Packet Multicast in Cognitive Radio Ad Hoc Networks: A Method Based on Random Network Coding

This paper studies packet multicast technology in cognitive radio ad hoc networks (CRAHNs) by using a random network coding (RNC)-based approach. We first specify the key problem of packet multicast applications in CRAHNs, called multichannel single-hop wireless multicast problem (MCSHWMP), then present the definition of MCSHWMP of its four-element tuple model. Next, we propose a framework for the network coding-based scheme in packet multicast applications of CRAHNs and provide several candidate schemes based on the framework. The proposed schemes have several desirable features: 1) necessary packet transmissions are reduced greatly by exploiting the broadcast nature of wireless transmissions by using RNC; 2) each packet transmission is tried to maximize the packet reception gain of the receivers by considering opportunistic accessibility of wireless channels and heterogeneous packet reception success ratio of different wireless channels; and 3) packet size to be transmitted is effectively shortened by reducing decoding information to be transmitted in the packet. Simulation results show that NC-based schemes decrease packet transmissions significantly comparing with non-NC-based schemes. The advantage of NC-based schemes is more distinctive when packet reception success ratio of wireless links are near but smaller than 1, and in these cases around 50% of packet transmissions could be saved.