Clayson Celes

Improving VANET Simulation with Calibrated Vehicular Mobility Traces

Simulation is the most frequently adopted approach for evaluating protocols and algorithms for Vehicular Ad hoc Networks (VANETs) and Delay-Tolerant Networks (DTNs). Usually, simulation tools use mobility traces to build the network topology based on the existing contacts between mobile nodes. However, quality of the traces, in terms of spatial and temporal granularity of each entry in the logfile, is a key factor that impacts the network topology directly. Therefore, the reliability of the results depends strongly on the accurate representation of the real network topology by the vehicular mobility model. We show that five widely adopted existing real vehicular mobility traces present gaps, leading to fallible outcomes. In this work, we propose a solution to fill those gaps, leading to more fine-grained traces, which lead to more trustworthy simulation results. We propose and evaluate a data-based solution using clustering algorithms to fill the gaps of real-world traces. In addition, we also present the evaluation results that compare the communication graph of the original and the calibrated traces using network metrics. The results reveal that the gaps do indeed induce network topologies differing from reality, decreasing the quality of the evaluation results. To contribute to the research community, we have made the calibrated traces publicly available, so that other researchers may adopt them to improve their evaluation results.

GeoSPIN: An Approach for Geocast Routing Based on SPatial INformation in VANETs

Vehicular Ad hoc NETworks (VANETs) have been widely used to provide data exchange services in Intelligent Transport Systems (ITS), which should facilitate users routines. At the same time that users routines are improved, they can also be used as an important source of data for helping the decision-making process of VANET services. These routines can be acquired from vehicles trajectories through the use of Global Positioning Systems (GPS). In this context, the combination of location-based data and data forwarding methods brings interesting challenges since these topics are not directly related. Therefore, the key idea of this work is to provide a geocast routing mechanism in VANETs based on daily movements of users in their vehicles. The main contribution is related to the delivery rate, which increases in partitioned and sparsely connected networks. The results show the efficiency of our new method to perform opportunistic routing based on location data, which discovers the best routes to forward packets through the network.

Users in the urban sensing process: Challenges and research opportunities

The popularization of portable devices such as smartphones and the worldwide adoption of social media services make it increasingly possible to be connected and share data anywhere and at any time. Data from this process represent a new source of sensing, which is called participatory sensor network (PSN). In this scenario, people participate as social sensors voluntarily providing data that capture their experiences of daily life. This large amount of social data can provide valuable new forms of information to be obtained that are currently not available within the same global reach and that can be used to improve the decision-making processes of different entities (eg, people, groups, services, and applications). The objective of this chapter is to discuss PSNs, presenting an overview of the area, challenges, and opportunities. We aim to show that PSNs (eg, Instagram, Foursquare, and Waze) can act as valuable sources of large-scale sensing, providing access to important characteristics of city dynamics and urban social behavior, more quickly and comprehensively. This chapter starts by studying the properties of PSN. Next, it discusses how to work with PSN, showing its applicability in the development of more sophisticated applications. In addition, it discusses several research challenges and opportunities in this area.The popularization of portable devices such as smartphones and the worldwide adoption of social media services make it increasingly possible to be connected and share data anywhere and at any time. Data from this process represent a new source of sensing, which is called participatory sensor network (PSN). In this scenario, people participate as social sensors voluntarily providing data that capture their experiences of daily life. This large amount of social data can provide valuable new forms of information to be obtained that are currently not available within the same global reach and that can be used to improve the decision-making processes of different entities (eg, people, groups, services, and applications). The objective of this chapter is to discuss PSNs, presenting an overview of the area, challenges, and opportunities. We aim to show that PSNs (eg, Instagram, Foursquare, and Waze) can act as valuable sources of large-scale sensing, providing access to important characteristics of city dynamics and urban social behavior, more quickly and comprehensively. This chapter starts by studying the properties of PSN. Next, it discusses how to work with PSN, showing its applicability in the development of more sophisticated applications. In addition, it discusses several research challenges and opportunities in this area.

Vehicular Networks to Intelligent Transportation Systems

Urban mobility is a current problem of modern society and large cities, which leads to economic and time losses, high fuel consumption, and high CO2 emission. Some studies point out Intelligent Transportation Systems (ITS) as a solution to this problem. Hence, Vehicular Ad hoc Networks (VANETs) emerge as a component of ITS that provides cooperative communication among vehicles and the necessary infrastructure to improve the flow of vehicles in large cities. The primary goal of this chapter is to discuss ITS, present an overview of the area, its challenges, and opportunities. This chapter will introduce the main concepts involved in the ITS architecture, the role of vehicular networks to promote communication, and its integration with other computer networks. We will also show applications that leverage the existence of ITS, as well as challenges and opportunities related to VANETs such as data collection and fusion, characterization, prediction, security, and privacy.

Communication analysis of real vehicular calibrated traces

Vehicular network applications are emerging to bring many benefits to the users during their journey. However, the design and deployment of such applications require studies that provide insightful information about the network formed by vehicles. To this end, in the last years researchers have been characterizing real mobility traces collected from taxis equipped with GPS devices. However, these traces present temporal and spatial gaps, as it was demonstrated in other studies. In this work, we compare the real original traces with their calibrated version (i.e., with no gaps) to show that the existing gaps expressively affect key metrics such as contact duration, inter-contact time, and network capacity. As result, we contribute to the research community by presenting important analysis of real vehicular network topology and by showing the importance of calibrating the traces before evaluating vehicular network applications.