Disclosed are a method and a system for generating switching control signal separating transmission signal on an access point and a mobile communication terminal in an optical repeater employing, for example, a TDD scheme. The method includes the steps of generating a control signal for generating a switching control signal in transmitting data from the AP and transmitting the control information to a remote during an idle time interval, detecting synchronization information on the downlink signal and time-delay information from the control information, delaying a time interval between the synchronization information and a starting point of the downlink signal, generating the switching control signal for the downlink signal according to the transmission time information of the downlink signal, and performing a switching operation according to the switching control signal and setting a downlink path.