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ITC (Installation, Testing & Commisioning), Radio Network Optimization & Drivetest
4C SAFETY
DES COMITTED
Company ProfileBackground : We are establish with experiences professional resources in parts to develop operator
communication system in quantity and quality network as an answer for rapidly growth telecommunication technology with our services.
With full commitment, expertise and experiences starting in Survey and Design Engineering, ITC (Installation, Testing & Commissioning), Radio Network Optimization & Drivetest, and Supervising CME.
Scope : Consultant and Supervision for BTS pre Installation, Installation, Commissioning and Integration.GSM, CDMA and WCDMA RF Measurement and Optimization.
Experience Drivetes : analyze, produce Optimization report and some recommendation to Improve Network Quality Presentation KPI report to telkomsel . Using TEMS Investigation. Drivetest 3G. And NEMO Outdoor Drivetest. Telkomsel Redeployment Project in Central & West Java, Sumatera, Bali-Nusra. New site Collocation DCS 1800.
2G RF Performance Optimization : analyze drive test result. Prepare Polygon Acceptance to customer. Perform drive test measurement. Process collected drive test measurement data. BTS functional test for cut over project Analyze drive test measurement data. Check antenna position and orientation Reporting for Telkomsel
Contents for Radio Network OptimizationContents for Radio Network Optimization
Concept of RN OptimizationConcept of RN Optimization
KPI of Radio NetworkKPI of Radio Network
Work flow of RN OptimizationWork flow of RN Optimization
Parameter Adjustment PrinciplesParameter Adjustment Principles
RN Optimization Tools IntroductionRN Optimization Tools Introduction
Common Problems of RN OptimizationCommon Problems of RN Optimization
Concept of RN OptimizationConcept of RN Optimization
Radio network optimization means network performance improvementutilizing existing network resources.
Steps in generalData collection and verificationData analysisParameter and hardware adjustmentOptimization result confirm and reporting
The purpose is increasing the utilization of network resources and solving the existing and potential problem on the network, dentifyingsolutions for future network planning.
Concept of RN OptimizationConcept of RN Optimization
Capacity
CoverageQuality
Optimize
Notes: Three main elements
of any mobile network is capacity,
quality and coverage. The main goal to
achieve in network optimization is to
create a balance between capacity,
quality and the coverage of the
network. This should be done by
optimizing the usage of available network
resources at the time.
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 by increasing subscribers and the changing environments.
RN Optimization is a continuous process that is required as the network evolves
Notes :
Many factors affect the quality of network, such as uncertainty of radio wave propagation, changes of building (e.g. newly developed downtown area, re-
planning of the streets and city blocks), traffic load varying with place and time (e.g. stadium), increased subscriber’s requirements.
Concept of RN OptimizationConcept of RN Optimization
• In the following case, the network should be optimizedNew network or expansion on existing networkThe 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.
Notes :Network optimization is long-term process throughout the network development.
To satisfy the requirements of increasing mobile subscribers, the network quality should be improved all the time.
During network optimization, network information can be collected via OMC traffic statistics, driving test, subscriber complaints and OMC alarm information.
If the network quality have some cases such as KPI is as low as unacceptable, too many subscribers complaints, number of subscriber increased, etc. The network
need optimization now.
Concept of RN OptimizationConcept of RN Optimization
TRAFFICSTATISTICS
DRIVE TEST
CUSTOMERCOMPLAINTS
OPTIMIZE
Input for Optimization
Notes :The input for Radio
Network Optimization can be obtain from
several sources: Customer complaints,
Drive test and also traffic statistics.
All these data can be co-related to each
other to have a more deeper understanding
on the problems that are faced in the
network.
Contents for Radio Network OptimizationContents for Radio Network Optimization
Concept of RN Optimization
KPI of Radio Network
Work Flow of RN Optimization
Parameter Odjustment Principles
RN Optimization Tools Introduction
Common Problems of RN Optimization
KPI of Radio NetworkKPI of Radio Network
• KPI (KEY PERFORMANCE INDICATORS)
Indicates overall performance of network over a period of timeGood way to monitor network trends and anticipate future problemsData obtained from drive test and traffic statistics
Notes :The KPI is a good way to measure the overall performance of the network. Several
KPI parameters will be defined in the network to enable the operator to monitor the network performance throughout important events, upgrades etc.
KPI of Radio NetworkKPI of Radio Network
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
Typical Radio Network KPI
Notes :
Normally the formula of KPI are defined by
operator, and usually different operator maybe
consider different KPI and using different formula. The KPI can be derived
from driving test and OMC traffic statistics.
