OFDM-IDMA System for Coginitive Radio with Spectral Nulling

Non-contiguous orthogonal frequency division multiplexing (NC-OFDM) provides a fast and flexible manner of non-contiguous spectrum bands and is ideally suitable for dynamic spectrum access. For overlay cognitive radio (CR) networks, complex subcarrier, bit and power allocation algorithms are needed for multiuser NC-OFDM system. For the purpose of improving multiple access capability of NC-OFDM, a new scheme combined with interleave division multiple access (IDMA) technology is presented. The new multiuser NC-OFDM based IDMA integrates the advantages of both NC-OFDM and IDMA to make full use of the other user's information and satisfies CR constraint. Simulation results demonstrate that the proposed system architecture achieves significant improvement on HER performance.