training drivetest amp optimization

7/30/2019 Training DriveTest Amp Optimization

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Main Tools for Radio Network

Optimization GSMStatistic Handling Tool

OSS Recording Tool

Cell Data Design Tools

Field Measurement

Cell Planning Tool

Field Measurement Analysis

NWS (C); SPOS&Turle, Statics (I)

PMR, RNO package (C)

CNA (C); IPOS, BSSTool (I)

TEMS only!!!

TEMS Cellplanner (C); MCOM (I)

TEMS, MapInfo (C); MCOM (I)



Radio Network Growth Flow



Model Tuning

Network Integration Test

Design & Rollout

Initial Tuning

Training

Operation & Improvement

Verification of Network Changes

Network Feature Optimization

Traditional Optimization

GPRS PerformanceVerification

Where does TEMSINVESTIGATION fit in



Network Integration Test

When a site is integrated to BSC it is tested

• Call set up test• Timeslot test, forced call test

DESIGN & ROLLOUT PHASE

* TEMS Pocket is the preferred tool for Network Integration Test



Initial Tuning

• Produce Coverage Plot

• Identify Coverage Holes

• Identify Interference Area

• Optimize Neighbor Relations

• Find Hardware/Installation Problems

• Verify Parameter Setting

DESIGN & ROLLOUT PHASE



GPRS Performance VerificationDESIGN & ROLLOUT PHASE

• Application Performance Test

• WWW, FTP, WAP etc.

• Mobility Test

• Cell Reselection, RA Update



Traditional Optimization

• Investigate & Trouble-shooting Specific Areas

• Neighbor Relation Optimization• Coverage Issues

OPERATION & IMPROVEMENT

PHASE



Network Feature Optimization

Parameter Settings:

• MS, BTS Power Control• HCS

• Idle Mode Behavior

• Locating Algorithm

• Frequency Hopping

• Intra-cell Handover


PHASE



Verification of Network Changes

Did a certain change in the network give desired results?

• New coverage area?• Less interference?

• Better speech quality?

• Is handover possible?


PHASE



?

Clear objective

Why should this

measurement be

done

Preparations Collect Data Analyze

Check equipment

Get input files

Prepare route

External Antenna?

Save logfile

Take notes

Monitor

Find problem

areas

Find solutions

What should be

changed?

Report

Give answer

to objective

Changes in

Network

TEMS Measurement & Analyzing

Process



?

Clear objective

Why should this

measurement be

done

Preparations

Check equipment

Get input files

Prepare route

External antenna?

Possible Objectives

• Coverage analysis

• Trouble shooting

• Scanning

• Verify network changes

Measurement Will Depend on

Objective



Drive Test

• Large areas

• Specific areasWalk Test

Scanning

Performing Measurements with TEMS



INPUT

Plots & Report

- Signal Strength

- Quality

Trouble Report /

Area for further

investigation

Acceptance

New sites on air

Frequency Re-plan

BSC Re-homing

OUTPUTINPUT MEASUREMENT

Drive defined

route/area

Record Logfile

Long / Short calls

Assure no data loss

Drive Test

- Large area



Manipulate

- Forced handover

- Lock on to Frequency

- Layer 3 messages

Analysis on-spot

Rectify & Verify on-spot

OUTPUTINPUT Measurement

Statistics

Customer complain

Large area drive test

Trouble Report

Trouble Report

- Identified problem

- Solution

Drive Test

- Specific area



Statistics

Customer complain

Micro cell planning

Indoor cell planning


Add file marks (GPS)

Scanning

Trouble Report

Planning Report

- Antenna location

- Frequency

- HCS setting

Walk Test

* TEMS Light is the preferred tool for indoor cell planning



Finding a new

frequency

Area Network

Scanning


Received SS on

different ARFCN

plot

New frequency

TEMS INV in

scanning mode

Set ARFCN to scan

Scanning



Analyzing Measurements



Post-Processing TEMS Logfiles

TEMS

Logfiles

Statistics

Report

Geographical

Presentation

Analysis



Low Signal Strength

• Interference

• Handover

• Call Setup Failure

• Dropped Call

•

Misc.

