2g tuning process flow - dt analysis

33
2G Tuning Activity Process Flow Drivetest Analysis

Upload: reza

Post on 30-Oct-2014

145 views

Category:

Documents


10 download

TRANSCRIPT

Page 1: 2G Tuning Process Flow - DT Analysis

2G Tuning Activity Process Flow

Drivetest Analysis

Page 2: 2G Tuning Process Flow - DT Analysis

2G Tuning Activity Process Flow

Drivetest Analysis

NTS NETWORK INDONESIA

Table of Contents

1 Low Signal strength Problem ................................................................... 3 1.1 Design and Acceptance Signal Strength Criteria for NTS 2G. ................ 3 1.2 Low Signal Strength Troubleshooting Process Flow: .............................. 4 1.3 Low Signal Strength Troubleshooting Solution Table ............................. 4 2 RXQUAL Problem .................................................................................... 5 2.1 Acceptance RXQUAL level for NTS 2G................................................... 5 2.2 RxQual Troubleshooting Solution Table .................................................. 6 2.3 RxQual Troubleshooting Process Flow: .................................................. 7 3 Call Setup Success Rate Problem ........................................................... 8 3.1 Call-Set-Up Success Troubleshooting Process Flow: ........................... 10 3.2 Call-Set-Up Success Troubleshooting Solution Table .......................... 11 4 SDCCH Congestion Problem ................................................................. 12 4.1 SDCCH Congestion Troubleshooting Process Flow ............................. 12 4.2 SDCCH Cong Problem Troubleshooting Solution Table ....................... 13 5 SDCCH Drop Problem ........................................................................... 15 5.1 SDCCH Drop Troubleshooting Process Flow ........................................ 15 5.2 SDCCH Drop Problem Troubleshooting Solution Table ....................... 15 6 TCH Congestion problem....................................................................... 17 6.1 TCH Congestion Troubleshooting Process Flow .................................. 17 6.2 TCH Congestion Troubleshooting Solution Table ................................. 19 7 Drop Call Problem .................................................................................. 19 7.1 Drop Call Troubleshooting Process Flow .............................................. 20 7.2 Drop Call Problem Troubleshooting table .............................................. 21 8 Handover Problems................................................................................ 22 8.1 Handover Analysis Process Flow .......................................................... 22 8.2 No or few Handover Attempts ................................................................ 24 8.3 No or few Handover Attempts troubleshooting table ............................. 24 8.4 Unsuccessful Handovers Process Flow ................................................ 25 8.5 Unsuccessful Handovers Troubleshooting Table .................................. 28 8.6 Handover Reversions Troubleshooting Table ....................................... 29 8.7 Ping Pong Handovers Troubleshooting Table ....................................... 29 8.8 Inter MSC Handover Analysis ................................................................ 30 9 GPRS Throughput Analysis ................................................................... 32 9.1 GPRS Throughput Troubleshooting Process flow ................................. 32 9.2 GPRS Throughput Troubleshooting Table ............................................ 32 9.3 GPRS Parameters to Check for ............................................................. 33 10 Contributers ............................................. Error! Bookmark not defined. 10.1 Members .................................................. Error! Bookmark not defined.

Page 3: 2G Tuning Process Flow - DT Analysis

1 Low Signal strength Problem

1.1 Design and Acceptance Signal Strength Criteria for NTS 2G.

Table 1: 2G Design Level

Low signal strength analysis is very much depending on the design and acceptance criteria referring

to the above table. Based on the acceptance value the following scenario are to be put into

consideration.

For drive test data additional of -6dBm to be add up to make it more into realistic value and this will

determine until what received level (in dBm) could be considered as “low signal strength problem”.

Table 2: 2G Acceptance Level

Environment Acceptance

Level Additional dBm Drive test acceptance level for Signal Strength

CBD -71dBm -6dBm -77dBm

Dense Urban -73dBm -6dBm -79dBm

Urban -75dBm -6dBm -81dBm

Suburban -78dBm -6dBm -84dBm

Rural -84dBm -3dBm -87dBm

Open(Hwy) -88dBm -3dBm -91dBm

2G Coverage – Design Levels

CBD Dense Urban

Urban Suburban Rural Open [Hwy.]

