Vehicle to Vehicle RF Propagation Measurements

We present results from vehicle to vehicle RF propagation measurements centered at Se0 M H z We focus on determining dehy s p r e a probability distribution parameters (in particular; the Rician K factor) and p t h loss rates. Our results are discussed with implications for the use of RF communication between automobiles in Intelligent Vehicle Highway System (IVHS). Our paper consists of a description of the IVHS concept along with a brief overview of wireless propagation thtory. We then discuss our measured parameters with respect to implementing an RF transmission system between vehicles. Recently, implementation of advanced communication technology has been propounded as a feasible alternative to solving ground transportation problems. Projects such as Road Automobile Communication Systems (RACS) in Japan, PROMETHEUS in Europe, and Partners for Advanced Transit and Highway (PATH) in the U.S. are currently engaged in the design of such systems called Intelligent Vehicle Highway Systems (IVHS) in Japan and the United States and Road Transport Informatics (RTI) in Europe. These projects encompass Automated Vehicle Control Systems (AVCS) and Advanced Vehicle Identification (AVI) as platforms from which IVHS can be realized. Many see these projects as a means of improving safety and efficiency of the highway system, which in turn would lead to an increase in the productivity of commuters as well as alleviate pollution. Shladover et. al. have proposed a method of efficient vehicle control by grouping vehicles in platoons. Platoons consist of several cars grouped together in a single lane such that consecutive cars are separated by short distances (on the order of a few meters). In IVHS projects employing the platoon concept, vehicle-to-vehicle communication is of critical importance. Although communication occurs only over relatively short ranges, from less than one meter to tens of meters, the communication links have to be extremely reliable, despite the presence of multipatb reflections and interfmnce from other links using the same frequency channel. The purpose of this paper is to present propagation measurements of RF signals between vehicles. The results will help determine the feasibility of using RF communication between vehicles in IVHS platoons. The results and discussion in the remainder of this paper will be presented as follows. Section 2.0 will consist of a review of RF propagation theories. Section 3.0 will outline our measurement procedure and present the results of our measurements. Section 4.0 will present a discussion of the results and conclude …