Joint Sensing and Power Loading Algorithms for OFDM-Based Cognitive Radio Systems

In this paper, we investigate joint sensing and power allocation schemes for OFDM-based cognitive radio (CR) systems. A CR system employing cooperative sensing based on energy detection is considered. Each primary user (PU) band is assigned a subset of sensors and equal gain combining is used at the access point to detect the presence of PU in that particular band. For such a system, we propose algorithms to jointly allocate sensing thresholds at the access point and power at the CR transmitters so that the throughput of the CR system is maximized while taking total transmit power, CR quality of service (QoS) constraints, and interference introduced to the PU band into consideration. The performance of the proposed schemes is compared to the schemes that only optimize either sensing thresholds or transmitted power. Presented numerical results demonstrate the strength of our proposed schemes.