If the eNB indicates Type 2 channel access procedure for the UE in the DCI, the eNB indicates the channel access priority class used to obtain access to the channel in the DCI.
15.2.1.1 Type 1 UL Channel Access Procedure
The UE may transmit the transmission using Type 1 channel access procedure after first sensing the channel to be idle during the slot durations of a defer duration Td; and after the counter N is zero in step 4. The counter N is adjusted by sensing the channel for additional slot duration(s) according to the steps described below.
1) set N=Ninit, where Ninit is a random number uniformly distributed between 0 and CWp, and go to step 4;
2) if N>0 and the UE chooses to decrement the counter, set N=N?1;
3) sense the channel for an additional slot duration, and if the additional slot duration is idle, go to step 4; else, go to step 5;
4) if N=0, stop; else, go to step 2.
5) sense the channel until either a busy slot is detected within an additional defer duration Td or all the slots of the additional defer duration Td are detected to be idle;
6) if the channel is sensed to be idle during all the slot durations of the additional defer duration Td, go to step 4; else, go to step 5;