VCAST: A Distance-Sensitive Scalable Information Dissemination Protocol

The future of intelligent transportation systems lies in dealing with safety and navigation of vehicles. Building a technology that provides the real-time information about the state of other vehicles like its location, speed and direction would help in developing a system that ensures safety along with navigation. However, the network limitations pose difficulty in obtaining the state information over multiple-hops, because of the bandwidth limitations and congestion in the shared wireless channel. Overcoming this challenge would yield an intelligent transportation system which gives information regarding the collisions, lane changes and merges, emergency vehicle approaching alerts, stopped vehicle alerts, etc., over larger distances. In my thesis I developed an algorithm VCAST that addresses this challenge by considering the grounds that the response time needed by vehicles at farther distances is more than that of at the smaller distances. This fact exploits the notion of distance sensitivity in information propagation, in which information is forwarded at a rate that decreases linearly with distance from source. The algorithm outputs traffic information with staleness, a measure of error in traffic information, bounded by O(dh 2), where dh is the single communication hop range. Also the communication rate per vehicle per unit time depends on the area of consideration but not on the density or number of vehicles in the region, which can be further reduced by considering the aggregated information over smaller regions. Thus, this technique would be able to supply timely information over large distances without compromising on data rates at smaller distances. Also, VCAST doesn\u27t need any special hardware or changes to the vehicular transmission standards. We evaluate the performance of VCAST by simulating a 4-lane highway of 5Kms occupied by 800 vehicles, wherein we vary the densities with and without fading apart from aggregated information propagation using the IEEE 802.11p communication model on NS-3