Performance analysis of wide zone AVI systems

The wide zone AVI system is an automatic vehicle identification system that can cope with more than one vehicle in the detection zone. Such a system includes a possibility of identification failure by the collision of ID packets, in addition to the ordinary transmission failure. A method to remedy this is to transmit the ID packet several times. This paper considers two methods of transmitting the ID packet from each vehicle. In the first, the packet transmission interval follows an exponential distribution, and in the second, a specified number of transmissions are made at random points which are distributed uniformly during the zone pass period. Using approximate analyses of the identification failure probability, the effects of the design parameters on the system performance are examined for each method. As a result, it is shown that the constant number transmission method has a better performance than the exponential transmission interval method, in terms of the probability of identification success, the number of ID packet transmissions, and other aspects.