8.17 GPRS Data, Signalling and SMS Transport

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

8.17.1 GA-PSR GPRS Data Transport Procedures

Figure 32 illustrates the transport of GPRS user data messages via GAN.

Figure 32: User Plane Data Transport

1. Optionally, if the GA-PSR is in GA-PSR-STANDBY state, the GA-PSR Transport Channel is activated as per description in clauses 8.16.1 or 8.16.4. Upon successful activation, the MS starts the GA-PSR Channel Timer.

2. The MS encapsulates the uplink LLC-PDU within the GA-PSR UNITDATA message that is forwarded to the GANC. The message includes parameters required for Gb interface procedures and TLLI as MS identifier. The MS restarts the GA-PSR Channel Timer.

3. The GANC forwards the LLC-PDU to the Core Network as per standard Gb interface procedures.

4. The Core Network sends the downlink LLC-PDU that contains GPRS user data via the Gb interface. The MS is identified with the TLLI.

5. Assuming that the corresponding GPRS TC is available, the GANC forwards the LLC-PDU to the MS encapsulated in the GA-PSR UNITDATA message. Upon receiving this message, the MS restarts the GA-PSR Channel Timer.

6. The GPRS data transfer (steps 2 to 5), both in uplink and downlink direction, can be processed as many times as necessary while the GA-PSR TC is active.

7. When the GA-PSR Channel Timer expires, the corresponding GA-PSR TC is deactivated as per description in clause 8.16.2.

8.17.2 GA-PSR GPRS Signalling and SMS Transport Procedures

8.17.2.1 General

The TCP connection that is used for GA-CSR signalling is also used for GA-PSR GPRS signalling and SMS transport identified by LLC SAPI 1 and SAPI 7 respectively. This TCP connection is available after GAN registration, so establishment of a separate channel, i.e. a TCP connection, for GPRS signalling and SMS transport is not required.

8.17.2.2 Network initiated GPRS Signalling

For Network initiated signalling/SMS, the Core Network sends a GMM/SM signalling or SMS message to the GANC via the Gb interface as per standard GPRS; e.g. the LLC PDU may include GMM attach accept or SM PDP context activation accept message. The GANC encapsulates the received LLC PDU within a GA-PSR DATA message that is forwarded to the MS via the existing TCP connection.

Figure 33: Downlink Control Plane Data Transport

1. The Core Network sends a GMM/SM signalling message or an SMS message as per GPRS via the Gb interface; e.g. the LLC-PDU may include GMM attach accept or SM PDP context activation accept message.

2. The GANC encapsulates the received LLC-PDU within a GA-PSR DATA message that is forwarded to the MS.

8.17.2.3 MS initiated GPRS Signalling

For MS initiated signalling/SMS, the MS GA-PSR receives a request from the LLC layer to transfer an uplink GMM/SM signalling message or SMS message; e.g. this could be a GMM attach request or SM PDP context activation message. The GMM/SM signalling messages are identified with LLC SAPI 1 and SMS messages with LLC SAPI 7. The MS GA-PSR encapsulates the LLC PDU within a GA-PSR DATA message including the parameters that will be required for Gb interface procedures. Subsequently, the message is forwarded to the GANC, and the GANC forwards the message to the Core Network as per standard Gb interface procedures.

Figure 34: Uplink Control Plane Data Transport

1. The MS GA-PSR receives a request from the LLC layer to transfer an uplink GMM/SM signalling message or SMS message; e.g. this could be a GMM attach request or SM PDP context activation message. The MS GA‑PSR encapsulates the LLC-PDU within a GA-PSR DATA message including the parameters that will be required for Gb interface procedures. Subsequently, the message is forwarded to the GANC.

2. The GANC forwards the message to the Core Network as per standard Gb interface procedure.