A base station 422 of a second system performs communication using a frequency adjacent to a frequency employed by communication between a base station 412 and a mobile station 414 of a first system. When the mobile station 414 is close to the base station 422, the communication of the base station 422 undergoes interference by the leakage power of the mobile station 414. To avoid the interference, the transmission is halted of the mobile station 414 of the first system, which provides the interference by the leakage power.