Methods and apparatuses for transmitting over sidelink multipath operations

1 . A computer-implemented method for a first terminal device, wherein the first terminal device conducts communications with a base station directly and indirectly, over an established first sidelink communication path, via a second terminal device that acts as a relay terminal device for the first terminal device, the method comprising the following steps:

while the established first sidelink communication path is active, transmitting, by the first terminal device, a first request to the second terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

receiving, by the first terminal device, a first response to the first request from the second terminal device;

transmitting, by the first terminal device, a second request to the third terminal device, the second request indicating that the second sidelink communication path between the third terminal device and the first terminal device should be activated for the sidelink multipath operation; and

setting up, by the first terminal device, the second sidelink communication path between the third terminal device and the first terminal device.

2 . The method according to claim 1 , comprising either or both of:

a) determining, by the first terminal device, whether the sidelink multipath operation should be activated in which the third terminal device serves as a further relay terminal device; and

b) performing, by the first terminal device, a discovery procedure for discovering the third terminal device for serving as the further relay terminal device.

3 . The method according to claim 2 , further comprising:

determining, by the first terminal device, that setup of the sidelink multipath operation is required.

4 . The method according to claim 1 , further comprising one or both of the following two steps of:

a) receiving, by the first terminal device, a second response to the second request from the third terminal device; and

b) performing, by the first terminal device, an operation based at least on the second response.

5 . The method according to claim 4 , further comprising any one or more of the following steps:

a) transmitting, by the first terminal device, an indication to the second terminal device indicating a status associated with the sidelink multipath operation including whether a setup of the sidelink multipath operation is completed;

b) receiving, by the first terminal device, an indication from the second terminal device that the first terminal device should perform a multipath relay selection; and

c) performing, by the first terminal device, at least some aspects of a multipath setup procedure jointly with the second terminal device to establish a multipath link with the third terminal device.

6 . A computer-implemented method of a second terminal device that serves a first terminal device as a relay over an established first sidelink communication path through which the first terminal device conducts indirect communications with a base station, the method comprising the following steps:

while the established first sidelink communication path is active, receiving, by the second terminal device, a first request from the first terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

transmitting, by the second terminal device and to the first terminal, a first response to the first request; and

performing, by the second terminal device, at least some aspects of a multipath setup procedure jointly with the first terminal device to establish a multipath link with the third terminal device.

7 . The method according to claim 6 , further comprising:

determining, by the second terminal device, the first response, wherein the determining includes either:

a) determining the first response independently of another entity including a network device; or

b) determining the first response jointly with the network device using explicit signaling with the network device.

8 . The method according to claim 6 , further comprising any one or more of the following six steps:

a) determining, by the second terminal device, whether the sidelink multipath operation should be activated;

b) performing, by the second terminal device, a discovery and/or sidelink setup associated with the second terminal device and the third terminal device;

c) receiving, by the second terminal device, an indication from the first terminal device indicating a status associated with the sidelink multipath operation including whether a setup of the sidelink multipath operation is completed;

d) transmitting, by the second terminal device, an indication to a network device indicating a status associated with the sidelink multipath operation including whether a setup of the sidelink multipath operation is completed;

e) receiving, by the second terminal device, an indication from a network device that the first terminal device should perform a multipath relay selection; and

f) transmitting, by the second terminal device, an indication to the first terminal device that the first terminal device should perform a multipath relay selection based on receiving the indication from the network device.

9 . A computer-implemented method of a third terminal device, the method comprising the following steps:

a) receiving, by the third terminal device, a second request from a first terminal device while an established first sidelink communication path, which is between the first terminal device and a second terminal device that serves the first terminal device as a relay terminal device for indirect communications between the first terminal device and a base station, is active, wherein:

the first terminal device conducts further communications directly with the base station;

the first terminal device transmits, while the established first sidelink communication path is active, a first request to the second terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path requesting activation of the sidelink multipath operation;

the first terminal device receives, from the second terminal device, a first response to the first request prior to transmitting the second request to the third terminal device;

the second request indicates that a second sidelink communication path between the third terminal device and the first terminal device should be activated as part of a sidelink multipath operation requested by the first terminal device via the established first sidelink communication path, the sidelink multipath operation including establishing the second sidelink communication path in response to the second request; and

the sidelink multipath operation includes a message being transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path via the second terminal device and the established second sidelink communication path via the third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

b) participating, by the third terminal device with the first terminal device, in setting up the second sidelink communication path between the third terminal device and the first terminal device; and

c) transmitting, by the third terminal device and to the first terminal device, a second response to the second request.

10 . The method according to claim 9 , comprising any one or more of the following steps:

a) performing, by the third terminal device, either or both of a discovery and a sidelink setup associated with the second terminal device and the third terminal device;

b) transmitting, by the third terminal device, an indication to a network device indicating a status associated with the sidelink multipath operation including whether a setup of the sidelink multipath operation is completed; and

c) serving, by the third terminal device, the first terminal device as a relay terminal device associated with the sidelink multipath operation.

