Layer 2.5 Network Coding to Improve 802.11 Network Efficiency

Thesis (Master's)--University of Washington, 2016-06

The principles of Network Coding have been developed conceptually for over a decade (starting with key results c. 2003 on network coding for butterfly networks). Despite several subsequent extensions to wireless networks, there exists remarkably few implementations of Wireless Network Coding (WNC) techniques within existing wireless networking technology. In this thesis, we present a novel Layer 2.5 implementation for WNC system that can be retrofitted to existing 802.11 nodes (APs and client) with some minimal changes (i.e. is backward compatible with legacy nodes that do not implement WNC) to improve network throughput, when there exist significant intra-network symmetric traffic flows. We implement L2.5 WNC on an 802.11 software defined radio test-bed to experimentally collect data and demonstrate feasibility. We experiment using a simple network with 2 clients and 1 access point. The clients saturate the network by sending messages to each other through the access point whenever possible. Our experimental results show that on average, adding L2.5 network coding to an 802.11 network increases the network efficiency by 11.7% and throughput by 13.6%.