Multicast Communications with Reed Solomon/Network Joint Coding in Wireless Multihop Networks

In wireless multihop networks, multihop packet transmissions over error-prone wireless links cause significant performance degradation. In this paper, we study a multicast system in wireless multihop networks with Forward Error Correction (FEC) for packet erasures. Although FEC is a powerful tool to recover packet erasures, it has an inherent problem that burdens the network with overhead due to redundant packets. In order to solve the problem, we propose a new multicast system with Reed Solomon/network joint coding. In the proposed system, information packets from a source node are encoded by Reed Solomon erasure (RSE) coding and transmitted into the network. At intermediate nodes on multicast paths, packets arriving from different links are encoded by linear network coding (LNC). The joint coding provides highly robust and efficient multicast communication because RSE coding provides a recovery mechanism from packet erasures and LNC reduces the number of relayed packets in the network. From the fact that both RSE coding and LNC are linear coding, we propose a new decoder for the joint coding. In the proposed decoder, a decoding matrix is constructed by combining the parity matrix of RSE coding and a coding matrix of LNC. Destination nodes retrieve information packets by solving a system of simultaneous equations constructed by the decoding matrix. Simulation experiments show that the joint coding provides highly robust and efficient multicast communications.