11 . A first terminal device configured to conduct communications with a base station directly and indirectly over an established first sidelink communication path via a second terminal device that serves the first terminal device as a relay terminal device, the first terminal device comprising:

a wireless communication interface;

a processing system that includes at least one processor; and

a memory on which are stored instructions that are executable by the processing system and that, when executed by the processing system, cause the processing system to:

while the established first sidelink communication path is active, transmit a first request to the second terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

receive a first response to the first request from the second terminal device;

transmit a second request to the third terminal device, the second request indicating that the second sidelink communication path between the third terminal device and the first terminal device should be activated for the sidelink multipath operation; and

set up the second sidelink communication path between the third terminal device and the first terminal device.

12 . An apparatus for a first terminal device, wherein the first terminal is configured to conduct communications with a base station directly and indirectly over an established first sidelink communication path via a second terminal device that serves the first terminal device as a relay terminal device, the apparatus comprising:

a wireless communication interface;

a processing system that includes at least one processor; and

a memory on which are stored instructions that are executable by the processing system and that, when executed by the processing system, cause the processing system to:

while the established first sidelink communication path is active, transmit a first request to the second terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

receive a first response to the first request from the second terminal device;

transmit a second request to the third terminal device, the second request indicating that the second sidelink communication path between the third terminal device and the first terminal device should be activated for the sidelink multipath operation; and

set up the second sidelink communication path between the third terminal device and the first terminal device.

13 . A computer-implemented method of a network device that supports communications between a first terminal device and a base station, the first terminal device conducting communications with the base station directly and indirectly over a first sidelink communication path via a second terminal device that serves the first terminal device as a relay terminal device, the method comprising:

determining, by the network device, a first response to be transmitted to the first terminal device by the second terminal device, responsive to the second terminal device receiving, while the established first sidelink communication path is active, a first request from the first terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device; and

causing the second terminal device to transmit the first response to the first terminal device, triggering the first terminal device to perform the sidelink multipath operation including transmitting a second request to a third terminal device and establishing a second sidelink communication path between the first terminal device and the third terminal device.

14 . A network device that supports communications between a first terminal device and a base station, the first terminal device conducting communications with the base station directly and indirectly over a first sidelink communication path via a second terminal device that serves the first terminal device as a relay terminal device, the network device comprising:

at least one communication interface;

a processing system that includes at least one processor; and

at least one memory storing instructions that, when executed by the processing system, cause the processing system to:

determine a first response to be transmitted to the first terminal device by the second terminal device, responsive to the second terminal device receiving, while the established first sidelink communication path between the first terminal device and the second terminal device is active, a first request from the first terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device; and

conduct a transmission with the second terminal device over the at least one communication interface, which causes the second terminal device to transmit the first response to the first terminal device, triggering the first terminal device to perform the sidelink multipath operation including transmitting a second request to a third terminal device and establishing a second sidelink communication path between the first terminal device and the third terminal device.

15 . An apparatus for a network device, wherein the network device supports communications between a first terminal device and a base station, the first terminal device conducting communications with the base station directly and indirectly over a first sidelink communication path via a second terminal device that serves the first terminal device as a relay terminal device, the apparatus comprising:

at least one communication interface;

a processing system that includes at least one processor; and

at least one memory storing instructions that, when executed by the processing system, cause the processing system to:

determine a first response to be transmitted to the first terminal device by the second terminal device, responsive to the second terminal device receiving, while the established first sidelink communication path between the first terminal device and the second terminal device is active, a first request from the first terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device; and

conduct a transmission with the second terminal device over the at least one communication interface, which causes the second terminal device to transmit the first response to the first terminal device, triggering the first terminal device to perform the sidelink multipath operation including transmitting a second request to a third terminal device and establishing a second sidelink communication path between the first terminal device and the third terminal device.

16 . A communication system, comprising:

a first terminal device that conducts communications directly with a base station and indirectly with the base station over an established first sidelink communication path and via a second terminal device that acts as a relay terminal device for the first terminal device, wherein the first terminal device is configured to:

while the established first sidelink communication path is active, transmit a first request to the second terminal device via a sidelink interface using a first sidelink communication over the established first sidelink communication path, wherein the first request requests activation, for the first terminal device, of a sidelink multipath operation, including establishing, in response to the first request, a second sidelink communication path, and wherein the sidelink multipath operation includes the first terminal device continuing to conduct communications with the base station and in which a message is transmitted between the first terminal device and the base station indirectly by selecting between the established first sidelink communication path for transmission via the second terminal device and the established second sidelink communication path for transmission via a third terminal device, the selecting including switching of relay roles between the second terminal device and the third terminal device;

receive a first response to the first request from the second terminal device;

transmit a second request to the third terminal device, the second request indicating that the second sidelink communication path between the third terminal device and the first terminal device should be activated for the sidelink multipath operation; and

set up the second sidelink communication path between the third terminal device and the first terminal device.