Resource allocation in bidirectional cooperative cognitive radio networks using swarm intelligence

In this work we consider an OFDMA-based two-way cognitive relay network that comprises multiple source-destination pairs and multiple relays. The relays assist communication between the source-destination pairs, and different relays transmit on orthogonal subcarriers. The relays employ amplify-and-forward relaying. For this network, we formulate a sum capacity maximization problem to determine the subcarrier assignment and power allocation to the relays. The optimization problem is formulated as a mixed integer nonlinear programming (MINLP). An intuitive way to obtain the optimal solution of MINLP is to exhaustively try all the combination of the discrete variables and solve the resulting non linear optimization problem. However, this approach is computationally intractable. Therefore, we use particle swarm optimization (PSO) to solve the MINLP. The proposed algorithm has low computational complexity, and we verify its effectiveness through simulation results.