2 Key Parameters About GSM Performance：Suggested Default Values + Check Tools + Deliverables...

7/28/2019 2 Key Parameters About GSM Performance Suggested Default Values + Check Tools + Deliverables 20100730

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

Security Level:2013/7/9

Prepared by: Zha Shuangliu

Reviewed by: Qi Haofeng

key Parameters About GSM Performance

Suggested Default Values + Check Tools +

Deliverables

July 30, 2010


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2

Abstract

This document introduces the suggested default values of

seven categories of key parameters in a GSM network (coverage

parameters, interference reduction parameters, accessibility

parameters, handover parameters, time delay parameters,

throughput parameters, and voice parameters), tells how to

check the default values (involved tools), lists the deliverables

that should be submitted, and explains why the parameters in

the existing network are set inconsistent with the reasonable

range.


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R&D Support

For why these default values are set for these key parameters and what will be the result if

values that are inconsistent with the default values are set, we can provide trainings and 7*24

hour technical support.

List of R&D Technical Support Engineers

Name ID Phone

Zha Shuangliu 57469 021-38902812/13601726216


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Contents

Coverage Key Parameters

Interference Reduction Key Parameters

Accessibility Key Parameters

Handover Key Parameters

Time Delay Key Parameters

Throughput Key Parameters

Voice Key Parameters

Matching Versions


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Summary of Coverage Key Parameters


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Coverage Key Parameters

Coverage Parameters:

Uplink: RACH Min. Access Level (dBm)

Downlink: Minum Access RXLEV

Basic Principle:

Uplink: To reduce unreasonable accesses, the BTS restricts the level of the RACH

reported by the MS.

Downlink: The MS resides in the cell only when it detects that

the level of the signals from the BTS is higher than this value.

Parameter Effect:

Uplink/downlink: Too great value may cause the MS fails to make a call even if signals are

available. Too small value, however, may cause too many error accesses and cannot guarantee

the basic voice quality.

Suggested Parameter Settings: RACH Min. Access Level (dBm): -109 dBm

Minum Access RXLEV: 8. Check range: [0,12].

Remarks: The sensitivity difference between the MS and the BTS is 6 dB to 8 dB.


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Multi-Density TRX Power Sharing

Parameters Related to Multi-Carrier Power Allocation (MCPA):

Multi-Density TRX Power Sharing (affect the coverage)

Channel Assign Allow for Insuff Power (affect the congestion rate)

Basic Principle:

Multi-Density TRX Power Sharing: The core idea of this parameter is to implement power sharing

between several TRXs at a timeslot according to the distance between users and the BTS. The purpose

of this parameter is to allow some channels to have a maximum output power greater than the average

available power of TRXs. Multi-density TRX power sharing is implemented based on multi-density TRX

boards. The feature of a multi-density TRX board is that multiple TRXs share one power amplifier andthe maximum output power of the power amplifier varies with the number of available TRXs.

Channel Assign Allow for Insuff Power: This parameter allows channel assignment even if only

insufficient power is available at a timeslot.

Suggested Parameter Settings:

Multi-Density TRX Power Sharing: It is recommended to set this parameter to Dynamic when the multi-

density TRXs in the existing network are configured with a power larger than the rated power. Thisreduces unnecessary power decrease and thus avoids poor user experience and indicator deterioration.

Channel Assign Allow for Insuff Power: It is recommended to set this parameter toYes when the multi-

density TRXs in the existing network are configured with a power larger than the rated power. This

reduces congestions of TCH resources.


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Summary of Interference Reduction Key Parameters


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DTX-Related Parameters

Parameters Related to Discontinuous Transmission (DTX):

Uplink: TCH/F Uplink DTX, TCH/H Uplink DTX

Downlink: TCH/F Downlink DTX, TCH/H Downlink DTX

Basic Principle:

The DTX function allows the transceiver to stop transmitting power when no voice signal is transferred.

Parameter Effect

1. Uplink: This parameter reduces the power consumption of the MS and intra-system

interference.

2. Downlink: This parameter reduces the power consumption of the BTS, intra-systeminterference, and intermodulation within the BTS.

3. Summary: For the entire network, this function reduces frequency interference and

improves the network quality.