Environment Bins >=

95% Bins >=

95% Bins >=

95% Bins >=

95% Bins >=

95% Bins >= 95%

RSSI [dBm] -64.0 dBm

-66.0 dBm -70.0 dBm -75.0 dBm -80.0 dBm -85.0 dBm

2G Coverage – Acceptance Levels

CBD Dense Urban

Urban Suburban Rural Open [Hwy.]

Environment Bins >=

95% Bins >=

95% Bins >=

95% Bins >=

95% Bins >=

95% Bins >= 95%

RSSI [dBm] -71.0 dBm

-73.0 dBm -75.0 dBm -78.0 dBm -84.0 dBm -88.0 dBm

Page 4: 2G Tuning Process Flow - DT Analysis

1.2 Low Signal Strength Troubleshooting Process Flow:

RXLEV problem

Parameter Setting

Correct?

Check neighbour

parameter

Rivert issue to cell

plan

Installation

Istallation error?

Coverage Performance

Antenna

Check for possible swap feeder ect.

Check parameter as

in CDD and defined.

A

YES

NO

NO

NO

YES

NO

YES

Site Location

Check antenna

placement

Check coverage objective

Antenna Location

Island Site?

Coverage Issue?

Check hardware

Parameter

Neighbour

Missing neighbours

suspected?

YES

NO

NO

YES

YES

NO

NO

YES

A

Alarm occurred?

YES

Alarm

Perform troubleshooting

Server

No dominant server?

End

1.3 Low Signal Strength Troubleshooting Solution Table

Possible Reason

ANTENNA ANTENNA HEIGHT - could mean a too large service area.

ANTENNA LOCATION - will cover large areas. A large

coverage area might mean that the cell takes a lot of traffic. Lower

antenna if there is no risk for loss of coverage (no coverage at all).

Page 5: 2G Tuning Process Flow - DT Analysis

ANTENNA TILT - Tilting of the antenna or changing antenna

type may also decrease the coverage area.

SITE LOCATION CHECK COVERAGE OBJECTIVE – The main purpose the site

were constructed at the area.

COVERAGE

PERFORMANCE

TMA – May not functioning properly.

UL/DL IMBALANCE

ANTENNA TYPE – Wrong antenna installed, different band etc.

FEEDER TYPE – Wrong feeder type.

BLOCKING/SURROUNDING SCENARIO – EIRP from

antenna been block by building, trees or billboards.

PARAMETER

SETTING BSPWRB/T – Low output power may cause low RF

ACCMIN – Setting of ACCMIN not to be too high such as -110.

CRO – Cell reselection parameter, work together with TO and PT.

TO - Defines a negative offset applied to CRO.

PT - Value indicates that the cell reselection offset is

negative and that the temporary offset is ignored.

Note: The setting only affects GSM phase 2 mobile.

MPWR – Maximum transmitter power of the TX at the power

amplifier (PA) output. MPWR must be specified for each

transmitter in the TG.

NEIGHBOUR

CHECK NEIGHBOUR PARAMETER – Check for the correct

setting.

MBCCH IDLE/ACTIVE – Frequency define same as the

neighboring frequency.

INSTALLATION SWAPPED CELL

SWAPPED TX/RX

SWAPPED TRU

SWAPPED FEEDER – Feeder from different sector been

connected to wrong sector.

ALARM RX DIVERSITY LOST

VSWR – From BSC alarms ( Threshold value = 1.3)

TRANSMISSION

NO DOMINANT

SERVER If no dominant cell or similar signal strengths of a few cells found

during drive test, it is recommended to add BTS.

2 RXQUAL Problem

Traditionally RXQUAL measure has been use to measure the downlink speech quality performance

of a GSM network.

2.1 Acceptance RXQUAL level for NTS 2G.

It has been a conclusion that from drive test result, which ever sample of RXQUAL > 3 with the

following clutter type received level environment should be taken into consideration of

Page 6: 2G Tuning Process Flow - DT Analysis

troubleshooting with improvement as the result. This term applies for all environments which are

BDC, Dense Urban, Suburban, Urban, Rural and Open (Hwy).

