Reliability of traffic management applications based on digital short-range communications

In this paper, the performance of short-range vehicle-roadside communication systems, which support RTTT (Road Traffic & Transport Telematics) services, is analysed. After introducing general communication requirements of RTTT applications in a road traffic environment, a short overview about the current status of the Dedicated Short-Range Communications DSRC prENV draft standards developed within CEN TC 278/ISO TC 204 will be given. Analytical techniques (Markov Chain modelling) will be introduced to demonstrate their capability to support the optimal choice of selected system parameters. In order to analyse the overall reliability of the communication system, the concept of the performance evaluation of vehicle-roadside systems based on integrated models of mobility, channel characteristics and communication protocols will be introduced. Simulation results based on an implementation of a high priority interactive service (Automatic Fee Collection) combined with an additional broadcast-oriented service (Dynamic Route Guidance) are analysed in detail (transaction failure rate, used length of the communication zone, interference between different applications, etc.). Optimal choices of system parameters such as antenna configurations are presented. The results show, that DSRC systems are able to provide multiple RTTT services using the same DSRC link to make best use of the available system capacity and to enhance the benefits for potential users