Collaborative Research: NeTS: Medium: Scalable Metasurface Array for mmWave Communication and Sensing

毫米波（mmWave）技术在5G通信和雷达传感应用中展现出令人兴奋的前景。然而，毫米波的有限覆盖范围仍然是其在实践中可用性的主要挑战。该项目的目标是利用毫米波通信/传感系统和可打印材料/电子产品的协同创新，以克服毫米波信号的固有局限性。PI团队探索了超大型超宽带元表面阵列的设计，以扩大毫米波覆盖范围并优化相关的性能权衡。该项目的成果可能会为毫米波网络的设计提供信息，影响超5G（B5 G）标准化，并推动许多B5 G应用，特别是在具有挑战性的毫米波车载网络和汽车传感领域。该项目还可以通过以极低的成本提高5G毫米波覆盖范围和可靠性来产生重大的经济影响。该项目的影响将通过吸引不同的学生研究人员和工业合作伙伴，并通过传播先进毫米波设备的开源实验硬件和低成本制造工作流程来进一步扩大。拟议的研究结合了新型可打印材料/电子器件，以推进毫米波超颖表面反射器领域。虽然有源和无源超颖表面已经在电磁研究中被广泛探索，但它们的尺寸、带宽有限，并且大多用于单个链路。有源超颖表面具有高成本和复杂性，因为它们需要电源、高频部件、高精度衬底和制造工艺以及单独的控制通道来与现有器件协调。另一方面，由于缺乏可重构性，无源超颖表面反射器通常被认为是低劣的并且仅适用于静态场景。 此外，最先进的有源/无源超颖表面仅限于厘米级，但实际部署需要米级（数百个波长）的尺寸，这会带来重大挑战，例如由于近场效应和频率选择性而导致的严重光束失真。 为了应对这些挑战，PI团队提出了3个研究方向：（1）设计新的波束合成模型，以实现超大元表面，以及增量重新配置无源元表面阵列（PMA）的新技术，以扩大角度覆盖范围，波束形成增益，支持移动性，并避免附近基站之间的干扰;（2）设计利用PMA作为无源“编码器”的新机制，以解决毫米波传感中的覆盖-分辨率-尺寸权衡;（3）探索基于石墨烯的超表面结构，以扩展毫米波联合通信和传感，使其超出传统RF硬件的带宽限制。这项研究将产生各种社区工具集和可重复的制造工作流程，用于通过3D打印或模具压印创建低成本的毫米波超颖表面。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Millimeter-wave (mmWave) technologies are demonstrating exciting prospects in both 5G communications and radar sensing applications. However, the limited coverage of mmWave remains a major challenge to its usability in practice. The objective of this project is to harness synergistic innovations in mmWave communication/sensing systems and printable materials/electronics to overcome the intrinsic limitations of mmWave signals. The PI team explores the design of an ultra-large and ultra-wideband metasurface array to expand mmWave coverage and optimize the associated performance tradeoffs. The project outcome will likely inform the design of mmWave networks, influence the beyond-5G (B5G) standardization, and advance many B5G applications, especially in the challenging mmWave vehicular networking and automotive sensing domains. The project can also generate substantial economic impacts by boosting the 5G mmWave coverage and reliability at signifcantly low cost. The project impact will be further extended by engaging a diverse group of student researchers and industrial partners, and by disseminating open-source experimental hardware and low-cost fabrication workflows for advanced mmWave devices. The proposed research incorporates novel printable materials/electronics to advance the field of mmWave metasurface reflectors. Although active and passive metasurfaces have been extensively explored in electromagnetic research, they are limited in size, bandwidth, and mostly employed for a single link. Active metasurfaces bear a high cost and complexity as they need power sources, high-frequency components, high-precision substrate and fabrication processes, and a separate control channel to coordinate with existing devices. On the other hand, passive metasurface reflectors are often deemed inferior and suitable only for static scenarios due to lack of reconfigurability. In addition, state-of-the-art active/passive metasurfaces are limited to centimeter-scale, yet practical deployment entails meter-level (hundreds of wavelengths) in dimension, which induces non-trivial challenges such as severe beam distortion due to near-field effects and frequency-selectivity. To address these challenges, the PI team proposes 3 research thrusts: (1) Designing new beam synthesis models to enable ultra-large metasurfaces, and new techniques to incrementally reconfigure a passive metasurface array (PMA), so as to expand the angular coverage, beamforming gain, support mobility, and to avoid interference between nearby base stations; (2) Designing new mechanisms that leverage the PMA as a passive "encoder" to address the coverage-resolution-dimension tradeoff in mmWave sensing; (3) Exploring graphene-based metasurface structures to scale mmWave joint communication and sensing beyond the bandwidth limit of traditional RF hardware. The proposed research will lead to various community toolsets and reproducible fabrication workflows for creating low-cost mmWave metasurfaces through 3D printing or mold imprinting.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.