Adaptive MAC protocol for high-load inter-vehicle communication

We have researched on dynamic media access (MAC) protocol for inter-vehicle communication (IVC) for automated vehicle control system (AVCS). In IVC, since there are no nodes that take care of the synchronization of vehicle communication, it is required for each node to sense media information and send its own vehicle information. Our target issues to be solved are the long career sensing time, difficulty of time slot or code allocation in case that vehicles are located so densely. Therefore, we propose a new scheme that solves those issues by changing the media sensing distance and frame transmission distance depending on the density of the nodes. The proposed scheme is basic MAC protocol and hence is adaptive for both collision and reserved MAC protocol. Moreover, we also propose a new scheme that transmits vehicles' own information by utilizing multi-hop communication to fulfil the AVCS system requested transmission distance. Finally, we evaluated our proposed scheme in the case of MCS/CDMA protocol. We clarified that our protocol improved the success ratio of code allocation from 20% to 60%. Moreover we clarified that only two hops is sufficient to fulfil the system requested transmission distance averagely.