Joint soft-decision cooperative spectrum sensing and power control in multiband cognitive radios

We consider joint optimization of cooperative spectrum sensing, channel access and power allocation in an overlay multi-band cognitive radio network to maximize the secondary users´ sum instantaneous throughput while keeping the interference to primary users under a specified threshold. A soft-decision cooperative spectrum sensing concept using the continuous-valued sensing test statistics is considered. The channel access decision about whether to access the channel or not is relaxed into allowing the secondary user to access channels with some probability. The decision is made at the secondary base station based on the sensing statistics received from all or a subset of secondary users. The problem is shown to be a convex optimization problem and the Lagrangian dual method is employed to obtain the optimal solution. Two heuristic algorithms are also proposed to reduce the complexity. Simulation results show that our soft sensing based algorithm significantly outperforms traditional hard decision sensing algorithms.