Uplink: Shall_Use (Be sure to use uplink and downlink DTX if it is supported by the MS)

Downlink: Yes (enable downlink DTX on the BSC)

Constraints:

Uplink DTX: Controlled by the BSC.

Downlink DTX: Determined by both the MSC and the BSC (You can check whether this function is

enabled for the core network according to the assign messages.


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Parameters Related to Power Control

Parameters Related to Power Control:

UL PC Allowed/DL PC Allowed

Power Control Algorithm Switch

III Power Control Optimization Algorithm Switch

Basic Principle:

Power control: This function reduces the uplink/downlink transmitting power

when the uplink/downlink signals are strong.

This reduces the interference of the entire network.

Remarks: Similar to the principle of implementing power control of partners,

3.5-generation power control algorithm also implements

power control based on the quality.


Currently, 3.5-generation power control algorithm is widely promoted globally.

To support this algorithm, it is required to enable both the III power control algorithm switch

and the III power control optimization algorithm switch.

If only the III power control algorithm switch is enabled, III power control algorithm is used.


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EICC

Parameters Related to Enhance Interference Cancellation Combining (EICC)

STIRC Allowed

Basic Principle:

Among signals received by dual antennas, the interference is related to both the space

(between antennas) and the time. The EICC function considers both the relation between

interference and space and the relation between interference and time. In this way, it

suppresses interference more effectively and improves the voice quality.


STIRC Allowed: Yes when serious interference exists.


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Summary of Accessability Key Parameters


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Accessability-Related Parameters

Accessability Parameters:

Allow Reassign/Assignment Cell Load Judge Enable

Level of Preempting Dynamic Channel

BSS Paging Co-ordination/A Interface Paging Co-ordination Switch

Channel Assign Allow for Insuff Power (see the description of Multi-Density TRX Power Sharing)

Basic Principle:

Reassign: When the BSC fails to assign a TCH to the MS for the first time, this function allows the BSC to attempt to

assign another TCH for the MS.

Preempting Dynamic Channel: This function allows the MS to preempt PS resources for CS services when CS services

are congested. This improves the connection rate of CS services.

Paging Co-ordination: This function allows delivering CS paging messages through the PACCH when the MS is dealing

with PS services while CS paging messages arrives.

This ensures that the MS can be paged and improves the paging success rate.

Parameter Effect:

Reassign: This parameter improves the experience of users, connection rate, and the assignment success rate.

Preempting Dynamic Channel: This parameter improves the experience of user to CS services, connection rate, and

assignment success rate. Paging Co-ordination: This parameter improves the experience of users and paging success rate.


Allow Reassign: Yes; Assignment Cell Load Judge Enable: Disable

Level of Preempting Dynamic Channel: LEVEL0

BSS Paging Co-ordination/A Paging Co-ordination Switch: It is recommended to set both parameters toYes when no Gs

interface is available.


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Handover-Related Parameters


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Measurement Report Type/MR.Preprocessing

Intracell F-H HO Allowed

Min UL/DL Level on Candidate Cell

PN of PBGT HO and PN of Inter-layer HO

Basic Principle

Measurement Report Type: It is recommended not to use enhanced measurement reports because such a measurement report

is not supported by the terminal currently.

MR.Preprocessing: This parameter determines to conduct power control on the BTS after the measurement report is

preprocessed. In addition, this parameter also affects the accuracy of handover decisions.

Intracell F-H HO Allowed: This parameter allows F-H HO for AMR calls when the C/I is high.

Min UL/DL Level on Candidate Cell: According to M rule, when selecting candidate cells, the BSC first filters out the unqualifiedcandidate cells. For a candidate cell, its uplink/downlink power should be greater than or equal to the minimum uplink/downlink

power of the target cell. The uplink/downlink power of a candidate cell is estimated based on the principle that the uplink power

and the downlink power should be in balance.

PN of PBGT HO and PN of Inter-layer HO: If this parameter is set with a too small value, poor experience may be the result.

Therefore, you cannot improve the handover success rate by increasing the number of handovers.


Measurement Report Type: ComMeasReport; MR.Preprocessing: BSC_ Preprocessing

Intracell F-H HO Allowed: It is recommended to set this parameter toYes for areas where AMR is enabled to improve the

experience of users.

