Data age based retransmission scheme for reliable control data exchange in platooning applications

Recent advances in cooperative driving hold the potential to significantly improve safety, comfort and efficiency on our roads. Platooning of heavy vehicles, where automated or semi-automated driving allows minimal inter-vehicle gaps, has shown considerable reductions in fuel consumption. Although using the same wireless communication technology, a platoon differs from a VANET (Vehicular Ad-hoc NETwork) in several points. It is centralized in its nature, with a well-defined group leader, its topology is fairly stable and it has very challenging requirements on timeliness and reliability of its control data exchange. Therefore, the IEEE 802.11p protocol suite and its recently defined message types do neither support the needs of a platooning application nor take advantage of its properties. A platoons control loop must continuously be fed with fresh data, so the information age is an important parameter to be closely monitored. In this paper, we therefore propose a framework for centralized channel access and retransmission capabilities for safety critical inter-platoon control data based on the data age of earlier received messages. A simulation evaluation compares our solution to a) the decentralized, standard-compliant IEEE 802.11p MAC (Medium Access Control) method, and a time-slotted scheme b) with and c) without retransmissions and shows that the centralized, data age based retransmission scheme clearly outperforms its competitors in terms of maintained data age.