
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Flow Chart of Network OptimizationFlow Chart of Network Optimization
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Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Course ContentsCourse Contents
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Parameter Adjustment PrinciplesParameter Adjustment Principles
IDENTIFY
PROBLEM
MAKE
CHANGES
MONITOR
EFFECT
MAKE
CHANGES
Parameter adjustment procedure
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Parameter Adjustment PrinciplesParameter 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 PrinciplesParameter Adjustment Principles
!Adjustment of cell data parameters
" Adjust the cell parameters according to the features of actualradio 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 PrinciplesParameter 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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Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Course ContentsCourse Contents
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Driving Test ToolsDriving 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 ToolsDriving 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 ToolsDriving Test Tools
! Example: Drive test data
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Signaling AnalyzerSignaling Analyzer
! Signaling analyzer
"
In real time, MA-10 signaling analyzer can trace A-bis interfacesignaling 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 AnalyzerSpectrum Analyzer
! Spectrum analyzer
"
The spectrum analyzer is mainly used to test the characteristicsof frequency, including spectrum, power of the adjacent channel,
and frequency scanning etc.
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OMC Traffic StatisticsOMC Traffic Statistics
! OMC
"
Provides flexible means to record different information from thenetwork
" 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 StatisticsOMC 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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Concept of RN optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Course ContentsCourse Contents
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Common Problems of RN OptimizationCommon Problems of RN Optimization
! The three most important performance criterias are coverage,
capacity quality. they mainly correspond to the followingnetwork problems:
" Coverage
" Congestion
" Interference
" Handover
" TCH call drop
" Dual-band network traffic distribution
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Common Problems --CoverageCommon Problems --Coverage
! Coverage
" Coverage hole
#Coverage hole may exist when coverage areas of two BTS
do not overlap or there are some big obstacles in the
coverage area, this lead to no signal or very poor signal
level.
" Over shooting
# In the actual network, the high BTS antenna can propagate
far away along a road and serve in area which its not
suppose to serve in; which result in the "isolate Island"
problem.
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Common Problems --CoverageCommon 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 --CoverageCommon 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 --CoverageCommon Problems --Coverage
! Coverage Problem Solution:
" Adjust Radio parameters
" Adjust antenna parameters
" Use booster, low loss combiner and tower mount amplifier
" Add new site (last resort)
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Common Problems --CapacityCommon Problems --Capacity
! Capacity
" TCH 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 --InterferenceCommon 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 --InterferenceCommon 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 --InterferenceCommon 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 --InterferenceCommon 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 --HandoverCommon 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 --HandoverCommon 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 --HandoverCommon 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 DropCommon 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 NetworkCommon 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 frequent
location update.
#Adjust layer thresholds to balance traffic between GSM 900 and
GSM 1800
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Common Problems Dual-band NetworkCommon Problems Dual-band Network
Dedicate mode
Idle mode Calling mode
Cell select Direct retry
Hand over
Cell reselect
Dual band network optimization elements
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ExerciseExercise
! 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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