Cooperative Spectrum Sensing for Wideband Cognitive OFDM Radio Networks

One of the fundamental requirements of cognitive radio networks is to reliably detect the presence of licensed primary users. Therefore, spectrum sensing should be performed prior to allowing unlicensed users to access the vacant licensed bands. Multiple secondary users can cooperate to increase the reliability of spectrum sensing. Previous work on wideband spectrum sensing showed that multiband joint detection, which jointly detects the signal energy over multiple frequency bands, is efficient in improving the dynamic spectrum utilization and reducing interference to the primary users. In this paper, we investigate the integration of basic wideband spectrum sensing with both data (soft) and decision (hard) fusion techniques to improve the performance in the presence of multiple secondary users. We formulate the optimization problem for the multiband joint detection when cooperation is used for both hard and soft decision approaches. Numerical results show the significant improvement in the performance, in terms of the aggregate opportunistic throughput and false alarm probability, achieved by using cooperative sensing. Also, better performance was achieved when the data fusion approach was used.