On the Need of Novel Medium Access Control Schemes for Network Coding enabled Wireless Mesh Networks

This paper advocates for a new Medium Access Control (MAC) strategy for wireless meshed networks by identifyingoverload scenarios in order to provide additional channelaccess priority to the relay. The key behind our MAC protocol isthat the relay will adjust its back off window size accordingto the incoming and outgoing packet ratio. We describe thenew protocol as an extension to the CSMA/CA protocol andimplement the protocol on our own hardware platform. By meansof our own testbed, we investigate two basic network structures,namely, the two-way relay and the cross topology. It is well knownthat network coding will improve the throughput in such systems,but our novel medium access scheme improves the performancein the cross topology by another 66 % for network coding and150 % for classical forwarding in theory. These gains translatein a theoretical gain of 33 % of network coding over classicalforwarding when both systems implement the improved MAC.However, our measurement results show an even larger gain fornetwork coding, namely, up to 65 % over forwarding, as it copesbetter with channel losses under high load scenarios