Opportunistic Spectrum Sharing Based on Full-Duplex Cooperative OFDM Relaying

In this paper, we propose an opportunistic spectrum sharing protocol where the secondary system can access to the licensed spectrum of the primary system based on full-duplex (FD) cooperative OFDM relaying. The secondary transmitter ST_b which provides the best primary performance is selected to forward the primary signal. Specifically, in the first phase, ST_b receives primary signal on some particular subcarriers. In the second phase, ST_b serves as a decode-and-forward (DF) relay by using a fraction of subcarriers to forward the primary signal in achieving the target rate. As a reward, the secondary system will be granted to use the remained subcarriers to transmit its own signal in both two phases. We study the joint optimization of subcarriers and power allocation in both two phases such that the transmission rate of the secondary system is maximized while the primary system can achieve its target transmission rate. Simulation results demonstrate the performance of the proposed spectrum sharing protocol as well as its benefit to both primary and secondary system.