Joint subcarriers suppression and relay selection in PLNC based Two-Way OFDM relaying system

This paper deals with the joint subcarriers suppression and relay selection (JSSRS) problem in Physical Layer Network Coding (PLNC) based Two-Way Orthogonal Frequency Division Multiplexing (OFDM) relaying system with decode-and-forward protocol over multipath Rayleigh fading channel. Relay selection, which is studied for more than ten years, is a technique used to select one or some relays to improve system bit error rate (BER) performance. Obviously, for the relay selection (RS) based multi-relay OFDM system without using subcarriers suppression (SS) technique, the BER performance will further be improved by applying SS to it. But the subcarriers suppression is a throughput reduction technique, the throughput performance of the OFDM relaying system will be degraded when SS is applied directly. To solve this problem and further improve the BER performance, a JSSRS scheme is proposed for PLNC based Two-Way OFDM relaying system in this paper. The simulation results show that the proposed JSSRS scheme not only enhances the reliability but also can improve the efficiency of the PLNC based Two-Way OFDM relaying system under some conditions. In other words, it is shown in this paper that the proposed JSSRS scheme achieves a significant performances gain both in BER and throughput under some conditions when compared with the traditional relay selection scheme.