Min DL Level on Candidate Cell: 10 for the entire network. Check range: [10, 15].


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Summary of PS Time Delay & Throughput Key Paramete


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PS Time Delay & Throughput Parameters

PS Time Delay Parameter:

Move Immediate Assignment Down to BTS

PS throughput Parameters: Network Control Mode

Support EGPRS Uplink MCS Dynamic Adjust, Uplink/Downlink Fixed CS Type, Uplink/Downlink Fixed MCS Type

AQM Switch

Flush_LL PDU Transfer Switch

Level of Preempting Dynamic Channel, Alloc Continue Timeslot Switch, Resource Reallocation to Different TRXs


Network Control Mode: NC0. NC1 only increases the uplink traffic based on NC0. NC2 is not fully verified yet.

Support EGPRS Uplink MCS Dynamic Adjust: 2(According to uplink quality measurements reported by BTS). This is becausethe uplink BEP estimated based on the downlink BEP may be incorrect.

Uplink/Downlink Fixed CS Type, Uplink/Downlink Fixed MCS Type: It is recommended to set these parameters to UNFIXED to

achieve the optimum uplink/downlink rate.

AQM Switch: It is recommended to set this parameter to CLOSE because it is not fully verified.

It is recommended to set this parameter to OPEN to allow an old cell to send unfinished data to a new cell. This improves the

rate.

Level of Preempting Dynamic Channel: LEVEL0(Preempt all dynamic TCHs). Check range: do not set this parameter to

LEVEL2 (No preempt of service TCHF). When CS services are congested, channels for PS services can be preempted.

It is recommended to set this parameter to OPEN to guarantee the channel resources for PS services. It is recommended to set this parameter to ALLOW because if this parameter is set to NOTAllow, resource congestion may be

caused.


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Optimization of PACK Block Retransmission

Parameter Related to Optimization of PACK Block Retransmission

Support Downlink TBF Schedule Optimize

Basic Principle:

According to the original algorithm, only the first PACK block is retransmitted. After the

optimization, all PACK blocks are retransmitted in turn. This improves the download rate

by taking advantage of the time for waiting for ACK.

Suggested Parameter Setting: Support Downlink TBF Schedule Optimize: Yes


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Summary of Voice Key Parameters


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Voice-Related Parameters

Voice-Related Parameters:

Speech Version

AMR Rate Control Switch

AMR Uplink Adaptive Threshold Allowed

Basic Principle:

AMR (speech version 3) is a new coding technology after EFR, FR, and HR. The core idea

of this technology is to achieve the best balance between the voice quality and systemcapacity by constantly adjusting the uplink and downlink speech coding modes according

to the changes in uplink and downlink signal quality over the air interface of the GSM

network.

AMR Rate Control Switch: Algorithm I selects the coding rate according to the C/I and

algorithm II selects the coding rate according to the BER.


Speech Version: Be sure to check the speech version if AMR is enabled by the carrier.

AMR Rate Control Switch: ALG I.


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Parameters Related to Improving the Voice

Performance

Parameters Related to Improving the Voice Performance in Poor Coverage

BTS software parameter 53

Basic Principle:

AMR Error Frame Filter: When the AMR FER reaches a specific threshold, the BTS determines whether

to fill in NoData frames. Before the optimization, the threshold is modified to a too small value. As a result,

some voice frames are discarded unnecessarily and this causes discontinuous voice.

dB domain filter: According to the RQI, the AMR adjusts the rate to rectify the problem that the reported

RQI value is too small.


BTS software parameter 53: It is recommended to set the last six bits of the parameter to 100011.

Parameter Location:

Location of software parameter 53: Press Ctrl + Shift + F12 and then choose Cell Parameters > Other

Parameters > BTS Software Parameters.


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Matching Version and Time Point

OMSTAR:

Version: OMSTAR V500R006C00SPC120

Support BSC6000R008C12 patrol


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Parameters Supported by the OMSTARSPC120

Currently, the OMSTAR supports the following parameters:


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2 Key Parameters About GSM Performance：Suggested Default Values + Check Tools + Deliverables...

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