Adaptive Communication Scheme for Cooperative Active Safety System

This paper presents 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, 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 broadcast to all neighbors within a certain communication range. The authors review the literature, which surmises that in order to be successful, CASS may need a vehicle to broadcast information as often as every 100 msec which may lead to channel congestion resulting in message loss rates above 20%. They present a new communication design scheme, supported by simulations, which indicates that CASS could be enabled by broadcasting, on average, as little as once every 500 msec. In the proposed scheme, each vehicle compares its self state estimates of the state outputs of their remote estimator. Then, based on a threshold crossing policy defined for longitudinal position error and lateral position error violation, the vehicle decides to broadcast or not.