M900/M1800 Base Station Subsystem Signaling Analysis Manual Contents

Issue 01 (2007-03-15) Huawei Technologies Proprietary i

Contents

6 Release Procedure ......................................................................................................................6-1 6.1 Overview...........................................................................................................................................................6-2 6.2 Normal Release Procedure ...............................................................................................................................6-2 6.3 BSC Local Release Procedure .........................................................................................................................6-3 6.4 Internal Handling of BSC.................................................................................................................................6-4

Figures M900/M1800 Base Station Subsystem

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ii Huawei Technologies Proprietary Issue 01 (2007-03-15)

Figures

Figure 6-1 Release procedure initiated by MS......................................................................................................6-2

Figure 6-2 BSC local release procedure................................................................................................................6-4

M900/M1800 Base Station Subsystem Signaling Analysis Manual 6 Release Procedure

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6 Release Procedure About This Chapter

The following table lists the contents of this chapter.

Title Description

6.1 Overview Introduces the classification of the BSC release procedures.

6.2 Normal Release Procedure Describes the normal release procedures.

6.3 BSC Local Release Procedure Describes the local release procedures of the BSC.

6.4 Internal Handling of BSC Describes the BSC internal handling of release procedures.

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6.1 Overview Common release procedure is classified into normal release procedure and local release procedure. Normal release means that the release procedure is initiated by MS or MSC. Local release means that the release procedure is initiated by BSC.

6.2 Normal Release Procedure

Signaling procedure After being normally accessed to the network, MS can initiate the release procedure, for the purpose of service requirements, such as hangup. Figure 6-1 shows the release procedure.

Figure 6-1 Release procedure initiated by MS

DISC

REL

REL CMP

Clear CMDClear CMPChannel REL

REL IND

Deactive SACCH

RF Channel REL

RF Channel REL ACK

DISCUA

RLSD

RLSD CMP

(1)

(2)

(3)

(4)

(5)

(6)(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

BTS BSC MSCMS

Step 1 After a call is completed, the caller hangs up, and the calling MS sends a Disconnect message to MSC.

Step 2 MSC returns a Release message to MS. In the meantime, it sends a Disconnect message to another calling MS.

Step 3 MS releases MM connections, and sends a Release Complete message to MSC.

Step 4 Upon receipt of the Release Complete message, MSC releases MM connections, and sends a Clear Command to BSC, notifying it to release the occupied A interface resources and the logical channels on Um interface.

Step 5 BSC delivers the channel Release message to MS, requesting that MS and BTS release the logical channels on Um interface.

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Step 6 MS sends a DISC frame to BTS, indicating that the logical channels have been released.

Step 7 BTS sends a UA frame to MS for acknowledgement. Upon receipt of the UA frame, MS returns to the idle mode.

Step 8 BSC sends a Deactivate SACCH message to BTS, requesting that SACCH be deactivated.

Step 9 After BTS receives the DISC frame from MS, BTS returns a Release Indication message to BSC to indicate that MS has released the logic channel on radio interface.

Step 10 BSC sends a RF Channel Release message to BTS, requesting that the physical channels on Um interface be released.

Step 11 BTS returns a Channel Release Acknowledge message to BSC, indicating that the physical channels on Um interface have been released.

Step 12 BSC sends a Clear Complete message to MSC.

Step 13 MSC sends a RLSD message to BSC, requesting the release of SCCP link connection.

Step 14 BSC returns a RLSD Complete message to MSC, indicating that the SCCP link connection has been released.

----End

Procedure explanation Step 1 In Figure 6-1, 1~3 are to release call connections.

The procedure described in Figure 5-1 is a release procedure initiated by MS. For the release procedure initiated by the network, except these 3 messages, which are transparently transmitted in reverse directions, all the messages are the same as those in Figure 6-1.

Step 2 4~14 are to release radio resources.

After the connections of CC layer and MM layer are released, the network will send a Clear Command message to BSC, requesting the release of SCCP signaling links. This message contains the call clearance cause values, such as "Handover completed" or "Location update completed". If the release is caused by Um interface message failure, radio link failure or equipment fault, BSC shall send the Clear Request message to MSC, and then MSC shall deliver the Clear Command message.

----End

6.3 BSC Local Release Procedure In the normal calling procedure, after assignment is completed, BSC shall initiate the local release procedure for signaling channels. Likewise, after handover is completed, BSC shall also initiate the local release procedure for the old channels. Figure 6-2 shows the release procedure.

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Figure 6-2 BSC local release procedure

BTS BSC MSC MS

REL Confirrm

Deactivate SACCH

RF Channel REL

RF Channel REL ACK

(1)

(3)

(4)

(5)

REL REQ(REL Local End) (2)

Step 1 BSC sends a Deactivate SACCH message to BTS, requesting that SACCH be deactivated.

Step 2 BSC delivers a Release Request message to BTS, with the cause value "Local end released". Here, the release procedure is unrelated to MS.

Step 3 Upon receipt of the Release Request message, BTS returns a Release Acknowledge message to BSC. If the Release Request message delivered by BSC contains other cause values, BTS should deliver a DISC frame to MS, and shall not report the Release Acknowledge message to BSC until it receives the UA (or DM) frame sent by MS.

----End

6.4 Internal Handling of BSC Refer to 6.2 "Normal Release Procedure."

ContentsFigures6 Release ProcedureAbout This Chapter6.1 Overview6.2 Normal Release Procedure6.3 BSC Local Release Procedure6.4 Internal Handling of BSC