An efficient MAC multicast protocol for reliable wireless communications with network coding

In wireless networks, network coding has been considered as an effective approach that utilizes the broadcast nature of the wireless channel to achieve energy efficiency and improve the network throughput. While network coding can be utilized in different forms of communications, including unicast, multicast and broadcast, the MAC layer transmissions used for network coding are mainly multicast, therefore, such network coding based communications are substantially affected by the performance of the underlying MAC layer multicast. However, the commonly used IEEE 802.11 MAC protocol performs only a basic CSMA/CA mechanism for multicast, making the transmissions and the network coding based communications unreliable and less efficient. In this paper we propose NC-MAC, a novel MAC layer multicast protocol that are specifically designed to support reliable network coding based communications. Compared to existing reliable MAC multicast protocols, NC-MAC takes advantage of the unique characteristics of network coding to expedite the multicast procedure. We evaluate the performance of NCMAC for two typical network coding algorithms through ns-2 simulations. The results demonstrate the superior performance of NC-MAC over other MAC protocols in maintaining both reliability and efficiency.