Adaptive physical-layer network coding in two-way relaying with OFDM

Adaptive physical layer network coding (PNC) has been shown to be effective in two-way relay communications (TWRC). Given that the existing PNC methods were developed for frequency-flat fading channels, this paper studies adaptive PNC in OFDM systems operating over frequency-selective fading channels. Proposed and investigated are three methods to determine a common clustering for all subcarriers in order to reduce the overhead information required in the broadcast phase. The “Min-SER” method is given based on the analysis of the error event in the multiple access phase, while the “Max-fade-SER” and “Min-fade-distance” methods are recommended to further reduce the computational complexity in determining the common clustering. Considering the trade-off among performance, overhead and complexity, the “Max-fade-SER” method is the most attractive clustering method for applying adaptive PNC in OFDM systems.