Environment Acceptance

Level (design)

Acceptance level (DT)

RXQUAL Value

CBD -71dBm -77dBm > 3

Dense Urban -73dBm -79dBm > 3

Urban -75dBm -81dBm > 3

Suburban -78dBm -84dBm > 3

Rural -84dBm -87dBm > 3

Open(Hwy) -88dBm -91dBm > 3

If the signal strength is lower the above indicator in any particular clutter, RXQUAL problems may

not be solved first until the coverage issues are attended. If the signal strength is greater than the

above indicators, all RXQUAL problems will be solved first.

2.2 RxQual Troubleshooting Solution Table

Possible Reason

FREQUENCY PLAN

BCCH – Check BCCH frequency

BSIC – Check BSIC

MIAO – Incorrect value

HSN – Unplanned value

HOPPING – Check if the frequency hopping on or off. If more than

1 TRU, turn on the frequency hopping.

COVERAGE

PERFORMANCE ANTENNA HEIGHT/DIRECTION – The height should be limit

especially in CBD area and the direction should be correct as

planned RND.

ANTENNA TILT/TYPE –Recommend electrical tilt, not to be more

than 8 degree down tilt.

COVERAGE OBJECTIVE – Check the objective from Radio

Network Design.

SURROUNDING BLOCKING – Possible to do site visit to check

either for obstacle in front of antenna such as building, hills or

billboards.

NEIGHBOUR MISSING NEIGHBOUR RELATION – Check for undefined

neighbor relation.

TOO MANY NEIGHBOUR RELATION – This will lead to

inaccuracy of sample rxlev in measurement to be send from MS.

WRONG BSIC DECODING – BSIC should be unique for every

cell.

CO-BCCH & CO-BSIC – Will result to very bad quality and always

end up with drop call and handover failure.

NEIGHBOUR POWER SETTING - If the interference is downlink

(causing by other BTS interference), Check BTS power regulation.

Page 7: 2G Tuning Process Flow - DT Analysis

If any poor setting found, correct parameter setting.

PARAMETER LOCATING

URGENCY

BSPWRB/T

IHO – Intracell handover usually indicates bad quality and high

signal strength. High number of intracell handover shows a bad

quality cell and if possible, you can reduce the number of intracell

handover of MAXIHO to a smaller value based on the channel

group.

BSPWR CONTROL – Check for the correct setting.

MSPWR CONTROL - Check for the correct setting.

DTX: DTXD & DTXU - Check if DTX feature is on or off. If off,

turn the DTX feature on. This will save the battery in the MS and

reduce the interference.

ALARM TRU FAULTY – TRU faulty should be replace

PATH BALANCE RX/TX -

VSWR – Threshold value 1.3

CONGESTION CONGESTION – Upgrade capacity

EXTERNAL UPLINK

INTERFERENCE Check from the statistics or scanning drive if there is any pattern of

bad quality reason. For example, for surveillance purpose, the

CCTV or might be turn on during night time only. In this case

statistic monitoring should be on hourly data.

EXTERNAL DOWNLINK

INTERFERENCE If external interference problem occurs, do drive test and frequency

scanning. Report the usage of the frequency to the relevant

authorities.

FREQUENCY PLANNING RE-LOOK STRATEGY – Plan hopping channel group again with

more frequencies, include more frequencies in BCCH group.

Improve frequency plan with additional spectrum.

UN-USE FEATURES

IRC - The purpose of Interference Rejection Combining is to

improve performance on the uplink in radio environments limited by

interference. IRC minimizes the disturbance an interferer by

combining the signal received on diverse antenna and suppressing

the interfering signal.

BCCH TYPE REUSE -

2.3 RxQual Troubleshooting Process Flow:

Page 8: 2G Tuning Process Flow - DT Analysis

RXQUAL problem

Parameter Setting

Correct?

Alarm

troubleshooting

Congestion

Pure congestion

Neighbour

Frequency

Upgrade capacity

Check parameter as

in CDD and defined.

A

YES

NO

NO

NO

YES

YES

Coverage

Check frequency

Check antenna location, tilt?

Frequency issue

Coverage Performance?

Neighbour issue? Check neighbour parameter ect

Parameter

Alarm

Alarm exist?

