A frame structure for a relay station operating in an OFDMA network includes a downlink sub-frame having a first allocated time zone dedicated for transmission between a base station in the network and the relay station, a second allocated time zone dedicated for transmission between the base station and a mobile station in the network, and a third allocated time zone dedicated for transmission between the relay station and the mobile station; and an uplink sub-frame having a first allocated time zone dedicated for transmission between the mobile station and the relay station, a second allocated time zone dedicated for transmission between the mobile station and the base station, and a third allocated time zone dedicated for transmission between the relay station and the base station.