Method and apparatus for avoiding circuit-switched call drop in mobile communications
Various solutions for avoiding circuit-switched call drop with respect to user equipment and network apparatus in mobile communications are described. An apparatus transmits a non-access stratum (NAS) message in a NAS signaling connection. The apparatus receives a NAS response message. The apparatus initiates a timer to control the NAS signaling connection. The apparatus further receives a circuit-switched (CS) service notification. The apparatus then stops the timer and execute a CS service procedure.
1. A method, comprising:
transmitting, by a processor of an apparatus, a non-access stratum (NAS) message in a NAS signaling connection;
receiving, by the processor, a NAS response message;
initiating, by the processor, a timer according to the NAS response message to control the NAS signaling connection by releasing the NAS signaling connection upon expiration of the timer;
receiving, by the processor, a circuit-switched (CS) service notification; and
stopping, by the processor responsive to receiving the CS service notification and before expiration of the timer, the timer to re-use the NAS signaling connection to execute a CS service procedure.
2. The method of claim 1 , wherein the executing comprises executing the CS service procedure by re-using the NAS signaling connection.
3. The method of claim 1 , wherein the NAS message comprises at least one of a tracking area update (TAU) request message, a detach request message or a service request message.
4. The method of claim 1 , wherein the NAS response message comprises at least one of a TAU accept message, a TAU reject message, a detach accept message or a service reject message.
5. The method of claim 1 , wherein the timer that controls the NAS signaling connection comprises T 3440 .
6. The method of claim 1 , wherein the CS service notification comprises a mobile-terminated (MT) CS call indication.
7. The method of claim 1 , wherein the CS service notification comprises a mobile-originated (MO) CS call request.
8. The method of claim 1 , further comprising:
performing, by the processor, a circuit-switched fallback (CSFB) procedure to execute the CS service procedure.
9. The method of claim 1 , further comprising:
releasing, by the processor, the NAS signaling connection in response to expiration of the timer.
10. The method of claim 1 , wherein the stopping comprises stopping the timer upon receiving the CS service notification in an evolved packet system mobility management (EMM)-service-request-initiated state.
11. An apparatus, comprising:
a transceiver capable of wirelessly communicating with a plurality of nodes of a wireless network; and
a processor communicatively coupled to the transceiver, the processor capable of:
transmitting, via the transceiver, a non-access stratum (NAS) message in a NAS signaling connection;
receiving, via the transceiver, a NAS response message;
initiating a timer according to the NAS response message to control the NAS signaling connection by releasing the NAS signaling connection upon expiration of the timer;
receiving, via the transceiver, a circuit-switched (CS) service notification; and
stopping, responsive to receiving the CS service notification and before expiration of the timer, the timer to re-use the NAS signaling connection to execute a CS service procedure.
12. The apparatus of claim 11 , wherein, in executing the CS service procedure, the processor is capable of executing the CS service procedure by re-using the NAS signaling connection.
13. The apparatus of claim 11 , wherein the NAS message comprises at least one of a tracking area update (TAU) request message, a detach request message or a service request message.
14. The apparatus of claim 11 , wherein the NAS response message comprises at least one of a TAU accept message, a TAU reject message, a detach accept message or a service reject message.
15. The apparatus of claim 11 , wherein the timer for controlling the NAS signaling connection comprises T 3440 .
16. The apparatus of claim 11 , wherein the CS service notification comprises a mobile-terminated (MT) CS call indication.
17. The apparatus of claim 11 , wherein the CS service notification comprises a mobile-originated (MO) CS call request.
18. The apparatus of claim 11 , wherein the processor is further capable of:
performing a circuit-switched fallback (CSFB) procedure to execute the CS service procedure.
19. The apparatus of claim 11 , wherein the processor is further capable of:
releasing the NAS signaling connection in response to expiration of the timer.
20. The apparatus of claim 11 , wherein, in stopping the timer, the processor is capable of stopping the timer upon receiving the CS service notification in an evolved packet system mobility management (EMM)-service-request-initiated state.