Method for receiving preamble from other communication system and method for changing adaptively the measurement gap to discover the other communication system

A method for receiving a preamble signal from a heterogeneous communication system and a method for changing adaptively the measurement gap to discover a heterogeneous communication system are provided to guarantee a mobility of a mobile terminal by supporting various communication systems. A fixed station allocates a measurement gap to a mobile terminal(10). Allocation of a measurement gap is processed by the determination of the fixed station or a request by the mobile terminal. The fixed station transmits scheduling information about allocated measurement gap which is a measurement gap scheduling information to the mobile terminal(11). The mobile terminal starts to perform measurement after receiving measurement gap information from fixed station(12). The mobile terminal enhances the preamble receiving probability from the another fixed station through the measurement gap modification(13). The mobile terminal receives preamble from another fixed station which is the fixed station #2 of a second communications system(14).