Safety

In vehicular ad-hoc networks, status update messages are used to disseminate vehicle state information so that each vehicle can track movements of its neighbors. In this paper, we focus on the aggregated power level from this kind of active safety messages and its impact on DSRC channel quality. With macroscopic model and LWR (Lighthill-Whitham-Richards) PDE, we show how the probability distribution of aggregated power level propagates along time and space. Based on our analysis, several rate-power control ideas for status update messages are discussed. In addition, microscopic traffic/...

We present an adaptive communication scheme for cooperative active safety system (CASS). CASS uses information communicated from neighboring vehicles via wireless communication in order to actively evaluate driving situations and provide warnings or other forms of assistance to drivers. In CASS, we assume that vehicles are equipped with a GPS receiver, a dedicated short range communications (DSRC) transceiver, and in-vehicle sensors. The information exchanges between vehicles include position, speed, heading, and other vehicle kinematic and dynamic information, and the information is...

Vehicular ad hoc networks play a critical role in enabling important active safety applications such as cooperative collision warning. These active safety applications rely on continuous broadcast of self-information by all vehicles, which allows each vehicle to track all its neighboring cars in real time. The most pressing challenge in such safety-driven communication is to maintain acceptable tracking accuracy while avoiding congestion in the shared channel. In this article we propose a transmission control protocol that adapts communication rate and power based on the dynamics of a...

Motivated by the proliferation of Smartphone devices, the authors present a system architecture to enable the delivery and exchange of intelligent transportation systems (ITS) messages to Smartphones on the road. The purpose is to provide an ITS situation awareness system architecture that would enable application developers to build Smartphone applications for ITS mobility and safety. The authors present a “Slow Traffic Ahead” application as a means to validate the architecture and perform a field experiment in the San Francisco Bay Area comprised of 30 users to test the performance of...