OFDM‐Modulated Physical‐Layer Network Coding

This chapter considers a two‐way relay network, where two terminals A and B desire to exchange information with the help of a relay R. It considers the application of physical‐layer network coding (PLNC) in underwater acoustic systems. With orthogonal frequency‐division multiplexing (OFDM) as the underlying modulation scheme, the chapter presents the receiver design at the relay node in the presence of underwater acoustic time‐varying multipath channels. It introduces the system model for the OFDM‐modulated PLNC at the relay node. The chapter derives outage performance bounds of the relay operation in a time‐invariant multipath channel. Performance results based on simulated and emulated data are presented. The data collected in the SPACE08 experiment are used to test the three iterative receivers. The data sets collected in a two‐input multiple‐output (TIMO) experimental setting are adopted to emulate a two‐way relay system. The chapter also demonstrates the block‐error‐rate performance of two decoding schemes.