YES

NO

NO

YES

YES

NO

NO

YES

A

External downlink?

External frequency

Scan frequency

Re-look frequency

planning strategy

End

Un-use features IRC, BCCH type re-use

3 Call Setup Success Rate Problem

Call Set-up Success Rate - The probability that a connection can be established within a specified

transmission tolerance, to the correct destination, with a given time interval, when requested by

MS.

This KPI will be measured per cluster with drive test short calls in dedicated mode.

Page 9: 2G Tuning Process Flow - DT Analysis

The measurement will be extracted from Layer 3 messages starting from Channel Request up to

Alerting. Repetitive Channel Requests will be excluded due to the fact that a single subscriber call

attempt may generate multiple Channel Requests.

Formula:

No. of Successful Call Establishments - Measured from Layer 3 Message, Alerting, unsuccessful are those

request which timed out and blocked due to no available SDCCH or TCH resources.

X – the repeated “Channel Request”

No. of Call Attempts - Measured form Layer 3 Message, Channel Request. Repeated channel request is

excluded.

Two Call Set-up Success Scenarios:

1. MS Originated Call to a PSTN (Fixed Line)

- This assumes a seamless connection between the network and the PSTNetwork. Successful

Establishment is until the Network have sent the Alerting confirmation to the MOC.

MOC- PSTN

2. MS originated Call to a Mobile Terminated Call

CSSR (%) = No. of Successful Call Establishments(MOC) X 100 % No. of Call Attempts (MOC) – x (MOC)

CSSR (%) = No. of Successful Call Establishments X 100 % No. of Call Attempts – x

Page 10: 2G Tuning Process Flow - DT Analysis

- CSSR will measure its success from MOC’s channel request but only until the MTC has confirmed

to the network an Alerting Message. Note that Successful Establishment is taken for the MTC.

-

MOC- MTC

3.1 Call-Set-Up Success Troubleshooting Process Flow:

Call set-up Process starts from Random Access towards the Alerting stages. Hence, the

process will pass thru RACH Access, SDCCH Transactions and TCH Assignment.

CSSR (%) = No. of Successful Call Establishments(MTC) X 100 % No. of Call Attempts (MOC) – x (MOC)

Page 11: 2G Tuning Process Flow - DT Analysis

3.2 Call-Set-Up Success Troubleshooting Solution Table

Low CSSR

RXQUAL RXLEV

Problem?

SDCCH congestion

?

SDCCH Drop?

TCH Congestion

?

See 1. RXQUAL Problem Troubleshooting. 2. Low Signal Strength Troubleshooting

HW Problem?

See SDCCH Congestion

Troubleshooting

See SDCCH Drop Troubleshooting

See TCH Congestion

Troubleshooting

Y

N

Y

N

Y

N

Y

N

Escalate to O&M Y

N

End

Page 12: 2G Tuning Process Flow - DT Analysis

No. PROBLEM DESCRIPTIONS SOLUTION

1 Interference

1. MS is retransmitting its channel requests,

BTS cannot decode the messages sent MS

vice versa. Timer T3126 often encountered.

2. High ICM Band when check on STS and

on real time network.

See RXQUAL or Low

signal Strength

Troubleshooting

2

SDCCH

Congestion

-MS has successfully sent the channel

Request message and received an

Immediate Assignment Reject Message.

T3126 has expired after the maximum

number of channel request has been sent.

See SDCCH Congestion

Troubleshooting

3 SDCCH Drop

Rate

MS while establishing connection on

SDCCH, SDCCH drop its connection.

(See SDCCH Drop

Troubleshooting)

4 TCH

Congestion

Call establishment failed due to no TCH

resource can be allocated

(See TCH Congestion

Troubleshooting)

5 Hardware

Problems

MS – MS is not sending channel request

message after the call sequence has been

initiated

BTS HW and others – faulty HW tends to

have an intermittent connection and

degrades connection performance.

Escalate to O&M:

- Faulty TRU,

Combiners, feeders,

antenna and etc.

- High Transmission

SLIPs.

4 SDCCH Congestion Problem

4.1 SDCCH Congestion Troubleshooting Process Flow

Page 13: 2G Tuning Process Flow - DT Analysis

4.2 SDCCH Cong Problem Troubleshooting Solution Table

Check Parameter Settings

Settings Ok?

