GeoDTN+Nav: A Hybrid Geographic and DTN Routing with Navigation Assistance in Urban Vehicular Networks

Position-based routing has proven to be well suited for highly dynamic environment such as Vehicular Ad Hoc Networks (VANET) due to its simplicity. Greedy Perimeter Stateless Routing (GPSR) and Greedy Perimeter Coordinator Routing (GPCR) both use greedy algorithms to forward packet and try to ¯nd a route by the right-hand rule in perimeter mode when it encounters a local maximum. These protocols could forward packets e±ciently given that the underlying network is fully connected. However, the dynamic nature of vehicular network, such as vehicle density, tra±c pattern, and radio obstacles could create unconnected networks partitions. To this end, we propose a hybrid geographic routing so- lution GeoDTN+Nav, an extension of VANET Cross Link Corrected Routing (VCLCR), which improves VCLCR by ex- ploiting the vehicular mobility and on-board vehicular naviga- tion systems. GeoDTN+Nav outperforms GPSR and GPCR because it is able to estimate network partitions and then im- proves partitions reachability by using a store-carry-forward procedure when necessary. We propose a virtual navigation interface (VNI) to provide generalized route information for the delay tolerant forwarding. We ¯nally evaluate the bene¯t of our approach ¯rst analytically and then with simulations. By using delay tolerant forwarding, GeoDTN+Nav greatly increases the packet delivery ratio in a sparse network.