P3R: Realizing Robust Routing for VANET Using Trajectory Prediction and Crossroad Recognition

High topology dynamics and intermittent connectivity in Vehicular Ad hoc Network (VANET) bring huge challenges to end-to-end communication. Existing routing protocols for MANET such as AODV and OLSR work fine under modest mobility, but have a difficult time to handle frequent topology changes in VANET. This paper proposes Peeking at the Past and Present Routing (P3R), a routing protocol that will calculate next-hops when the past forwarding is considered invalid. The next-hop calculation is based on the predicted locations of forwarder's neighbors and the packet's destination node, overcoming the inaccuracy caused by stale location information. Furthermore, we differentiate vehicles on crossroads as they have high connectivity in actual urban streets. In this way, P3R is able to deal with link breakages quickly and exploit new links. Simulation results show that P3R outperforms state-of-the-art alternatives in terms of packet delivery ratio, delay and cost, while maintaining strong scalability and robustness. We also implement P3R in a real vehicular testbed and the results reveal it has high connectivity on real streets.