Performance Evaluation of a System for Estimating Relative Positions of Vehicles During GPS Outages

Active safety applications for vehicles have been at the forefront of the automotive safety community for a number of years. Cooperative collision warning based on vehicle-to-vehicle radio communications and GPS systems is one such promising active safety application that has evoked considerable interest among automobile manufacturers and research communities worldwide. In this paper, we address one of the key functional components of the cooperative collision warning application, which is, accurate estimation of relative positions of all the neighboring vehicles based on real-time exchange of their individual GPS position coordinates, and then we propose a novel system solution for achieving the same (relative positioning functionality) during persistent GPS outages. Our proposed system solution essentially involves integration of the most suitable set of vehicle clustering, radio based ranging, and relative position coordinate establishment techniques, and based on the results of a comprehensive literature survey, we reason that the two-way reciprocal time of arrival based ranging, and the distributed beacon-less relative positioning techniques may constitute the most viable set for our proposed system solution. Having developed a system simulator to accurately model the functionality of our proposed system solution, we then quantify the impact of various levels of ranging error on the overall performance of the system and thereby assess the functional viability of our proposed system solution. The simulation results look quite promising and support the fact that our proposed system solution can enable relative positioning of vehicles without any GPS information within acceptable levels of positioning accuracy, as required for the 360-degrees cooperative collision warning application