3. A method for a base station, the method comprising:performing a channel sensing on a Licensed-Assisted Access (LAA) secondary cell (SCell) for a transmission;
managing a counter based on whether or not the channel is sensed to be idle;
determining one of (i) the base station performs the transmission and (ii) the base station does not perform the transmission after the counter reaches zero; and
performing the transmission in a case that the base station determines to perform the transmission, otherwise deferring the transmission and performing an additional channel sensing for the transmission.