Power allocation for cognitive OFDM with separated interference limits

In order to protect primary users´ communication, most existing power resource allocation methods focus solely on a total interference limit over all subchannels, which may lead to serious disturbance on some frequencies. In this paper, we investigate the power allocation problem for cognitive OFDM with interference limit on each subcarrier. By formulating the problem as a convex optimization, an optimal iterative allocation algorithm is proposed to maximize the cognitive throughput. Furthermore, a linear sub-optimal algorithm is proposed for fast convergence with little throughput loss. Finally, performances of our proposed algorithms are investigated by simulation results.