Analysis of a Network Coding-Aware MAC Protocol for IEEE 802.11 Wireless Networks with Reverse Direction Transmissions

The implementation of Network Coding (NC) in IEEE 802.11-based wireless networks presents the important challenge of providing additional transmission priority for the relay nodes responsible for coding. These nodes are able to convey more information in each transmission than those that forward single packets, by combining several received packets in a single coded packet. To transmit data, the nodes execute the IEEE 802.11 Medium Access Control (MAC) protocol, called the Distributed Coordination Function (DCF). Thus, they compete for the access to the wireless channel and get equal transmission opportunities under high congestion. As a result, congested relay nodes will severely limit the performance of the network. In this paper, we investigate a backwards-compatible mechanism, called Reverse Direction DCF (RD-DCF), that allows relay nodes to transmit data upon successful reception of data. We analyze the performance limits of the proposed protocol with and without NC in terms of throughput and energy efficiency. The performance evaluation considers different traffic loads, packet lengths, and data rates. The results of this work show that the proposed RD-DCF+NC protocol can improve throughput and energy efficiency up to 335% when compared to legacy DCF.