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Countering small drones has become increasingly difficult as unmanned aircraft grow smaller, cheaper, and more numerous. Traditional radar systems can detect many aerial threats, but they also emit signals that reveal their location. In contested environments, this can make surveillance assets vulnerable to detection or targeting. Researchers are therefore exploring passive sensing technologies capable of monitoring the airspace without broadcasting their own signals.
A new development (by Cohere Technologies) aims to achieve exactly that by transforming existing cellular infrastructure into a distributed drone-detection network.
Instead of relying on dedicated radar installations, the system uses commercial 5G and future 6G communications networks as a sensing platform. By analyzing radio signals already present in the environment, it is designed to detect, classify, and track aerial and ground objects while remaining effectively invisible to adversaries.
The approach falls under a concept known as Integrated Sensing and Communications (ISAC), which combines wireless communications and environmental sensing within the same infrastructure. Rather than building separate networks for communications and surveillance, the technology allows both functions to operate simultaneously.
The prototype incorporates two different waveform technologies. One is Orthogonal Frequency-Division Multiplexing (OFDM), the modulation method already used by modern cellular networks. The second is Pulsone Technology, based on Zak Orthogonal Time Frequency Space, which is designed to improve sensing performance in complex and dynamic environments.
The system also includes software capable of generating three-dimensional tracks of detected objects in real time. According to NextGenDefense, by combining information collected from multiple cellular transmitters and receivers, it can support bistatic and multistatic sensing, techniques that observe targets from several different locations simultaneously to improve detection accuracy.
From a defense perspective, passive sensing offers several advantages. Because the network relies on existing communications signals instead of dedicated radar emissions, it becomes much harder for opposing forces to identify where sensing is taking place. The widespread availability of cellular infrastructure also creates opportunities to expand surveillance coverage without deploying large numbers of specialized sensors.
Before operational deployment, the technology must complete security, integration, and field validation requirements.
As communications infrastructure continues evolving toward 6G, researchers increasingly see cellular networks as more than communication systems. Future wireless networks may simultaneously provide connectivity, positioning, and persistent environmental awareness, allowing the same infrastructure to support both civilian communications and advanced defense sensing capabilities.
