01-19 sms procedure

M900/M1800 Base Station Subsystem Signaling Analysis Manual Contents

Issue 02 (2007-06-30) Huawei Technologies Proprietary i

Contents

19 SMS Procedure .......................................................................................................................19-1 19.1 Overview of SMSs ....................................................................................................................................19-2 19.2 Procedure for SMSs ..................................................................................................................................19-2

19.2.1 Short Message Transmission Procedure for an Idle MS ..................................................................19-2 19.2.2 Short Message Reception Procedure for an Idle MS .......................................................................19-3 19.2.3 Short Message Transmission Procedure for a Busy MS ..................................................................19-5 19.2.4 Short Message Reception Procedure for a Busy MS .......................................................................19-5

19.3 Signaling Procedure in the BSC................................................................................................................19-6 19.4 Abnormal Cases and Troubleshooting.......................................................................................................19-7

19.4.1 SMS Failure Due to Disabled Authentication and Encryption.........................................................19-7

Figures M900/M1800 Base Station Subsystem

Signaling Analysis Manual

ii Huawei Technologies Proprietary Issue 02 (2007-06-30)

Figures

Figure 19-1 Short message transmission procedure for an idle MS .................................................................19-2

Figure 19-2 Short message reception procedure for an idle MS ......................................................................19-4

Figure 19-3 Short message transmission procedure for a busy MS..................................................................19-5

Figure 19-4 Short message reception procedure for a busy MS.......................................................................19-6

M900/M1800 Base Station Subsystem Signaling Analysis Manual 19 SMS Procedure

Issue 02 (2007-06-30) Huawei Technologies Proprietary 19-1

19 SMS Procedure

About This Chapter

The following table lists the contents of this chapter.

Section Describes

19.1 Overview of SMSs An overview of short message services (SMSs).

19.2 Procedure for SMSs The procedures for different types of SMSs.

19.3 Signaling Procedure in the BSC

The signaling procedure in the BSC.

19.4 Abnormal Cases and Troubleshooting

The abnormal cases when the SMS procedure fails and how to troubleshoot them.

19 SMS Procedure M900/M1800 Base Station Subsystem


19-2 Huawei Technologies Proprietary Issue 02 (2007-06-30)

19.1 Overview of SMSs For an idle MS, short messages are transmitted over the SDCCH. For a busy MS, however, short messages are transmitted over the SACCH. The point-to-point SMS comprises two fundamental procedures: mobile-terminated SMS and mobile-originated SMS.

For details of the SMS procedure, refer to the specifications in GSM 0408.

19.2 Procedure for SMSs 19.2.1 Short Message Transmission Procedure for an Idle MS

Signaling Procedure Figure 19-1 shows the signaling procedure for short message transmission of an idle MS. procedure

Figure 19-1 Short message transmission procedure for an idle MS

MS BTS BSC

Authentication Request

Authentication Response

Ciphering Mode Command

Ciphering Mode Complete

SABM (SAPI 3) (2)Establish Indication

(SAPI 3)(3)UA(4)

CP DATA(5)

CP Acknowledge(6)

CP Acknowledge(8)

CP DATA(7)

Immediate Assignment Procedure

CM Service Accepted (1)

MSC

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

Release Procedure



Procedure Explanation The following part explains the short message transmission procedure for an idle MS:

In Figure 19-1, steps 1 to 4 illustrate a random access and immediate assignment procedure, in which the BSS allocates a signaling channel to the MS.

In Figure 19-1, steps 5 to 8 illustrate a short message transmission procedure.

The MS sends an SABM frame again, notifying the network side of the request for establishing an SMS. Then, the BSC provides a transparent-transmission channel for short message exchange between the MS and the MSC. In this procedure, the MSC, if allowed, sends the BSC an ASS REQ message for channel allocation. The time for sending an ASS REQ message is the same as that for an ordinary call. The BSC provides SMSs either by allocating a new channel or by using the original SDCCH.

The protocol on Point-to-Point SMS covers four layers, and they are the connection management layer (CM), relay layer (RL), transport layer (TL), and application layer (AL). Both the CP_DATA message and the CP_ACK message are transmitted over the CM layer. The CP_DATA message is used to transmit the contents of RL and AL messages. The CP_ACK message is the acknowledgement message of CP_DATA.

