A cellular network that is based on relay station and a space division duplex communication method are disclosed. The cellular network based on RS includes a base station, a RS and a UE, wherein the base station has at least one antenna and the RS has at least two antennas. The base station allocates resources for the UE, transmits a downlink signal in a current slot and receives an uplink signal from the UE through the RS in a next slot; the RS receives the downlink signal from the base station and the uplink signal from the UE in the current slot and transmits the received downlink signal to the UE and the uplink signal to the base station in the next slot; the UE transmits the uplink signal in the current slot and receives the downlink signal through the RS in the next slot, wherein the uplink signal and the downlink signal transmitted in the same slot are orthogonal. With the cellular network and the communication method of embodiments of the present invention, the use efficiency of each channel can be improved effectively and the system complexity can be reduced.