Mechanisms for signaling out-of-coverage sidelink devices in wireless communication

1. A method of wireless communication by an apparatus, the method comprising:

receiving sidelink grant information from a scheduling entity; and

transmitting a direction selection signal (DSS) in a first transmission time interval (TTI) included in a subframe to one or more first scheduled entities located outside a coverage area of the scheduling entity, wherein the DSS comprises sidelink scheduling information based on the sidelink grant information;

receiving after transmitting the DSS, a source transmit signal (STS) in the first TTI from an out-of-coverage (OoC) scheduled entity of the first scheduled entities, wherein the STS is configured to request a duration of time to keep a sidelink channel available; and

transmitting, in the first TTI, a destination receive signal (DRS) to the OoC scheduled entity to indicate availability of the sidelink channel such that the sidelink channel is established between the apparatus and the OoC scheduled entity based on the sidelink grant information.

2. The method of claim 1 , wherein the DSS is configured to indicate to the one or more first scheduled entities that the apparatus does not have priority access to the sidelink channel.

3. The method of claim 1 , further comprising:

receiving a timing feedback from the one or more first scheduled entities; and

transmitting the sidelink scheduling information on the condition that the timing feedback is received.

4. The method of claim 1 , wherein the sidelink scheduling information comprises sidelink specific grant information destined to one or more predetermined out-of-coverage (OoC) scheduled entities of the first scheduled entities.

5. The method of claim 4 , wherein the sidelink specific grant information is configured to facilitate establishing a predetermined sidelink channel between two of the predetermined OoC scheduled entities.

6. The method of claim 1 , further comprising:

receiving a sidelink handshake signal in a second TTI from a second scheduled entity located outside the coverage area of the scheduling entity, without receiving a prior sidelink handshake signal from the second scheduled entity.

7. A method of wireless communication by an apparatus, the method comprising:

receiving at a location outside a coverage area of a scheduling entity, from a first scheduled entity, a direction selection signal (DSS) comprising sidelink scheduling information in a transmission time interval (TTI) included in a subframe, wherein the first scheduled entity is located inside the coverage area, wherein the sidelink scheduling information is based on sidelink grant information originated from the scheduling entity;

transmitting, in the TTI, a source transmit signal (STS) based on the sidelink scheduling information to a second scheduled entity, wherein the STS is configured to indicate a requested duration of time to utilize a sidelink channel; and

receiving, in the TTI, a destination receive signal (DRS) from the second scheduled entity configured to indicate availability of the sidelink channel; and

transmitting, in the TTI, sidelink data utilizing the sidelink channel established according to the sidelink scheduling information.

8. The method of claim 7 , wherein the DSS is configured to indicate that the first scheduled entity does not have priority access to the sidelink channel.

9. The method of claim 7 , wherein the second scheduled entity is a primary device of the sidelink channel.

10. The method of claim 7 , wherein the second scheduled entity is the same as the first scheduled entity.

11. The method of claim 7 , wherein the second scheduled entity is different from the first scheduled entity.

12. An apparatus for wireless communication, comprising:

a communication interface;

a memory stored with executable code; and

a processor operatively coupled with the communication interface and memory,

wherein the processor is configured by the executable code to:

receive sidelink grant information from a scheduling entity; and

transmit a direction selection signal (DSS) in a first transmission time interval (TTI) included in a subframe to one or more first scheduled entities located outside a coverage area of the scheduling entity, wherein the DSS comprises sidelink scheduling information based on the sidelink grant information;

receive after transmitting the DSS, a source transmit signal (STS) in the first TTI from an out-of-coverage (OoC) scheduled entity of the first scheduled entities, wherein the STS is configured to request a duration of time to keep a sidelink channel available; and

transmit, in the first TTI, a destination receive signal (DRS) to the OoC scheduled entity such that the sidelink channel is established between the apparatus and the OoC scheduled entity based on the sidelink grant information.

13. The apparatus of claim 12 , wherein the DSS is configured to indicate to the one or more first scheduled entities that the apparatus does not have priority access to the sidelink channel.

14. The apparatus of claim 12 , wherein the processor is further configured to:

receive a timing feedback from the one or more first scheduled entities; and

transmit the sidelink scheduling information on the condition that the timing feedback is received.

15. The apparatus of claim 12 , wherein the sidelink scheduling information comprises sidelink specific grant information destined to one or more predetermined out-of-coverage (OoC) scheduled entities of the first scheduled entities.

16. The apparatus of claim 15 , wherein the sidelink specific grant information is configured to facilitate establishing a predetermined sidelink channel between two of the predetermined OoC scheduled entities.

17. The apparatus of claim 12 , wherein the processor is further configured to:

receive a sidelink handshake signal in a second TTI from a second scheduled entity located outside the coverage area of the scheduling entity, without receiving a prior sidelink handshake signal from the second scheduled entity.

18. An apparatus for wireless communication, comprising:

a communication interface;

a memory stored with executable code; and

a processor operatively coupled with the communication interface and memory,

wherein the processor is configured by the executable code to:

receive at a location outside a coverage area of a scheduling entity, from a first scheduled entity, a direction selection signal (DSS) comprising sidelink scheduling information in a transmission time interval (TTI) included in a subframe, wherein the first scheduled entity is located inside the coverage area, wherein the sidelink scheduling information is based on sidelink grant information originated from the scheduling entity;

transmit, in the TTI, a source transmit signal (STS) based on the sidelink scheduling information to a second scheduled entity, wherein the STS is configured to indicate a requested duration of time to utilize a sidelink channel;

receive, in the TTI, a destination receive signal (DRS) from the second scheduled entity configured to indicate availability of the sidelink channel; and

transmit, in the TTI, sidelink data utilizing the sidelink channel established according to the sidelink scheduling information.

19. The apparatus of claim 18 , wherein the DSS is configured to indicate that the first scheduled entity does not have priority access to the sidelink channel.

20. The apparatus of claim 18 , wherein the second scheduled entity is a primary device of the sidelink channel.

21. The apparatus of claim 18 , wherein the second scheduled entity is the same as the first scheduled entity.

22. The apparatus of claim 18 , wherein the second scheduled entity is different from the first scheduled entity.