Provided are an apparatus and a method for providing a relay service in a wireless communication system. The apparatus includes a modulator, an encoder, and a transmission unit. The modulator modulates a transmission signal according to a modulation degree. The encoder encodes a modulation symbol provided from the modulator using a convolution code of a ring domain. The transmission unit transmits the signal provided from the encoder to a relay station. The relay station detects a signal where signals received from different transmission ends are added in a real domain, and relays the detected signal, thereby providing a relay service without an additional time resource.