Provided are a device in a wireless communication system and a method. A main carrier on a licensed frequency band and a plurality of auxiliary carriers on an unlicensed frequency band exist in the wireless communication system, and a device at a base-station side in the wireless communication system comprises: a control unit configured to conduct power adjustment according to a result of detecting the usability of the plurality of auxiliary carriers, so as to enable a predetermined transmission power pre-allocated to one or more unavailable auxiliary carriers to be allocated to an auxiliary carrier to be used in available auxiliary carriers; and a communication unit configured to send a power adjustment result of the control unit to a user equipment, wherein the power adjustment result at least comprises information instructing whether the power allocation changes. According to embodiments of this disclosure, dynamic power adjustment conducted on carriers on an unlicensed frequency band can be implemented, and the adjustment can be notified to a user equipment to optimize the system performance and the frequency spectrum use efficiency.