Physical Layer Network Coding for the Multiple Access Relay Channel
The authors consider the two users wireless Multiple Access Relay Channel (MARC), in which nodes A and B want to transmit messages to a destination node D with the help of a relay node R. For the MARC, Wang and Giannakis proposed a Complex Field Network Coding (CFNC) scheme. As an alternative, they propose a scheme based on Physical layer Network Coding (PNC), which has so far been studied widely only in the context of two-way relaying. In a wireless network, due to the superposition nature of the wireless channel, signals interfere at the nodes. Avoiding this interference by making the nodes transmit in orthogonal time/frequency slots incurs a loss of spectral efficiency.