V2V

V2V, vehicle-to-vehicle communication, is a form of V2X technology that enables direct wireless data exchange between nearby vehicles to improve safety and traffic efficiency. It provides timely information about position, speed, and intent to help prevent collisions. V2V generally operates over short range with low latency and can function when other networks are unavailable.

Two main approaches dominate: DSRC, based on IEEE 802.11p, and cellular V2X (C-V2X), based on 3GPP sidelinks. In the United States, DSRC/IEEE 802.11p is common and uses SAE J2945/1 for data content (basic safety messages) and SAE J2735 for message sets. In Europe and parts of Asia, ITS-G5 with ETSI CAM and DENM is used; C-V2X is also being deployed to extend range and reliability. Interoperability efforts aim to ensure that devices from different vendors and regions can exchange data effectively.

V2V messages typically include basic safety messages that broadcast state such as position, speed, heading, and braking status. Event-driven messages warn of hazards. Latency targets are often in the tens of milliseconds. Security and privacy measures, such as authentication and pseudonymity, are integral to most V2V standards.

Applications include collision avoidance, intersection movement assist, emergency-vehicle preemption, and cooperative adaptive cruise control. Shared data can improve awareness beyond vehicle sensors, potentially reducing crashes and improving traffic flow. Adoption varies by region, with pilots and limited deployments in selected urban and highway corridors.

Challenges include spectrum allocation, cross-standard interoperability, and ensuring security and privacy at scale. The ecosystem requires roadside units and back-end support for V2I integration. Ongoing standardization and industry cooperation aim to broaden deployment and integration with 5G networks and future smart-city systems.