Call Reestablishment

7/24/2019 Call Reestablishment

1/21

Huawei Proprietary and Confidential

Copyright Huawei Technologies Co., Ltd

Call Reestablishment Feature ParameterDescription

Copyright Huawei Technologies Co., Ltd. 2010. All rights reserved.

No part of this document may be reproduced or transmitted in any form or by any means without prior written

consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.

All other trademarks and trade names mentioned in this document are the property of their respective holders.

Notice

The information in this document is subject to change without notice. Every effort has been made in the

preparation of this document to ensure accuracy of the contents, but all statements, information, and

recommendations in this document do not constitute the warranty of any kind, express or implied.


2/21


3/21

BSS

Call Reestablishment Contents

Issue 01 (2010-01-12) Huawei Proprietary and Confidential


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 of Call Reestablishment .......................................................................................2-1

3 Call Reestablishment Procedure ..........................................................................................3-1

4 MS Mode ......................................................................................................................................4-1

5 Parameters .................................................................................................................................5-1

6 Counters ......................................................................................................................................6-1

7 Glossary ......................................................................................................................................7-1

8 Reference Documents .............................................................................................................8-1


4/21


5/21

BSS

Call Reestablishment 1 Introduction



1-1

1 Introduction

1.1 Scope

This document describes the call reestablishment procedure, and MS mode of the call reestablishment.

1.2 Intended Audience

This document is intended for:

Personnel who need to understand call reestablishment.

Personnel who work with Huawei products

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:

Feature change: refers to the change in the call reestablishment feature of a specific product version.

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

Document Issues

The document issues are as follows:

01 (2010-01-12)

01 (2010-01-12)

This is the first commercial release of GBSS9.0.


6/21


7/21

BSS

Call Reestablishment 2 Overview of Call Reestablishment



2-1

2 Overview of Call Reestablishment

When the MS encounters a radio link failure during the call, the call reestablishment procedure can beused to reestablish the radio link connection so that the original call can proceed. This mechanism

shortens the call intermission, and thus improves the user experience.


8/21


9/21

BSS

Call Reestablishment 3 Call Reestablishment Procedure



3-1

3 Call Reestablishment Procedure

The parameter Call Reestablishment Forbidden specifies whether to enable call reestablishment.

When the MS encounters a radio link failure during the call, the call reestablishment procedure can beused to reestablish the radio link connection so that the original call can proceed. Call reestablishmentmay occur in a new cell or a new location area. If a cell supports call reestablishment, the start of a callreestablishment attempt depends on the calling status of the cell.

After the call reestablishment is started, the MSC starts the encryption and assignment procedures.Then, the MSC checks whether the calling status and attaching status of the MS are correct. If the callingstatus and attaching status of the MS are correct, the call is reestablished.

During the call reestablishment, the MS cannot return to theIDLEstate. Thus, the MS cannot performlocation update when its source cell and target cell for call reestablishment are in different location areas.After the ongoing call is complete, the MS can perform location update.

The call reestablishment procedure is controlled by the MSC. The BSC sets up channels and forwards

layer 3 messages.

Figure 3-1 shows the call reestablishment procedure.


10/21

3 Call Reestablishment Procedure

BSS

Call Reestablishment

3-2 Huawei Proprietary and Confidential


Issue 01 (2010-01-12)

Figure 3-1 Call reestablishment procedure

1. Step 1 through step 4 in Figure 3-1 show the release of radio channel resources. The procedure ofresource release in call reestablishment is the same as that in normal calls.

2. Step 5 through step 9 in Figure 3-1 show the procedure of immediate assignment and seizure ofsignaling channels.

3. Step 10 and step 11 in Figure 3-1 show the encryption procedure.

4. Step 12 and step 11 in Figure 3-1 show the assignment procedure.

The call reestablishment procedure starts from step 5. The call reestablishment mechanism differsaccording to the NE that first detects radio link failures.

When the MS detects a radio link failure, the MS sends the Channel Request message with thecause value Call re-establishment in its selected cell (either the current cell or a new cell).Whenthe timer at the BTS side expires, the previous channel resources are released by the BSC. Thetimer is specified by the parameter TREESTABLISH. If the parameter TREESTABLISH is set to atoo great value, the radio resources for call-reestablishment-enabled cells are kept for a long time. Itresults in network congestion in busy hours.


11/21

BSS

Call Reestablishment 3 Call Reestablishment Procedure



3-3

When the BTS detects a radio link failure, it sends the Connection Failure Indication messagewith the cause value Radio Link Failureto the BSC. Upon receiving the message, the BSCreleases related radio resources and waits the MS to initiate call reestablishment.


12/21


13/21

BSS

Call Reestablishment 4 MS Mode



4-1

4 MS Mode

During the call reestablishment, the MS cannot return to theIDLE state. Thus, the MS cannot performlocation update when its source cell and target cell for call reestablishment are in different location areas.

After the ongoing call is complete, the MS can perform location update.


14/21


15/21

BSS

Call Reestablishment 5 Parameters



5-1

5 Parameters

This chapter describes the parameters related to Call Reestablishment.

For the description of each parameter, see Table 5-1. For the default value, value ranges, and MMLcommands of each parameter, see Table 5-2.

Table 5-1 Parameter description (1)

Parameter Name Description

Call ReestablishmentForbidden

Whether to allow call re-establishment. Burst interference or

blind spots due to high buildings may lead to a radio link failure.If a call drop is caused by such a failure, the MS can start callre-establishment to resume the conversation.

TREESTABLISH Call reestablishment timer

Table 5-2 Parameter description (2)

ParameterID

Default Value GUI ValueRange

Actual ValueRange

Unit MMLCommand

Impact

CallReestablishment

Forbidden

YES NO(No),YES(Yes)

NO, YES None

SETGCELLBASICPARA(Optional)

Cell

TREESTABLISH

15000 5000~40000

5000~40000 ms SETGCELLTMR(Optional)

Cell


16/21


17/21

BSS

Call Reestablishment 6 Counters



6-1

6 Counters

None.


18/21


19/21

BSS

Call Reestablishment 7 Glossary



7-1

7 Glossary

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


20/21


21/21

BSS

Call Reestablishment 8 Reference Documents

Issue 01 (2010-01-12) Huawei Proprietary and Confidential 8-1

8 Reference Documents 3GPP TS 24.008: Mobile radio interface Layer 3 specification; Core network protocols; Stage 3

3GPP TS 44.018: Mobile radio interface layer 3 specification; Radio Resource Control (RRC)

protocol

3GPP TS 48.008: Mobile Switching Centre - Base Station system (MSC-BSS) interface; Layer 3specification

3GPP TS 48.058: Base Station Controller - Base Transceiver Station (BSC-BTS) Interface; Layer 3specification

BSC6900 Feature List

BSC6900 Optional Feature Description

GBSS Reconfiguration Guide

BSC6900 GSM Parameter Reference

BSC6900 GSM MML Command Reference