Radio Wave Characterization in Wireless Sensor Network-based Intelligent Transportation Systems for Traffic Light Control Systems

With the growing demand of Intelligent Transportation Systems (ITS) for safer and more efficient transportation, the research and development of such vehicular communication systems have increased considerably in the last years. The use of wireless networks has been extended in an exponential growing in vehicular environments. However, it is highly important to conduct previous radio propagation analysis when deploying a wireless sensor network in such complex scenarios. In this work, the radio wave characterization for ISM 2.4GHz Wireless Sensor Networks (WSN) for a traffic light control system has been assessed. By means of an in-house developed 3D Ray Launching algorithm, the impact of topology as well as morphology of the environment has been analyzed, emulating the realistic operation in the framework of the scenario. The complexity of the scenario, which is an intersection city area with traffic lights, vehicles, people, buildings, vegetation and urban environment, makes necessary the channel characterization with accurate models before the deployment of wireless networks. A measurements campaign has been conducted by deploying a ZigBee Wireless Sensor Network in such specific environment emulating the traffic light control system. Experimental measurements and simulations results are analyzed and compared in this paper. Results show that the use of deterministic tools in WSN deployment can aid in providing optimal layouts in terms of coverage, capacity and energy efficiency of the network, making the use of these systems essential before the deployment of WSN for traffic light control applications in urban areas.