2 OMU010000 GPRS Network Optimization Parameters ISSUE2.0(for External PCU)

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Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Parameters of GPRS Network Optimization

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Page1Copyright © 2009 Huawei Technologies Co., Ltd. All rights reserved.

Foreword

� The PCU performance parameters are essential to the

GPRS network. Proper setting of such parameters can

improve performance of the packet services.

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Contents

� GPRS Cell Parameters

�� Parameters of Cell ReselectionParameters of Cell Reselection

�� Performance ParametersPerformance Parameters

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GPRS Cell Parameters� NMO

� T3168

� T3192

� DRX_TIMER_MAX

� ACCESS_BURST_TYPE

� CONTROL_ACK_TYPE

� BS_CV_MAX

� PAN

� T3172

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NETWORK_MODE

PCHPCHCCCHCCCH

PPCHPCHYesNoIII

CCCHCCCHPCHPCHNoNoII

-PACCH

PCHPCH PACCHPCCCH

Or CCCH

PPCHPPCH

YesYesI

DedicatedIdle ModeGPRS Paging

Channel

Channel for circuit paging

Configure PCCH

Configure

GsNetwork

Mode

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T3168

T3168 is used to set the maximum duration for the

MS to wait for the packet uplink assignment message

PCU

PACKET CHANNEL REQUEST

PACKET UPLINK ASSIGNMENT/ IMMEDIATE ASSIGNMENT COMMAND

PACKET RESOURCE REQUEST

2000Bad

1000Good

500Very Good

T3168 recommendation（ms）Condiction

T3168 PACKET UPLINK ASSIGNMENT

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T3192

The timer is for the MS to wait for TBF release after receiving

the last data block.

PCU

T3192

PACKET DOWNLINK ACK/NACK （FAI=1）

PACKET DOWNLINK ASSIGNMENT

TFI

Final ACKIdentifier

20016012080015001000500value（ms）

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DRX_TIMER_MAX

The MS request keeps the maximum value of non-DRX mode.

Packet transmission mode

Non_DRX DRX

Packet idle mode

Non_DRX

DRX_TIMER_MAX (s)

64321684210Value（Sencond）

Packet idle mode

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Packet Signaling Processing

PACKET DOWNLINK ACK/NACK （FAI=1）

RLC DATA BLOCK (FBI)

