huawei 2g abis bypass

7/30/2019 Huawei 2G Abis Bypass

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GSM BSS

Abis BypassFeature Parameter Description

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Huawei Proprietary and ConfidentialCopyright Huawei Technologies Co., Ltd.


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GSM BSSAbis Bypass Contents

Issue 01 (2010-06-30) Huawei Proprietary and ConfidentialCopyright Huawei Technologies Co., Ltd.

i

Contents

1 Introduction to This Document .............................................................................................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 Descrip tion ..............................................................................................................3-1

3.1 Key Technologies..........................................................................................................................3-1

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

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

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

7 Reference Documents .............................................................................................................7-1


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GSM BSSAbis Bypass 1 Introduction to This Document


1-1

1 Introduction to This Document

1.1 Scope

This document describes the application scenarios and key technologies related to Abis Bypass.(GBFD-116601 Abis Bypass)

1.2 Intended Audience

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

This document is intended for:

zPersonnel working on Huawei GSM products or systems

zSystem operators who need a general understanding of this feature

1.3 Change HistoryThis section provides information on the changes in different document versions.

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

zFeature change

Feature change refers to the change in the Abis Bypass feature of a specific product version.

zEditorial change

Editorial change refers to the change in wording or the addition of the information that was notdescribed in the earlier version.

Document IssuesThe document issues are as follows:

z01 (2010-06-30)

zDraft (2010-03-30)

01 (2010-06-30)

This is the first release of GBSS12.0.

Compared with issue draft (2010-03-30) of GBSS12.0, issue 01 (2010-06-30) of GBSS12.0 incorporatesthe changes described in the following table.

Change Type Change Descrip tion Parameter Change

Feature change None. None.

Editorial change Parameters are presented in the form of Parameter ID instead ofParameter Name.

None.

Draft (2010-03-30)

This is the draft release of GBSS12.0.


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GSM BSSAbis Bypass 2 Overview


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2 Overview

In the chain topology, if a BTS in the network is powered off or a transmission link is faulty, services on allthe BTSs following the faulty BTS or following the faulty transmission link are disrupted. The TMU stops

working if the BTS is powered off. For example, in a chain topology without the Abis Bypass as shown inFigure 2-1, if BTS 2 is powered off and its TMU stops working, the services on both BTS 2 and BTS 3 aredisrupted.

Figure 2-1 Influence of BTS power failure without Abis Bypass

BSC

BTS1

BTS2

BTS3

Abis Bypass is introduced in the network with the chain topology to avoid the problem of servicedisruption on other BTSs upon the power failure of one BTS. With the Abis Bypass feature, a bypasstransmission link is formed within the BTS that is powered off to transfer data to other BTSs following thefaulty BTS on the chain. Thus, the power failure of a BTS will not affect the normal services on the

subsequent BTSs on the chain. For example, in a chain topology with Abis Bypass as shown in Figure2-2, the bypass board within BTS 2 provides a bypass transmission link if the TMU stops working uponpower failure of BTS 2. In this case, only the services on BTS 2 are disrupted without affecting theservices on BTS 3.

Figure 2-2 Influence of BTS power failure with Abis Bypass

BSC

BTS1

BTS2

BTS3

Bypass

board 1

Bypass

board 3Bypass

board 2

The BSS uses bypass loopback upon power failure to identify whether a failure is due to a faultytransmission link or the BTS power failure.


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GSM BSSAbis Bypass 2 Overview


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The 3012 series base stations support bypass loopback upon power failure, but the 3900 series base stations do notsupport this function.


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GSM BSSAbis Bypass 3 Technical Description


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3 Technical Descript ion

3.1 Key Technologies

Bypass Upon BTS Power Failure

The following description takes the BTS3012 as an example (seeFigure 3-1). When the BTS is poweredon, switches K1 and K2 are connected to contact 1 and contact 2 respectively. Thus, the data flow goesto the DTMU first. When the BTS is powered off, switches K1 and K2 are connected to contact 1' andcontact 2' respectively to form a bypass within the DABB.

Figure 3-1 Bypass upon BTS power failure

DABB

DTMU

1

1'

2

2'K1 K2

Loopback Upon BTS Power Failure

In a chain topology as shown in Figure 3-2,

z If the transmission link between BTS 1 and BTS 2 is faulty, BTS 2 and all the following BTSs cannot beobserved on the BSC.

z If BTS 2 is powered off, only BTS 2 is not observed on the BSC.

Figure 3-2 Schematic view of the BSS configured with bypass boards

BSC

BTS1

BTS2

BTS3

Bypass

board 1

Bypass

board 2

Bypass

board 3

The loopback function upon power failure helps to identify the BTS power failure from the transmissionlink fault. The function, however, is not applicable to the last BTS on the chain. For the last BTS on thechain, set the DIP switches on its bypass board so that the transmission link through the last BTS is


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GSM BSSAbis Bypass 3 Technical Description


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short-circuited when the BTS is powered off. Thus, the loopback test can be performed on the BSC sideto locate the fault.


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GSM BSSAbis Bypass 4 Parameters


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4 Parameters

None.


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GSM BSSAbis Bypass 5 Counters


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5 Counters

For the counters, see the BSC6900 GSM Performance Counter Reference.


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GSM BSSAbis Bypass 6 Glossary


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6 Glossary

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


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GSM BSSAbis Bypass 7 Reference Documents


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7 Reference Documents

[1] BSC6900 Feature List

[2] BSC6900 Optional Feature Description