A base station side device and method and user side device and method for wireless communication. The device includes: a sending unit configured to send instruction on an unauthorized frequency band detection to a user equipment (UE) served by the cell where the device is located; a receiving unit configured to receive from the UE a signal representing occupancy status of the unauthorized frequency band; and a determination unit configured to determine based on the signal received by the receiving unit whether to use the unauthorized frequency band for communication, the unauthorized frequency band occupancy status includes occupied/idle status and the type of the occupying system, and the type of occupying system includes one of an unauthorized communication system and an authorized communication system.