Huawei 2G Abis Bypass

GSM BSS

Abis Bypass Feature Parameter Description

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GSM BSS Abis Bypass

Contents

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 Description ..............................................................................................................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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1 Introduction to This Document

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 of GSM telecommunication. This document is intended for: z

Personnel working on Huawei GSM products or systems

z

System operators who need a general understanding of this feature

1.3 Change History This section provides information on the changes in different document versions. There are two types of changes, which are defined as follows: z

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

z

Editorial change Editorial change refers to the change in wording or the addition of the information that was not described in the earlier version.

Document Issues The document issues are as follows: z

01 (2010-06-30)

z

Draft (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 incorporates the changes described in the following table. Change Type

Change Description

Parameter Change

Feature change

None.

None.

Editorial change Parameters are presented in the form of Parameter ID instead of None. Parameter Name.

Draft (2010-03-30) This is the draft release of GBSS12.0.

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2 Overview

2 Overview In the chain topology, if a BTS in the network is powered off or a transmission link is faulty, services on all the 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 in Figure 2-1, if BTS 2 is powered off and its TMU stops working, the services on both BTS 2 and BTS 3 are disrupted. Figure 2-1 Influence of BTS power failure without Abis Bypass

BSC BTS 1

BTS 2

BTS 3

×

×

Abis Bypass is introduced in the network with the chain topology to avoid the problem of service disruption on other BTSs upon the power failure of one BTS. With the Abis Bypass feature, a bypass transmission link is formed within the BTS that is powered off to transfer data to other BTSs following the faulty 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 Figure 2-2, the bypass board within BTS 2 provides a bypass transmission link if the TMU stops working upon power failure of BTS 2. In this case, only the services on BTS 2 are disrupted without affecting the services on BTS 3. Figure 2-2 Influence of BTS power failure with Abis Bypass

Bypass board 1

Bypass board 2

BTS 1

BTS 2

Bypass board 3

BSC BTS 3

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

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2 Overview

The 3012 series base stations support bypass loopback upon power failure, but the 3900 series base stations do not support this function.

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3 Technical Description

3 Technical Description 3.1 Key Technologies Bypass Upon BTS Power Failure The following description takes the BTS3012 as an example (see Figure 3-1). When the BTS is powered on, switches K1 and K2 are connected to contact 1 and contact 2 respectively. Thus, the data flow goes to the DTMU first. When the BTS is powered off, switches K1 and K2 are connected to contact 1' and contact 2' respectively to form a bypass within the DABB. Figure 3-1 Bypass upon BTS power failure

● K1

■1

■

■

1'

2' DABB

● K2 2■

DTMU

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 be observed 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

Bypass board 1

Bypass board 2

BTS 1

BTS 2

Bypass board 3

BSC BTS 3

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

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3 Technical Description

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

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4 Parameters

4 Parameters None.

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5 Counters

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

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6 Glossary

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

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7 Reference Documents

7 Reference Documents [1] BSC6900 Feature List [2] BSC6900 Optional Feature Description

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