The present disclosure relates to vehicle-mounted devices and communication method. One example vehicle-mounted device in a first vehicle may obtain first position information, where the first position information indicates a position of the first vehicle. The vehicle-mounted device generates first-level information based on the first position information, where the first-level information indicates a first height level to which the position of the first vehicle belongs or a first height level to which a future driving track of the first vehicle belongs, and sends the first-level information.