automatic level control

Automatic Level Control Feature Parameter Description

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Issue 02 (2009-09-30) Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd. i

BSS Automatic Level Control Contents

Issue 02 (2009-09-30) Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd.

iii

Contents 1 Introduction ................................................................................................................................1-1

1.1 Scope ............................................................................................................................................ 1-1 1.2 Intended Audience ........................................................................................................................ 1-1 1.3 Change History.............................................................................................................................. 1-1

2 Overview .....................................................................................................................................2-1

3 Technical Description ..............................................................................................................3-1

4 Parameters .................................................................................................................................4-1

5 Counters......................................................................................................................................5-1

6 Glossary ......................................................................................................................................6-1

7 References..................................................................................................................................7-1

BSS Automatic Level Control 1 Introduction


1-1

1 Introduction 1.1 Scope This document describes automatic level control (ALC) feature of Huawei GSM BSS. It covers the function of and technologies mechanisms regarding ALC.

1.2 Intended Audience It is assumed that users of this document are familiar with GSM basics and have a working knowledge of GSM telecommunication.

This document is intended for:

Personnel working on Huawei GSM products or systems System operators who need a general understanding of this feature

1.3 Change History Automatic Level Control Change History provides information on the changes between different document versions.

There are two types of changes, which are defined as follows:

Feature change Feature change: refers to the change in the Automatic Level Control feature of a specific product version.

Editorial change Editorial change: refers to changes in information that has already been included, or the addition of information that was not provided in the pervious version.

Document Issues The document issues are as follows:

02 (2009-09-30) 01 (2009-06-30)

02 (2009-09-30) This is the second commercial release of GBSS9.0.

Compared with issue 01 (2009-06-30)) of GBSS9.0, issue 02 (2009-09-30) of GBSS9.0 incorporates the changes described in the following table.

Change Type

Change Description Parameter Change

Feature change

None. None.

Editorial change

The structure of the document is optimized.

None.

1 Introduction BSS

Automatic Level Control

1-2 Huawei Proprietary and Confidential Copyright Huawei Technologies Co., Ltd.

Issue 02 (2009-09-30)

01(2009-06-30) This is the initial commercial release of GBSS9.0.

Compared with 01 (2008-04-30) of GBSS8.1, issue 01(2009-06-30) of GBSS9.0 incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change None. None.

Editorial change The structure of the document is optimized.

None.

BSS Automatic Level Control 2 Overview


2-1

2 Overview In the communication system, the voice level fluctuates according to the mobile terminal and transmission line. That is, different mobile terminals and transmission lines result in different levels of voice fluctuation. This deteriorates the voice quality and adversely affects the user experience.

To solve this problem, the Automatic Level Control (ALC) feature is introduced. ALC adjusts the gain of uplink and downlink digital speech signals every 20 ms and changes the amplitude of digital speech signals in static or dynamic mode. This keeps the voice level of the entire network within an appropriate range, prevents volume fluctuation for the two parties during a call, and prevents voice distortion.

ALC keeps the voice level within an appropriate range and improves user experience. As a result, the average call duration in the communication system is prolonged, and the operator's revenue is increased.

If the voice volume in the network is stable, you are advised to adopt the default configuration of ALC.

BSS Automatic Level Control 3 Technical Description


3-1

3 Technical Description There are three ALC modes: fixed gain mode, fixed level mode, and adaptive level mode.

The ALC feature is enabled only when the ALC Switch parameter is set to Open.

Fixed gain mode When the ALC Mode parameter is set to Fixed Gain Mode, the uplink and downlink voice data is sent to the fixed gain module. ALC increases or decreases the amplitude of the voice level according to the predefined ALC Fix Gain.

Fixed level mode When the ALC Mode parameter is set to Fixed Level Mode, the uplink and downlink voice data is sent to the fixed level module. ALC increases or decreases the amplitude of the voice level according to the predefined ALC Fix Target Level to keep the voice level in compliance with the predefined ALC Fix Target Level.

Adaptive level mode When the ALC Mode parameter is set to Adaptive Mode, the uplink and downlink voice data is sent to the adaptive level module. ALC increases or decreases the amplitude of the voice level according to the predefined ALC Min Target Level and ALC Max Target Level to keep the voice level within the range defined by ALC Min Target Level and ALC Max Target Level.

Generally, the ALC mode that best suits the actual configuration is adopted to process the uplink and downlink voice data, thus achieving the gain control over the voice data flow.

ALC is effective for both uplink voice level and downlink voice level. Therefore, when the ALC Mode parameter is set to

Fixed Gain Mode, the ALC Fix Gain parameter should not be set to a too great value to prevent too high to too low voice level caused by the dual application of ALC.

The ALC Max Gain parameter specifies the maximum gain of the voice level. This parameter is valid only when the ALC Mode parameter is set to Fixed Level Mode or Adaptive Mode. By default, this parameter is set to 6 dB. If the setting of the ALC Max Gain parameter affects the actualization of the target level in the fixed level mode or the adaptive level mode, you are advised to set the ALC Max Gain parameter to the largest possible difference between the voice level and the expected target level.

If the Tandem Free Operation (TFO) feature is enabled during a call, the ALC feature does not take effect for this call.

BSS Automatic Level Control 4 Parameters


4-1

4 Parameters The following describes the parameters related to ALC.

For the meaning of each parameter, see Table 4-1. For the default value, value range, and related MML commands of each parameter, see Table 4-2.

Table 4-1 Parameter description (1)

Parameter Description

ALC Switch Whether to enable the adaptive level control (ALC) function

ALC Mode ALC level control mode

ALC Fix Gain Fixed gain value in fixed gain mode

ALC Fix Target Level Target level in fixed level mode

ALC Min Target Level Mimumum target level in adaptive ALC mode

ALC Max Target Level Maximum target level in adaptive ALC mode

Table 4-2 Parameter description (2)

Parameter Default Value GUI Value Range

Actual Value Range Unit

MML Command Impact

ALC Switch CLOSE CLOSE(Close), OPEN(Open) CLOSE, OPEN None

SET TCPARA(Optional) Board

ALC Mode FIXEDGAIN

FIXEDLEVEL(Fixed level mode), ADAPTIVE(Adaptive mode), FIXEDGAIN(Fixed gain mode)

FIXEDLEVEL, ADAPTIVE, FIXEDGAIN None


ALC Fix Gain 6 -12~12 -12~12 dB


ALC Fix Target Level -18 -23~-4 -23~-4 dBm


ALC Min Target Level -23 -23~-4 -23~-4 dBm


ALC Max Target Level -4 -23~-4 -23~-4 dBm


BSS Automatic Level Control 5 Counters


5-1

5 Counters None.

BSS Automatic Level Control 6 Glossary


6-1

6 Glossary For the acronyms, abbreviations, terms, and definitions, see the Glossary.

BSS Automatic Level Control 7 Reference Documents


7-1

7 Reference Documents ITU-T Recommendation G.169, Automatic Level Control Devices, 1999/06 BSC6900 Feature List BSC6900 Optional Feature Description GBSS Reconfiguration Guide BSC6900 GSM Parameter Reference BSC6900 GSM MML Command Reference
1 Introduction 1.1 Scope 1.2 Intended Audience 1.3 Change History 2 Overview 3 Technical Description 4 Parameters 5 Counters 6 Glossary 7 Reference Documents