DCAR: Distributed Coding-Aware Routing in Wireless Networks

The practical network coding system proposed in (S. Katti et al., 2006) has two fundamental limitations: 1) the coding opportunity is crucially dependent on the established routes; 2) the coding structure is limited within a two-hop region. To overcome these limitations, we propose DCAR, the first distributed coding-aware routing mechanism which combines (a) the discovery for available paths between a given source and destination, and (b) the detection for potential network coding opportunities. DCAR has the potential to find high throughput paths with coding opportunities while conventional routing fails to do so. In addition, DCAR can detect coding opportunities on the entire path, thus eliminating the "two-hop" coding limitation in (S. Katti et al., 2006). We also propose a novel routing metric called "CRM" (coding-aware routing metric) which facilitates the comparison between coding-possible and coding-impossible paths. We implement the DCAR system in NS-2 and conduct extensive evaluation, which shows that DCAR achieves 7% to 20% throughput gain over the coding system in [1].