Contents for Radio Network OptimizationContents for Radio Network Optimization
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
Flow Chart of Network OptimizationFlow Chart of Network Optimization
Notes :
The raw date for network evaluation include Network Statistic, Drive Test and Trouble Ticket are obtained to determine the current network condition. Then the KPI
Targets is set based on the consideration from all the data collected and agreed by both parties. The Action Plan is proposed based on the studies of the network.
The Action Plan should be agreed by both parties before the optimization is started. The Frequency, Cell
Parameters/Configuration and Hardware Changes may proposed in the Action Plan. For Implementing the
Action Plan, the operation may include cells frequencies changes, cell parameters retune and Cell Hardware
Reconfiguration. After all the works are done as per Action plan, the network statistic and Drive Test is performed again to determine the KPI achieve the
required Target. For the case where the KPI target is not achieved as requirements, the optimization work is
repeated again until the achievement of KPI targets. The KPI Acceptance report is prepared and signed by the
customer to indicate the optimization process is ended. An further improvement plan may summated to
customer for future reference in order to bring the network performance to greater heights in the future.
NO YES
Network Statistic Drive Test Trouble Ticket
KPI Target
Propose Action Plan
Frequency, Parameter, Configuration and Hardwared Changes
Implementation Action Plan
ENDAchieved KPI
Contents for Radio Network OptimizationContents for Radio Network Optimization
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
Parameter Adjustment PrinciplesParameter Adjustment Principles
IDENTIFYPROBLEM
MONITOREFFECT
MAKECHANGES
•Parameter Adjustment Procedure
Notes:It is important to
understand the actual problems before
changes are proposed and implemented. It should be confirmed
that the identified problem is a valid radio
network problem and not related to hardware
faults. After any parameter changes are
implemented, the performance of the
corresponding cell(s) should be monitored
for any improvement or else need to reverted.
Parameter Adjustment PrinciplesParameter Adjustment Principles
•Parameter Types
Notes:Parameter types can be divided into 2 types,
Radio Parameters (BSS) and the site engineer parameter (Antenna). The radio parameter changes are done in the OMC while the site
engineering parameters will be done at the site.
Radio Parameters Engineering Parameters
Handover
Parameters
Handover
Parameters
Handover
Parameters
Antenna
Orientation
Antenna
D-tilt
Antenna
Height
Parameter Adjustment PrinciplesParameter 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 eselect,callsetup, 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.
Notes :In GSM system, most of radio parameters are based on cells or some areas, while
parameters between areas are closed related, we should consider the negative influence for the the adjacent areas before adjust the parameters.
Usually , if there are problems in some areas, first confirm whether there is equipment faulty (including connection problem), second make sure the problem is
caused by the parameters, and then radio parameters can be adjusted.
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.
Contents for Radio Network OptimizationContents for Radio Network Optimization
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
Driving Test ToolsDriving Test Tools
The following are the frequently used drive test tools:
TEMS Investigation (Sony Ericsson K800i) GPSLaptop Donggle (HASP Emulator)Inverter
Notes :ANT and TEMS driving test tools are suggested. The test methods can be cell
selection, reselection, frequency scanning in idle mode, regular dial test and continuous conversation test in dedicate mode. The data include Rx-level, Rx-
quality and others. In the meantime, the actual installation of antenna and feeder system can be verified.
Driving Test ToolsDriving Test Tools
Drive test Tool ApplicationIdentify specific problems in the networkAttend to customer complaintsPerform network benchmarking with other operatorsCollect periodic network data for reportingCheck coverage in new areas
Notes:The drive test tool unlike
the traffic statistics analysis, enables the
investigation of more specific network
optimization problems. These problems might
not be obvious in the traffic statistics since
they might be localized in a specific area of a cell.
Driving Test ToolsDriving Test Tools
• Example: Drive Test Data
Notes:The drive test tool
unlike the traffic statistics analysis,
enables the investigation of more
specific network optimization
problems. These problems might not
be obvious in the traffic statistics since
they might be localized in a specific
area of a cell.
OMC Traffic StatisticOMC Traffic Statistic
OMC Provides flexible means to record different information from the networkAble to sample large amounts of data to give a better picture of the network on a longer period of time
Notes:The OMC traffic statistics tool provide the means to capture the
performance of the network 24hrs of the day.Analysis can be done to solve gradual problems in the network. Unlike drive test, where the data collected are only valid for the
time the drive test was conducted.
OMC Traffic StatisticOMC Traffic Statistic
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
Notes:OMC provide advance traffic statistics monitoring functions. This provides flexibility
in terms of getting additional information for network optimization.
