Update delay: A new information-centric metric for a combined communication and application level reliability evaluation of CAM based Safety Applications

Although Intelligent Transport System (ITS) communications is based on the WLAN standard IEEE 802.11, the requirements of safety related ITS applications have been changed completely. Basically, they require up-to-date information about the status of other vehicles in the vicinity, which is currently implemented by each vehicle broadcasting periodically such status information. Consequently, the usual performance metrics like throughput, latency, reception probability, etc. are not suitable for analysis and evaluation of ITS applications. In this paper we first introduce Awareness Quality, which we define as the application level metric for CAM based safety applications. Then we define a new information-centric network level metric called Update Delay, which is highly correlated with the Awareness Quality. Finally we show how to obtain the Awareness Quality from a communications perspective by using Update Delay measurements, and use it to evaluate the reliability of CAM-based traffic safety related applications.