Araçlar arası ağlar için güvenlik mesajlarının çoklu-hop gönderimi

VANET is a network type envisioned for the future of ITS application services to improve road safety and efficiency. The main objective of VANET is to provide a guaranteed communication environment in which high speed vehicles exchange information successfully in a region distributed from any central infrastructure. By the time being, existing ITS systems are not well known due to expensive deployments or being dependent on infrastructure but in VANET vehicle is able to communicate with each other and warn them before a dangerous situation occurs in the transmission range. In this thesis, a new MAC design is presented for the multi-hop propagation of safety messages. Furthermore, to understand the nature of vehicular environment and the behavior of vehicles, a prior work has been conducted. The proposed mechanism is based on the selection of relay node per hop utilizing discriminative vehicle physical and MAC layer quantities which then gives an access probability to vehicles in the directed range. This access probability tells vehicle how much slot unit will be deferred from the wireless medium.The first vehicle which ends the back off timer according to given probability will be qualified as candidate relay node. To verify the effectiveness of the MAC protocol design, computer based simulations have been conducted in NS-3. Scenarios and mobility trace of vehicles are imported from the urban mobility simulator SUMO. The results show that the protocol performs well even under poor channel quality in terms of packet delivery ratio and delay.