New Spreading Codes for Spectrum Sharing by MC-CDMA Structure in Cognitive Radio Network

In multi-carrier based cognitive radio, transmitter must inactive some subcarriers to avoid interference with primary users. This process causes the loss of orthogonality among the spreading codes and therefore the performance of the system reduces. In this paper, a new set of orthogonal code for using in MC-CDMA system is introduced. It will be shown that the length of these codes unlike the Walsh-Hadamard codes can be any integer. The performance of new codes is investigated theoretically and simulation results evaluate the performance of system.