RLC DATA BLOCK

T3192=500ms

Non DRX mode= 4s

DRX mode

DRX mode

Ready Mode

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ACCESS_BURST_TYPE

MS uses 8bit format or 11bit format in the following three types

of messages

� PACKET CHANNEL REQUEST

� PTCCH UPLINK BLOCK

� PACKET CONTROL ACKNOWLEDGMENT

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BS_CV_MAX

PCU

T3198

RLC DATA BLOCK

CV=X

RLC DATA ACK

RLC DATA BLOCK

CV=X

Timeout

设BS_CV_MAX=10

200ms

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BS_CV_MAX

PCU

MS buffer – UL RLC blocks

CV=0 CV=1 CV=2 CV=3 CV=15 CV=15 CV=15 CV=15

CV=0 CV=1 CV=2More data CV=3 CV=15 CV=15

suppose suppose suppose suppose BBBBS_CV_MAX=3S_CV_MAX=3S_CV_MAX=3S_CV_MAX=3

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PAN

� PAN_DEC Set the decrease step length of the N3102 counter of the MS

� PAN_INC Set the increase step length of the N3102 counter of the MS

� PAN_MAX Set the maximum value of the N3102 counter of the MS

Packet Uplink Ack/NackN3102

PAN_MAX

- PAN_DEC

+ PAN_INC

Abnormal Release

T3182

T3182

T3182 T3182

T3182

Perform Cell Re-selection

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PAN

PCU

N3102+2

RLC DATA BLOCK

PACKET DATA ACK

Timeout

设PAN_INC=2

RLC DATA BLOCK

PACKET DATA ACKT3182

设PAN_DEC=1

N3102- 1

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T3172

WAIT_INDICATIONWAIT_INDICATIONWAIT_INDICATIONWAIT_INDICATION

PCU

T3172


PACKET ACCESS REJECT


PACKET ACCESS REJECT

T3172

Phase I

Phase II



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Compare with GSM

T3122T3172

RLT(SACCH Mul-frame)PAN

ST3168

GSMGPRS

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Contents




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NETWORK_CONTROL_ORDER

Controlled by network

Only ReadyYesNetwork Control Mode

NC2

Controlled by MS

Only ReadyYesMS Control with M.R Mode

NC1

Controlled by MS

Ready & Standby

NoNormal MS Control Mode

NC0

Cell Selection Mode

MS modeWhether the MS send the

M.RDescription

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NC2 Feature NC2 Feature

Serving cell A

Neighbor cell B

Neighbor cell c

change to cell C

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GPRS Cell Selection

If no PBCCH channel exists, the cell reselection of GPRS is

basically the same as GSM cell reselection, only two

situations are different.

� when the MS on the standby mode ,if it occur the cell

reselection to the other route area cell : NC2>SC2+CRH

� when the MS on the ready mode ,if it occur the cell

reselection :NC2>SC2+CRH

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GPRS Cell Change on Standby ModeGPRS Cell Change on Standby Mode

NC2 > SC2+CRH

RA 1 RA 2

Cell A

Cell B

Cell C

AC2>BC2 CC2>BC2＋CRH

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GPRS Cell Change on Ready ModeGPRS Cell Change on Ready Mode

NC2 > SC2+CRH

BC2>AC2＋CRHRA 1

Cell A Cell B

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NACC

Set this parameter to Yes only when the cell supports GPRS services.

This parameter requires the support of licenses.

Remarks

This parameter indicates whether the cell supports the Network

Assisted Cell Change (NACC) function. The NACC function means

that the network notifies the MS (in the packet transmission state)

of the system information about the neighboring cells in advance in

NC0, NC1, or NC2 network control mode. Thus the cell reselection

of the MS is quickened. The BSC plays a minor role in the NACC

function. It sends the system information about the cell and the

information about the neighboring cells to the PCU instead of

participating in the NACC processing.

Description

Yes, NoValue Range

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NACC

Cell ACell B

System information of cell B

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ALPHA & GAMMA� ALPHA

� The ALPHA parameter is used by the MS to calculate the output power value PCH

of its uplink PDCH

� For open loop power control, it should be set to 1.0.

A=0.10A=0.9……A=0.2A=0.1A=0.0ALPHA Value

10101001……001000010000codec

� GAMMA

� Expected receiving signal strength at the BTS side when the MS GPRS dynamic

power control is active

� Value range: 0~62dB, default value is 0

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ALPHA & GAMMA� According GPRS principle, GPRS MS output power as below：

Pch = Min〔 Ro - Rch – a*( C+48) , Pmax〕

Pmax: GPRS MS max transmitting power:29dBm

a：ALPHA，normally is 1

Ro：BTS max transmitting power:39dBm

Rch：GAMMA

C：MS receiving level

If there is power control，Ro - Rch – a*( c+48) < Pmax

39－GAMMA －C－48<Pmax

C> -38－GAMMA

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ALPHA & GAMMA

So if GAMMA=0，power control will be triggered when the receiving level higher than －38dB. But in the project network, normally receiving level lower than -38dB.

The recommended value is 14，each unit is 2dB，so －38－2X14＝－66dB，when the MS receiving level higher than -66dB, power control will be triggered.

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Contents




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RAC

Route Area Code

� When RAC and LAI appear concurrently, the RAC is unique

� When CI and LAI or RAI appear concurrently, the CI is unique

RAI = MCC+MNC+LAC+RAC

LA

RA RA

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RAC

Route Area Update

� When an MS to which the GPRS is attached discovers that it

gets into a new routing area

� After timeout of the periodical Routing Area (RA) timer T3312

� When a “suspended” MS is not “recovered” by network

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T3312

Routing_Area_update_request

Routing_Area_update_accept

Routing_Area_update_complete

RA1RA1RA1RA1RA2RA2RA2RA2

SGSN

Ready or StandbyIncluding T3312

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GPRS Coding SchemeA configuration command that sets the GPRS coding scheme of a cell

