An apparatus and method are provided for transmitting high-speed data through a plurality of transmitter antennas using a relay network, receiving signals transmitted from the plurality of transmitter antennas, and removing interference in a mobile communication system. The received signals are despread on a transmitter antenna-by-transmitter antenna basis according to a preset spreading factor. The despread signals are divided into data signals and noise. The signals transmitted through the plurality of transmitter antennas are regenerated from recovered data signals. Data components and interference signal components are identified. The interference signal components are removed from the signals transmitted on the transmitter antenna-by-transmitter antenna basis.