Contention-based data transmissions on return link

1. A method of wireless communication in a satellite system, the method performed by a user terminal (UT) and comprising:

receiving data for transmission to a gateway via a satellite;

receiving, from the gateway, an activation of contention-based resources of the satellite system;

transmitting, during a time period, a first portion of the data on a plurality of subframes of the contention-based resources prior to receiving a grant of scheduled return link resources; and

terminating data transmissions on the contention-based resources after an expiration of the time period or upon receiving the grant of scheduled return link resources, irrespective of collisions on the contention-based resources.

2. The method of claim 1 , wherein the activation comprises a signal received from the gateway via a dedicated physical forward link control channel (PFCCH) that is independent of the contention-based resources.

3. The method of claim 1 , wherein the activation indicates a modulation and coding scheme (MCS) to be used by the UT when transmitting data on the contention-based resources.

4. The method of claim 1 , wherein the plurality of subframes of the contention-based resources are allocated to the UT by a radio controller circuit (RRC) associated with the gateway.

5. The method of claim 1 , wherein transmission of at least part of the first portion of the data comprises an implicit scheduling request for the grant of scheduled return link resources.

6. The method of claim 1 , further comprising:

transmitting a scheduling request, on a dedicated physical return link control channel (PRCCH) that is independent of the contention-based resources, during the time period.

7. The method of claim 6 , wherein the PRCCH is allocated to the UT only between selected pairs of subframes of the contention-based resources.

8. The method of claim 1 , further comprising:

receiving the grant for the scheduled return link resources prior to the expiration of the time period;

transmitting a second portion of the data on the scheduled return link resources during the time period; and

terminating data transmissions on the contention-based resources in response to receiving the grant.

9. The method of claim 1 , further comprising:

receiving the grant for the scheduled return link resources after the expiration of the time period; and

transmitting a second portion of the data on the scheduled return link resources indicated by the received grant.

10. The method of claim 1 , further comprising:

receiving, from the gateway, an indication of a collision on the contention-based resources; and

re-transmitting data associated with the indicated collision on the scheduled return link resources after the expiration of the time period.

11. The method of claim 1 , further comprising:

triggering a buffer status report (BSR) in response to receiving the data; and

commencing the time period based on the triggering of the BSR.

12. The method of claim 11 , further comprising:

preventing additional data transmissions on the contention-based resources until a subsequent BSR is triggered.

13. The method of claim 1 , further comprising:

commencing the time period based on transmission of the data on a first of the plurality of subframes of the contention-based resources.

14. The method of claim 1 , wherein the time period is determined by a radio resource control (RRC) associated with the gateway.

15. The method of claim 1 , wherein the contention-based resources are shared between a plurality of UTs during the time period.

16. The method of claim 15 , wherein each of the plurality of UTs transmits data on the contention-based resources using a unique demodulation reference signal (DM-RS) shift selected by a scheduler associated with the gateway.

17. A user terminal (UT) configured for wireless communication in a satellite system, the user terminal comprising:

one or more processors; and

a memory storing instructions that, when executed by the one or more processors, cause the user terminal to:

receive data for transmission to a gateway via a satellite;

receive, from the gateway, an activation of contention-based resources of the satellite system;

transmit, during a time period, a first portion of the data on a plurality of subframes of the contention-based resources prior to receiving a grant of scheduled return link resources; and

terminate data transmissions on the contention-based resources after an expiration of the time period or upon receiving the grant of scheduled return link resources, irrespective of collisions on the contention-based resources.

18. The user terminal of claim 17 , wherein the activation comprises a signal received from the gateway via a dedicated physical forward link control channel (PFCCH) that is independent of the contention-based resources.

19. The user terminal of claim 17 , wherein the activation indicates a modulation and coding scheme (MCS) to be used by the UT when transmitting data on the contention-based resources.

20. The user terminal of claim 17 , wherein the plurality of subframes of the contention-based resources are allocated to the UT by a radio controller circuit (RRC) associated with the gateway.

21. The user terminal of claim 17 , wherein transmission of at least part of the first portion of the data comprises an implicit scheduling request for the grant of scheduled return link resources.

22. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

transmit a scheduling request, on a dedicated physical return link control channel (PRCCH) that is independent of the contention-based resources, during the time period.

23. The user terminal of claim 22 , wherein the PRCCH is allocated to the UT only between selected pairs of subframes of the contention-based resources.

24. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

receive the grant for the scheduled return link resources prior to the expiration of the time period;

transmit a second portion of the data on the scheduled return link resources during the time period; and

terminate data transmissions on the contention-based resources in response to receiving the grant.

25. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

receive the grant for the scheduled return link resources after the expiration of the time period; and

transmit a second portion of the data on the scheduled return link resources indicated by the received grant.

26. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

receive, from the gateway, an indication of a collision on the contention-based resources; and

re-transmit data associated with the indicated collision on the scheduled return link resources after the expiration of the time period.

27. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

trigger a buffer status report (BSR) in response to receiving the data; and

commence the time period based on the triggering of the BSR.

28. The user terminal of claim 27 , wherein execution of the instructions causes the user terminal to further:

prevent additional data transmissions on the contention-based resources until a subsequent BSR is triggered.

29. The user terminal of claim 17 , wherein execution of the instructions causes the user terminal to further:

commence the time period based on transmission of the data on a first of the plurality of subframes of the contention-based resources.

30. The user terminal of claim 17 , wherein the time period is determined by a radio resource control (RRC) associated with the gateway.

31. The user terminal of claim 17 , wherein the contention-based resources are shared between a plurality of UTs during the time period.

32. The user terminal of claim 31 , wherein each of the plurality of UTs transmits data on the contention-based resources using a unique demodulation reference signal (DM-RS) shift selected by a scheduler associated with the gateway.