LAC Border

Cell?

SDCCH Congestion

Radio Network Features

ACLC Activated?

Adjust Hysteresis

Adjust Parameters

Activate Feature

Increase SDCCH Active?

Activate Feature Upgrade

TRU

Upgrade SDCCH

SDCCH Maximum?

Improved? End

Y

N

Y

N

Y

N

Y

N

Y

N

Improved?

END

Y

N

Page 14: 2G Tuning Process Flow - DT Analysis

No. Item Remarks Descriptions

1 Parameter

Adjustments

SDCCH

Measurement Filters

Filters might be too aggressive or having so

much delay in provide reliable measurements.

This should be standardized with the network

unless it is necessary to modify.

Filters: SSEVALSI, QEVALSI, SSRAMPSI

Cell might be more

attractive than other

cells

Check parameters: CRO, PT, TO, ACCMIN

etc

2 Border Cell

Cell caters more

traffic than normal,

such as locations

updates

Check parameter: CRH

3

Activate

Adaptive

Configuration

of Logical

Channels

Dynamic allocation of

SDCCH Resource Activate feature

4

Activate

Increase

SDCCH

Capacity

SDCCH is at

maximum which is

equal to the number

of TRU installed

Activating this feature needs a redimensioning

of TRH/TRU resource in BSC level. Hence,

the draw back is the decrease on TRH capacity

but savings on the TRU resources.

Parameters: MAXNOSDCCHTRX

** Combined SDCCH is not considered due to

an assumption of high paging load and to

avoid paging deletion.

5 TRU Upgrade

Features can’t

compensate traffic

demand

Upgrade TRU resource to upgrade SDCCH

Page 15: 2G Tuning Process Flow - DT Analysis

5 SDCCH Drop Problem

5.1 SDCCH Drop Troubleshooting Process Flow

5.2 SDCCH Drop Problem Troubleshooting Solution Table

No. PROBLEM DESCRIPTIONS SOLUTION

Check Parameter Settings

Parameter Settings Ok?

Weak Coverage?

SDCCH Drop

See low Signal Strength Problem Troubleshooting

Adjust Parameters

Interfered? See RXQUAL Problem Troubleshooting

HW Problem?

Escalate to O&M

Cell Plan Review End

Y

N

Y

N

Y

N

Y

N

Page 16: 2G Tuning Process Flow - DT Analysis

1 Parameter

Adjustments

SDCCH

Measurement Filters

Filters might be too aggressive or having so

much delay in providing reliable

measurements. This should be standardized

with the network unless it is necessary to

modify.

Filters: SSEVALSI, QEVALSI, SSRAMPSI

2 Interference

MS is experiencing

interference despite of

good coverage.

See RXQUAL Problem Troubleshooting

3 Weak coverage

No dominant Server,

area is obstructed or

far from sites

See Low signal Strength Problem

Troubleshooting

4 Hardware

Problems

SDCCH connections

is disrupted, quality

and coverage is

intermittent.

Escalate to O&M:

- Faulty TRU, Combiners, feeders, antenna

and etc.

- High Transmission SLIPs.

5 Cell Coverage

Review

High Timing

Advance

Perform an MRR analysis to review cells

coverage and coverage scope.

1. High Antenna – down tilt, lowering location

2. High Antenna Gain – change out to lower

gain antenna

3. High BTS power – power down

Obstruction

1. Consider antenna relocation

2. Consider site relocation

3. Consider site nomination

Page 17: 2G Tuning Process Flow - DT Analysis

6 TCH Congestion problem

6.1 TCH Congestion Troubleshooting Process Flow

Page 18: 2G Tuning Process Flow - DT Analysis

Check Parameter Settings

Settings Ok?

Missing

Neighbours?

TCH Congestion

Radio Network Features

HR/FR Activated?

Dynamic Mode Adaptation

Active?

Add

Neighbours

Adjust Parameters

Activate Feature

Activate Feature

CLS Active?

Activate Feature

Thresholds so High?

Monitor KPI TRU Upgrade

N

Y Y

N

Y

N

Y

N

Y

N

Y

N

Compute for TCH Utilization

Check Transcoder Utilization/Congestion

GOS > 5% Imbalance?

