Methods to Improve V2V Communications in Platoons of Heavy Duty Vehicles
Sammanfattning: In the coming years V2V communications will probably be mandated and vehicle OEMs strive to find business opportunities to finance its investments in V2V communications technology. For heavy vehicles, platooning can be this business opportunity, with the motivation for the fleet owners that platooning can decrease the fuel consumption by up to 15 % when driving in platoons. However, challenges still exists with respect to the quality and reliability of the V2V communications, which is essential in order to enable platooning in a safe way.In this thesis, two proposals of improving the quality and reliability of V2V communications in a platooning scenario are presented. The first proposal is the Curvature Based Antenna Selection Method that utilize the curvature of the road in order to estimate which antenna have the highest probability of having line of sight conditions, hence highest probability of successful communication. The method assumes a platoon of heavy vehicles with one antenna mounted in each rear view mirror. It also assumes that the leading vehicle can estimate the yaw rate of the platoon in order to determine if it is turning or not. The second proposal include two message forwarding algorithms, the Reachability Matrix forwarding algorithm and the Data Age Dependent forwarding algorithm. Both algorithms utilize information on the preceding communication capability in order to estimate which node to choose as forwarding candidate. The Reachability Matrix Algorithm puts its focus on keeping the overhead low, while at the same time improve the information up-to-dateness. The Data Age Dependent algorithm instead puts its main focus on performance with respect to improving the information up-to-dateness, with the cost of higher overhead compared to the Reachability Matrix algorithm.Both proposals show potential of improving the quality of the V2V communication in a platooning scenario. The first proposal, the antenna selection method, is able to maintain a Data Age deadline of 150 ms approximately twice as often as when selecting transmission antenna in a round robin fashion. For the second proposal, the Reachability Matrix Algorithm reduces the miss of a 0.2 s Data Age deadline in the communication between the first and the fourth vehicle in a platoon from 18 % to 11 %, while only increasing the number of sent messages from 40 to 48.5 per second compared to when only broadcast is used. The Data Age Dependent algorithm shows even better performance with respect to reducing the missing of the 0.2 s Data Age deadline, i.e., with a reduction from 18 % to 5 %.
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