2007.10.01
www.huawei.com
Confidential: Internal Open
GSM RF Optimization Basic
Wang Song
EtisalatMisr TK Project RNP Team
Training
Course Contents
Concept of Optimization
KPI of radio network
Work flow of Optimization
Parameter adjustment principles
Optimization tools introduction
EtisalatMisr TK Project RNP Team
Training
Concept of 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
EtisalatMisr TK Project RNP Team
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Concept of Optimization
Capacity
Coverage
Quality
Optimize
EtisalatMisr TK Project RNP Team
Training
Concept of 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.
Optimization is a continuous process that is required as the
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Concept of 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.
EtisalatMisr TK Project RNP Team
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Concept of Optimization
TRAFFIC
STATISTICS
DRIVE
TEST
CUSTOMER
COMPLAINTS
OPTIMIZE
EtisalatMisr TK Project RNP Team
Training
Concept of optimization
KPI of radio network
Work flow of Optimization
Parameter adjustment principles
Optimization tools introduction
Common problems of Optimization
Course Contents
EtisalatMisr TK Project RNP Team
Training
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
Source
Call Drop Rate
Stat. & DT
Congestion Rate
Stat.
Handover Success Rate
Stat. & DT
Busy Hour Traffic
Stat.
TCH Utilization
Stat. & Alarms
Call Setup success rate
Stat. & DT
Coverage
DT
EtisalatMisr TK Project RNP Team
Training
Concept of optimization
KPI of radio network
Work flow of optimization
Parameter adjustment principles
Optimization tools introduction
Common problems of Optimization
Course Contents
EtisalatMisr TK Project RNP Team
Training
EtisalatMisr TK Project RNP Team
Training
Concept of Optimization
KPI of radio network
Work flow of Optimization
Parameter adjustment principles
Optimization tools introduction
Common problems of Optimization
Course Contents
EtisalatMisr TK Project RNP Team
Training
Parameter Adjustment Principles
IDENTIFY
PROBLEM
MAKE
CHANGES
MONITOR
EFFECT
MAKE
CHANGES
EtisalatMisr TK Project RNP Team
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Parameter Adjustment Principles
•
Parameter Types
Radio Parameters Engineering Parameters
Handover
Parameters
SI
Parameters
CC&PWC
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.
EtisalatMisr TK Project RNP Team
Training
Concept of Optimization
KPI of radio network
Work flow of Optimization
Parameter adjustment principles
Optimization tools introduction
Common problems of Optimization
Course Contents
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Driving Test Tools
The following are the frequently used drive test tools:
Genex Probe and Assistant
TEMS
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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
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Driving Test Tools
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Signaling Analyzer
Signaling Trace
In BSC6000 LMT, Interface signaling trace support:
A: BSSAP SCCP MTP3 MTP2
Abis: RSL OML LAPD
Pb: Application LAPD
Um
Single User
Other equipment : MA10 , K15
Signaling Analyze
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Spectrum Analyzer
Scaner (Spectrum analyzer)
The spectrum analyzer is mainly used to test the characteristics
of frequency, including spectrum, power of the adjacent
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OMC
Huawei Wireless System OMC is M2000
Provides flexible means to record different information
from the network: Config /Alarms /Stats.
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
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 alarm
High drop
rate
Drop call
measure
Rx_q & Rx_l
measure
List of alarm
TCH
statistics
List of alarm
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Measurement Units Related to Call
1 Immediate Assignment Measurement per Cell 11Intra-Cell Handover Measurement per Cell
2 Assignment Measurement per Cell 12Incoming Internal Inter-Cell Handover Measurement per Cell 3 Call Drop Measurement per Cell 13Outgoing Internal Inter-Cell Handover Measurement per Cell 4 Short Message Measurement per Cell 14Incoming External Inter-Cell Handover Measurement per Cell 5 Channel Activation Measurement per Cell 15Outgoing External Inter-Cell Handover Measurement per Cell 6 Flow Control Measurement per Cell 16Incoming Inter-RAT Inter-Cell Handover Measurement per Cell 7 KPI Measurement per Cell 17Outgoing Inter-RAT Inter-Cell Handover Measurement per Cell 8 Channel Seizure Measurement per TRX 18GSM Cell to GSM Cell Incoming Handover Measurement 9 Calls Discarded due to Overload per LAPD 19GSM Cell to GSM Cell Outgoing Handover Measurement 10 Call Duration Measurement per BSC 20Measurement of MRs upon Handover Initiation per Cell
The counters measured in such flows as immediate assignment, assignment, and
handover during call can reflect the operation of the traffic of BSC.
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Measurement Units Related to MR
C
ell
T
R
X
After occupying a dedicated channel,
MS will report measurement reports
periodically. BSC performs power
decisions and handover decisions
according to the reported measurement
reports. The units listed in the left table
are used to measure the counters
related to measurement reports and
help the users to analyze and optimize
the network performance.
1Number of MRs per Cell
2Power Control Messages per Cell
3Neighbor Cell Level Measurement per Cell 4Interface Band Measurement per TRX 5TCHF Receive Level Measurement per TRX 6TCHH Receive Level Measurement per TRX 7Receive Quality Measurement per TRX
8Uplink-and-Downlink Balance Measurement per TRX 9Number of MRs based on TA per TRX
10Radio Link Failure Measurement per TRX
11Radio Link Failure Measurement based on TA per TRX
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Measurements Related to Channel
1 Channel Configuration Measurement per Cell 2 Channel Conversion Measurement per Cell 3 Channel Busy Duration Measurement per Cell 4 Measurement of Maximum Busy Channels per Cell 5 Channel State Measurement per Cell
6 Channel Assignment Request Measurement per Cell 7 Channel Assignment Failure Measurement per Cell
8 Channel Assignment Concentric Cell Measurement per Cell
9 Channel Assignment Queue Measurement per Cell 10 Channel Assignment GPRS Measurement per Cell 11 Channel Assignment Success Measurement per TRX
During operation, BSC performs
dynamic adjustment to such channel
resources as TCH, SDCCH, and PDCH
to optimize the utilization of resources.
At the same time, the system is required
to regularly output the statistic about the
state of the channels, such as busy,
idle, or blocked. The previous data is
very useful for you to learn about the
operation condition of the system and
the distribution condition of the traffic.
EtisalatMisr TK Project RNP Team
Training
Concept of Optimization
KPI of radio network
Work flow of Optimization
Parameter adjustment principles
Optimization tools introduction
Common problems of Optimization
EtisalatMisr TK Project RNP Team
Training
Common Problems of Optimization
The three most important performance criteria are coverage,
capacity and quality. they mainly correspond to the
following network problems:
Coverage
Congestion
Interference
Handover
TCH call drop
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Common Problems --Coverage
Coverage Gap
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.
EtisalatMisr TK Project RNP Team
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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)
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Common Problems --Coverage
Check the coverage problem:
Call Drop Measurement Function ( Statistics)
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 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, 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)
Uplink Frequency Scan in LMT
Scaner (YBT250)
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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.
EtisalatMisr TK Project RNP Team
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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:
