Joint Subcarrier and Power Allocation Considering Fairness in OFDM-Based Cognitive Radio Systems

Abstract

Orthogonal frequency division multiplexing (OFDM) is an attractive modulation candidate for cognitive radio networks. In OFDM-based cognitive radio (CR) networks, effective and reliable subcarrier and power allocation is a challenging problem. And the fairness of resource allocation is another important problem in this network.In this paper, We present a joint subcarrier and power allocation algorithm considering fairness (JSPACF) among secondary users (SUs) for OFDM-based CR networks. In JSPACF, we allocate the subcarriers to SUs in the first step, not only considering the channel gain and the interference introduced to primary users (PUs) by SUs, but also considering proportional fairness among SUs. Then in the second step, we allocate the power to the subcarriers to maximize sum capacity of all SUs with total power constraint and interference constraint, considering proportional fairness among SUs too. Theory analysis and simulation results show that JSPACF can offer the beneficial tradeoff between system performance and fairness, while largely reducing complexity compared to the optimal solution.KeywordsOFDMcognitive radiosubcarrier and power allocationfairness