In the last few years Intelligent Transportation Systems (ITS) based on wireless vehicular networks have been attracting interest, since they can contribute towards improving road transport safety and efficiency and ameliorate environmental conditions and life quality. In order to widely spread these technologies, standardization at each layer of the networking protocol stacks has to be done. Therefore, a suite of protocols along with the architecture for the wireless environments with vehicles has been developed and standardized. Both in the US as well as in Europe the selected wireless communication protocol has been the 802.11p protocol developed by the IEEE. In this chapter, we discuss the potential impact of ITS towards achieving the above targets of improving road safety and traffic control. We review the overall architecture and the protocol functionality and present in detail a number of applications that have been developed demonstrating selected use-cases on an 802.11p compliant system prototype. Specifically, we discuss the implementation of selected applications on the NEC's Linkbird-MX platform, which supports IEEE 802.11p based communications, showing how its functionality can be exploited to build efficient road safety and traffic management applications, and evaluate the performance of the system using an experimental testbed.
TopIntroduction
Road safety, air pollution and traffic management are three major concerns that the residents of urban centers around the world have to face promptly given the immense growth in cities’ population. Road traffic accident mortality is high among young people with transport accidents causing 8% of all losses among citizens with an age below 65 years in the EU-27, higher than any disease (Cayotte & Buchow, 2009). Across EU, transport is most dangerous in regions of Portugal, Lithuania, Latvia, Corsica, Greece and Poland. While road traffic injuries are a major cause of death and disability globally, a disproportionate number occurs in developing countries. Road traffic injuries are currently ranked ninth globally among the leading causes of disability-adjusted life years lost, and the ranking is projected to rise to third by 2020. In 1998, developing countries accounted for more than 85% of all deaths due to road traffic crashes globally and for 96% of all children killed (Murray & Lopez, 1996; Nantulya & Reich, 2002). On the other hand, air pollution is tightly related to traffic management and plays a substantial role to the climate change while burdening the commitment of Europe to decrease the CO2 emissions. In urban areas, an increase in average speed may dramatically reduce fuel consumption, while traffic signal synchronization has the potential to increase intersection throughput for private traffic by 15%. Guiding traffic (e.g. through route advisory systems) away from problematic areas may lead to up to 8% less emissions (Murray & Lopez, 1996). Today, according to the Panorama of Transport (2009), 30% of energy is consumed for transportation of humans and goods and almost 18% of the CO2 emissions from combustion come from road transportation (IEA, 2005). Although the broadening of the road infrastructures increases their capacity, it cannot keep up with the pace of the increase in urban populations worldwide, due to cost and time reasons, leading the city authorities to pursue “soft” measures to solve the problem (Pincus, 2011). Furthermore, there are many efforts by the scientific community to combat many critical issues that hold back the vehicular network’s deployment but also support the Intelligent Transportation Systems (ITS) development by performing standardization efforts concerning vehicular communications (Kadas & Chatzimisios, 2011; Leontiadis et.al, 2011).
To tackle the previously reported issues and problems, the design and development of ITS has been pursued extensively in the last decade. These systems rely on intelligent collection and processing of information which enables decision making and information/decision dissemination to enhance the citizen’s experience either through enhancing transportation efficiency or safety. They can be classified in advanced public transport systems, advanced traveler information systems, advanced Traffic Management Systems, incident management systems, electronic toll collection systems, Vehicle Information and Communications System, and Video Transmission Systems for road surveillance. ITS are expected to play a major role in enhancing road safety, transportation efficiency and improving environmental conditions, both in developed as well as in developing countries as mentioned above. Their impact will be critically affected by the adoption of standardized and low-cost technologies that can result in massive production of commodity hardware components and wide deployment of interoperable systems.
In order to achieve the objective of providing citizens using the roads with improved traffic safety, reduced traffic congestion, and environment-friendly driving, countries worldwide had to standardize communication protocols for common communication between vehicles and between vehicles and infrastructure. Vehicular networking combines wireless communication, in-vehicle sensing module, and Global Positioning System (GPS) to enable a variety of applications in road safety, traffic efficiency, and infotainment domains. In the US, the networking protocols of choice for vehicles and infrastructure associated with these patterns are included in the WAVE (Wireless Access in Vehicular Environments) family of standards formulated by the IEEE (Institute of Electrical and Electronics Engineers) and are mainly based on the IEEE 802.11p and IEEE 1609 protocols (IEEE 802.11p, 2010; IEEE 1609.0, 2013). This set of standards defines the architecture, communication model and mechanisms of high-speed short-range wireless low-latency communications.