DCAR: Distributed Coding-Aware Routing in Wireless Networks

Recently, there has been a growing interest of using network coding to improve the performance of wireless networks, for example, authors of proposed the practical wireless network coding system called COPE, which demonstrated the throughput gain achieved by network coding. However, COPE has two fundamental limitations: (1) the coding opportunity is crucially dependent on the established routes and (2) the coding structure in COPE is limited within a two-hop region only. The aim of this paper is to overcome these limitations. In particular, we propose DCAR, the distributed coding-aware routing mechanism which enables: (1) the discovery for available paths between a given source and destination and (2) the detection for potential network coding opportunities over much wider network region. One interesting result is that DCAR has the capability to discover high throughput paths with coding opportunities, while conventional wireless network routing protocols fail to do so. In addition, DCAR can detect coding opportunities on the entire path, thus eliminating the ??two-hop?? coding limitation in COPE. We also propose a novel routing metric called coding-aware routing metric (CRM) which facilitates the performance comparison between ??coding-possible?? and "coding-impossible?? paths. We implement the DCAR system in ns-2 and carry out extensive evaluation. We show that when comparing to the coding mechanism in, DCAR can achieve much higher throughput gain.