Handover Re Establishment

Handover Re-establishment Feature Parameter Description

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

BSS Handover Re-establishment Contents

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

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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 Implementation in the BSS............................................................................................................ 3-1 3.2 Impact on the KPI.......................................................................................................................... 3-2

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

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

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

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

BSS Handover Re-establishment 1 Introduction to This Document


1-1

1 Introduction to This Document 1.1 Scope This document describes the benefits of handover re-establishment and its implementation.

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 The change history 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 a change in the handover re-establishment 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 02 (2009-09-30) z 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.

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

1 Introduction to This Document BSS

Handover Re-establishment

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Issue 02 (2009-09-30)

Compared with issue 01 (2009-04-30) of GBSS8.1, issue 01 (2009-06-30) of GBSS9.0 remains unchanged.

BSS Handover Re-establishment 2 Overview


2-1

2 Overview In the handover procedure generally, if the BSC does not receive a response from the MS but receives an Error Indication message from the BTS after sending the Handover Command to the MS, the BSC regards that call drop occurs and then initiates the release procedure. After Handover Re-establishment is enabled, the BSC initiates the procedure for re-establishing the connection at the data link layer of the Um interface on the source channel. If the connection re-establishment is successful, the MS resumes the call without a call drop.

Handover Re-establishment reduces the call drop rate during handover, thus improving user satisfaction and network KPIs.

Handover Re-establishment does not support directed retry.

BSS Handover Re-establishment 3 Technical Description


3-1

3 Technical Description 3.1 Implementation in the BSS The implementation of Handover Re-establishment in the BSS is as follows:

1. If the parameter Activate L2 Re-establishment is set to Yes and the BTS TRX supports Handover Re-establishment, the BSC can enable Handover Re-establishment.

2. After receiving the Error Indication message, the BSC determines the phase at which the call is being processed.

3. When the call is waiting for intra-cell handover completion or waiting for inter-cell handover completion, the BSC sends the Establish Request message on the source channel, requesting the BTS to re-establish the connection at the data link layer of the Um interface.

4. After receiving the Establish Request message, the BTS initiates the procedure for re-establishing the connection at the data link layer of the Um interface.

5. The MS cooperates with the BTS to re-establish the connection at the data link layer of the Um interface.

6. The call is re-assigned to the source channel, and thus the call resumes.

Figure 3-1 shows the signaling procedure of Handover Re-establishment

Figure 3-1 Signaling procedure of Handover Re-establishment

Channel Activation

Channel Activation Acknowledge

Handover Command

Establishment Confirmed

SABM

UA

Error Indication

SABM

UA

Establishment Reuqest

Initiating Handover Re-establishment

MS BTS BSC

3 Technical Description BSS

Handover Re-establishment

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3.2 Impact on the KPI Enabling Handover Re-establishment may reduce the call drop rate during the handover and assignment procedures.

BSS Handover Re-establishment 4 Parameters


4-1

4 Parameters This chapter describes the parameters related to handover re-establishment .

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

Table 4-1 Parameter description (1)

Parameter Description

Activate L2 Re-establishment

Whether to activate the function of L2 re-establishment. If this function is activated, the BSC starts the attempt of L2 re-establishment when the BSC receives an ERR IND message reported by the BTS in a conversation of MSs. If the L2 re-establishment succeeds, the conversation continues; otherwise, a call drop occurs.

Table 4-2 Parameter description (2)

Parameter

Default Value

GUI Value Range

Actual Value Range

Unit MML Command

Impact

Activate L2 Re-establishment NO

NO(No), YES(Yes) NO, YES None

SET GCELLSOFT(Optional) Cell

BSS Handover Re-establishment 5 Counters


5-1

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

BSS Handover Re-establishment 6 Glossary


6-1

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

BSS Handover Re-establishment 7 Reference Documents


7-1

7 Reference Documents z BSC6900 Feature List z BSC6900 Optional Feature Description z BSC6900 GSM Parameter Reference z BSC6900 GSM MML Command Reference z BSC6900 Performance Counter Reference

1 Introduction to This Document 1.1 Scope 1.2 Intended Audience 1.3 Change History 2 Overview 3 Technical Description 3.1 Implementation in the BSS 3.2 Impact on the KPI

4 Parameters 5 Counters 6 Glossary 7 Reference Documents