Uplink resource scheduling control in response to channel busy condition
A wireless access network node transmits scheduling information assigning an uplink resource for a user equipment (UE), detects whether the UE has not transmitted using the assigned uplink resource, determines, based on the detecting, that the UE has failed a Listen-Before-Talk (LBT) check at the UE, and further schedules and assigns an uplink resource for the UE.
1. A method comprising:
transmitting, by a wireless access network node, scheduling information assigning an uplink resource for a user equipment (UE);
detecting, at the wireless access network node, whether the UE has not transmitted using the assigned uplink resource;
determining, based on the detecting, that the UE has failed a Listen-Before-Talk (LBT) check at the UE;
in response to the determining that the UE has failed the LBT check, performing, by the wireless access network node, a backoff process on behalf of the UE; and
further scheduling and assigning, by the wireless access network node, an uplink resource for the UE.
2. The method of claim 1 , wherein the LBT check at the UE comprises the UE detecting an ongoing transmission having a transmit power above a power threshold.
3. The method of claim 1 , wherein the detecting comprises the wireless access network node checking an indication of a received power or signal to interference ratio for a transmission of the UE.
4. The method of claim 1 , wherein the detecting comprises the wireless access network node performing channel estimation processing based on processing of a demodulation reference signal (DMRS) corresponding to a transmission of the UE.
5. The method of claim 1 , wherein the detecting is based on an explicit indication provided by the UE.
6. The method of claim 1 , wherein the scheduling information comprises a Downlink Control Information (DCI) message on a Physical Downlink Control Channel (PDCCH) or Enhanced Physical Downlink Control Channel (E-PDCCH).
7. The method of claim 1 , wherein the further scheduling is based on the backoff process.
8. The method of claim 1 , wherein the backoff process on behalf of the UE comprises maintaining, by the wireless access network node, an uplink timer or counter for the UE.
9. The method of claim 8 , wherein the wireless access network node maintains multiple uplink timers or counters for performing backoff processes for respective different UEs.
10. The method of claim 1 , wherein the further scheduling involves a category 4 LBT with a variable sized contention window.
11. The method of claim 10 , wherein the further scheduling uses the variable sized contention window that grows in length of time with each successive retry before next assigning an uplink resource to the UE.
12. A wireless access network node comprising:
a communication interface to communicate over a wireless network; and
at least one processor configured to:
transmit scheduling information assigning an uplink resource for a user equipment (UE);
detect whether the UE has not transmitted using the assigned uplink resource;
determine, based on the detecting, that the UE has failed a Listen-Before-Talk (LBT) check at the UE;
in response to the determining that the UE has failed the LBT check, perform a backoff process on behalf of the UE; and
further schedule and assign an uplink resource for the UE.
13. The wireless access network node of claim 12 , wherein the LBT check at the UE comprises the UE detecting an ongoing transmission having a transmit power above a power threshold.
14. The wireless access network node of claim 12 , wherein the detecting comprises the wireless access network node:
checking an indication of a received power or signal to interference ratio for a transmission of the UE, or
performing channel estimation processing based on processing of a demodulation reference signal (DMRS) corresponding to a transmission of the UE.
15. The wireless access network node of claim 12 , wherein the detecting is based on an explicit indication provided by the UE.
16. The wireless access network node of claim 12 , wherein the scheduling information comprises a Downlink Control Information (DCI) message on a Physical Downlink Control Channel (PDCCH) or Enhanced Physical Downlink Control Channel (E-PDCCH).
17. The wireless access network node of claim 12 , wherein the backoff process uses a variable sized contention window.
18. The wireless access network node of claim 12 , wherein the backoff process on behalf of the UE comprises maintaining, by the wireless access network node, an uplink timer or counter for the UE.
19. A non-transitory machine-readable storage medium comprising instructions that upon execution cause a wireless access network node to:
transmit scheduling information assigning an uplink resource for a user equipment (UE);
detect whether the UE has not transmitted using the assigned uplink resource;
determine, based on the detecting, that the UE has failed a Listen-Before-Talk (LBT) check at the UE;
in response to the determining that the UE has failed the LBT check, perform a backoff process on behalf of the UE; and
further schedule and assign an uplink resource for the UE.
20. The non-transitory machine-readable storage medium of claim 19 , wherein the backoff process on behalf of the UE comprises maintaining, by the wireless access network node, an uplink timer or counter for the UE.