MAC protocol supporting physical-layer network coding with overhearing

Physical-layer network coding (PNC) is a promising technique for improving the throughput of wireless networks. To implement PNC in practice, a suitable medium access control (MAC) protocol is needed. Existing works mainly focus on bidirectional PNC, where two nodes exchange their packets with each other. Considering the case where unidirectional flows exist, in this paper, we propose a distributed MAC protocol to support PNC with overhearing. The proposed protocol is compatible with conventional relaying methods, including conventional network coding and plain routing. It is based on the Request-to-Send/Clear-to-Send (RTS/CTS) mechanism and can be regarded as an extension to the IEEE 802.11 MAC protocol. Simulation results show that the proposed protocol can increase the throughput of networks with unidirectional flows, especially when the traffic load is heavy.