Method and apparatus for session release in wireless communication

1. An electronic apparatus for wireless communication including processing circuitry that is configured to:

send one or more packet data unit (PDU) session release requests to a wireless communication network system to request a PDU session release procedure, a timer being used for the one or more PDU session release requests;

start the timer when each of the one or more PDU session release requests is sent, wherein the one or more PDU session release requests include a procedure transaction identifier (PTI) allocated for the PDU session release procedure;

determine whether a network response is received from the wireless communication network system before the timer expires,

restart the timer when a network response is not received and the timer expires;

count a number of times that the timer expires and the network response is not received from the wireless communication system;

determine whether the number of times that the timer expires reaches a predetermined number of times that is two or more times; and

when the network response is not received and the number of times that the timer expires reaches the predefined number of times:

locally release the PDU session;

abort the PDU session release procedure; and

release the allocated PTI.

2. The electronic apparatus of claim 1 , wherein the processing circuitry is further configured to:

send a PDU session status to the wireless communication network system after locally releasing the PDU session.

3. The electronic apparatus of claim 1 , wherein

the one or more PDU session release requests include an identifier allocated for the PDU session release procedure; and

when the network response is not received and the number of times that the timer expires reaches the predefined number of times, the processing circuitry is further configured to:

abort the PDU session release procedure; and

release the allocated identifier.

4. The electronic apparatus of claim 1 , wherein the processing circuitry is further configured to:

for each of the one or more PDU session release requests,

determine whether the network response is received before the timer expires; and

when the timer expires and the network response is not received, determine whether the number of times that the timer expires reaches the predetermined number of times.

5. The electronic apparatus of claim 1 , wherein the timer is a timer T 3582 .

6. The electronic apparatus of claim 1 , wherein

the wireless communication network system is a fifth generation (5G) wireless communication network system (5GS), the PDU session is between the electronic apparatus and a 5G core network (5GC) of the 5GS, and the one or more PDU session release requests includes an initial PDU session release request message followed by L additional PDU session release request messages, L being a positive integer; and

the processing circuitry is further configured to:

start the timer (L+1) times when the initial PDU session release request message and the L additional PDU session release request messages are sent, respectively; and

send each of the L additional PDU session release request messages each time the timer expires.

7. The electronic apparatus of claim 6 , wherein the processing circuitry is further configured to locally release the PDU session when the timer expires (L+1) times.

8. The electronic apparatus of claim 7 , wherein the processing circuitry is further configured to:

send a registration request to the 5GC that includes a PDU session status information element after locally releasing the PDU session.

9. The electronic apparatus of claim 7 , wherein

L is 4; and

the processing circuitry is further configured to locally release the PDU session when the timer expires five times.

10. A method for wireless communication, comprising:

sending one or more PDU session release requests to a wireless communication network system to request a PDU session release procedure, a timer being used for the one or more PDU session release requests;

starting the timer when each of the one or more PDU session release requests is sent, wherein the one or more PDU session release requests include a procedure transaction identifier (PTI) allocated for the PDU session release procedure;

determining whether a network response is received from the wireless communication network system before the timer expires,

restarting the timer when a network response is not received and the timer expires;

counting a number of times that the timer expires and the network response is not received from the wireless communication system;

determining whether the number of times that the timer expires reaches a predetermined number of times that is two or more times; and

when the network response is not received and the number of times that the timer expires reaches the predefined number of times:

locally releasing the PDU session;

aborting the PDU session release procedure; and

releasing the allocated PTI.

11. The method of claim 10 , further comprising:

sending a PDU session status to the wireless communication network system after locally releasing the PDU session.

12. The method of claim 10 , wherein

the one or more session PDU release requests include an identifier allocated for the PDU session release procedure; and

when the network response is not received and the number of times that the timer expires reaches the predefined number of times, the method further includes:

aborting the PDU session release procedure; and

releasing the allocated identifier.

13. The method of claim 10 , further comprising:

for each of the one or more PDU session release requests,

determining whether the network response is received before the timer expires; and

when the timer expires and the network response is not received, determining whether the number of times that the timer expires reaches the predetermined number of times.

14. The method of claim 10 , wherein the timer is a timer T 3582 .

15. The method of claim 10 , wherein

the wireless communication network system is a fifth generation (5G) wireless communication network system (5GS), the PDU session is between the electronic apparatus and a 5G core network (5GC) of the 5GS, and the one or more PDU session release requests includes an initial PDU session release request message followed by L additional PDU session release request messages, L being a positive integer; and

the method includes:

starting the timer (L+1) times when the initial PDU session release request message and the L additional PDU session release request messages are sent, respectively; and

sending each of the L additional PDU session release request messages each time the timer expires.

16. The method of claim 15 , wherein the locally releasing the PDU session comprises locally releasing the PDU session when the timer expires (L+1) times.

17. The method of claim 16 , further comprising:

sending a registration request to the 5GC that includes a PDU session status information element after locally releasing the PDU session.

18. A non-transitory computer readable medium having computer readable instructions stored thereon which, when executed by a processing circuit, cause the processing circuit to perform a method of wireless communication, the method comprising:

sending one or more PDU session release requests to a wireless communication network system to request a PDU session release procedure, a timer being used for the one or more PDU session release requests;

starting the timer when each of the one or more PDU session release requests is sent, wherein the one or more PDU session release requests include a procedure transaction identifier (PTI) allocated for the PDU session release procedure;

determining whether a network response is received from the wireless communication network system before the timer expires;

restarting the timer when a network response is not received and the timer expires;

counting a number of times that the timer expires and the network response is not received from the wireless communication system;

determining whether the number of times that the timer expires reaches a predetermined number of times that is two or more times; and

when the network response is not received and the number of times that the timer expires reaches the predefined number of times:

locally releasing the PDU session;

aborting the PDU session release procedure; and

releasing the allocated PTI.