gprs edge optimizaftion2

04/18/2023 Prepared by Mohyedeen Alkousy 1

GPRS/EDGE Optimizationin Huawei Networks


1. Introduction

2. GPRS/EDGE problems classification

3. GPRS/EDGE Simplified Optimization plan

4. Main KPIs Used in Monitoring

5. Resolving Air Interface Bottlenecks

6. Resolving Abis Interface Bottlenecks

7. BSC Hardware and License limitations

8. GB Link Utilization

Topics Presented


• Resolving quality issues improve both CS and PS quality related KPIs

• On the other hand capacity issues on the PS need a dedicated effort and not necessarily will improve with CS.

• Optimizing the PS KPIs depend on finding the largest bottleneck and resolve it , that way the accessibility, the drop and the throughput improve ,and the traffic increase

GPRS/EDGE Optimization


GPRS/EDGE problems classification

Capacity related issues

• Radio interface: number of fixed PDCHs , percentage of dynamic PDCHs ,number of TBFs per PDCH.

• Abis interface: fix ,flex or abis over ip. Number of idle timeslots available.

• Gb interface : GB bandwidth available for use .

• BSC hardware capability: CPU processing, number of DPU boards

• BSC license capability: number of licensed EDGE TRXs , number of licensed PDCHs timeslots.CS3CS4 license. EDGE+ features

Quality related issues

• internal/external interference issues.

• Bad coverage issues.• Abis stability and quality related

issues.• Clock and Synchronization issues• Radio wrong configuration issues.• Hardware fault issues.


GPRS/EDGE Simple Optimization Plan

Resolving Air Interface Bottleneck Capacity study of the air interface , based on resources utilization , congestion and current configuration and list of actions will be proposed

Resolving abis Interface Bottleneck Capacity study of the abis and BSC resources , based on resources utilization , congestion and current configuration and list of actions will be proposed

Resolving BSC and GB Link BottlenecksCapacity study of the abis and BSC resources , based on resources utilization , congestion and current configuration and list of actions will be proposed


Points of bottlenecks

• Bottlenecks can exist in any interface or any NE• Each bottleneck should be resolved starting from the

radio interface and moving upward.• The bottlenecks will be resolved as a serial sequence and

not in parallel to avoid re-dimensioning and over or under utilization results.

PDCHs EDGE TRXs

Abis bandwidth

DPUs and License

GS bandwidth

Processing and license

Um Abis Gs


Counters related to congestion

function name counter namePacket Switch Call

MeasurementA9303:Number of Failed Downlink EGPRS TBF Establishments due to No

ChannelPacket Switch Call

Measurement A9309:Number of Downlink EGPRS TBF Abnormal Releases due to No Channel

Packet Switch Call Measurement A9103:Number of Failed Downlink GPRS TBF Establishments due to No Channel

Packet Switch Call Measurement A9109:Number of Downlink GPRS TBF Abnormal Releases due to No Channel

Packet Switch Call Measurement A9203:Number of Failed Uplink EGPRS TBF Establishments due to No Channel

Packet Switch Call Measurement A9210:Number of Uplink EGPRS TBF Abnormal Releases due to No Channel

Packet Switch Call Measurement A9003:Number of Failed Uplink GPRS TBF Establishments due to No Channel

Packet Switch Call Measurement A9010:Number of Uplink GPRS TBF Abnormal Releases due to No Channel


Counters related to quality

Function Name Counter NameMeasurement of GSM Cell Performance

A9304:Number of Failed Downlink EGPRS TBF Establishments due to MS No Response

Measurement of GSM Cell Performance

A9315:Number of Failed Downlink EGPRS TBF Establishments due to Other Cause


A9204:Number of Failed Uplink EGPRS TBF Establishments due to MS No Response

Measurement of GSM Cell Performance A9216:Number of Failed Uplink EGPRS TBF Establishments due to Other Cause


A9306:Number of Downlink EGPRS TBF Abnormal Releases due to N3105 Overflow


A9317:Number of Downlink EGPRS TBF Abnormal Releases due to Other Cause


A9206:Number of Uplink EGPRS TBF Abnormal Releases due to N3101 Overflow (MS No Response)


A9207:Number of Uplink EGPRS TBF Abnormal Releases due to N3103 Overflow (MS No Response)

Measurement of GSM Cell Performance A9218:Number of Uplink EGPRS TBF Abnormal Releases due to Other Cause


