Joint optimal sensing and power allocation for cooperative relay in cognitive radio networks

In this paper, we investigate the joint optimization of sensing and power allocation for cooperative relay in cognitive radio networks (CRNs). Specifically, in the sensing time slot, the source secondary user (SU) and the relay SUs individually sense the channel, and then the relay SUs send their sensing results to the source SU, in which a fusion rule is employed to determine whether the primary user (PU) is idle or not on the channel. In the data transmission slot, the selective amplify-and-forward (S-AF) cooperative relay scheme is considered to assist the source SU for data transmission. By jointly considering the two slots, the optimization problems are respectively formulated to maximize the CRN´s average throughput and minimize the outage probability of secondary transmission under the average transmit power constraint of SUs and the average interference power constraint of PU. The optimal algorithms are developed to acquire the optimal sensing time and power allocation. Moreover, in the S-AF scheme, a relay selection scheme is also considered in the optimization problem. Finally, we provide simulation results to validate our proposed algorithms.