Contents for Radio Network OptimizationContents for Radio Network Optimization
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
Common Problems of RN OptimizationCommon Problems of RN Optimization
The three most important performance criteria's are coverage, capacity quality. They mainly correspond to the following network problems:
CoverageCongestionInterferenceHandoverTCH call dropDual-band network traffic distribution
Common Problem CoverageCommon Problem Coverage
Coverage
Coverage holeCoverage 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 shootingIn 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.
As for Signal Coverage Hole:Improve the coverage of BTS or add new BTS, we should consider the co-channel and
adjacent-channel interference may occur after the coverage is extended. The coverage holes in valleys and slopes can be covered by using of new BTS or repeaters, we should
consider the interference also. For tunnels, underground garage and high buildings coverage, the repeater , leaking cable technology and micro-cell technology can be used.
For Over Shooting:Adjust the antenna downtilt and output power of TRX. Change the azimuth of antenna
to avoid the direction of antenna facing to the road, so as to reduce the coverage radius.Add missing adjacent cells for the cell.
Common Problem CoverageCommon Problem 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)
How to Make a Judgment:In power control measurement function, the average uplink/downlink signaling
strength is too low.In power control measurement function, whether the average distance between MS
and BTS is consistent with designed. In power control measurement function, the maximum distance between MS and BTS
goes abnormal in many continuous periods. In receiving level measurement function, poor signal account for a high percentage.
In cell measurement function and inter-cell handover measurement function, the average receiving level are too low when trigger handover.
Common Problem CoverageCommon Problem 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)
Notes :In call drop measurement function, the level is too low when call drop, and the TA
value is normal before call drop. In defined adjacent cell measurement function, the specific adjacent cell with too low average level can be found.
In undefined adjacent cell measurement function, there are many undefined adjacent cells with too high average receiving level.
In defined adjacent cell measurement function , the average receiving level of the defined adjacent cell is too high (over shooting). In out-going inter cell handover
measurement function, there are few handover to some certain neighbor cell
Common Problem CoverageCommon Problem Coverage
Coverage Problem Solution:Adjust Radio parametersAdjust antenna parametersUse booster, low loss combiner and tower mount amplifierAdd new site (last resort)
Notes :
Adjust network parameters (BTS transmitting power, antenna downtilt and height, the minimum access level of MS, adjacent relationship between cells, minimum
access level of candidate cells for handover)
Common Problem CapacityCommon Problem 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.
Notes :Approach for traffic adjustment Change the downtilt and height of the directional
antenna, adjust the cell parameters, e.g., transmitting power of the cell, change the the coverage area, so as to implement the traffic adjustment. For the increase
of accidental traffic, the signal coverage range can be changed by adding more carriers temporarily or increasing the transmitting power, so as to change the signal coverage areas. Change number of cell TRX is one of the most popular
methods for traffic adjustment. 3. Check the RXLEV_ACCESS_MIN value. According to the ucell reselection test, adjust the cell reselection offset parameter
CRO; adjust the handover threshold and hysteresis, change the normal handover threshold for traffic load sharing; enable direct retry and load handover.
4. Dual-band network traffic adjustment. Adopt layered cell structure on GSM900 and GSM1800 systems(HCS). Settings different priority for the layers, layer handover threshold and layer handover hysteresis, then the GSM1800 cell can successfully
absorb the traffic of the dual-band mobile phones.
Common Problem InterferenceCommon Problem Interference
How to locate the interferenceInterference band in TCH Measurement Function ( Statistics)Receiving Level Measurement Function ( Statistics)Rx_Qual ( Drive test)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)
Interference location 1.Analysis of the rules of interference band in TCH measurement function.
Interference usually occurs when more than one idle channel appear in the interference band 3, 4 and 5. If the interference is internal, it will usually increase with the growth of traffic. If the interference is from external, it is usually not related to traffic, but it may increase with the traffic growth if the interference is from the
close analog network. Note that the interference band is reported to BSC by BTS via RF resource indication message for idle channel. If the current channel are all busy, the interference
can not be measured. Therefore, the measurement of interference bands should be taken into comprehensive consideration with others..2. Receiving level measurement function .
This is a measurement task statistics for TRX. If there are high Rx-level but bad quality existing frequently, it indicates that there are co-channel and adjacent-channel interference existed.
3. Ratio of handovers for uplink/downlink quality. In inter-cell handover measurement function, or in outgoing inter-cell handover measurement function, the outgoing handover attempt times for various reasons are kept in the statistics. If the handover caused by bad quality frequently, it indicates that there is possible interference. Moreover, it tells the interference status
of uplink/downlink have relationship with handover times caused by bad uplink quality and bad downlink quality. 4. Receiving quality measurement
For TRX, measure the average receiving quality rank for reference. 5. Call drop measurement function
It records the average level and quality in case of call drop. this is for reference. 6. Too many handover and reestablishment failure too.
