Resource allocation in OFDM-based cognitive two-way multiple-relay networks

In this paper, a joint resource allocation problem in amplify and forward (AF) OFDM-based two-way multiple-relay cognitive radio network is considered, where two transceiver nodes exchange information via a relay node. The full transmission happens in two phases: multiple access (MA) phase and broadcast (BC) phase. Considering individual power and interference constraints, the power allocation, subcarrier pairing and relay selection are jointly optimized in order to maximize the sum-rate. The dual decomposition technique is applied to obtain the optimal solution. Additionally, an efficient suboptimal algorithm which drastically reduces the computational complexity of the optimal solution with a small performance degradation is proposed. Finally, simulation results are shown to demonstrate the performance gain of the proposed algorithms.