VC-MAC: A Two-Cycle Cooperative MAC Protocol in Vehicular Networks

With the rapid growth and evolution of the vehicular network with the highly increasing demand of vehicular traffic management, vehicular infotainment applications, and the vehicular cloud computing, massive vehicular information is required to be downloaded from roadside-deployed gateways. With the nature of high mobility and intermittent connectivity, it is challenging to provide a highly reliable media access control (MAC) protocol in vehicular networks to increase the broadcast efficiency of the information downloaded to all vehicles. This paper proposes a new MAC protocol, called the two-cycle cooperative MAC protocol (VC-MAC), for vehicular networks. This work mainly improves an existing VC-MAC protocol with the concept of cooperative communication for vehicular networks, particularly for gateway-downloading scenarios. The VC-MAC protocol performs one cycle of relaying, which is called the one-cycle relaying MAC protocol throughout this paper. Unfortunately, many vehicles cannot successfully receive the messages from the relaying vehicles within one-cycle relaying in situations where there are intermittent link disruptions. This paper further utilizes the concept of two-cycle relaying to not only significantly improve the reachability and the downloading efficiency but also significantly reduce the packet overhead and the network access time. Finally, simulation results are examined to illustrate the performance achievements of dissemination success rate and message overhead. Keywords—Vehicular network; cooperative communication; media access control; relay.