Problem Cases



Signal Strength Case

INPUT

Large area DT

Specific area DT

Post-Processing

Analysis

TEMS

Logfiles

• Identify areas with low signal strength e.g. SS < -100dBm (outdoor)

• Look at RxLev distribution (for acceptance)

• Compare with design level or new requirements



• Shadowed Antenna

• Antenna Direction

•

Antenna Height / down tilt

• Output Power

• Missing Neighbor Relation

•Site Location

• Faulty Hardware e.g. antenna & TMA

• Cell is down


–

Possible Reasons



Shadowed Antenna Faulty Hardware

Height/down Tilt

Output Power

Visit site

Check antenna installation

Is there a better antenna

position at same site?

Add reduce down tilt?

Can antenna be placed

lower or higher to give

better coverage?

Check output power

Parameters

BSPWRT - NON BCCH FREQ

BSPWRB - BCCH FREQ

Site Location

Possible to move site?

New antenna location at

same site? Is it necessary

to expand and build a new

site?

Check alarm & BTS Error

log

Visit site


–

Analysis

Missing Neighbor

Is the call dragged?

Is low SS due to missing

neighbor relations



• Change parameter BSPWR , BSPWRT.

• Add neighbor relation.

• Physical changes:

• Antenna direction

• Antenna height, tilt or position

• New site as last option.


–

Possible Solutions



INPUT

Large area DT

Identify areas with Rxqual > 5

Identify source using Map and STS

New drive test around problem area?

Specific area DT

Post-Processing

Analysis

Interference Case

TEMSLogfiles



From logfile & map:

What channel group suffer from interference? HOP or Non HOP?

• Check Current channel information in TEMS INV, hopping

channel and hopping frequency.

Where does the interference come from? Cell name?

• Study map and logfile, look for co-channel or adjacent channel

interference.

Does the interference lead to lower SQI?

• Look at SQI measurement during high RxQual.

Use STS & RNO to assist analysis.

Interference Case

–

Logfile analysis



BCCH 590

BCCH 590

High site

BCCH 590

BCCH 590

BCCH 595

BCCH 600 CASE 1

CASE 2

Types of Interference

• Co - Channel interference

• Adjacent Interference



• Poor frequency plan

• No dominant cell --> low C/I ---> increased Rxqual

• Frequency Hopping is off

• External interference e.g. jammer

Example of high Rxqual

due to low Signal Strength

Interference Case

– Possible Reasons



Interference Case

–

Possible solutions• Enable Frequency Hopping or add frequencies to Hopping group.

• Enable BTS Power Control, MS power control and make it less aggressive.

• Change frequency of interferer or interfered cell:

– Possible to find new frequency by using TEMS Scanning.

• Down tilt or change antenna of interferer.

• Redo frequency plan.

• Add new site.



INPUT

Large area DT

Specific area DT

Post-Processing

Analysis

Look for:

Repeated handover (Ping Pong)

Repeated Intra-cell handover

Handover failure,

Unrealistic handover

Handover Case



Repeated Handover (Ping Pong)

- Examples




- Possible Reason 1

Merry-go-r ound Handover, Offset >

Hysterisis




- Possible Reason 2 • Offset only in one direction e.g A-B for Inter

BSC relation

CELL A CELL B

A -> B OFFSET = -5dB

BSC 2BSC 1

No B -> A OFFSET



No dominant Server


–

Other Possible Reasons• No dominant server

• Locating penalty settings

e.g. PSSBQ, PTIMBQ

• Too small hysterisis

setting



Antenna direction

Antenna Tilts

Plan for new site

Change Locating Parameter e.g.

