2026-08-06
White paper
Introduction: Why OTA testing matters for V2V communication
Wireless communication is becoming an increasingly important part of modern vehicles. Vehicle-to-Vehicle (V2V) communication enables cars to exchange real-time data about position, speed and driving conditions, including safety-critical messages that help prevent collisions and support cooperative driving. V2V is one part of the broader Vehicle-to-Everything (V2X) ecosystem, which extends to communication with infrastructure, networks and other road users. What all these applications have in common is a requirement that cannot fail: a stable and reliable wireless communication link.
Traditional measurement methods, where antennas and radio components are tested separately, often with the antenna measured in isolation in an anechoic chamber, provide valuable insights but do not capture how the complete system behaves during real operation. Once the antenna is integrated into the vehicle, its performance is influenced by the body shape, material selection and nearby components. As a result, actual radio performance often differs from what was theoretically expected. This is where OTA testing (Over-The-Air) becomes essential: by testing the complete, integrated system in a controlled radio environment, it becomes possible to measure how communication actually performs.
At the same time, vehicles do not operate in a single, uniform radio environment. Two vehicles approaching each other on a highway or at a rural intersection communicate via a link dominated by a direct signal path, known as a LOS environment (Line-of-Sight). In dense urban traffic, a vehicle is surrounded by reflections from buildings and other vehicles. This is approximated in testing by a RIMP (Rich Isotropic Multipath) environment – a standardized reference case where signals arrive equally from all directions. LOS and RIMP represent opposite ends of the spectrum, and each reveals different characteristics of a system’s performance.
For V2V communication specifically, there is an additional factor: the relative angle between vehicles is constantly changing. One may approach head-on, cross from the side or overtake from behind. It is this continuous shift in geometry, and not just the environment itself, that makes V2V one of the more demanding wireless applications to test correctly. The RLOS model (Random Line-of-Sight) is designed to capture exactly this.
Conclusion
V2V communication places unique demands on wireless system performance. Safety-critical messages must get through reliably – under continuously changing vehicle orientations, at varying distances and without a second chance. As this paper has shown, the difference between a system that performs and one that fails can be as little as 1–2 dB of received signal variation.
The scenarios that matter most for V2V performance – highway driving, rural roads, approaching intersections, long-range cooperative driving – are dominated by direct line-of-sight conditions. In these situations, the angle between communicating vehicles changes continuously: approaching head-on, crossing paths at an intersection, overtaking on a motorway. The RLOS model captures exactly this – the full range of antenna angles a real deployment will encounter, without multipath to mask weak directions. These are the conditions where performance margins are thinnest, and where controlled LOS/RLOS testing reveals what matters.
Controlled LOS/RLOS testing enables the development decisions that matter: identifying coverage nulls before they become field problems, quantifying how much diversity gain different antenna placements actually provide, and understanding at what signal level the communication link becomes unreliable. These are the answers that antenna engineers, system integrators and OEM development teams need – and they are most clearly obtained in a controlled, repeatable LOS environment, at a stage when changes are still practical.
The critical question is not whether the system works under ideal test conditions – but whether it works when it matters most. That is the question LOS/RLOS-based testing, realized through RanLOS test systems, is designed to answer.
“To develop and verify V2V systems, test methods must reflect the radio environments in which the systems are actually intended to operate.”
Example animation of how RanLOS test system can be used for testing drones and military applications
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