Distributed MAC protocol for physical layer network coding

Physical layer (PHY) network coding (PLNC), which performs the operation of network coding at physical layer, is an attractive means to improve throughput of wireless multi-hop networks. The PLNC requires multiple nodes to transmit their packets with accurate synchronization at symbol-level. Therefore, in many works of literature, centralized scheduling with perfect synchronization has been assumed to be employed on top of PLNC. Another common assumption is perfect channel state information (CSI) availability for end-nodes to decode their desired packets. However, these assumptions are challenged when we attempt to apply PLNC to large-scale and distributed networks. Therefore, in this paper, we propose a distributed medium access control (MAC) protocol for wireless multi-hop networks employing PLNC. The proposed MAC protocol is a random access protocol, which solves the PHY-specific problems, such as synchronization and CSI, jointly with distributed scheduling at MAC layer. We evaluate throughput of PLNC employing the proposed MAC protocol by computer simulation, and compare it with that of conventional relaying. With numerical results, we investigate the effectiveness of PLNC in distributed wireless multi-hop networks.