Cooperative Intelligent Transportation Systems (CITS) have gained an increasing interest in the last few years. Within these systems, vehicles use wireless communications to cooperatively exchange information in the perspective of enhancing traffic efficiency and comfort. Public transport represents an excellent candidate for C-ITS support. Indeed, unlike private cars, public transport vehicles are inherently cooperative and can be easily augmented with wireless communication capabilities. In this paper, we analyze the communication contact opportunities between public transport buses. Understanding these contacts is a basic building block towards the design and deployment of intelligent, distributed and cooperative applications on top of bus public transport systems. We particularly investigate bus-to-bus contacts in the actual bus public transport of the entire Luxembourg city over a whole day. This city is a representative example of many other European cities. Our study shows that both space and time are chief factors in the characterization of bus-to-bus contacts. Different geographical regions and daytimes show varied contacts properties. Our analysis thus stresses the importance of considering large-scale scenarios when evaluating C-ITS.

Conflict detection is an important research issue in Unmanned Aerial Vehicles to ensure safety and collision free flights. In this paper, we first propose a comprehensive analytical framework for a three dimensional conflict detection. Then, we propose SLIDE a new Straight LIne conflict DEtection and alerting algorithm for a set of UAVs to safely share a common airspace. SLIDE is fully distributed and requires a limited state information exchange between UAVs. The assumptions of precise state information and packet-loss free communications are relaxed so as to guarantee the applicability and efficiency of the algorithm in real world situations. A thorough discussion is also presented to deal with appropriate tuning of the different parameters of the collision detection framework. Extensive simulations based on OMNeT++ are used to validate SLIDE and evaluate its performance. Simulation results indicate that SLIDE guarantees a reduced number of false and missed alarms even in high density traffic scenarios and communication perturbed environments, yet it leaves adequate time to accomplish the required maneuver actions.

This paper deals with conflict detection for Unmanned Aerial Vehicles (UAVs). We provide an exhaustive mathematical framework for 3D conflict detection and propose a novel distributed conflict detection algorithm. The suggested algorithm requires minimal communication. Indeed, only the state information (i.e., position and velocity vectors) is periodically exchanged between the UAVs. We carry out simulations, using the OMNET++ simulator, to evaluate its performance. Simulation results indicate that the proposed algorithm performs well in terms of false alarms, missed alarms and scalability to increased number of UAVs.

Sensing coverage in wireless sensor networks is one of the most fundamental issues, which have been extensively addressed in the literature. It is viewed as one of the critical performance measures in large-scale sensor networks. In this context, researchers have designed several coverage protocols. Throughout the variety of research works in this topic, most interests focused purely on the coverage problem under the restrictive assumption that each deployed node is equipped with a GPS receiver that provides a sensor node with its accurate location. However, in some wireless sensor network applications GPS service may be inaccessible, unpractical and very expensive. Faced to this challenge, several GPS-less localization algorithms for wireless sensor networks have been proposed. Such localization algorithms enable sensor nodes to locate themselves with some degree of accuracy. In this paper, we address the issue of maintaining coverage from the perspective of a GPS-less localization. We particularly integrate two well-known coverage and GPS-less localization solutions, namely CCP and AT-Dist. This integration yields key insights for handling coverage and GPS-less localization in a unified framework in contrast to several existing approaches that address the two issues in isolation. To the best of our knowledge, this will be the first work that integrates those two solutions. Extensive simulations show the effectiveness of this integrated framework to provide guaranteed coverage and localization.