A signal amplifying device and methods for control a signal amplifying device and for identifying a signal amplifying device are provided. The device includes: a baseband module, a user identification module interface, return side RF modules and antennas, access side RF modules and antennas. The return side antenna receives a downlink signal, which is transmitted to a corresponding access side RF module and the baseband module. An uplink signal is received by the access side antenna, which is transmitted to a corresponding return side RF module and the baseband module. The baseband module is adapted to process the uplink/downlink signal, control synchronization of the return side RF module and the access side RF module and control turning on and off of the same, read a user information. Accordingly, a cellular network can control a micro-power repeater effectively, and further more functionality can be added and performance can be improved.