Communication-Based Intersection Safety : Motivation , Challenges and State-ofthe-Art

V2X communication has recently attained significant attention from both academia and industry because it has the potential to improve road safety and to reduce road accidents and fatalities. For this reason, V2X communication has been considered an important part of future Intelligent Transportation Systems (ITS). In V2X communication, vehicles are equipped with IEEE 802.11-based wireless network interfaces and can spontaneously form an ad hoc network among themselves. Vehicles can use this ad hoc network to communicate with each other in order to support safety applications such as cooperative collision warning. Several R&D projects around the world have been investigating various aspects of V2X communication. Some of these projects focus on specific issues of V2X communication for intersection safety because intersections are the most complex driving environments and include not only vehicles but also other road users such as pedestrians and cyclists. Thus, distraction or unpredictable behavior of a single driver can have a grave impact on many other road users. For this reason, intersection accidents occur frequently. Further, these accidents are usually very serious and usually involve several users. In this paper, we first review use cases for communication-based intersection safety. We then derive the requirements from these use cases and discuss their challenges. Based on these requirements, we present a protocol architecture for communicationbased intersection safety that fits into the overall architecture of V2X communication.