Systems, methods, and devices for efficient device-to-device channel contention

1. An apparatus for a user equipment (UE), the apparatus configured to:

process a first signal received during a single request period of time, the first signal indicating a request to transmit to the UE from a first transmitting UE;

process one or more additional signals received during the single request period of time, the one or more additional signals indicating that one or more additional transmitting UEs are requesting to transmit to corresponding target UEs;

identify, based on a received power of the first signal and the one or more additional signals, one or more incompatible UEs by identifying those of the first transmitting UE and the one or more additional transmitting UEs that would interfere with each other during simultaneous device-to-device communications;

determine to block transmission of at least one of the one or more incompatible UEs by selecting to block at least one of the one or more incompatible UEs that would interfere with at least another of the one or more incompatible UEs;

in response to the determination to block transmission of the at least one of the one or more incompatible UEs, cause a signal to be sent, the signal indicating a block on transmission by the at least one of the one or more incompatible UEs.

2. The apparatus of claim 1 , the apparatus further configured to determine, based at least in part on a priority of the first transmitting UE, the one or more additional transmitting UEs, and the corresponding target UEs, whether to block transmission by the incompatible UEs.

3. The apparatus of claim 1 , wherein the UE is configured to identify the one or more potentially incompatible UEs based at least in part on an estimated signal-to-interference ratio (SIR) determined using the received first signal and the one or more additional signals.

4. The apparatus of claim 1 , wherein the signal indicating the block on transmission comprises a grant signal, wherein sending the grant signal comprises transmitting a tone matrix comprising a plurality of tones corresponding to each of the first transmitting UE and the one or more additional transmitting UEs.

5. The apparatus of claim 4 , wherein the grant signal indicating the grant to the first transmitting UE comprises a tone matrix with power on a first tone corresponding to the first transmitting UE.

6. The apparatus of claim 5 , wherein the tone matrix comprises power on one or more additional tones corresponding to the one or more potentially incompatible UEs, wherein the first tone comprises a higher priority than any of the one or more additional tones and wherein the power on priority tones lower than the first tone indicates disabling transmission of a corresponding UE of the one or more additional transmitting UEs.

7. The apparatus of claim 5 , wherein the tone matrix comprises two tones for at least one of the one or more potentially incompatible UEs, wherein the two tones comprise a grant tone and a deny tone for a corresponding UE, and wherein the grant signal comprises power on a deny tone for the at least one of the one or more potentially incompatible UEs.

8. The apparatus of claim 1 , wherein processing the received first signal and the one or more additional signals comprises processing the received first signal and the one or more additional signals received at an optimal link power and wherein causing the grant signal to be sent comprises causing the grant signal to be sent at a full power.