Wireless Communication Alternatives for Intelligent Transportation Systems: A Case Study

Abstract

Communication systems are the basis of every effective and reliable traffic control and management application. While cellular-based communication through commercial carriers is widely used for online traffic management applications, public agencies have also begun to consider other technologies, such as WiFi and WiMAX. Most such agencies still seek additional guidelines for the selection of suitable wireless options for different traffic control and management applications under different physical and environmental conditions. Performance and reliability are among the most important parameters to be considered when examining wireless communication options for traffic control and management applications. The authors first conducted interviews with selected traffic agencies regarding their experiences with performance of wireless communication infrastructure, as well as their interests and plans on future expansion. Next, they conducted a thorough literature review focusing on various wireless technologies that could be used in an intelligent transportation system environment. Last, the authors conducted a case study in which a section of the South Carolina Department of Transportation traffic camera system was wirelessly connected via either WiFi or WiMAX network architecture. This case study followed the proposed network design process presented in the article using WiFi and WiMAX technologies to support a traffic surveillance system that considered coverage range and two different network topologies: mesh/ad hoc (devices forward data to neighboring devices to reach the destination) and infrastructure (devices send data to an access point directly). The network simulator ns-2 was used to assess the average throughput that each camera can receive in different network topologies. Throughput/cost analysis of WiFi and WiMAX mesh and infrastructure topologies indicated that for given number of devices, a mesh network has better throughput for every dollar spent than infrastructure based topology. This article provides a foundation for further investigation of WiFi and WiMAX performance and reliability under different network topologies. Findings from this research will benefit transportation agencies and other stakeholders in evaluating and selecting wireless communication options and network topologies for various traffic control and management applications.