Y

N

Review HW Alarms

Redimension Transcoder Resource

Cell Plan Review

Improved?

Y N

Page 19: 2G Tuning Process Flow - DT Analysis

6.2 TCH Congestion Troubleshooting Solution Table

No. PROBLEM DESCRIPTIONS SOLUTION

1

Parameter

Settings

Review

Cells might be more

attractive compare

to its neighbors.

Parameters to check:

1. Power – BSPWRB, BSPWRT

2. Locating 1 or 3 Parameters

3. HCS

Check coverage (TA) thru MRR – if applicable

2 Missing

Neighbors

Cells can’t handover

to its best

neighbors.

1. Perform NCS if applicable

2. Perform Drivetest ,Frequency Scanning to

locate for missing neighbours.

3 Compute

Utilization

Utilization might be

low bt TCH

congestion is still

present. This could

be on Transcoder

resource

congestion.

Balance FR/EFR, HR, Fr AMR resource.

4 Hardware

Problem

Faulty TRU – Hang

up without alarms

and rejecting traffic

Escalate to O&M

5

Inactive

Dynamic Full

Rate/ Half Rate

Feature

Activate Feature Activate to increase TCH BPCs.

6 Inactive

DYMA Activate Feature Activate Feature in increase FR/HR Flexibility

7 Inactive ACLC Activate Feature Activate Feature on selected Neighbors (Low

utilization and good handover success rate)

9 TRU Upgrade

Current traffic is

beyond its capacity

and traffic balancing

is optimum

TRU upgrade

Reassess DYMA, CLS and HR/FR resources

10 Cell Plan

Review

High Timing

Advance

Perform an MRR analysis to review cells

coverage and coverage scope.

1. High Antenna – down tilt, lowering location

2. High Antenna Gain – change out to lower

gain antenna

3. High BTS power – power down

Obstruction

1. Consider antenna relocation

2. Consider site relocation

3. Consider site nomination

7 Drop Call Problem

Page 20: 2G Tuning Process Flow - DT Analysis

Drop Call is the abnormal termination of after the Call Establishment and before the message release

or the disconnect message is received by the MS or the Network.

7.1 Drop Call Troubleshooting Process Flow

Dropped calls on TCH

Check dropped call reason

Bad quality?

Low signal strength?

Most dropped calls during handover?

Check lost handovers

See RXQUAL

Troubleshooting

See Low SS

Troubleshooting

See Handover

Analysis

Swap & repair HW

Check Cell Plan

Site covering too much?

Best server exists?

Check radio network features

Power regulation

used properly?

DTX used?

Check output power

Check locating parameters

Bad parameter setting?

Ensure Improvement

Wait for Site to be

Integrated

Forward to Design Team

for Site Nomination

Check BTS error log

HW fault?

Transmission fault?

Check link quality

Power balance? Adjust output power

Introduce DTX

Correct parameter setting

Limit Coverage

Physical adjustments

Perform link investigation

Add site

High timing

advance?

END

F

F

Check site location & TALIM

NO

Correct power regulation parameters

YES

NO

YES

YES

NO

NO

YES

YES

YES

NO

YES

NO

NO

YES

NO

YES

YES

NO

NO

YES

Missing neighbours suspected?

Run NCS/Check on Drivetest. Add

Neighbors

High ICM? Check frequency plan,

external interferers and/or filters

YES

NO

Page 21: 2G Tuning Process Flow - DT Analysis

7.2 Drop Call Problem Troubleshooting table

No. PROBLEM DESCRIPTIONS SOLUTION

1 Bad Parameter

Settings

The quality

Parameters are too

aggressive.

Locating Parameters:

1. Urgency Condition Parameters

2. Locating 1 or 3 Parameters

2 Power

Regulation

The quality

Parameters are too

aggressive or too

sloppy.

Power Control Settings Review

3 Power Balance Uplink and Downlink Adjust BTS power (BSPWRB, BSPWRT) or

MS power (MSTXPWR)

4 DTX Feature Optional Feature Activate feature, this will minimize drop call

due to an improved radio environment.