Meaning: default CS type of the uplink

Value range: cs1, cs2, cs3, cs4

Explanation: default CS type of the uplink. To dynamically adjust the

CS type of the uplink, set the CS type for transmitting the first TBF

through this parameter. Then, the CS types of other TBFs are

dynamically adjusted based on the signal transmission quality. Default

value: cs1

UpDefaultCs

Meaning: fixed CS type of the uplink

Value range: cs1, cs2, cs3, cs4, unfixed

Explanation: fixed CS type of the uplink. To adopt the fixed CS type of

the uplink, set this parameter to CS-1, CS-2, CS-3, or CS-4. To

dynamically adjust the CS type of the uplink, set this parameter to

unfixed. Default value: unfixed

UpFixCs

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GPRS Coding Scheme

Meaning: default CS type of the downlink

Value range: cs1, cs2, cs3, cs4

To dynamically adjust the CS type of the downlink, set the CS type

for transmitting the first TBF through this parameter. Then, the CS

types of other TBFs are dynamically adjusted based on the signal

transmission quality.

Default value: cs2

DnDefaultCs

Meaning: retransmission rate threshold for the uplink TBF to

change from CS-1 to CS-2

Value range: 0-64

Explanation: When the retransmission rate of the uplink TBF is

smaller than or equal to the value of this parameter, the code

scheme of the uplink TBF changes from CS-1 to CS-2.

Default value: 5

UpThdCsUpGrade1

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GPRS Coding Scheme

UpDefaultCs:CS2

UpThdCsUpGrade1:5

UpThdCsUpGrade2:3

UpThdCsUpGrade3:2

CS1

CS4

CS3

CS2Retrans rate:2

UpThdCsUpGrade3:5

UpThdCsUpGrade3:5

UpThdCsUpGrade3:10

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PDCH Channel Parameters

Value range: 10-80

Explanation: Downlink multiplex threshold of dynamic channel

conversion

Default value: 20

Downlink Multiplex

Threshold of Dynamic

Channel Conversion

Value range: 10-70

Explanation: Uplink multiplex threshold of dynamic channel

conversion. When the number of subscribers reaches this

threshold, the dynamic channels are used. If this threshold is

high, it is difficult to seize dynamic channels. If this threshold is

low, it is easy to seize dynamic channels.

Default value: 20

Uplink Multiplex

Threshold of Dynamic

Channel Conversion

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Value range: 10-80

Explanation: The maximum downlink TBFs on one PDCH

channel

Default value: 80

PDCH Downlink

Multiplex Threshold

Value range: 10-70

Explanation: The maximum downlink TBFs on one PDCH

channel. If this threshold is set to a higher value, the TBFs

established on the PDCH and the subscribers are more,

and the uplink bandwidth for each subscriber is lower.

Value 10 indicates a maximum of one TBF can be

established on the PDCH.

Default value: 70

PDCH Uplink

Multiplex Threshold

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Downlink Multiplex Threshold of Dynamic Channel Conversion:20

PDCH PDCH PDCH PDCH Dynamic PDCH

Dynamic PDCH

Dynamic PDCH

Dynamic PDCH

MS1

MS2

PDCH PDCH PDCH PDCH

MS3

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PDCH Channel ParametersPD

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GPRS Channel Priority TypePD

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GPRS Channel Priority Type

When Channel Type is set to non-PDTCH, the default value is None-GPRS

Channel.When Channel Type is set to PDTCH and the cell does not support EDGE

services, the default value is EGPRS Normal Channel.When Channel Type is set to

PDTCH and the cell supports EDGE services, the default value is EGPRS Normal

Channel.

Description

When Channel Type is set to non-PDTCH, the default value is None-GPRS

Channel. When Channel Type is set to PDTCH and the cell does not support

EDGE services, the default value is EGPRS Normal Channel. When Channel Type

is set to PDTCH and the cell supports EDGE services, the default value is EGPRS

Normal Channel.

Default Value

GPRS Channel, EGPRS Normal Channel, EGPRS Priority Channel, EGPRS

Special Channel, None-GPRS Channel

Value Range

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TRX2

EGPRS

Normal

EDGE MS GPRS MS

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TRX2

EGPRS

Priority

EDGE MS

××××reject

EGPRSPriority

GPRS MSGPRS MS

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TRX2

EGPRS

Priority

GPRS MSEDGE MS

××××release

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EDGESPARAPD

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EDGESPARA� EDGE codec will be dynamically adjusted the MCS depended on BEP.

