In this report we present a framework to assist Intelligent Transportation System(ITS) service providers with the deployment of ITS user services requiring wide-area wireless communications. Our study focuses on a scenario in the San Francisco East Bay Area. Based on the projected ITS Early Deployment plan for the San Francisco Bay Area, we determine the applicable ITS user services and provide a complete description of the reverse-link wide-area wireless messaging requirements for the phased deployment of ITS services in our cell of interest, for the 1995 time frame. We next provide an in-depth survey of wireless technology alternatives and compare their characteristics in terms of their abilities to support vehicle-to-roadside ITS applications. We present our simulation model of Cellular Digital Packet Data, a leading wireless candidate, we have developed using SHIFT, an object-oriented programming language developed at UC Berkeley. We examine the reverse-link performance of CDPD for one cell sector of our scenario under normal peak-period conditions and during a major incident. Our simulation results indicate that small delays, on the order of several hundred milliseconds, are encountered when there is one dedicated CDPD channel for use in the cell sector. CDPD should adequately meet the data loads under peak-period and incident conditions for our scenario. In this work we also show that it is possible to increase the step size of our SHIFT simulations and still retain the essential delay characteristics of the CDPD system; thereby significantly reducing the simulation duration. The amount the step size can be increased is dependent on the loading requirements of the scenario. (A)
Abstract