A wireless communication system, an apparatus, and a method in a wireless communication system. The apparatus includes a processing circuit. The processing circuit is configured to: detect whether a pre-set power margin reporting trigger event is satisfied; and trigger, if the pre-set power margin reporting trigger event is satisfied, reporting of a power margin of a user equipment to a base station, wherein the pre-set power margin reporting trigger event includes at least one of the following events: a first event of having detected an idle channel on an unlicensed band; and a second event of having received uplink scheduling licensed signalling from the base station. A power margin in an LAA system can be effectively reported.