5 Bad Quality Drop call due to bad

quality

See RXQUAL Analysis

6

Low Signal

Strength UL/

DL

Drop call due to Low

Signal Strength

(Ul/DL/BL)

See Low Signal Strength Analysis

7 Missing

Neighbours

Undefined

neighbours, calls

dropped due after

failure to handover

after

- Review neighbour relations; update the best

neighbours to be defined.

-If available, generate NCS and MRR

- Conduct actual drivetest if necessary, do

frequency scanning.

8 High ICM Interference on

Uplink

-Check possible faulty TRU, check

connection error count rate of each TRU.

- Check possible internal and external

interference.

- check repeaters

- See RXQUAL Analysis

10 High TA Disconnection due to

High Timing

Advance

- Site must be overlapping, review coverage

- Do physical adjustments:

a. Downtilting

b. Antenna Change-out

- Power Down

- Parameter adjustment – TALIM

11 DCR due to

Lost Handover

After handover the,

the call was

disconnected and the

call was

-Check HW faults:

1. Transmission Problem

2. TRU Faults, etc.

-Review neighbours, delete unnecessary

neighbours

12 Cell Plan Site may be

overshooting or

serving on a wrong

coverage

- Check Antenna Height, Direction Tilting,

create changes if necessary

- Check antenna specification – recommend

change out if necessary

Page 22: 2G Tuning Process Flow - DT Analysis

13 HW Fault Intermittent signal

strength or quality

which results to drop

call

Escalate to O&M:

- Faulty TRU, Combiners, feeders, antenna

and etc.

- High Transmission SLIPs.

14 Link Failure Transmission

disturbance within 3

seconds or repeated

with 10 seconds the

call will be dropped.

Check MO SLIP2 counter (DIPS) increment

rate, this shows the number of transmission

dips.

15 No Best Server No dominant server,

maybe the coverage is

weak

See Low Signal Strength Analysis

8 Handover Problems

8.1 Handover Analysis Process Flow

Handover analysis

Check successful handovers per cell

Success below x%?

E

Select worst relation

External? Start Inter-BSC/MSC analysis

High ratio of urgency

handovers? High ratio of lost

handovers?

YES

YES

NO

Next cell High ratio of retensions?

NO NO

YES YES

Page 23: 2G Tuning Process Flow - DT Analysis
Page 24: 2G Tuning Process Flow - DT Analysis

8.2 No or few Handover Attempts

No or few handover attempts

Unnecessary

neighbouring cell

relations?

Unfortunate

parameter setting?

Remove unnecessary

relations

Rectify parameter

setting

BTS defined but

not in service?

Rectify parameter

setting

YES

YES

YES

NO

NO

Check neighbouring cell relations,use NCS if necessary

Check locating parameters

END

Check BTS definition

NO

8.3 No or few Handover Attempts troubleshooting table

Page 25: 2G Tuning Process Flow - DT Analysis

8.4 Unsuccessful Handovers Process Flow

Page 26: 2G Tuning Process Flow - DT Analysis

Unsuccessful

handovers

Check congestion

performance

TCH congestion?

Check SAE setting

NO

SW congestion?

Check Locating parameters

Check neighbouring cell definitions

Wrong cells

defined?

Missing

neighbours?

Too many

neighbours?

Too many

measurement

channels?

Strange or corrupt

parameter setting?

NO

NO

NO

NO

NO

Check use of radio

features

Add TCH capacity YES

Increase SAE YES

Remove incorrect

definitions YES

Run NCS, addmissing relation YES

Remove unnecessary

relations YES

Review and correct the

defined MBCCHNO YES

B

NO

Rectify parameters YES

B

NO

Are all radio

features used? YES

Check coverage

NO

Low SS on cell

border?

Perform drive test

YES Improve coverage

Check interference, run MRRand/or FAS; check ICM

YES

Bad quality? Reduce interference for

potential candidate YES

Delayed handover

decision

Check handover

parameters YES

Introduce unused

features

Timer expiry after

MS is lost?

NO

C

NO

Page 27: 2G Tuning Process Flow - DT Analysis

C

Check BTS Error Log

HW fault?

Check link quality

Transmission fault?