GPRS/EDGE main KPIs

DL TBF Establishment Success Rate

• ([Number of Successful Downlink GPRS TBF Establishments]+[Number of Successful Downlink EGPRS TBF Establishments]) x {100}/{[Number of Downlink GPRS TBF Establishment Attempts]+[Number of Downlink EGPRS TBF Establishment Attempts]}

DL TBF Drop Rate

• {[Number of Downlink GPRS Intermit Transfers]+[Number of Downlink EGPRS Intermit Transfers]} x {100%}/{[Number of Successful Downlink GPRS TBF Establishments]+[Number of Successful Downlink EGPRS TBF Establishments]}


GPRS/EDGE main KPIs

Average Throughput of Downlink GPRS LLC per User(kbps)

• [Throughput of Downlink GPRS Users LLC PDU]/([Total Bytes of Downlink GPRS Users LLC PDU] x {8}/{1024})

DL LLC Data Volume (GB)

• {[Number of Downlink GPRS Intermit Transfers]+[Number of Downlink EGPRS Intermit Transfers]} x {100%}/{[Number of Successful Downlink GPRS TBF Establishments]+[Number of Successful Downlink EGPRS TBF Establishments]}


Resolving bottleneck issues:

Um Interface

Topics Presented


• Vertical vs Horizontal Allocation: Huawei give priority to horizontal allocation.

• The recommended Huawei setting is to convert the idle TCHs to dynamic PDCH if the number of TBF exceed 2 (Parameter: DWNDYNCHNTRANLEV)

• Number of idle timeslots should not be less than 2.• The percentage of converted TCHs to Dyn-PDCH will not exceed the

parameter MAXPDCHRATE

PDCH and TBF Allocation Method

PDCHTCHTCHTCHTCHTCHTCHTCH

TBF1

TBF2

TBF3


1. Extract the following counters to specify the top cells which suffer from radio resource congestion:• Counters:

Resolving bottleneck issues: Radio Interface

Counter DescriptionCR3001:Number of Initially Configured Channels (Static PDCH)AR9303:Average Number of Available PDCHsAR9311:Average Number of Occupied PDCHsR9344:Number of Reclaimed Busy Dynamic PDCHsR9346:Number of Dynamic PDCH Requests Without Application Attempts Because the Number of Activated PDCHs Reaches Board SpecificationR9347:Number of Dynamic PDCH Requests Without Application Attempts Because No Abis Timeslot is Available for UseR9393:Number Of PDCH Application AttemptsR9394:Number of PDCH Application Failures due to no Convertable TCHsR9395:Number of PDCH Application failures For CELL PDCH Ratio Thresh


2. Extract the following counters and parameters to specify the top cells which suffer from radio resource congestion:• Parameters:


MO Parameter ID Parameter Name Recommended Value

GCELLIDLEBASIC PI Cell Reselect Parameters Indication YES

GCELLIDLEBASIC CRO Cell Reselect Offset 0

GCELLPSCHM MAXPDCHRATE Maximum Rate Threshold of PDCHs in a Cell 30

GCELLPSCHM UPDYNCHNTRANLEV Uplink Multiplex Threshold of Dynamic Channel Conversion 20

GCELLPSCHM DWNDYNCHNTRANLEV Downlink Multiplex Threshold of Dynamic Channel Conversion 20

GCELLPSCHM PDCHUPLEV PDCH Uplink Multiplex Threshold 70

GCELLPSCHM PDCHDWNLEV PDCH Downlink Multiplex Threshold 80

GTRXBASE MAXPDCHNUM Maximum Number of PDCH 8GTRXCHAN GPRSCHPRI PDCH Channel Priority Type EGPRSNORCH


• If the counter R9394:Number of PDCH Application Failures due to no Convertable TCHs is showing high values it means we have congestion on the number of PDCH due to lack of Idle TCH , we need to do the following :

1. Confirm that there is no TRX availability or Cell availability issues.

2. Check CS+PS utilization and check number of Dyn-PDCH and Stat-PDCH. if the CS+PS utilization is approaching 90 % frequently it means we need to perform TRX expansion on this sector for PS congestion



If the counter R9395:Number of PDCH Application failures For CELL PDCH Ratio Thresh is showing high values it means we have congestion on the number of PDCH due to parameter MAXPDCHRATE, we need to do the following :

1. Confirm that the license of Number of PDCHs in BSC level is not already exceeded (alarm should be raised in that case).

