Improvement of Physical-Layer Network Coding Method in Relay Networks

Physical-layer network coding (PNC) is a new electromagnetic-wave based network coding scheme proposed recently to enhance network capacity, which deals with two nodes exchanging information through a relay node. In this article, based on Turbo code and M-ary phase-shift keying (MPSK), an improved PNC method is proposed. More specifically, the transmitting information of each node is encoded by Turbo codes and modulated to an MPSK signal, and the sum-signal of any two MPSK signals corresponds to a unique exclusive OR (XOR) value of the two transmitting information bits, which can be modulated to a unique MPSK signal. Considering the noise existing in wireless relay channels, Turbo code is adopted to ensure the correctness of signals. Moreover, we analyze the transmission energy consumption of the proposed scheme. It is shown by simulation that the enhanced PNC method can reduce half transmission energy in the relay node over the original PNC.