� BEP：Bit Error Probability .Each radio block is consist of 4 bursts, there is a BEP

value for each block, such as BEP1，BEP2，BEP3，BEP4.

� Mean-BEP is the average of four BEPs, from BEP1 TO BEP4. MEAN_BEP=

（BEP1+BEP2+BEP3+BEP4）/4. So Mean-BEP is the average quality of

receiving signal.

� CV_BEP is the result of standard deviation. It shows us the stability of receiving

quality.

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BEP Table

MCS-7MCS-7MCS-7MCS-7MCS-7MCS-7MCS-6MCS-615














MCS-5MCS-5MCS-5MCS-5MCS-5MCS-5MCS-5MCS-518PSKMEANBEP

87654321

8PSK_CV_BEP BEP

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EDGESPARA

Meaning: fixed MCS type of the uplink

Value range: MCS1-MCS9, unfixed

Explanation: To adopt the fixed MCS type of the uplink,

set this parameter to a value among MCS1-MCS9; to

dynamically adjust the MCS type of the uplink, set this

parameter to unfixed. Default value: unfixed

UpFixMcs

Meaning: link quality control mode

Value range: IR-0, LA-1

Explanation: link quality control mode Default value: LA

LqcMode

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LA and IR

� The network dynamically adjusts the coding scheme EDGE

based on the link quality. The link quality is determined by

8PSK MEAN BEP and 8PSK CV BEP carried in the Packet

EGPRS Downlink Ack/Nack message.

� The network should retransmit different data blocks with the

puncturing coding scheme. The MS buffers the history error

information and the data blocks are retransmitted through

combined error correction.

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EDGESPARA

Meaning: fixed MCS type of the downlink


DnDefaultMcs

Meaning: default MCS type of the uplink

Value range: MCS1-MCS9

Explanation: To dynamically adjust the MCS type of the

downlink, set the MCS type for transmitting the first TBF

through this parameter. Then, the MCS types of other TBFs

are dynamically adjusted based on the signal transmission

quality. Default value: MCS3

UpDefaultMcs

Meaning: fixed MCS type of the downlink


DnFixMcs

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N3101

M S Network

A

RLC block(with USF valid)

RLC block (with USF valid)

NO RESPONSE FROM MS

N3101=N3101_MAX

� N3101 will be increased by 1 every time no uplink data block is received.� The TBF will be released by network if N3101 reaches the threshold.

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N3103

M S Network

A

PACKET UPLINK ACK/NACK(FAI=1)

NO RESPONSE FROM MS

N3103=N3103_MAX

PACKET UPLINK ACK/NACK(FAI=1)

� N3103 will be incremented by 1 every time no “ACKOWNLEDGEMENET”

message is received during TBF release.

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MS Network

A

DOWNLINK DATA BLOCK (RRBP)



MS no response.....

N3105� Network will send the RLC data block with RRBP periodically to wait response

message from MS. N3105 will be increased by 1 every time no ” PACKET DOWNLINK

ACK/NACK” is received , otherwise N3105 will be reset.

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GPRS&EDGE Coding Scheme

8PSKGMSK

9.05

13.415.6

21.4

8.811.2

14.817.6

22.4

29.6

44.8

54.4

59.2

0.00

10.00

20.00

30.00

40.00

50.00

60.00

CS-1 CS-3 CS-4 MCS-1 MCS-2 MCS-3 MCS-4 MCS-5 MCS-6 MCS-7 MCS-8 MCS-9

Kbps

GPRS

EGPRS

CS-2

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Appendix

1+31+21+11+0Idle timeslot

MCS9MCS8MCS7MCS6MCS5MCS4MCS3MCS2MCS1

CS4CS3CS2CS1Codec

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AppendixPD

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Summary

In this course, we have learned:

� The function of GPRS cell parameters

� The function of GPRS cell selection parameters

� The function of GPRS performance parameters

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2 OMU010000 GPRS Network Optimization Parameters ISSUE2.0(for External PCU)

Documents

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egprs normal

seize dynamic

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packet idle

dynamically

rlc data block

fixed cs type