Connected Vehicles (CV) and Vehicle-to-Everything (V2X) communication systems are integral to modern transportation infrastructure, enhancing safety and efficiency by enabling vehicles to communicate with each other and with traffic management systems [1]. Historically, there has been uncertainty about the timeline for deployment of this technology, which stalled market adoption. Now that there is more clarity on the use of the safety spectrum (e.g., 30 MHz within the 5.9 GHz spectrum), and that the technology platform will include Long-Term Evolution (LTE) Cellular-V2X (LTE C-V2X), the time has come to accelerate the deployment of interoperable V2X connectivity to save energy and enhance safety. In October 2023, the U.S. Department of Transportation (DOT) released a draft deployment plan (“Savings Lives with Connectivity: A Plan to Accelerate V2X Deployment”) with short-,medium-, and long-term goals and targets to achieve interoperable connectivity at a national scale [2].

C-V2X has emerged as a more advanced technology, leveraging cellular networks for broader and more reliable communication. C-V2X includes both direct communication (device-to-device) and network communication (through cellular networks). Direct C-V2X, using PC5 mode (direct communication with vehicles or infrastructure, as described in the SAE J3161 family of standards [3]) in the 5.9 GHz band, enables real-time communication between vehicles and infrastructure without relying on cellular networks, ensuring low latency for critical safety applications. Network C-V2X (Cellular Uu mode (communications are transmitted through a cellular network, either 4G or 5G) utilizes cellular networks to connect vehicles with cloud-based services, providing a wider range of applications, including traffic management and infotainment [4].

Other forms of interoperable V2X connectivity includes unlicensed Wi-F, satellite and other emerging options such as ultra-wideband. The core of deployment has always been interoperability between diverse technologies and ensuring performance requirements for different applications.

Connected Automation represents the integration of connectivity and automation in vehicles, leading to the development of Connected Automated Vehicles (CAVs). This synergy enhances the capabilities of automated driving systems (ADS) by leveraging real-time data exchange.

The USDOT and the Federal Highway Administration (FHWA) are advancing cooperative driving automation through programs like CARMA [5], which focuses on enabling vehicles and infrastructure to work together using connected technology. This approach improves traffic flow and safety by allowing vehicles to share information about their movements and the surrounding environment. The Society of Automotive Engineers (SAE) also defines Cooperative Driving Automation (CDA) as systems that enable vehicles to cooperate through communication, enhancing the effectiveness of automated driving technologies [6].

Connected automation is not merely a combination of connectivity and automation; it involves sophisticated communication protocols and data sharing that enhance the automated driving stack. Key aspects include cooperative perception and cooperative maneuvering.

Cooperative perception involves sharing sensor data between vehicles and infrastructure to improve situational awareness. This is a non-trivial process because there are many real-world challenges in fusing data between multiple agents, such as delays and differences in data formats (i=e.g., different outputs of different autonomy stack).
Cooperative maneuvering involves coordinating vehicle actions to optimize traffic flow and safety. Applications include platooning, where vehicles travel closely together at coordinated speeds to improve roadway capacity and reduce aerodynamic drag (for trucks) and increase fuel efficiency; cooperative signal control, where traffic signals and vehicles communicate to optimize signal timings for smoother traffic flow; and speed harmonization, where vehicles adjust their speeds based on real-time traffic conditions to prevent congestion and reduce accidents. By integrating these applications, connected automation aims to create a more efficient, safer, and responsive transportation system.