Reliable Periodic Safety Message Broadcasting in VANETs Using Network Coding

Reliable local information dissemination is the primary concern for periodic safety broadcasting in VANETs. We propose a sublayer in the application layer of the WAVE stack to increase the reliability of safety applications. Our design uses rebroadcasting of network coded safety messages, which considerably improves the overall reliability. It also tackles the synchronized collision problem stated in the IEEE 1609.4 standard as well as congestion problem and vehicle-to-vehicle channel loss. We propose a discrete phase type distribution to model the time transitions of a node state. Based on this model, a tight loss probability upper bound for the network coding algorithm is derived. Numerical results based on our analysis as well as ns-2 simulations show that our method outperforms the previous repetition-based algorithms.