19.2.2 Short Message Reception Procedure for an Idle MS

Signaling Procedure Figure 19-2 shows the signaling procedure for short message reception of an idle MS.




Figure 19-2 Short message reception procedure for an idle MS

BTS BSC

CR(Complete(3)Layer3 Information

CC(4)

Authentication Request(5)

Authentication Response(6)

Cipherding Mode(7)Commnd

Cipering Mode(8)Complete

SABM (SAPI 3)(11)

Establis Request(10)(SAPI 3)

UA(12)

CP DATA(14)

CP Acknowledge(17)

CP Acknowledge(15)

Paging(1)Paging Command(2)

CP DATA(9)

Establish Confirm(13)(SAPI 3)

CP DATA(16)

Immediate Assignment Procedure

Release Procedure

MS MSC

PCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

SDCCH

Paging Request

Procedure Explanation The following part explains the short message reception procedure for an idle MS:

In Figure 19-2, steps 1 to 3 illustrate a paging response and immediate assignment procedure. The MSC sends a Paging CMD message, paging the called MS. Then, the MS requests an SDCCH channel and responds with a Paging Response message.

In Figure 19-2, steps 14 to 17 illustrate a connection establishment and short message transmission procedure.



During the mobile-terminated SMS procedure, the BSC sends the MS an EST REQ message for establishing a connection. After the BSC receives an EST CNF message from the MS, the channel for SMS is established. The BSC transmits short messages over the transparent channel until the procedure is complete.

19.2.3 Short Message Transmission Procedure for a Busy MS

Signaling Procedure Figure 19-3 shows the signaling procedure for short message transmission of a busy MS.

Figure 19-3 Short message transmission procedure for a busy MS

CM Servic Request(1)

MS BTS BSC

SABM (SAPI 3)(3)

UA(5)Establish Indication(4)

MSC

CP DATA(6)

CP Acknowledge(9)

CP Acknowledge(7)

CP DATA(8)

CM Servic Accepted(2)

FACCH

FACCH

FACCH

FACCH

SACCH

SACCH

SACCH

SACCH

Active Call

Active Call

Procedure Explanation The following part explains the short message transmission procedure for a busy MS:

Over the FACCH, the busy MS sends the MSC a CM SERV REQ message. After the MSC responds with a CM SERV ACC message, a link at the CC layer is established.

Over the SACCH, a link at the CC layer is established for transmitting short messages.

19.2.4 Short Message Reception Procedure for a Busy MS

Signaling Procedure Figure 19-4 shows the signaling procedure for short message reception of a busy MS.




Figure 19-4 Short message reception procedure for a busy MS

MS BTS BSC MSC

SABM (SAPI 3)(3)Establish Request (SAPI 3)(2)

CP DATA(6)

CP Acknowledge(9)

CP Acknowledge(7)

CP DATA(1)

Establish Conform(SAPI 3)(5)

CP DATA(8)

UA(4)FACCH

FACCH

SACCH

SACCH

SACCH

SACCH

Active Call

Active Call

Procedure Explanation The following part explains the short message reception procedure for a busy MS:

On receipt of a CP DATA message from the MSC, the BSC establishes an SMS link at the RR layer.

On receipt of a CP ACK message from the MS, the MSC begins to send short messages.

19.3 Signaling Procedure in the BSC When an SMS procedure is performed, the signaling procedure in the BSC is as follows:

Step 1 Based on the classmark reported by the MS, the BSC checks whether the MS supports SMS.

Step 2 On receipt of a short message from the MS, the BSC checks the Cell Call Control Table for the configuration of the Short message uplink disabled field. If the field is set to Yes, short message transmission is disabled.

Step 3 On receipt of a short message from the MSC, the BSC checks the Cell Call Control Table for the configuration of the Short message downlink disabled field. If the field is set to Yes, short message reception is disabled.

----End



19.4 Abnormal Cases and Troubleshooting 19.4.1 SMS Failure Due to Disabled Authentication and Encryption

Case Description Some MSs fail to transmit short messages because the authentication encryption function is disabled.

Probable Causes The SMS procedure specified in the GSM protocols involves authentication and encryption. For some MSs, short message transmission fails if authentication or encryption is not involved in an actual SMS procedure.

Troubleshooting The MSC initiates an authentication and encryption procedure.

01-19 sms procedure

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