Optimized geographical routing protocol for inter-vehicle communications

New applications of mobile communications require improved quality and reliability of inter-vehicle communications protocols. Taking in account problems related with absorbing and scattering energy of wireless signals, the presence of "grey zones" in reception, raise the necessity of improving present inter-vehicle communications protocols. We present a reliable hierarchical routing protocol that takes in account those issues. Our protocol is based on geographical routing. It enables point-to-point communications between cars in highway. The protocol is designed for highway travelers but can be used in any mobile ad-hoc network. The highway is divided in virtual cells, which moves as the vehicles moves. The cell members might choose one or two centers that will behave for a certain time interval as base stations. Every node has its geographical position given by Global Positioning System (GPS). In this protocol we take in consideration the presence of high traffic areas, "grey areas", in which receivers experience significant variable and unstable reception over time and failure of transmission between random cell leaders. Our simulation results show that our proposed protocol improves the network utilization compared to existing inter-vehicles protocols. The protocol can be used to implement differentiated mobile services and message prioritization.