If the UE has not transmitted a transmission including PUSCH or SRS on a carrier on which LAA Scell(s) transmission(s) are performed after step 4 in the procedure above, the UE may transmit a transmission including PUSCH or SRS on the carrier, if the channel is sensed to be idle at least in a slot duration Tsl when the UE is ready to transmit the transmission including PUSCH or SRS, and if the channel has been sensed to be idle during all the slot durations of a defer duration Td immediately before the transmission including PUSCH or SRS. If the channel has not been sensed to be idle in a slot duration Tsl when the UE first senses the channel after it is ready to transmit, or if the channel has not been sensed to be idle during any of the slot durations of a defer duration Td immediately before the intended transmission including PUSCH or SRS, the UE proceeds to step 1 after sensing the channel to be idle during the slot durations of a defer duration Td.
The defer duration Td consists of duration Tf=16 us immediately followed by mp consecutive slot durations where each slot duration is Tsl=9 us, and Tf includes an idle slot duration Tsl at start of Tf;
A slot duration Tsl is considered to be idle if the UE senses the channel during the slot duration, and the power detected by the UE for at least 4 us within the slot duration is less than energy detection threshold XThresh. Otherwise, the slot duration Tsl is considered to be busy. CWmin,p≤CWp≤CWmax, p is the contention window. CWp adjustment is described in sub clause 15.2.2.
CWmin,p and CWmax,p are chosen before step 1 of the procedure above.