Connection release method and apparatus

1 . A method, comprising:

sending, by an access stratum of a first terminal device, first indication information to an upper layer of the access stratum of the first terminal device, wherein the upper layer of the access stratum of the first terminal device is a non-access stratum layer, and the first indication information indicates to the upper layer of the access stratum of the first terminal device to detect whether a previously-established unicast connection is still valid and to initiate a keep-alive procedure for the unicast connection, and wherein a message of the keep-alive procedure is carried on a signaling bearer of the access stratum of the first terminal device; and

detecting, by the upper layer of the access stratum of the first terminal device, the unicast connection according to the first indication information.

2 . The method according to claim 1 , wherein the first indication information comprises identifier information of the unicast connection.

3 . The method according to claim 2 , wherein the identifier information of the unicast connection is allocated by the upper layer of the access stratum of the first terminal device to the unicast connection.

4 . The method according to claim 1 , the detecting further comprising:

sending, by the first terminal device, a detection message to a second terminal device; and

in response to the first terminal device receiving no acknowledgment message in response to the detection message from the second terminal device after a timer expires, determining, by the first terminal device, that the previously-established unicast connection does not currently exist, wherein the unicast connection is a sidelink connection, and the sidelink connection is a wireless transmission link between the first terminal device and the second terminal device.

5 . The method according to claim 1 , further comprising:

sending, by the upper layer of the access stratum of the first terminal device, a release request message and first identifier information to the access stratum of the first terminal device, wherein the release request message requests a second terminal device to release the unicast connection, and the first identifier information identifies the unicast connection;

sending, by the access stratum of the first terminal device, the release request message to an access stratum of the second terminal device;

receiving, by the upper layer of the access stratum of the first terminal device, a release acknowledgment message from the second terminal device;

releasing, by the upper layer of the access stratum of the first terminal device, the unicast connection of the upper layer of the access stratum of the first terminal device;

sending, by the upper layer of the access stratum of the first terminal device, second indication information to the access stratum of the first terminal device, wherein the second indication information notifies the access stratum of the first terminal device that the upper layer of the first terminal device has released the unicast connection; and

releasing, by the access stratum of the first terminal device according to the second indication information, a configuration of the access stratum corresponding to the unicast connection.

6 . The method of claim 5 , further comprising:

sending, by the first terminal device, notification information to a network device, wherein the notification information notifies the network device that the unicast connection of the access stratum of the first terminal device has been released, and the notification information includes an updated destination identifier list that does not include a destination identifier corresponding to the released unicast connection.

7 . The method according to claim 1 , wherein the upper layer of the access stratum of the first terminal device is an application layer or a vehicle-to-everything (V2X) layer.

8 . The method according to claim 1 , wherein the AS stratum includes one or more of the following: a service data adaptation protocol layer, a radio resource control layer, a sidelink radio resource control layer, a media access control layer, or a physical layer.

9 . The method according to claim 1 , wherein the upper layer of the access stratum of the first terminal device is a layer that is higher than a sidelink radio resource control layer.

10 . A device, wherein the device is a first terminal device or an apparatus included in the first terminal device, and the device comprises:

at least one processor, and

one or more non-transitory memories coupled to the at least one processor and storing programming instructions that are executable by the at least one processor, wherein the programming instructions comprise instructions for:

sending, by an access stratum of the first terminal device, first indication information to an upper layer of the access stratum of the first terminal device, the first indication information indicating to the upper layer of the access stratum of the first terminal device to detect whether a previously-established unicast connection is still valid and to initiate a keep-alive procedure for the unicast connection, wherein the upper layer of the access stratum of the first terminal device is a non-access stratum layer, and wherein a message of the keep-alive procedure is carried on a signaling bearer of the access stratum of the first terminal device; and

detecting, by the upper layer of the access stratum of the first terminal device, the unicast connection according to the first indication information.

11 . The device according to claim 10 , wherein the first indication information comprises identifier information of the unicast connection.

12 . The device according to claim 10 , wherein the programming instructions for the detecting further include instructions for:

sending a detection message to a second terminal device; and

in response to the first terminal device receiving no acknowledgment message in response to the detection message from the second terminal device after a timer expires, determining that the previously-established unicast connection does not currently exist, wherein the unicast connection is a sidelink connection, and the sidelink connection is a wireless transmission link between the first terminal device and the second terminal device.

13 . The device according to claim 10 , wherein sending, by the access stratum of the first terminal device, the first indication information to the upper layer of the access stratum of the first terminal device comprises:

sending, by the access stratum of the first terminal device, the first indication information to the upper layer of the access stratum of the first terminal device according to a preset time.

14 . The device according to claim 13 , wherein the preset time is implemented by a timer.

15 . The device according to claim 10 , wherein the programming instructions further include instructions for:

sending, by the upper layer of the access stratum of the first terminal device, a release request message and first identifier information to the access stratum of the first terminal device, wherein the release request message requests a second terminal device to release the unicast connection, and the first identifier information identifies the unicast connection;

sending, by the access stratum of the first terminal device, the release request message to an access stratum of the second terminal device;

receiving, by the upper layer of the access stratum of the first terminal device, a release acknowledgment message from the second terminal device;

releasing, by the upper layer of the access stratum of the first terminal device, the unicast connection of the upper layer of the access stratum of the first terminal device;

sending, by the upper layer of the access stratum of the first terminal device, second indication information to the access stratum of the first terminal device, wherein the second indication information notifies the access stratum of the first terminal device that the upper layer of the first terminal device has released the unicast connection; and

releasing, by the access stratum of the first terminal device according to the second indication information, a configuration of the access stratum corresponding to the unicast connection.

16 . A non-transitory computer-readable storage medium storing at least one computer program, the at least one computer program being executable by one or more processors, and when the at least one computer program is executed, the at least one computer program causes the one or more processors to perform operations comprising:

sending, by an access stratum of a first terminal device, first indication information to an upper layer of the access stratum of the first terminal device, the first indication information indicating to the upper layer of the access stratum of the first terminal device to detect whether a previously-established unicast connection is still valid and to initiate a keep-alive procedure for the unicast connection, wherein the upper layer of the access stratum of the first terminal device is a non-access stratum layer, and wherein a message of the keep-alive procedure is carried on a signaling bearer of the access stratum of the first terminal device; and

detecting, by the upper layer of the access stratum of the first terminal device, the unicast connection according to the first indication information.

17 . The non-transitory computer-readable storage medium according to claim 15 , wherein the detecting further comprises:

sending, by the first terminal device, a detection message to a second terminal device; and

in response to the first terminal device receiving no acknowledgment message in response to the detection message from the second terminal device after a timer expires, determining, by the first terminal device, that the previously-established unicast connection does not currently exist, wherein the unicast connection is a sidelink connection, and the sidelink connection is a wireless transmission link between the first terminal device and the second terminal device.