2. Increase the value of the parameter MAXPDCHRATE until the counter stops showing any failures



If the counter [R9346:Number of Dynamic PDCH Requests Without Application Attempts Because the Number of Activated PDCHs Reaches Board Specification] is showing high values it means we have congestion on the number of PDCH due to DPU board limitation on BSC , we need to do the following :

1. Check the available and occupied PDCH on BSC level and compare it to the number of DPU boards *1024 (each Board support 1024 PDCH)

2. Add additional DPU boards if needed.3. If adding board is not possible , then check if we have high

number of Fixed PDCH in the network. If yes then decrease the number of fixed PDCH to allow for more Dyn-PDCH to work.



Hardware development in BSC6900

DPU version C

•Provides the speech format conversion and data forwarding functions.• Encodes and decodes voice

services.•Provides the Tandem Free

Operation (TFO) function.• Supporting 960 TCH/Fs.

DPU version F

•Provides the speech format conversion and data forwarding functions.• Encodes and decodes voice

services.•Provides the Tandem Free

Operation (TFO) function.• Supporting 1,920 TCHFs.

DPUc DPUf

DPUd DPUg

DPU version D

•1,024 simultaneously active PDCHs where signals are coded in MCS9

DPU version G• Less power consumption• 1,024 simultaneously active PDCHs

where signals are coded in MCS9


Resolving bottleneck issues:

Abis Interface

Topics Presented


Differences between Fixed Abis , Flex-Abis and Abis over IP :

Fixed-Abis :

Resolving bottleneck issues: Abis Interface

BCCH

SDCCH

PDCH

TCH

Radio Interface

Abis Interface



Flex-Abis :


BCCH

SDCCH

PDCH

TCH

Radio Interface

Abis Interface



Abis Over IP :


BCCH

SDCCH

PDCH

TCH

Radio Interface

Abis Interface

Bandwidth


• Main counters can be used:


Counter Name ForR9109:Number of Unsuccessful Application Attempts of Abis Timeslot Because of no Idle

Timeslot Fix-AbisA9336:Number of Abnormal Downlink EGPRS TBF Releases due to Abis Resource Preemption Flex-AbisA9138:Number of Abnormal Downlink GPRS TBF Releases due to Abis Resource Preemption Flex-AbisA9238:Number of Abnormal Uplink EGPRS TBF Releases due to Abis Resource Preemption Flex-AbisA9040:Number of Abnormal Uplink GPRS TBF Releases due to Abis Resource Preemption Flex-Abis

L1151A:Mean number of occupied timeslots on the Abis interface Flex-AbisR2741:Number of Available Flex Timeslots Flex-Abis

R2742:Number of Faulty Flex Timeslots Flex-AbisT66007:Maximum Number of Occupied Flex Timeslots Flex-Abis

T66008:Average Number of Available Flex Timeslots Flex-AbisR9101:Number of Application Attempts of Abis Timeslot Flex-Abis

R9102:Number of Successful Application Attempts of Abis Timeslot Flex-Abis


• Main Parameters can be used:


MO Parameter ID Parameter Name Recommended Value

BTS FLEXABISMODE Flex Abis Mode FIX_16K_ABISBTS MPMODE Multiplexing Mode MODE4_1

BTSFLEXABISPARA ABISRESADJTCHHFUNSW TCHH Function Switch YES

BTSFLEXABISPARA PRIORABISLOADTHRED Flex Abis Prior Choose Load Thred 8020

BTSIDLETS TSCOUNT Idle TS Count As needed


Depending on the purchased features and number of E1s in each site , different actions can be taken.• in case Flex-abis , HDLC and abis over IP are not available , then the

only mode working will be fixed abis :1. Check the parameters MPMODE , and make sure its put as 4:1 in

order to efficiently use the resource , to avoid congestion on signaling we need to activate MR preprocessing on BTS.

2. Check the counter R9109:Number of Unsuccessful Application Attempts of Abis Timeslot Because of no Idle Timeslot , if it shows large values, then maybe the abis interface need dimensioning.

3. Check the bts summary report from the CME . If there are considerable amount of unused timeslots , then we need to configure them as idle timeslots.

4. If no un used time slots is available , then abis expansion is needed to resolve the issue of congestion on abis



In case flex-abis can be activated . Then1. Check the counters :R9101:Number of Application

Attempts of Abis Timeslot and R9102:Number of Successful Application Attempts of Abis Timeslot to calculate the abis application success rate . If the rate is very low :

2. Check the number of idle timeslots . The number of idle timeslots should equal to four times the number of fixed pdchs , no more no less.

3. If the number of idle timeslots is correct , then check if there is any faulty flex timeslots, if yes then these faulty flex timeslots should be cleared.

4. If no faulty flex timeslots ,then the abis expansion is necessary to resolve this issue.



BSC Hardware and license limitations

Topics Presented

gprs edge optimizaftion2

Documents

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