zgo-04-02-007_amr_radio_link_timers_fg_20101030

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ZGO-04-02-007 AMR Radio Link

Timers

Feature Guide


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ZGO-04-02-007 AMR Radio Link Timers

ZTE Confidential Proprietary 2010 ZTE CORPORATION. All rights reserved. I


Version Date Author Approved By Remarks

V1.00 2010-10-30 Not open to the Third Party

2010 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL:This document contains proprietary information of ZTE and is not to bedisclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information in this document issubjected to change without notice.


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ZTE Confidential Proprietary 2010 ZTE CORPORATION. All rights reserved. II

TABLE OF CONTENTS

1 Feature Property ............................................................................................. 12 Overview ......................................................................................................... 12.1 Feature Introduction .......................................................................................... 12.2 Correlation with Other Features ........................................................................ 23 Technical Description .................................................................................... 24 Parameters and Configuration....................................................................... 34.1 Parameters List ................................................................................................ 34.2 Parameter Configuration ................................................................................... 45 Related Counters and Alarms ........................................................................ 55.1 Related Counters .............................................................................................. 55.2 Related Alarms ................................................................................................. 66 Engineering Guide .......................................................................................... 66.1 Application Scenario ......................................................................................... 66.2 Configuration Description.................................................................................. 66.3 Impact on the Network ...................................................................................... 67 Abbreviation .................................................................................................... 68 Reference Document ...................................................................................... 7


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ZTE Confidential Proprietary 2010 ZTE CORPORATION. All rights reserved. III

FIGURES

Figure 4-1 Cell basic parameter 2 Configuration Interface .................................................... 5

TABLES

Table 4-1 Parameters List .................................................................................................... 3Table 5-1 Related Counters ................................................................................................. 5


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ZTE Confidential Proprietary 2010 ZTE CORPORATION. All rights reserved. 1

1 Feature Property

IBSC version: [iBSC V6.20]

BTS version: [independent of BTS software and hardware]

Attribute: [optional functions]

NEs involved

NE Name Involved or Not Special Requirement

MS -

BTS

BSC

MSC -

MGW -

SGSN -

GGSN -

HLR -

Dependency: [Enable this function after the AMR function is enabled]

Mutual exclusion: [None]

Remarks: None

2 Overview

2.1 Feature Introduction

With the introduction of the AMR, the reliability of the voice encoding has been improved

greatly. In the common voice encoding mode, the wireless quality is so poor as to make

the voice service intolerable to the user, resulting in abnormal termination of the

conversation; in the AMR encoding mode, the voice service quality is tolerable to the user


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under similar wireless quality and does not lead to abnormal termination of the

conversation. Therefore, if the common voice encoding mode and the AMR encoding

mode adopt the same wireless link timer, it may lead to voice channel abnormal release

when the signal quality is poor. This is obviously unreasonable. Therefore, it is necessary

to configure a wireless link timer for the common voice encoding and the AMR encoding.

The introduction of the AMR wireless link timer can reduce the call drop rate when the

AMR voice encoding is adopted and make the voice quality match the signaling quality.

2.2 Correlation with Other Features

This feature correlates with the following features:

ZGO-01-01-003 Adaptive Multi-Rate(AMR) Codec

Details are as follows:

The relation between this feature and AMR (Adaptive Multi-Rate): The feature is based

on a feature of the AMR. To use this feature, ensure that the AMR function is enabled.

3 Technical Description

The wireless link timer is used to evaluate the quality of a wireless link and is one of the

wireless link control parameters. This chapter describes the wireless link timer based on

the MS and the BSS:

The MS obtains the wireless link timer parameters from the BCCH and the SACCH

channels, and includes the parameters as a part of the wireless link management. In the

MS, there is counter S. The initial value of the counter is RADIO_LINK_TIMEOUT. When

the MS cannot resolve the SACCH message (BFI = 1), the value of the counter

decreases by 1. On the contrary, when the MS can resolve the SACCH message, the

value of the counter increases by 2. When the value of timer S reaches

RADIO_LINK_TIMEOUT, the value decreases to 0 and timer S reports wireless link

failure. The value of counter S actually reflects the quality of a wireless link. The timer is


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irrelevant to voice encoding, but depends on RADIO_LINK_TIMEOUT and wireless link

quality (namely quality of the SACCH channel).

For the BSS, the BTS can judge whether a wireless link fails according to two standards:

uplink SACCH error rate and RXLEV/RXQUAL based measurement value. Which mode

should be adopted can be configured in the daemon. When the SACCH error rate is used

as the criteria of judging whether a connection fails, the BTS uses the value of the

RadioLkTimeout parameter and a process that are the same as those of the MS. This

can avoid judgment criteria inconsistency between the uplink direction and downlink

direction. Meanwhile, the receive electrical level threshold and receive quality threshold

are invalid.

The wireless link timer can be configured for the FR, HR, AMR FR, and AMR HR

respectively in the OMCR according to the network conditions and operation policies.

The BTS controls the wireless link when a call is set up or encoding switchover takes

place.

The wireless link timer of AMR FR can be configured when Bss detects the maximum

value of the wireless link fault counter AMR FR; the wireless link timer of AMR HR can be

configured when the Bss detects the maximum value AMR HR of the wireless link fault

timer S.

4 Parameters and Configuration

4.1 Parameters List

Table 4-1 Parameters List

Full name Bss Radio Link Timer's Max Value for AMR FR Bug

Abbreviation AMR FR

Description

Fault detection period in AMR-FR channel. Withinthis period, pick

average value through s times of measurement, and judge link fault

threshold, to dertermine whether the channel is failed.


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Management

ObjectCell

Value Range 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64

Unit None

Default 64

Full name Bss Radio Link Timer's Max Value for AMR HR Bug

Abbreviation AMR HR

Description

Fault detection period in AMR-HR channel. Within this period, pick

average value through s times of measurement, and judge link fault

threshold, to dertermine whether the channel is failed.

ManagementObject

Cell

Value Range 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64

Unit None

Default 64

4.2 Parameter Configuration


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Figure 4-1 Cell basic parameter 2 Configuration Interface

5 Related Counters and Alarms

5.1 Related Counters

Table 5-1 Related Counters

Counter ID What It Counts

C901070002 Number of SDCCH drops due to radio link failure

C901070009 Number of signaling TCH/F drops due to radio link failure

C901070023 Number of data TCH/F drops due to radio link failure

C901070030 Number of signaling TCH/H drops due to radio link failure

C901070044 Number of data TCH/H drops due to radio link failure


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3GPP 3rd Generation Partnership Project

GSM Global System for Mobile communications

BSC Base Station Controller

BTS Base Transceiver Station

MS Mobile Station

HR Half Rate

FR Full Rate

SACCH Slow Associated Control Channel

AMR Adaptive Multi Rate

BCCH Broadcast Control Channel

TCH Traffic Channel

8 Reference Document

[None]

zgo-04-02-007_amr_radio_link_timers_fg_20101030

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