Key Takeaways
- Zak-OTFS delivers up to four times better detection and tracking performance than conventional OFDM in high‑Doppler environments.
- The waveform can detect objects as small as one‑quarter the size detectable by OFDM, thanks to superior link‑budget properties.
- Funded by the FutureG Office of the Department of War, the technology builds on an NSF VINES Phase 2 project and aims to provide sovereign, mission‑first ISAC capability using existing and future 5G/6G commercial infrastructure.
- By operating in commercial spectrum bands, sensing activity can blend with normal cellular traffic, making it harder for adversaries to distinguish surveillance from routine communications.
- Officials, including Tom Rondeau, Principal Director for FutureG, emphasize that the system addresses the urgent U.S. defense priority of countering drone swarms.
Introduction and Overview
The Department of War is pursuing advanced sensing technologies to maintain situational awareness in contested environments where adversaries employ high‑speed, agile platforms such as drone swarms. To meet this challenge, the department has awarded a contract to Cohere for the development of a Zak‑OTFS (Zero‑Padding Orthogonal Time Frequency Space) waveform‑based Integrated Sensing and Communication (ISAC) system. This effort leverages recent advances in waveform design to provide robust detection, classification, tracking, and cueing capabilities against aerial threats while operating within existing commercial telecommunications bands. The initiative reflects a broader strategy to repurpose ubiquitous 5G/6G infrastructure for dual‑use military applications, thereby reducing reliance on bespoke, proprietary sensor networks and enhancing resilience against electronic warfare.
Zak‑OTFS Waveform Performance in High‑Doppler Scenarios
Zak‑OTFS is specifically engineered to thrive in conditions where objects move at high velocities relative to transmitters and receivers, a regime that traditionally degrades the performance of orthogonal frequency‑division multiplexing (OFDM) due to severe Doppler spread. By spreading information across the delay‑Doppler domain, Zak‑OTFS concentrates signal energy in a manner that is invariant to rapid time‑varying channels, thereby preserving coherence and improving detection reliability. Cohere’s internal assessments indicate that the Zak‑OTFS waveform yields up to four times better performance than OFDM for tasks such as target detection and the simultaneous tracking of multiple moving objects. This advantage translates directly into enhanced situational awareness when confronting fast‑moving drone swarms that would otherwise blur or mask conventional radar returns.
Comparison with OFDM Detection Capabilities
Beyond raw performance gains, Zak‑OTFS offers a tangible improvement in the minimum detectable target size. Laboratory and field tests show that the waveform can detect objects as small as one‑quarter the cross‑section detectable by a comparable OFDM‑based system operating under the same power and bandwidth constraints. This refinement stems from Zak‑OTFS’s superior ability to resolve fine‑grained delay‑Doppler signatures, which enables the discrimination of tiny, low‑radar‑cross‑section (RCS) unmanned aerial vehicles (UAVs) that might be missed by OFDM. Consequently, defense planners can rely on the system to spot micro‑drones and other diminutive threats earlier in their approach trajectory, expanding the engagement window for counter‑measures.
Link‑Budget Advantages Over Existing Systems
Cohere highlights that the Zak‑OTFS waveform possesses link‑budget characteristics that outperform those of legacy radar and communication‑centric waveforms. The waveform’s inherent resistance to Doppler‑induced SNR loss means that, for a given transmit power, the achievable detection range is extended compared with OFDM‑based alternatives. Additionally, the efficient use of the time‑frequency grid reduces interference from multipath reflections and enables more effective processing gain through advanced matched‑filter techniques in the delay‑Doppler domain. These link‑budget improvements not only boost detection performance but also allow the system to operate at lower power levels, a valuable attribute for covert or size‑constrained platforms.
Funding, Project Background, and Institutional Support
The Zak‑OTFS ISAC initiative is financed by the FutureG Office within the Department of War’s Office of the Under Secretary for Research & Engineering. This funding builds upon prior work supported by the National Science Foundation’s VINES (Virtual Integrated Networked Environment for Sensing) Phase 2 project, which explored novel waveforms for joint communication and sensing in dynamic environments. By leveraging the NSF‑funded research foundation, the current contract accelerates technology maturation from laboratory proof‑of‑concept toward a field‑deployable prototype. The alignment of civilian research investments with defense priorities exemplifies a growing trend of dual‑use innovation, where advances in commercial telecommunications are repurposed for national security objectives.
