A method of transmitting data in a multi-carrier communication system is disclosed. More specifically, the method includes mapping at least one data symbol to at least one subcarrier of a first frequency domain and at least one data symbol to at least one subcarrier of a second frequency domain, wherein the first frequency domain and the second frequency domain are mutually exclusive and the at least one data symbol mapped to the at least one subcarrier of the second frequency domain is multiplied by a spreading code, transforming the at least one data symbol mapped to the first frequency domain and the at least one data symbol mapped to the second frequency domain by an inverse discrete Fourier transform (IDFT) module, and transmitting the transformed data symbols to a receiving end.