User equipment

1. A method performed by a user equipment (UE) for control signal management, the method comprising:

transmitting a first Protocol Data Unit (PDU) session establishment request message containing a first request type field to a network node to establish a first PDU session associated with a Data Network Name (DNN) and a Single Network Slice Selection Assistance Information (S-NSSAI);

receiving a PDU session establishment reject message;

setting a second request type field within a second PDU session establishment request message to establish a second PDU session based on a cause value included in the PDU session establishment reject message indicating that the first PDU session has not been established; and

transmitting the second PDU session establishment request message to the network node to establish the second PDU session.

2. The method of claim 1 , wherein the second PDU session is associated with the DNN and the S-NSSAI when the DNN and the S-NSSAI are indicated in the second PDU session establishment request message.

3. The method of claim 1 , wherein the second PDU session is associated with the S-NSSAI but not with the DNN when no DNN is indicated in the second PDU session establishment request message.

4. The method of claim 1 , wherein the second PDU session is associated with the DNN but not with the S-NSSAI when no S-NSSAI is indicated in the second PDU session establishment request message.

5. The method of claim 1 , wherein the second PDU session is not associated with the DNN and not associated with the S-NSSAI when no DNN and no S-NSSAI are indicated in the second PDU session establishment request message.

6. The method of claim 1 , wherein the cause value is-comprises a 5G Session Management (5GSM) cause value.

7. A user equipment (UE) for performing control signal management, the UE comprising:

at least one processor; and

at least one non-transitory computer-readable medium coupled to the at least one processor, and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to:

transmit a first Protocol Data Unit (PDU) session establishment request message containing a first request type field to a network node to establish a first PDU session associated with a Data Network Name (DNN) and a Single Network Slice Selection Assistance Information (S-NSSAI);

receive a PDU session establishment reject message;

set a second request type field within a second initial PDU session establishment request message to establish a second PDU session based on a cause value included in the PDU session establishment reject message indicating that the first PDU session has not been established; and

transmit the second PDU session establishment request message to the network node to establish the second PDU session.

8. The UE of claim 7 , wherein the second PDU session is associated with the DNN and the S-NSSAI when the DNN and the S-NSSAI are indicated in the second PDU session establishment request message.

9. The UE of claim 7 , wherein the second PDU session is associated with the S-NSSAI but not with the DNN when no DNN is indicated in the second PDU session establishment request message.

10. The UE of claim 7 , wherein the second PDU session is associated with the DNN but not with the S-NSSAI when no S-NSSAI is indicated in the second PDU session establishment request message.

11. The UE of claim 7 , wherein the second PDU session is not associated with the DNN and not associated with the S-NSSAI when no DNN and no S-NSSAI are indicated in the second PDU session establishment request message.

12. The UE of claim 7 , wherein the cause value comprises a 5G Session Management (5GSM) cause value.

13. A method performed by a network node for control signal management, the method comprising:

receiving, from a user equipment (UE), a first Protocol Data Unit (PDU) session establishment request message containing a first request type field to establish a first PDU session associated with a Data Network Name (DNN) and a Single Network Slice Selection Assistance Information (S-NSSAI);

determining whether the first PDU session has not been established based on at least one of the DNN and the S-NSSAI;

transmitting, to the UE, a PDU session establishment reject message including a cause value indicating that the first PDU session has not been established in response to determining that the first PDU session has not to be established; and

receiving, from the UE, a second PDU session establishment request message to establish a second PDU session,

wherein a request type field is set within the second PDU session establishment request message to establish the second PDU session.

14. The method of claim 13 , wherein the second PDU session is associated with the DNN and the S-NSSAI when the DNN and the S-NSSAI are indicated in the second PDU session establishment request message.

15. The method of claim 13 , wherein the second PDU session is associated with the S-NSSAI but not with the DNN when no DNN is indicated in the second PDU session establishment request message.

16. The method of claim 13 , wherein the second PDU session is associated with the DNN but not with the S-NSSAI when no S-NSSAI is indicated in the second PDU session establishment request message.

17. The method of claim 13 , wherein the second PDU session is not associated with the DNN and not associated with the S-NSSAI when no DNN and no S-NSSAI are indicated in the second PDU session establishment request message.

18. The method of claim 13 , wherein the cause value comprises a 5G Session Management (5GSM) cause value.