Multi-carrier listen before talk
Systems, apparatus, user equipment (UE), evolved node B (eNB), computer readable media, and methods are described for multi-carrier listen before talk operations. In various embodiments, a transmitting device may assign one or more primary carriers to perform listen before talk (LBT) operations, with non-primary carriers performing a channel sensing operation at the end of the LBT operations of at least one primary channel. In various embodiments, the LBT operations at the primary carriers may use a shared random countdown number or an independent random countdown.
1. An apparatus of an evolved node B (eNB), the eNB configured for Licensed Assisted Access (LAA) secondary cell (Scell) transmissions on multiple carriers, the apparatus comprising: processing circuitry; and memory,
wherein the processing circuitry is configured to:
perform a channel access procedure on each carrier of a plurality of carriers before an LAA Scell transmission on multiple carriers, wherein the channel access procedure for each carrier for a physical downlink shared channel (PDSCH) transmission comprises:
first sensing a channel to be idle during slot durations of a defer duration;
decrementing a counter and sensing the channel to be idle for an additional slot duration; and
sense the channel until either a busy slot is detected within an additional defer duration or all the slots of the additional defer duration are detected to be idle; and
encode the PDSCH for transmission on the plurality of carriers, if the channel is sensed to be idle for at least in a slot duration when the eNB is ready to transmit the PDSCH and if the channel has been sensed to be idle during all the slot durations of a defer duration immediately before the transmission, and
wherein the memory is configured to store a value indicating the defer duration immediately before the transmission.
2. The apparatus of claim 1 wherein the processing circuitry is configured to maintain a common contention window for more than one channel of the SCell.
3. The apparatus of claim 2 wherein the processing circuitry is to configure the eNB for transmissions over a primary channel of a non-LAA Scell without performing a clear channel access procedure.
4. The apparatus of claim 3 wherein the processing circuitry is configured to adjust a value for the contention window based on access class priority.
5. The apparatus of claim 1 , wherein as part of the channel access procedure for the LAA Scell transmission, the processing circuitry is to configure the eNB to sense the channel for a sensing interval of approximately 25 microseconds (us).
6. The apparatus of claim 1 wherein the processing circuitry comprises a baseband processor.
7. The apparatus of claim 6 further comprising: an interface to couple transceiver circuitry to the processing circuitry.
8. The apparatus of claim 7 wherein the processing circuitry generates baseband signals for transmission by the transceiver via multiple antennas.
9. A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of an evolved node B (eNB), the eNB configured for Licensed Assisted Access (LAA) secondary cell (Scell) transmissions on multiple carriers, the processing circuitry configured to:
perform a channel access procedure on each carrier of a plurality of carriers before an LAA Scell transmission on multiple carriers, wherein the channel access procedure for each carrier for a physical downlink shared channel (PDSCH) transmission comprises:
first sensing a channel to be idle during slot durations of a defer duration;
decrementing a counter and sensing the channel to be idle for an additional slot duration; and
sense the channel until either a busy slot is detected within an additional defer duration or all the slots of the additional defer duration are detected to be idle; and
encode the PDSCH for transmission on the plurality of carriers, if the channel is sensed to be idle for at least in a slot duration when the eNB is ready to transmit the PDSCH and if the channel has been sensed to be idle during all the slot durations of a defer duration immediately before the transmission.
10. The non-transitory computer-readable storage medium of claim 9 wherein the processing circuitry is configured to maintain a common contention window for more than one channel of the SCell.
11. The non-transitory computer-readable storage medium of claim 10 wherein the processing circuitry is to configure the eNB for transmissions over a primary channel of a non-LAA Scell without performing a clear channel access procedure.
12. The non-transitory computer-readable storage medium of claim 11 wherein the processing circuitry is configured to adjust a value for the contention window based on access class priority.
13. The non-transitory computer-readable storage medium of claim 9 , wherein as part of the channel access procedure for the LAA Scell transmission, the processing circuitry is to configure the eNB to sense the channel for a sensing interval of approximately 25 microseconds (us).
14. An apparatus of a user equipment (UE), the UE configured for Licensed Assisted Access (LAA) secondary cell (Scell) transmissions on multiple carriers, the apparatus comprising: processing circuitry; and memory,
wherein the processing circuitry is configured to:
perform a channel access procedure on each carrier of a plurality of carriers before an LAA Scell transmission on multiple carriers, wherein the channel access procedure for each carrier for a physical uplink shared channel (PUSCH) transmission comprises:
first sensing a channel to be idle during slot durations of a defer duration;
decrementing a counter and sensing the channel to be idle for an additional slot duration; and
sense the channel until either a busy slot is detected within an additional defer duration or all the slots of the additional defer duration are detected to be idle; and
encode the PUSCH for transmission on the plurality of carriers, if the channel is sensed to be idle for at least in a slot duration when the UE is ready to transmit the PUSCH and if the channel has been sensed to be idle during all the slot durations of a defer duration immediately before the transmission, and
wherein the memory is configured to store a value indicating the defer duration immediately before the transmission.
15. The apparatus of claim 14 wherein the processing circuitry is configured to maintain a common contention window for more than one channel of the SCell.
16. The apparatus of claim 15 wherein the processing circuitry is to configure the UE for transmissions over a primary channel of a non-LAA Scell without performing a clear channel access procedure.
17. The apparatus of claim 16 wherein the processing circuitry is configured to adjust a value for the contention window based on access class priority.
18. The apparatus of claim 14 , wherein as part of the channel access procedure for the LAA Scell transmission, the processing circuitry is to configure the UE to sense the channel for a sensing interval of approximately 25 microseconds (us).
19. The apparatus of claim 14 wherein the processing circuitry comprises a baseband processor.