Sovereign Surveillance and Mission‑First ISAC Capability
Cohere characterizes the resulting system as a sovereign, mission‑first ISAC capability that intends to harness both existing and forthcoming 5G and 6G commercial infrastructure for persistent aerial and ground surveillance. The “sovereign” label underscores the intent to retain operational control over the sensing functions, ensuring that data collection, processing, and decision‑making remain under U.S. authority despite reliance on shared commercial networks. By embedding sensing functions within the communications layer, the system can provide continuous, wide‑area monitoring without the logistical burden of deploying dedicated radar sites, thereby offering a scalable solution for defending critical assets and populated areas against airborne threats.
Multi‑Waveform Prototype Functionality
The prototype under development incorporates a multi‑waveform approach, enabling the platform to detect, classify, track, and cue defeat systems against drone threats in real time. This flexibility allows the system to adapt its transmission strategy‑switch between waveforms optimized for different environmental conditions—for instance, employing Zak‑OTFS for high‑Doppler scenarios while falling back to more conventional OFDM or other specialized waveforms when the channel is relatively static. The integrated processing pipeline fuses raw sensor returns with classification algorithms to generate actionable tracks, which can then be handed off to kinetic or non‑kinetic defeat mechanisms (e.g., directed energy, electronic jamming, or interceptor launch) via established command‑and‑control interfaces.
**Operation of the system in commercial spectrum bands further enhances its utility, as it can leverage the extensive infrastructure already deployed by cellular operators.
Use of Commercial Spectrum and Stealthy Sensing
Operating within licensed commercial spectrum bands offers a distinctive tactical advantage: the sensing activity can blend indistinguishably with ordinary cellular traffic, complicating adversarial attempts to detect, locate, or jam the ISAC signals. Because the waveform occupies the same frequency resources as routine 5G/6G transmissions, an adversary would need to perform sophisticated traffic analysis to differentiate purposeful sensing beams from standard user data—a task that is both computationally intensive and likely to provoke collateral disruption if attempted. This low probability of intercept (LPI) and low probability of detection (LPD) characteristic enhances the survivability of the sensing platform in contested electronic warfare environments, allowing it to persistently gather intelligence while remaining hidden in plain sight.
Statements from Tom Rondeau and Strategic Priorities
Tom Rondeau, Principal Director for FutureG within the Office of the Under Secretary of War for Research & Engineering, emphasized that the Zak‑OTFS‑based ISAC system directly addresses a pressing defense priority: protecting forces and infrastructure from drone swarms. He noted that “ISAC is a mission‑first priority for the U.S. Department of War to defend against drone swarms,” underscoring the department’s commitment to integrating sensing and communication functions to achieve a decisive edge against distributed, low‑cost aerial threats. Rondeau’s remarks highlight the alignment of the technology development effort with the department’s broader modernization strategy, which seeks to exploit commercial advances to close capability gaps more rapidly and cost‑effectively than traditional acquisition pathways permit.
Strategic Implications for Drone‑Swarm Defense
The deployment of a Zak‑OTFS‑enabled ISAC layer could transform the defensive posture against drone swarms by providing persistent, high‑resolution tracking across large swaths of territory. Early detection of micro‑UAVs permits the initiation of defeat mechanisms at greater ranges, reducing the probability that swarms can penetrate defended zones or saturate point‑defense systems. Furthermore, the ability to cue multiple defeat assets—such as laser systems, microwave disruptors, or interceptor drones—based on a unified tracking picture enhances coordination and reduces engagement latency. By utilizing commercial infrastructure, the Department of War can potentially scale coverage quickly, leveraging existing cell towers and small‑cell deployments as distributed sensor nodes, thereby achieving a resilient, network‑centric defense architecture that is difficult for adversaries to undermine through kinetic or electronic means.
Conclusion and Future Outlook
In summary, the Zak‑OTFS waveform represents a significant advancement in joint sensing and communication technology, offering superior detection performance, enhanced link‑budget characteristics, and the ability to operate covertly within commercial spectrum bands. Backed by the FutureG Office and rooted in NSF‑funded VINES research, the program aims to deliver a sovereign, mission‑first ISAC capability that can detect, classify, track, and cue defeat systems against drone threats using existing and future 5G/6G networks. Statements from senior defense officials affirm the strategic urgency of this work in countering evolving drone‑swarm challenges. As the prototype matures and transitions to field trials, the technology is poised to provide a persistent, low‑observable sensing layer that strengthens the United States’ ability to safeguard critical assets and maintain operational superiority in an increasingly congested and contested electromagnetic environment.