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.