Efficient and reliable communication between base stations and vehicles is becoming increasingly important for meeting the demands of many intelligent transportation applications. The key challenge here is to deal with constant topological changes in the underlying communication network resulting from vehicular mobility. In this paper, we propose a mobility management scheme MMDD that helps base stations track the location of vehicles registered to their services. Registered vehicles send their location updates to corresponding base stations by following either a distance-based or a time-based mechanism. The location information is subsequently leveraged in transmitting data packets in an efficient and reliable manner. We also propose a paging mechanism through which base stations can obtain the latest location information of any registered vehicle. Through a detailed simulation study, we demonstrate that our location management scheme outperforms a state-of-the-art approach RLSMP, both in terms of average packet delay and success percentage. We also show that the impact of control packets from location update and paging mechanisms on the overall performance is minimal.

Recently, vehicular communication systems have attracted much attention, fueled largely by the growing interest in Intelligent Transportation Systems (ITS). These systems are aimed at addressing critical issues like passenger safety and traffic congestion, by integrating information and communication technologies into transportation infrastructure and vehicles. They are built on top of self organizing networks, known as a Vehicular Ad hoc Networks (VANET), composed of mobile vehicles connected by wireless links. While the solutions based on the traditional layered communication system architectures such as OSI model are readily applicable, they often fail to address the fundamental problems in ad hoc networks, such as dynamic changes in the network topology. Furthermore, many ITS applications impose stringent QoS requirements, which are not met by existing ad hoc networking solutions. The paradigm of cross-layer design has been introduced as an alternative to pure layered design to develop communication protocols. Cross-layer design allows information to be exchanged and shared across layer boundaries in order to enable efficient and robust protocols. There has been several research efforts that validated the importance of cross-layer design in vehicular networks. In this article, a survey of recent work on cross-layer communication solutions for VANETs is presented. Major approaches to cross-layer protocol design is introduced, followed by an overview of corresponding cross-layer protocols. Finally, open research problems in developing efficient cross-layer protocols for next generation transportation systems are discussed.

Vehicular networking has significant potential to enable diverse applications associated with traffic safety, traffic efficiency and infotainment. In this survey and tutorial paper we introduce the basic characteristics of vehicular networks, provide an overview of applications and associated requirements, along with challenges and their proposed solutions. In addition, we provide an overview of the current and past major ITS programs and projects in the USA, Japan and Europe. Moreover, vehicular networking architectures and protocol suites employed in such programs and projects in USA, Japan and Europe are discussed.

Vehicular communication systems facilitate communication devices for exchange of information among vehicles and between vehicles and roadside equipment. These systems are used to provide a myriad of services ranging from traffic safety application to convenience applications for drivers and passengers. In this paper, we focus on the design of communication protocols for vehicular access networks where vehicles access a wired backbone network by means of a multi-hop data delivery service. Key challenges in designing protocols for vehicular access networks include quick adaptability to frequent changes in the network topology due to vehicular mobility and delay awareness in data delivery. To address these challenges, we propose a cross-layer position-based delay-aware communication protocol called PROMPT. It adopts a source routing mechanism that relies on positions independent of vehicle movement rather than on specific vehicle addresses. Vehicles monitor information exchange in their reception range to obtain data flow statistics, which are then used in estimating the delay and selecting best available paths. Through a detailed simulation study using ns-2, we empirically show that PROMPT outperforms existing routing protocols proposed for vehicular networks in terms of end-to-end packet delay, packet loss rate, and fairness of service.

Intelligent transportation systems are targeted to improve the traffic safety and driving experience of passengers. Vehicular ad hoc networks are wireless communication networks proposed to be used as parts of ITS. VANETs facilitate communication among vehicles, and between vehicles and roadside equipment. A key challenge in developing such systems is to design routing and MAC protocols that not only provide good end-to-end packet delay but can also quickly adapt to changes in the network topology due to vehicular mobility. In this article we outline a new framework for location- and delay-aware cross-layer communication that addresses these challenges. Our framework provides an efficient V2I data delivery system that relays packets over low-delay paths to a fixed base station or access point. Furthermore, an instance of this framework is also presented as a protocol. Our preliminary evaluations show that our design approach is promising, and provides delay predictability, fairness, and a good packet delivery ratio.

In this paper, we present the architecture of an Integrated Wireless Intersection Simulator (IWIS) that is used to study the effect of different communication-based solutions on vehicle traffic and vehicle behavior in Intelligent Transportation Systems (ITS). IWIS consists of two components, a Vehicle Intersection Traffic Simulator (VITS) that simulates vehicle traffic, and a Wireless Simulator (WS) that simulates wireless packet transmission. The user can provide a variety of traffic configurations such as buildings, traffic lights, and vehicle density through a friendly graphical user interface. The modular nature of our simulator gives the ability to compare different communication protocols easily. The output from WS (packet collision rate and transmission delay) is fed to a collision warning system in VITS. We evaluate IWIS under different traffic conditions and different MAC protocols.

With the increasing importance of energy consumption considerations and new requirements of emerging applications, in-network processing of information gains recognition as a viable solution for wireless sensor networks (WSNs). The required processing capability can be achieved through locally collaborative information processing among sensors. Task mapping and scheduling plays an important role in efficient collaborative information processing. Although task mapping and scheduling in wired networks of processors has been well studied in the past, its counterpart for WSNs remains largely unexplored. In this paper, a task mapping and scheduling solution for real-time applications in WSNs, real-time task mapping and scheduling (RT-MapS), is presented. RT-MapS incorporates wireless channel modeling, hyper-DAG extension, concurrent task mapping, communication and computation scheduling, and dynamic voltage scaling (DVS) methods. Simulation results show significant performance improvements compared with existing mechanisms in terms of providing deadline guarantee with minimum energy consumption