VANETs Routing Protocols Survey: Classifications, Optimization Methods and New Trends The specific characteristics of vehicular adhoc networks, such as highspeed nodes, frequent topology changes and predefined vehicle movement paths, make mobile adhoc networks routing protocols not convenient to disseminate data in the vehicular environment. In addition, the new vision towards Internet of Vehicles concept along with the advent of autonomous cars contribute to the proliferation of new innovative applications with different QoS requirements, rising new challenging issues. In this paper, we survey the different taxonomies for vehicular routing protocols, while exposing several optimization techniques used to enhance routing protocols. Moreover, in order to foster the deployment of robust Internet of Vehicles routing protocols at large scale, we give some directions for future research work.

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 endtoend 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 nexthops when the past forwarding is considered invalid. The nexthop calculation is based on the predicted locations of forwarderu0027s neighbors and the packetu0027s 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 stateoftheart 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.