It is most likely caused by interference in the target cell. This is for reference.
Common Problem InterferenceCommon Problem Interference
Check and solve the interference problemsCheck 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).
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.
Notes :1. Perform driving test, check the quality of interferential. Analyze the interference caused by over shooting. Avoid
interference through adjusting the downtilt of antenna , transmitting power, relationship between adjacent cells, handover parameters, or by adjusting the frequency planning.
2. Analyze with a spectrum analyzer, locate the interferential frequency, and find out the interference’s source. 3. Frequency hopping, DTX and power control can decrease the interference within GSM system..
4. Resolve equipment problems (e.g. TRX, tower mount amplifier, filter)
Common Problem HandoverCommon Problem 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.
Notes :
When we perform continuous conversation driving test, such problems as handover failure, handover delay or frequently handover can be captured. Through traffic statistic, cell
handover success rate and the ratio of outgoing and incoming also handover can be found.
Common Problem HandoverCommon Problem 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)
How to Make a Judgement:Check the handover parameters: threshold, hysteresis, period and etc.
Inter-cell handover measurement function: too many handover failure and reestablishment failures too.Inter cell handover measurement function: too many handover failures, and many reestablishment
successes as well. Undefined adjacent cell measurement function : the number of reports of undefined adjacent cell level
goes beyond the threshold.Outgoing inter cell handover measurement function : When successful rate of outgoing handover is low (for some specific cell), and then find out the successful rate of which target adjacent cell is low,
further search the target cell for cause. When the successful rate of incoming handover is low, the parameters setting in the original cell are
improper. TCH measurement function : handover times is out of proportion to TCH seizure for call successful
times. (handover/call>3).
Common Problem HandoverCommon Problem 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 vendor’s cells, the external cell’s parameters (such as LAC, CI and BCCH) must be corrected.
Common Problem Call DropCommon Problem 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.
The causes for radio link failure include:1.When the MS is in the coverage hole, call drop will be resulted from poor signal.
2.Internal or external interference of uplink leads to SACCH frame decoding failure, this can cause call drop too.3.When the MS move to the border of the coverage area, BSC will judge whether need handover or not. But because the adjacent
cell congestion or adjacent cell had not been defined in the BSC data, no handover can be performed, MS will call drop in this case. 4.Call drop after handover in case of unbalance between uplink and downlink: MS is in serving CELL1. Uplink/downlink unbalance exists in the adjacent cell CELL2 (suppose CELL2 downlink signal strength is enough before handover, but the uplink is poor after
handover). This can lead to call drop after handover because of poor uplink signal. 5.Some other call drops are caused by Abis interface failure, A interface failure.
Common Problem Call DropCommon Problem Call Drop
Optimization for Dual-Band NetworkTake 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
Notes: We should pay more attention to the inter-band handovers. Properly set the handover threshold, and avoid frequent location update caused by inter-band handovers. When there are not many dual-band MS on the network, M1800 construction are expected to absorb traffic effectively, so the parameters
should be set as conducive for GSM 900 handover to GSM 1800. When the dual-band mobile phones on the network are balanced relatively with the actual traffic, we should avoid inter-band handovers to
decrease the signaling load of the system.When GSM 900M and GSM 1800M cells are different BSC but same LAC, we should consider some timer
such as T3212, It will cause some problem for MTC when T3212 values in cells are different.
Dedicate mode
Idle mode Calling mode
Cell select Direct retry
Hand over
Cell reselect
Common Problem Dual Band NetworkCommon Problem Dual Band Network
• Dual band network optimization elements
We should pay more attention to the inter-band handovers. Properly set the handover threshold, and avoid
frequent location update caused by inter-band handovers. When there are
not many dual-band MS on the network, M1800 construction are
expected to absorb traffic effectively, so the parameters should be set as
conducive for GSM 900 handover to GSM 1800. When the dual-band
mobile phones on the network are balanced relatively with the actual traffic, we should avoid inter-band
handovers to decrease the signaling load of the system.
When GSM 900M and GSM 1800M cells are different BSC but same LAC,
we should consider some timer such as T3212, It will cause some problem
for MTC when T3212 values in cells are different.
Thank you For your kind attention
Thank you Thank you For your kind attentionFor your kind attention
Kompleks RNI Jl. Anyer IX No. 1 Menteng
Jakarta 10320 Indonesia
621. 392.0393 621. 230.5236
www.dwierasetunggal.com support@dwierasetunggal.com
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