Risk management in a vehicle-to-vehicle safety system

Abstract

A method is described for managing risk messages in a distributed, vehicle-to-vehicle (V2V) safety system that limits broadcast storms during an omnidirectional rebroadcast of risk messages in a range larger than a radio range. A group of self-organized transponders, such as may be in vehicles, broadcasts, in a shared medium, real-time safety messages, using self-assigned time slots in regular, contiguous time intervals. Relative locations of up to four distinct transponders are computed and compared, along with a geographic angle formed by three transponders. Risk messages are not rebroadcast when another vehicle, farther from the originating vehicle, has already rebroadcast the same message. Risk values may be single-digit integers, created by adding sub-risk values responsive to real-time vehicle behavior, traffic, weather, road conditions, and the risk history of a road segment. Risk messages are free of fixed vehicle or transponder identification.