Abstract
Smart cities are increasingly playing a fundamental role in managing the city's asset. Smart transportation is an important building block of a smart city as it can efficiently resolve many issues related to the traffic on the road. Vehicular ad hoc networks (VANETs) in smart cities may ensure wide inter-vehicle communication and disseminate data and safety-related information. VANETs have their specific characteristics such as long lifetime battery energy, high mobility, and large storage capabilities. In certain circumstances, VANETs may not ensure timely detection of road events and connectivity between vehicles due to their low density, high mobility, or low deployment of roadside unit (RSU) infrastructure. Wireless sensor networks (WSNs) are equipped with low processing and low storage capabilities but they ensure high detection of events. To overcome VANETs limitations, and as VANET and WSN have complementary characteristics, the combination of VANET and wireless sensor network (WSN) technologies into one hybrid architecture enables to identify new aspects and fields of intelligent transportation systems and may offer new services for the smart cities. In this kind of hybrid network, sensor nodes have small size and can be deployed densely inside the road to monitor traffic, roads status, and weather conditions. This chapter describes the hybrid vehicular sensor networks and discusses their deployed applications, communication paradigms, challenges, and existing architectural solutions. Moreover, a heterogeneous VANET-WSN architecture is proposed and open issues and future directions are discussed to help stimulating future studies in this emerging research field.