2. Call Processing and Supplementary Services

3G-IOS V4.0.0 V&V DRAFT Section 2

5 November 1999 Call Processing and Supplementary Services

2. Call Processing and Supplementary Services

In some of the call processing and services functions described below, it is possible that an inter-BS handoff may occur during the process. In such an event, the target BS (i.e., the BS to which the MS has been handed off) shall assume responsibility for functionality ascribed to the BS as defined herein. For example, if an inter-BS handoff occurs during a mobile terminated call setup while the MS is in the Waiting for Answer state, the new serving BS shall send a Connect message to the MSC upon receipt of the Connect Order message on the air interface even though that BS was not involved with previous portions of the call setup process.

2.1

None.

2.14.2 A8/A9 Interface Clearing Procedures and Messages

Procedures for clearing the A8 interface are described in this section. An A8 interface clearing is initiated whenever the state of the packet service changes from the active/control hold state to the dormant/null state.

2.14.2.1 Successful Clearing Scenarios

An A8 interface clearing occurs:

· when the packet data inactivity timer in the BS expires. The BS, after sending the Clear Request message, sets timer T300 and waits for a Clear Command message from the MSC. To release all allocated resources, the MSC shall send a Clear Command message to the BS, start timer T315, and wait for the Clear Complete message from the BS. After stopping timer T300 and releasing the air resources with the Extended Release/Extended Release Response messages, the BS sends an A9-Release-A8 message to the PCF and starts timer Trel9. The PCF responds with an A9-Release-A8 Complete message. Then the BS sends a Clear Complete message and stops timer Trel9. The call flow scenario is illustrated in section 2.14.5.3.

· when the packet data inactivity timer in the MS expires. When the BS receives a Peer-to-Peer Resource Control message requesting the state transition from active to dormant, the BS shall send a Clear Request message to the MSC. The rest of the procedure is same as the previous BS initiated scenario. The call flow scenario is illustrated in section 2.14.5.4

· when the MS releases the call. When the BS receives a Release Order, the BS shall send a Clear Request message to the MSC and start timer T300. To release all allocated resources, the MSC shall send a Clear Command message to the BS, start timer T315, and wait for the Clear Complete message from the BS. After stopping timer T300 and releasing the air resources with the Release Order, the BS sends an A9-Release-A8 message to the PCF and starts timer Trel9. The PCF releases the A10/A11 connection and responds with an A9-Release-A8 Complete message. Then the BS sends a Clear Complete message and stops timer Trel9. The call flow scenario is illustrated in section 2.14.5.5.

· when the R-P interface is released initiated by the PDSN. When the PCF detects that the A10/A11 connection is released, the PCF sends an A9-Disconnect-A8 message to the BS and starts timer Tdiscon9. Then the BS initiates to release the A8 connection by sending an A9-Release-A8 message and starts timer Trel9. The PCF responds with an A9-Release-A8 Complete message and stops timer Tdiscon9. The BS, after sending the Clear Request message and stopping timer Trel9, sets timer T300 and waits for a Clear Command message from the MSC. To release all allocated resources, the MSC shall send a Clear Command message to the BS, start timer T315, and wait for the Clear Complete message from the BS. Then the BS stops timer T300, releases the air resources, and responds with a Clear Complete message. The call flow scenario is illustrated in section 2.14.5.6

2.14.2.2 Unsuccessful A8 Interface Clearing Procedures

See sections 2.14.2.3.2, 2.14.2.4.2, and 2.14.2.5.2 for unsuccessful call clearing procedures related to the A9-Release-A8, A9-Release-A8 Complete and A9-Disconnect-A8 messages.

2.14.2.3 A9-Release-A8

This A9 interface message is sent from the BS to the PCF to release the associated dedicated resource.

2.14.2.3.1 Successful Operation

When the BS needs to release an A8 connection, it sends an A9-Release-A8 message to the BS. The BS starts timer Trel9 and waits for the A9-Release-A8 Complete message from the PCF.

