RR-Aloha+: A slotted and distributed MAC protocol for vehicular communications

The state of the art of vehicular communications includes extensive investigations on distributed-contention approaches (mostly focused on WiFi CSMA/CA optimal and/or custom configurations), while scalable solutions for a distributed but contention-free wireless architecture remain unexplored. In this paper, starting from an existing protocol called RR-Aloha, we propose some novel extensions to it, in order to solve some technical open issues, improve its scalability and overcome some criticalities concerning the dynamic setting of vehicular mobility. The study is based both on conceptual tests and on PC simulations on NS-2 (network simulator). The proposed scenarios are meant to validate the extensions and confirm the feasibility; the preliminary results show that the enhanced RR-Aloha+ may actually exert a potentially relevant role in the vehicular communications, with a deterministic, reservation-based, QoS-capable and distributed access channel.