9.7 GA-RRC Connection handling

3GPP43.318Generic Access Network (GAN)Release 17Stage 2TS

The GAN Iu mode GA-RRC CS and PS connections are logical connections between the MS and the GANC.

A GA-RRC connection is established when the upper layers in the MS request the establishment of a signalling connection for either CS or PS domain and the MS is in GA-RRC-IDLE state for that domain; i.e., no GA-RRC connection exists. When a successful response is received from the network, GA-RRC replies to the upper layer that the MS has entered the RRC connected mode (i.e., the GA-RRC-CONNECTED state). The upper layers then have the possibility to request transmission of NAS messages to the network.

Note that in the case of a network-initiated CS or PS session, the GA-RRC connection is implicitly established when the MS responds to the GA-RRC PAGING REQUEST message from the GANC with the GA-RRC INITIAL DIRECT TRANSFER containing the paging response. This is illustrated in clause 9.11 for the CS case and clause 9.16.7.2 for the PS case.

Also, in the case of handover from GERAN or UTRAN to GAN Iu mode, the GA-RRC connection is implicitly established when the MS sends the GA-RRC RELOCATION ACK message to the GANC (normal case) or the GA-RRC RELOCATION ACCESS message to the GANC (exception case), as described in sub-clause 9.14.

9.7.1 GA-RRC Connection Establishment

The following figure shows successful and unsuccessful establishment of the GA-RRC connection for either the CS or PS domain.

Figure 43: GA-RRC Connection Establishment

1. The MS initiates GA-RRC connection establishment by sending the GA-RRC REQUEST message to the GANC. The message includes the CN Domain identity (CS or PS) and the Establishment Cause indicating the reason for GA-RRC connection establishment.

2. The GANC signals the acceptance of the connection request to the MS by sending the GA-RRC REQUEST ACCEPT and the MS enters the GA-RRC-CONNECTED state.

3. If the GANC determines that the GA-RRC connection request shall be rejected, it sends a GA-RRC REQUEST REJECT to the MS indicating the reject cause, completing the procedure.

9.7.2 GA-RRC Connection Release

The following figure shows release of the logical GA-RRC connection between the MS and the GANC.

Figure 44: GA-RRC Connection Release

1. The CN indicates to the GANC to release the resources allocated to the MS, via the RANAP Iu Release Command message.

2. The GANC commands the MS to release resources, using the GA-RRC RELEASE message. The message includes the CN Domain Identity (CS or PS).

3. The GANC confirms resource release to the CN using the Iu Release Complete message. The GANC may optionally wait for receipt of the GA-RRC RELEASE COMPLETE message from the MS before sending the Iu Release Complete message to the CN.

4. The MS confirms resource release to the GANC using the GA-RRC RELEASE COMPLETE message and the GA-RRC state of the CS domain GA-RRC sublayer entity or the PS domain GA-RRC sublayer entity (i.e., depending on the value of the CN Domain Identity received in step 2) in the MS changes to GA-RRC-IDLE.

9.7.3 GA-RRC Connection Release Request

The following figure shows release of the logical CS or PS GA-RRC connection between the MS and the GANC when initiated by the MS or the GANC (i.e., due to abnormal conditions).

Figure 45: GA-RRC Connection Release Request

1. The MS may initiate CS or PS GA-RRC connection release by sending the GA-RRC RELEASE REQUEST message to the GANC. The message includes the CN Domain identity (CS or PS) and the Cause indicating the reason for GA-RRC connection release.

2. On receipt of the GA-RRC RELEASE REQUEST from the MS or due to local conditions in the GANC, the GANC initiates Iu release for the particular CN domain by sending the Iu Release Request message to the CN Domain entity.

3. The CN triggers the release of connection as described in clause 9.7.2.