RF Optimization Scenarios

RF Optimization Scenarios

This is a brief description of the common scenarios that the RF team experience during optimization. Also described are the databases that needs checking.


Problem Parameters Physical

Dropped_Calls 1. Wrong parameter settings (perform consistency checks on adjcell/adjres, hoctrl, pwrctrl, and bts objects.) 1. Wrong azimuth orientation (check site/antenna config database, also MapInfo maps)
2. Verify if default parameters matches with the current database of omc or check for mismatches between customer settings and omc settings. 2. Wrong antenna/feeder cable connections (requires site visit)
3. Analyze drive data using TEMS 3. Faulty hardware installation (see site documentation)
4. Verify the neighbor list (this falls on consistency checks) 4. Site down (check omc site alarms and status)
5. In case of interference, check BCCH database or design data 5. Analyze data, look for interference

Handover Failures 1. Wrong parameter settings (perform consistency checks on adjcell/adjres, hoctrl, pwrctrl, and bts objects.) 1. Investigate coverage plots (verify coverage holes)
2. Check LAC assignment on the release_omc or perform consistency checks on lac listings. 2. Check antenna configuration/orientation database
3. Check Pwrctrl parameters (check mismatches between default and omc settings) 3. Analyze drive test data.

Multiple Handovers 1. Verify Hoctrl parameters, PwrBgtAvePeriod, HO_Margin etc. 1. Investigate coverage plots (verify coverage holes)
2. Check Adjcell list (verify RxLevMinAccess and HO_Margin values) 2. Check antenna configuration/orientation database
3. Analyze drive test data.

Interference 1. Check BCCH listings 1. Check site reports for possible hardware problems
2. Check cluster listings and verify cells with co-channel and adjacent channel 2. Use TEMS/other tools to analyze and distinguish internal and external interference
3. Check antenna ht.database 3. Check maps and locate sites with interfering BCCHs

Wrong (Invalid) Handovers 1. Check the neighbor list and verify mutuality between adjacent cells. 1. Check antenna azimuths and tilts

Blocking 1. Check PMS statistics (daily and weekly reports) 1. Add RTs
2. Check site database and verify number of RTs .


Methods and Tools:

Cluster Testing is done to fine tune the fixed network and identify coverage issues. Identifying what type of cluster methodology is used.

Data Analysis and Sorting (Radio Link and Cluster Performance Test)
Drive Test Data indicates the status of the cluster before, and after, the addition of sites. Also indicates coverage issues.
Customer Complaints (Trouble Tickets) are collected from the Customer Service Department and RF related issues are sent to the Network Planning department. The complaints are sorted into clusters and are given to the RF engineers to work on.
PMS (Performance Measurement Sub-system) monitors network performance and creates reports that are then analyzed by the RF engineers during the performance testing.
OMC Data is accessed and used to assess current network status information

Cluster Drive Testing involves:
1. Defining Drive Routes
2. Drive Test Scheduling:
Night Drive(off-peak time testing)
Day Drive (peak-time testing)
3. Data Analysis and Recommendations
Analysis concentrates on coverage and quality issues. The drive test data analyzed is RXLevel, RXQual, MSTXPWR, and intra-Cluster connectivity.
4. Fine Tuning:
Changes in parameters after analysis have been made.
5. Determining RF Coverage holes
6. Post- Processing of Drive Test Data using MapInfo and GIMS
7. Analysis using TEMS
8. Site visits if necessary
9. Printing and analyzing drive test plots for analysis and presentation

Main Issues of Concern:
Dropped calls
Call setup failures
Poor coverage
Handover Failures
Transmission and Synchronization
Interference
Blocking, etc.

Actions:
Workorders are produced for implementation of new services, and changes to the existing networks.

Drive Test and Analysis Tools:

MapInfo – desktop/pc mapping software
GIMS – TEMS post processing software in MapInfo
Ericsson TEMS mobile phone (1 or 2)
GPS and external antennas
Notebook computer and accessories
Switch Terminal/AUI/GUI – real time switch terminal necessary for retrieving current network status information, cell parameters, BSS parameters, etc.



Initial Optimization

The purpose is to verify the basic performance of the radio-network and identify severe RF problems and possible hardware problems.

Responsibilities of the RF engineering group:
Preparation phase:
• Reviewing frequency plan
• Preparing and checking of RF related OSS BSS data
• Handover performance
• Handover order
• Inter BCE Handover
• Inter MSC handovers
• Coverage
• Service quality

In contrast, ongoing RF optimization can cover issues such as resolving the main reasons of the degradation of the radio-network performance, which are the following:
• Congestion
• Oscillating Handovers
• Actual network reconfiguration
• Interference caused by increasing traffic








A summary of Radio Performance Test and RF Optimization Tasks:

Task Radio Performance Test RF Optimization
Call setup possibility Checking the feasibility of setting up
MS originated calls and MS
terminated calls During RF optimization it is
possible to keep track of call setup
performance, because sufficient
number of network statistics data
and drive test data will be available.
Handover performance Verification of proper handover
function for each defined neighbor
relationships - identifying handover areas
between all neighboring site(s)
- identify and prioritize all abnormal
handovers
- adjustments for the elimination
of oscillating handovers
- the handover areas are identified
on a map for future optimization
Handover order check correct handover sequence
Traffic distribution Shifting or reducing the traffic from
congested site(s) to its neighboring
sites and optimize traffic flow in the
network, handle hot-spot areas
Frequency plan
adjustment When new site is going to be integrated into network the initial frequency plan will be reviewed and
readjusted if necessary Due to the sufficient amount of
network statistics data and drive
test data more efficient frequency
will be possible to be implemented
and achieve higher capacity of the
network
Coverage During each site testing it will be
possible to check correct per cell
coverage distribution and identify-
resolve general service degrading
coverage problems Due to the more extensive drive
tests detailed mapping of the cove-
rage will be available. In this case
collected data will be sufficient for
fine tune of antenna configuration in
order to achieve evenly distributed
coverage along clusters of sites
Service Quality Any potential or identified interfe-
rence issues, during the site tests,
are analyzed and minimized Increasing traffic and capacity up-
grades of the network will result in
new interference issues that can be
identified and resolved only by regu-
lar monitoring of the network from
network statistics and drive test
data inputs.