8.4.4 SCG Deactivation and Activation

38.4013GPPArchitecture descriptionNG-RANRelease 17TS

This clause gives the NR SCG deactivation and activation procedures in MR-DC given that the SN consists of a gNB-CU and gNB-DU(s).

8.4.4.1 SN Addition with SCG Activation or Deactivation

Figure 8.4.4.1-1: SCG Activation or Deactivation in SN Addition procedure

1. The MN sends the SN Addition Request message to the SN, indicates the request of SCG activation or deactivation.

2. The SN-CU-CP may send the BEARER CONTEXT SETUP REQUEST message to the SN-CU-UP to setup bearer context and notify the activation or deactivation of the SCG.

3. The SN-CU-UP sends the BEARER CONTEXT SETUP RESPONSE message to the SN-CU-CP.

4. The SN-CU sends the UE CONTEXT SETUP REQUEST message to the SN-DU to setup UE context and indicate the request of SCG activation or deactivation.

5. The SN-DU sends the UE CONTEXT SETUP RESPONSE message to the SN-CU, indicates the SCG status. In case SCG activation is requested, the SN-DU shall indicate SCG activated in the message.

6. The SN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the SN-CU-UP as described in clause 8.9.2 and may notify the SCG status if needed.

7. The SN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the SN-CU-CP.

8. The SN sends the SN Addition Request Acknowledge message to the MN, indicates the SCG status. In case SCG activation is requested, the SN shall indicate SCG activated in the message.

9. The MN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the MN-CU-UP to notify the SCG status.

10. The MN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the MN-CU-CP.

8.4.4.2 MN initiated SN Modification with SCG Activation or Deactivation

Figure 8.4.4.2-1: SCG Activation or Deactivation in MN initiated SN Modification procedure

1. SCG is deactivated or activated.

2. The MN sends the SN Modification Request message to the SN, indicates the request of SCG activation or deactivation.

3. The SN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the SN-CU-UP to notify the SCG activation or deactivation.

4. The SN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the SN-CU-CP.

5. The SN-CU sends the UE CONTEXT MODIFICATION REQUEST message to the SN-DU to indicate the request of SCG activation or deactivation.

6. The SN-DU may send the UE CONTEXT MODIFICATION RESPONSE message to the SN-CU, indicates the SCG status.

7. The SN-CU-CP sends the BEARER CONTEXT MODIFICATION REQUEST message to the SN-CU-UP to notify the SCG status.

8. The SN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the SN-CU-CP.

NOTE: Step 7 and 8 may be skipped in case the SN-DU accepted the SCG activation or deactivation request.

9. The SN sends the SN Modification Request Acknowledge message towards the MN, indicates the SCG status.

10. The MN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the MN-CU-UP to notify the SCG status.

11. The MN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the MN-CU-CP.

8.4.4.3 SN initiated SN Modification with SCG Activation or Deactivation

Figure 8.4.4.3-1: SCG Activation or Deactivation in SN initiated SN Modification procedure

1. SCG is deactivated or activated.

2. The SN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the SN-CU-UP to notify the SCG activation or deactivation.

3. The SN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the SN-CU-CP.

4. The SN-CU sends the UE CONTEXT MODIFICATION REQUEST message to the SN-DU to indicate the request of SCG activation or deactivation.

5. The SN-DU sends the UE CONTEXT MODIFICATION RESPONSE message to the SN-CU, indicates the SCG status.

6. The SN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the SN-CU-UP to notify the SCG status.

7. The SN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the SN-CU-CP.

NOTE 1: Step 6 and 7 may be skipped in case the SN-DU accepted the SCG activation or deactivation request.

8. The SN sends the SN Modification Required message to the MN, indicates the request of SCG activation or deactivation.

9. The MN-CU-CP may send the BEARER CONTEXT MODIFICATION REQUEST message to the MN-CU-UP to notify the SCG status.

10. The MN-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the MN-CU-CP.

NOTE 2: Based on implementation, step 9 and 10 can be performed after step 11.

11. The MN sends the SN Modification Confirm message to the SN.

NOTE 3: Step 8-11 are not performed in case the SN-DU rejected the SCG activation or deactivation request.