Swap & repair HW YES

NO

Improve transmission YES

Perform site visit

NO

Check antenna installation

Antenna connected to wrong feeder?

Incorrect downtilt?

Hidden antenna?

Bad antenna installation?

NO

NO

NO

Change feeder YES

Rectify tilting YES

Change antenna position

YES

Rectify installation YES

END

NO

Page 28: 2G Tuning Process Flow - DT Analysis

8.5 Unsuccessful Handovers Troubleshooting Table

Page 29: 2G Tuning Process Flow - DT Analysis

8.6 Handover Reversions Troubleshooting Table

8.7 Ping Pong Handovers Troubleshooting Table

Page 30: 2G Tuning Process Flow - DT Analysis

8.8 Inter MSC Handover Analysis

Page 31: 2G Tuning Process Flow - DT Analysis

Inter MSC HO Analysis

Check parameter setting in

either MSC or BSC

Check Exchange properties

Check Software version

Check Software File Congestion

SAE 500 Block MHIC, MHOC,MHO & MHOAP

Check link performance :

#7 Signalling Link Failure /Congestion

Check signalling Performance:

MAP signalling performance

Check ratio of Handover Command toHandover Attempts

Check all address definitions in MSC

Check all BSC definitions in the MSC

Check all software route definitions

in the MSC

Correct Problem

Page 32: 2G Tuning Process Flow - DT Analysis

9 GPRS Throughput Analysis

9.1 GPRS Throughput Troubleshooting Process flow

throughput

good?

congestion

blocking

high?

BLER voice traffic concurrent TBFs mobility

Yes

No

high? many

reconfigurations?many? high? high?

new frequency plan

coverage plan

Yes

dimensioningtimeslot

dimensioning

application

behaviour:

nothing to do!cell reselection

Yes Yes Yes Yes

TBF drop rate

high?

frequency plan

mobility

voice traffic

Yes

packet loss

high?

buffer size

traffic

quality of links

mobility

Yes

Yes

Yes

9.2 GPRS Throughput Troubleshooting Table

S.No Troubleshooting Steps

1 CHECK THE STATISTICS OF THE PROBLEMETIC CELL/AREA

2

IF THERE ARE MANY GPRS USERS, INCREASE CAPACITY/ DEDICATE MORE

TIME SLOTS FOR GPRS

3 CHECK IF COVERAGE IS GOOD OR NOT

4

CHECK RXQUAL IN THE AREA, AND IMPROVE THE RXQUAL, CHECK

FREQUENCY PLAN

5 CHECK TA

6

CHECK CELL RESELECTION PARAMETERS (C31/C32 IF PBCCH DEFINED)

AND TUNE ACCORDINGLY

7 CHECK AND OPTIMIZE POWER CONTROL PARAMETERS CAREFULLY

8 CHECK RAC AND LAC PLAN CAREFULLY, AND OPTIMISE IT ACCORDINGLY

9

CHECK GEOGRAPHICAL PLAN OF PCU, PROBLEM OCCURS IF THERE ARE

CELL RESELECTIONS IN CELLS WHICH ARE IN DIFFERENT PCU

10 CHECK THE CONGESTION ON Abis INTERFACE

11

CHECK IF THE PCU HAS BEEN EQUIPPED WITH SUFFICIENT CAPACITY OR

NOT

12 CHECK IF THERE ARE ENOUGH RESOURCES AVAILABLE AT Gb INTERFACE

Page 33: 2G Tuning Process Flow - DT Analysis

9.3 GPRS Parameters to Check for

NON_DRX_TIMER

Resource Allocation Methods

T3168

T3192Network Control Order

Format of

PACK_CTRL_ACK-Messages

BS_CV_MAX

Access Type

(One-Phase / Two-Phase)

ACCESS_BURST_TYPE

PAN_INC, PAN_DEC,

PAN_MAX

RLC

MAC

NON_DRX_TIMER

Resource Allocation Methods

T3168

T3192Network Control Order

Format of

PACK_CTRL_ACK-Messages

BS_CV_MAX

Access Type

(One-Phase / Two-Phase)

ACCESS_BURST_TYPE

PAN_INC, PAN_DEC,

PAN_MAX

RLC

MAC

Power control parameters like Alpha and Gamma should be checked.