Differential Network Coded Transmission for Two-Way Relay Networks with Large Antenna Array

—This paper considers a two-way relay network (TWRN) with two sources and one relay node, where each source is equipped with a single antenna, while the relay node is equipped with a large number of antennas. We propose two low-complexity physical-layer differential network coding schemes for such TWRNs, namely, Superimposition Coding based Differential Beamforming (SC-DBF) and Decode-andForward based Differential Beamforming (DF-DBF). In the proposed schemes, no Channel State Information (CSI) is required at each source node for signal detection. It is shown that as the number of relay antennas becomes large, the received signal at each source node includes the desired signal only, and simple linear detector can be used to exploit the benefits of massive array in both schemes. Numerical results are presented to demonstrate the Bit-to-Error Rate (BER) performance of the proposed SC-DBF and DF-DBF schemes.