Safety-oriented communication in mobile networks for vehicles

Sammanfattning: Accidentstatistics indicate that every year a large number of casualtiesand extensive property losses arerecorded due to traffic accidents. Consequently, efforts aredirected towards developing passive and active safetysystems that help reducing the severity of crashes or preventvehicles to collide with each other. Within thedevelopment of these systems, technologies such as sensor systems,computer vision and vehicularcommunication are considered of importance. Vehicular communicationis defined as the exchange of databetween vehicles, and is considered a key technology for trafficsafety due to its ability to provide the vehicleswith information that cannot be acquired using other means (e.g.radar and video systems). However, due to thecurrent early stage in the development of in-vehicle safetysystems, the applicability of communication forimproving traffic safety is still an open issue. Furthermore, dueto the specificity of the environment in whichvehicles travel, the design of communication systems that providean efficient exchange of safety-related databetween vehicles poses a series of major technical challenges.In this thesis we focus on the development of a communicationsystem that provides support for in-vehicleactive safety systems such as collision warning and collisionavoidance.We begin by studying the applicability of communication forsupporting the development of effective activesafety systems. Within our study, we investigate different safetyaspects of traffic situations. For performingsuch investigations we develop ECAM, a temporal reasoning systemfor modeling and analyzing accidentscenarios. This system gives us the possibility of analyzingrelations between events that occur in traffic andtheir possible consequences. We use ECAM for analyzing the degreeof accident prevention that can be achievedby applying crash countermeasures based on communication inspecific traffic scenarios.By acknowledging the potential of communication for traffic safety,we further focus in the thesis on thedesign of a safety-oriented vehicular communication system. Wepropose a new solution for vehicularcommunication in the form of a distributed communication protocolthat allows the vehicles to organize thenetwork in an ad-hoc decentralized manner. For disseminatinginformation, we develop an anonymous contextbasedbroadcast protocol that requires the receivers to determine whetherthey are the intended destination ofsent messages based on knowledge about their momentary situation intraffic. We further design a vehicularcommunication platform that provides an implementation frameworkfor the communication system, andintegrates it within a vehicle. Investigations of the communicationperformances, which evaluate metrics such astransmission delay, send errors, packet collisions and informationfiltering, indicate that the proposed vehicularcommunication system is able to provide a reliable and timelyexchange of data between vehicles.