Vehicular backbone networking protocol for highway broadcasting using directional antennas

Vehicular Ad Hoc Network technology facilitates real time information dissemination by enabling efficient inter-vehicle communications for the wide broadcasting of public safety and other message flows. A key challenge in VANET broadcasting is to develop a networking mechanism to coordinate data transmissions among moving vehicles. We propose a Directional Vehicular Backbone Network (DVBN) protocol for the distribution of messages generated by a Road Side Unit located at a position along a linear highway to vehicles that travel along this highway. Using GPS (Global Positioning System), an election algorithm is used so that vehicles that are positioned close to those nominal positions are elected to act as relay nodes. The aim of this paper is two-fold: a. We examine the utility of using varying inter-RN nominal position ranges in contributing to the enhancement of the system's broadcast throughput rate. We show that when minimum inter-vehicular spacing requirements are imposed, it is effective to select equal inter-RN distance levels. b. We demonstrate the superior performance offered by this DVBN protocol when compared with a corresponding (VBN) protocol that employs omni-directional antennas. We illustrate scenarios under which broadcast throughput capacity rate gains as high as three to ten fold are achieved by the DVBN scheme.