Improving IEEE 802.11 Performance in Chain Topologies through Distributed Polling and Network Coding

Wireless multi-hop networks often rely on the use of IEEE 802.11 technology. Despite of the robustness of the IEEE 802.11 Distributed Coordination Function (DCF) for working in various network scenarios, it has been proven that critical inefficiencies can arise in the case of multi-hop packet forwarding. In this paper, we propose a MAC scheme, based on the visualization of the Point Coordination Function, optimized for working on chain topologies with bidirectional traffic flows. Our scheme is based on a token-like access mechanism coupled with network coding. The basic idea is the use of multiple Point Coordinators (PCs) along the node chain, which are elected by passing special token frames. Since traffic sources are located at the edge of the chain and intermediate nodes act as relays, we also exploit network coding for merging uplink and downlink traffic. Analytical and simulation results prove that our scheme can provide an aggregated uplink and downlink throughput comparable with bidirectional point-to-point transmissions.