Various kinds of repeaters have been introduced and used in order to effectively solve the shadow area in the mobile cellular radio network and to ensure the service continuity. In particular, RF repeaters provide the best solution for covering indoor dead spot area with low traffic. 5G mobile cellular network mainly adopts TDD (Time Division Duplexing) method, and downlink and uplink switching timing is essential factor for the normal operation of RF repeater in TDD network. DABIN Systems ensures the normal operation of the RF repeater in the 5G mobile cellular network by providing means to obtain accurate switching information between downlink and uplink in the absence of GPS signal.