Contention-based data transmissions on return link

1. A method of wireless communication in a satellite system, the method performed by a network controller of the satellite system and comprising:

allocating contention-based resources of the satellite system to a plurality of user terminals (UTs);

activating the allocated contention-based resources by transmitting an activation signal to the plurality of UTs;

receiving, from a first UT via a satellite of the satellite system, a first portion of data on a plurality of subframes of the contention-based resources during a time period; and

suspending the allocation of the contention-based resources to the first UT after an expiration of the time period or upon a grant of scheduled return link resources to the first UT, irrespective of collisions on the contention-based resources.

2. The method of claim 1 , wherein the activation signal is transmitted 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 signal indicates a modulation and coding scheme (MCS) to be used by the plurality of UTs when transmitting data on the contention-based resources.

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

5. The method of claim 1 , further comprising:

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

6. The method of claim 5 , wherein the PRCCH is allocated to the first UT only between selected pairs of subframes of the contention-based resources.

7. The method of claim 5 , further comprising:

transmitting the grant for the return link resources in response to the received scheduling request; and

receiving a second portion of the data on the scheduled return link resources during the time period.

8. The method of claim 7 , wherein transmission of the grant terminates the allocation of the contention-based resources to the first UT.

9. The method of claim 1 , further comprising:

transmitting a grant for the return link resources after expiration of the time period;

receiving a second portion of the data on the scheduled return link resources after the expiration of the time period; and

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

10. The method of claim 1 , wherein the activation signal assigns a unique demodulation reference signal (DM-RS) shift to the first UT.

11. The method of claim 1 , further comprising:

receiving, on the contention-based resources, a buffer status report (BSR) indicating an amount of data stored in a buffer of the first UT.

12. The method of claim 1 , further comprising:

detecting a collision on the contention-based resources;

identifying one or more of the plurality of UTs that transmitted data associated with the collision based on unique demodulation reference signal (DM-RS) shifts assigned to the plurality of UTs; and

requesting the one or more identified UTs to re-transmit the data on the scheduled return link resources.

13. A network controller configured for wireless communication in a satellite system, the network controller comprising:

one or more processors; and

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

allocate contention-based resources of the satellite system to a plurality of user terminals (UTs);

activate the allocated contention-based resources by transmitting an activation signal to the plurality of UTs;

receive, from a first UT via a satellite of the satellite system, a first portion of data on a plurality of subframes of the contention-based resources during a time period; and

suspend the allocation of the contention-based resources to the first UT after an expiration of the time period or upon a grant of scheduled return link resources to the first UT, irrespective of collisions on the contention-based resources.

14. The network controller of claim 13 , wherein the activation signal is transmitted via a dedicated physical forward link control channel (PFCCH) that is independent of the contention-based resources.

15. The network controller of claim 13 , wherein the activation signal indicates a modulation and coding scheme (MCS) to be used by the plurality of UTs when transmitting data on the contention-based resources.

16. The network controller of claim 13 , wherein reception of at least part of the first portion of the data comprises an implicit scheduling request for the grant of scheduled return link resources.

17. The network controller of claim 13 , wherein execution of the instructions causes the network controller to further:

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

18. The network controller of claim 17 , wherein the PRCCH is allocated to the first UT only between selected pairs of subframes of the contention-based resources.

19. The network controller of claim 17 , wherein execution of the instructions causes the network controller to further:

transmit the grant for the return link resources in response to the received scheduling request; and

receive a second portion of the data on the scheduled return link resources during the time period.

20. The network controller of claim 19 , wherein transmission of the grant terminates the allocation of the contention-based resources to the first UT.

21. The network controller of claim 13 , wherein execution of the instructions causes the network controller to further:

transmit a grant for the return link resources after expiration of the time period;

receive a second portion of the data on the scheduled return link resources after the expiration of the time period; and

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

22. The network controller of claim 13 , wherein the activation signal assigns a unique demodulation reference signal (DM-RS) shift to the first UT.

23. The network controller of claim 13 , wherein execution of the instructions causes the network controller to further:

receive, on the contention-based resources, a buffer status report (BSR) indicating an amount of data stored in a buffer of the first UT.

24. The network controller of claim 13 , wherein execution of the instructions causes the network controller to further:

detect a collision on the contention-based resources;

identify one or more of the plurality of UTs that transmitted data associated with the collision based on unique demodulation reference signal (DM-RS) shifts assigned to the plurality of UTs; and

request the one or more identified UTs to re-transmit the data on the scheduled return link resources.