A method of determining synchronization timing, comprising: transmitting transmission power information of a first base station (BS) which connects a mobile station (MS) and a second BS; switching reception frequency of the MS in the transmission period for the first BS to transmit reference signal between transmission frequencies of reference signal of the first BS and the second BS; measuring reception power received by the MS from the first BS and the second BS; determining propagation loss from the first BS and the second BS to the MS based on the measured reception power and transmission power information; determining a propagation delay difference between the first BS and the second BS to the MS based on the propagation loss; determining synchronization timing of the second base apparatus to the MS based on synchronization timing of the first BS to the MS and the propagation delay difference.