A route-aware delay tolerant routing protocol for sparse vehicular ad-hoc networks

In vehicular ad-hoc networks (VANETs), vehicles move highly and non-randomly along roads while exchanging information with other vehicles. Rapid movement of vehicles and frequent topology changes cause repeated link breakages, increasing the packet loss rate. Because of these characteristics, routing protocols based on greedy forwarding such as greedy perimeter stateless routing (GPSR) are known to be very suitable for VANETs. Greedy forwarding based routing protocols select the vehicle nearest to the destination as a relay vehicle within the transmission range of the sender vehicle. Therefore, it is challenging for selecting the next relay vehicle in a low density of vehicles. To this end, we propose a route-aware delay tolerant routing (RADTR) protocol by combing greedy forwarding and store-carry-forwarding for spare VANETs such as the early morning hours. RADTR uses map data to generate a scheduled route and to predict the moving position during the relay node selection process. And each vehicle is assumed to be aware of its route to its destination and a route is specified by a sequence of its scheduled roads. Simulation results using ns-2 revealed that RADTR performs much better than the existing routing protocols in sparse VANETs. © 2013 SERSC.