Inter-vehicle communication apparatus and method with restrictions on size of network

Abstract

When a network is formed among vehicles with the use of inter-vehicle communication units, a network-forming-request-source vehicle sends its position serving as a reference position, its moving direction, and requested information to surrounding vehicles by the use of a free ID. Among the surrounding vehicles, vehicles which are to subscribe to the network receive the position, the moving direction, and the requested information, determine where the vehicles are positioned among positions specified in advance relative to the reference position, and respond at a timing corresponding to their positions by the use of free IDs. The network-forming-request-source vehicle receives the responses, stops receiving responses when the number of responded vehicles reaches an appropriate number of vehicles, and sends its genuine ID and a vehicle communication order. Then, a restriction, such as a restriction based on the number of times relay processes are allowed, a restriction based on a predetermined-distance area from the center of balance or the center, or a restriction based on a communication period equal to a predetermined time or shorter from when the network is formed, all of which correspond to the type of network, is applied to form an appropriate-area network.