GSM Network Optimization
Contents
Concept of Radio Network optimization
KPI of radio network
Work flow of RN optimization
Parameter adjustment principles
RN optimization tools introduction
Common problems of RN optimization
Concept of RN (Radio Network) Optimization
Radio network optimization means network
performance improvement utilizing existing network
resources.
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 Optimization
Capacity
Quality Coverage
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
• Input for Optimization CUSTOMER
COMPLAINTS
OPTIMIZE
TRAFFIC DRIVE
STATISTICS TEST
Steps of RNO optimization
Data collection and verification
Data analysis
Parameter and hardware adjustment
Optimization result confirm and reporting
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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
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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
KPI Parameter Source
Call Drop Rate OMC/Drive test
Congestion Rate OMC
BTS1
Handover Success Rate OMC/Drive test
Busy Hour Traffic OMC
TCH Utilization OMC BTS3 BTS2
Call Setup success rate OMC/Drive test
Coverage Drive test BTS4
Quality Drive test
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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
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Flow 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
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Parameter adjustment procedure
Parameter Adjustment Principles
MONITOR IDENTIFY
EFFECT PROBLEM
MAKE
MAKE
CHANGES
CHANGES
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Parameter Adjustment Principles
Parameter Types
Radio Parameters Engineering Parameters
Handover Antenna
Parameters D-tilt
Accessibility Retainability Antenna Antenna
parameter parameter
Height Orientation
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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 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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• 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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Driving Test Tools
The following are the frequently used drive test tools:
Nemo Handy
Nemo out door
GPS
NEPTUNE
TEMS and GIMS
Ant Pilot and GSM 2000
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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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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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• 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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Common Problems of RN Optimization
The three most important performance criteria's 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
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 it’s not
suppose to serve in; which result in the "isolate Island"
problem.
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Common 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 --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, down tilt, 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
Ratio of handovers for uplink/downlink quality
Interference band in TCH
Receiving RxQual of signal measurement ( Drive test)
Call drop measurement function
Too many handover failure and reestablishment failures
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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
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.
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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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Thank you!!