When the PCF receives the A9-Release-A8 message, it stops timer Tdiscon9 if it is active and performs the appropriate procedure to release the associated dedicated resources.

Please refer to section 6.1.10.4, “A9-Release-A8,” for the format and content of this message.

2.14.2.3.2 Failure Operation

If an A9-Release-A8 Complete message is not received from the PCF while timer Trel9 is active, the BS may resend the A9-Release-A8 message to the PCF and restart timer Trel9. If the A9-Release-A8 Complete message is not received from the PCF before timer Trel9 expires a second time or if the BS chooses to not resend the A9-Release-A8 message, the BS shall cease further supervision of this call connection, release all dedicated resources, and shall release the connection.

2.14.2.4 A9-Release-A8 Complete

This A9 interface message is sent from the PCF to the BS to acknowledge completion of the request to release the connection.

2.14.2.4.1 Successful Operation

Upon receipt of the A9-Release-A8 message from the BS, the PCF closes the A8 connection and sends an A9-Release-A8 Complete to notify the BS of the outcome. The BS stops timer Trel9 upon receipt of this message.

Please refer to section 6.1.10.5, “A9-Release-A8 Complete,” for the format and content of this message.

2.14.2.4.2 Failure Operation

None.

2.14.2.5 A9-Disconnect-A8

This A9 interface message is sent from the PCF to the BS to request to release the associated dedicated resource.

2.14.2.5.1 Successful Operation

When the PCF needs to release an A8 connection, it sends an A9-Disconnect-A8 message to the BS. The PCF starts timer Tdiscon9.

Please refer to section 6.1.10.3, “A9-Disconnect-A8,” for the format and content of this message.

2.14.2.5.2 Failure Operation

If an A9-Release-A8 message is not received from the BS while timer Tdiscon9 is active, the PCF may resend an A9-Disconnect-A8 message to the BS and restart timer Tdiscon9. If the A9-Release-A8 message is not received from the BS before timer Tdiscon9 expires a second time or if the PCF chooses to not resend the A9-Disconnect-A8 message, the PCF shall cease further supervision of this call connection, release all dedicated resources, and shall release the connection

2.14.3 A8/A9 Interface Handoff Procedures and Messages

This section contains the messages used during handoff procedure.

2.14.3.1 A9-Air Link (AL) Connected

When the mobile station performs inter-PCF handoff during active state, the A9-AL Connected message is sent from the target BS to the target PCF. This message is employed in order to notify the target PCF that handoff is successfully completed and that the air link has been established. An A9-AL Connected Ack message is expected in response.

2.14.3.1.1 Successful Operation

After the mobile station performs inter-PCF handoff during active state successfully, the target BS sends the A9-AL Connected message to the target PCF and starts timer Talc9.

Upon the receipt of the A9-AL Connected message, the PCF updates its routing table to route packet data sent from PDSN to the target BS. The PCF performs A10/A11 connection establishment if the A10/A11 connection has not been established yet.

Please refer to section 6.1.10.8, “A9-AL Connected”, for the format and content of this message.

2.14.3.1.2 Failure Operation

If timer Talc9 expires, the message may be resent.

2.14.3.2 A9-Air Link (AL) Connected Ack

The A9-AL Connected Ack message is sent from the target PCF to the target BS to indicate the result of processing the A9-AL Connected message.

2.14.3.2.1 Successful Operation

Upon receipt of an A9-AL Connected message from the target BS, the PCF shall transmit an A9-AL Connected Ack message to the target BS to indicate the outcome of processing the received message. The target BS shall stop timer Talc9.

Please refer to section 6.1.10.9, “A9-AL Connected Ack,” for the format and content of this message.

2.14.3.2.2 Failure Operation

None.

2.14.3.3 A9-Air Link (AL) Disconnected

When the mobile station performs hard handoff during active state, the A9-AL Disconnected message is sent from the source BS to the source PCF. This message is employed in order to notify the source PCF that the air link is temporary disconnected. An A9-AL Disconnected Ack message is expected in response.

