This CAREER project is motivated by the belief that Vehicular Ad Hoc Networks (VANETs) based inter-vehicle communications could enhance traffic safety and traffic operation. VANET networks differ from general mobile ad hoc networks (MANET) because of the stringent requirements on real-time, robust, and secure communications and coordination in a critical highly dynamic environment. Building on research concerning run-time static relative-position relation among neighboring vehicles, this project addresses the major challenges in access technology, dynamic power control, robust multi-hop communication, and security and privacy provisioning. In particular, this project will develop new approaches to access technology enabling high channel availability over dynamic multi-path wireless channels, delay-bounded dynamic power control augmenting real-time communications over high mobility, robust multi-hop message disseminations in the presence of frequent fragmentations, and security implementation promoting cooperative communication and balancing privacy and security. It is envisioned that VANET communications will open the door for many new applications such as traffic safety, vehicular mobility, traffic operation, information sharing, vehicle data acquisition, and opportunistic pervasive communications.