KHYST or LHYST


– Possible Solutions



Change Parameter, KHYST or LHYST

Hysterisis

CELL A CELL B

Handover From A to B


– Possible Solution



Check layer 3 message

Handover command BSC correct?

Check reason for handover SS, RXQUAL

Target cell?

Handover Case

–

Handover Reversion



Duplicates of BSIC BCCH combinations in neighboring list

610_31 610_31

610_12

606_33

608_32

608_32

Serving cell

Neighbor cell 1

Road

Neighbor cell 2

Handover command?

Handover Reversion

– Common Reason



Uplink interference in target cell

Downlink interference at MS

Solutions

Interference Investigation

• MRR

• Statistics

• Scanning

Handover Reversion

– Other Reasons



Possible Reasons

Wrong intra-cell handover settings

External Uplink Interference

Possible Solutions

Consider to change parameters:

• SSOFFSETUL, SSOFFSETDL

• QOFFSETUL, QOFFSETDL

A wrong setting of parameters will cause “unnecessary” IHO

Turn off Intra-cell Handover?

Handover Case

– Repeated Intra-cell Handover



Handover Case

– Unrealistic Handover



Possible Reasons

Wrong locating settings, in Serving or Target cell

Note: Could be on purpose e.g. Dual Band network with HCS

Solution

• Fix locating settings e.g. MSRXSUFF, BSRXSUFF

Unrealistic Handover

– Reason & Solution



Call Setup Failure



Call Setup Failure

–

Input Activities, Initial Tuning Activities

Initial Tuning(Acceptance Test)

Troubleshooting

(Customer complaint etc.)

Measurement Type

•Large Area Drive Test

•Short Call Sequences

Post-Processing Output

•Statistics Report•Geographical Report

showing failure positions



Call Setup Failure

–

Input Activities, Troubleshooting Input Activities

Initial Tuning(Acceptance Test)

Troubleshooting

(Customer complaint etc.)

Measurement Type•Small Area Drive Test

•Lock on problem cell’s BCCH •Force handover to the cell

Post-Processing Output

•Geographical Report (if necessary)



Call Setup Failure Analysis

- Initial Tuning Scenario

• Check the TEMS statistics report (Blocked Call)

if there is Call Setup Failure.

• If yes, identify the problem cells and which

logfile from geographical report.

•

Replay the logfile and jump to the Blocked Callevent.

• Check if there is any successful call setup to the

problem cell.




- Initial Tuning Scenario cont.• Review the layer 3 messages to check at which

sequence the failure occur (random access,

SDCCH, TCH assignment etc.).

• Check STS report on the problem cell. Is there

any traffic (SDCCH & TCH) in the cell, SDCCH

& TCH seizures, congestion etc.

• Check fault report & CDD configuration.




- Troubleshooting Scenario• Before performing drive test, check STS report &

fault report.

• If can not identify the problem, perform drive

test.

•

During measurement, lock the BCCH of the problem cell.

• Review the layer 3 messages to check at which

sequence the failure occur (random access,




- Possible solutions

• Low signal strength Signal strength analysis.

• Interference Interference analysis.

• High Congestion on SDCCH:Define more SDCCHs.

Activate adaptive configuration of logical channel

feature and immediate assignment to TCH.• High Congestion on TCH:

Add capacity/Tune coverage array.

Activate assignment to worse cell.



Failed Call Setup (Blocked Call)

Example

Multiple Channel Requests.

Successful Random Access after the

third try.

Congestion in SDCCH.



Dropped Call Case

- Input • Statistics Report

• Note from drive test.



Dropped Call Case

- Analysis• From plot, identify which & where in logfile

the dropped call occurs.

• In the log file, Jump the drop call event.

• Check if there is a disrupt in the recording. If

yes

could be a false drop due to TEMSmobile disconnection during recording!!!

d C ll C



Dropped Call Case

- Analysis (cont)

• Check the Radio environment just before drop:

– If High Rxqual for a longer period of time and

RLINKT expire Interference problem.