2.14.3.3.1 Successful Operation

When the source BS receive the Handoff Command message which instructs to perform hard handoff, the source BS shall send an A9-AL Disconnected message to the PCF and starts timer Tald9.

Upon receipt of an A9-AL Disconnected message from the source BS, the PCF shall stop transmitting packet data and starts buffering packets from the PDSN.

Please refer to section 6.1.10.10, “A9-AL Disconnected,” for the formant and content of this message.

2.14.3.3.2 Failure Operation

If timer Tald9 expires, the message may be resent.

2.14.3.4 A9-AL (Air Link) Disconnected Ack

The A9-AL Disonnected Ack message is sent from the PCF to the BS to indicate the result of processing the A9-AL Connected message.

2.14.3.4.1 Successful Operation

Upon receipt of an A9-AL Disconnected message from the BS, the PCF shall transmit an A9-AL Disconnected Ack message to the BS to indicate the outcome of processing the received message. The target BS shall stop timer Tald9 upon receipt of the A9-AL Disconnected Ack message.

Please refer to section 6.1.10.11, “A9-AL Disconnected Ack,” for the format and content of this message.

2.14.3.4.2 Failure Operation

None.

2.14.4 Packet Data Service State Transitions

This section contains descriptions of procedures for the MAC state transitions. There are four states(Active, Control Hold, Suspended, Dormant) in MAC Layer. The following figure shows the state transition for packet data service.

Figure 2-29 - IS-2000 MAC State Transitions for Packet Data

For purposes of the protocol of this standard, the Active and Control Hold states can be considered equivalent. Likewise, the Dormant and Suspended states can be considered equivalent. This results in the following simplified diagram.

Figure 2-30 - Simplified State Transitions for Packet Data

From the viewpoint of the A8/A9 interfaces, A1 and A8 connections are maintaind during the Active / Control Hold States and released during the Suspended / Dormant States. Therefore, state transition of Active to Control Hold and Suspended to Dormant do not have any effect on A8/A9 interfaces.

2.14.5 A8/A9 Interface Call Flows

2.14.5.1 Mobile Initiated Initial Call Setup and Mobile IP Registration – Successful Operation

When an MS initiates a call and Mobile IP Registration has not initiated yet, Mobile IP Registration is performed before transmitting packet data.

Figure 2-31 - Mobile Initiated Initial Call Setup and Mobile IP Registration – Successful Operation

a. The MS transmits an Origination Message, with layer 2 acknowledgment required, over the access channel of the air interface to the BS to request packet data service.

b. The BS acknowledges the receipt of the Origination Message with a Base Station Acknowledgment Order to the MS.

c. The BS constructs the CM Service Request message, places it in the Complete Layer 3 Information message, sends the message to the MSC, and starts timer T303.

d. The MSC sends an Assignment Request message to the BS to request assignment of radio resources and starts timer T10. For packet data service terrestrial circuit between the MSC and the BS is not required.

e. The BS and the MS initiate the establishment of a radio traffic channel.

f. The BS transmits an A9-Setup-A8 message to PCF to establish an A8 connection and starts timer TA8-setup.

g. Procedure for establishing A10/A11 connection is performed.

h. Upon receipt of the A9-Setup-A8 message from the BS, the PCF establishes A8 connection and transmits an A8-Connect Message.

i. Upon receiving an A9-Connect-A8 message, the BS stops the timer TA8-setup and transmits Assignment Complete message.

j. PPP connection establishment procedure and Mobile IP Registration on the PPP connection are performed between the MS and PDSN.

2.14.5.2 Inter-BS Dormant Handoff – Mobile Served by a New PDSN

When an MS in dormant state moves into a different packet zone which is coverage area of different PDSN, the MS initiates Mobile IP Registration.

Figure 2-32 - Inter-BS Dormant Handoff – Mobile Served by a New PDSN