– If Low SS DL, SSDL < MSSENS ( -104dBm) low

signal strength problem.

– If TA > 63 too far from the cell.

• If DL radio is good, check the TX power. If

there is MS power down regulation when the

MS is close to the cell. If full power suspect

uplink interference or antenna, TMA problem.



From TEMS Logfile

• Good Signal strength DL, Good Rxqual DL

• No call set up possible unless very close to site = high SS

• Dropped call when SS < approx. -75dBm

Analysis

• Since DL SS & Rxqual is good

Suspect UL problems e.g. external uplink interference

Conclusion

TMA power turned off

Miscellaneous Case 1



From TEMS Logfile

• TCH has lower Signal strength than BCCH (Own BCCH included in

BA-list)

• BTS power control = OFF


CHG0 B C C H

T C H

T C H

T C H

T C H

T C H

T C H

S D C C H \ 8

CHG1 T C H

T C H

T C H

T C H

T C H

T C H

T C H

T C H

Configuration/cellSEKTOR A

SEKTOR B

SEKTOR C

Conclusion

Antenna cable for TCH is swapped between sectors (CDU-A)



From TEMS Logfile

• Fail to perform Call Setup

Analysis

• Check if any success call setup to the same cell No

• Check if handover is possible Yes

• Suspected wrong cell definition in MSC but Cell is properly

defined in MCS and LA

Conclusion

• Corrupted block in MSC




GPRS Verification &

Optimization

with TEMS Investigation



GPRS Measurement Activities• GPRS Performance Prediction

• GPRS Field Measurement



GPRS Performance Prediction- Overview• GPRS RNAP Service uses TEMS Inv to predict

following performance:

– Throughput

– Cell Reselection & Routing Area Update



GPRS Throughput Prediction• Perform Throughput prediction for each

coding scheme



Cell Reselection Prediction• Dedicated mode drive

test



Cell Reselection Prediction• BCCH Scanning

• Simulate the cell update with different CRH

valuesCRH = 4 dB CRH = 8 dB

CRH # HO

0 365

2 246

4 211

6 178

8 156

10 147

12 138

14 130



GPRS Field Measurement

- ProcedureSet up files

Cell definitionsPreparations

TEMS,

IP Sniffers

…

Dig maps

Excel

Mapinfo

Graphical

presentation of route

Charts / Tables

Report

?GIMS




- Type of Measurements• Application Performance Test

– Ping

– WWW

– FTP

– WAP

• Mobility Performance Investigation

– Cell Reselection

– RA Update

GPRS Fi ld M




- Application Performance Test

• Attached performance

– Attached Time = Attach Complete msg – Attach

Request msg

– Attach Success Rate

• PDP context activation performance

– PDP context activation = Activate PDP Context

Accept msg – Activate PDP context request

• Throughput on RLC level

• Dela



GPRS Application Test Tools

• General

– Windump, Commview, Ethereal, Protocol Analyser

for Gb

• PING

– MS DOS ping command

• WWW

– IE, Netscape

• FTP

– DOS FTP, WS_FTP, TEMS built in sequence




- Mobility Performance

Investigation

• Number of Cell Reselection & RA Update

• TCP Outage Time

•

Cell Reselection Failure



Mobility test CRH = 4, CRO = 4



Cell Reselection Sample ReportRouting Area Time Cell Target

CellReselection

timeResult Comments

BSC1 16:30:42 D0241A D0241C 2 s OK NA

BSC1 16:33:18 D0241B D0242A 2 s OK NA

BSC1 16:35:04 D0242A D0248C 21 s OK This cell reselection wasmade to a cell located quitefar away (not the closest),

thus the RxLev was quitebad!

BSC1 16:37:44 D0244B D0248C -- NA No throughput before or after the cell reselection.This is due to that the cellDF0242B were halted by

some reason!

BSC1 16:38:11 D0248C D0244B -- Failed The through put was never resumed and the FTP

connection was aborted bythe ftp-server!

.

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