CAREER:Optically-enabled Scanning and Utilization of Radio Spectrum Opportunities (OSCARS)

射频频谱是一种宝贵的资源，如果有效利用，可以促进经济增长，改善我们的生活质量，并加强公共安全。然而，由于对无线服务的需求不断增长，射频频谱变得过于拥挤。尽管频谱似乎被各种无线系统完全占用，但仍有许多频率未被主动使用，可以动态分配给其他用户。然而，即使对于最先进的电子设备来说，这也是具有挑战性的，因为搜索未使用的频率需要大量的计算资源和复杂的硬件。该提案旨在利用光子学来克服这一挑战，光子学是一种替代信号处理方法，比电子学中的对应方法具有更宽的带宽和更快的速度。利用所提出的光子学技术，射频信号首先被转换成光信号，然后几乎可以即时处理。该项目的研究工作将致力于频谱资源的快速发现和有效利用。本项目还提出了与研究工作密切相关的综合教育计划。它包括开发用于学习光纤的移动应用程序，为当地社区组织光纤研讨会，开发本科新生研讨会和跨学科课程，以及为高中生和本科生，特别是那些来自代表性不足群体的学生提供研究经验。频谱使用的改进将有利于社会的许多重要无线服务，包括移动通信、远程医疗保健、远程学习和移动计算。为了适应越来越多的无线设备的使用，需要一种更有效的方法来搜索、查找、使用和共享无线电频谱。本研究的重点是从根本上改变如何通过光子学技术快速发现和有效利用频谱资源。本文提出了两个密切相关的研究主题：(i)基于可调谐/可重构多频段射频滤波器开发实时“扫描-查找”射频频谱扫描系统；（ii）基于光子学在信号同时传输和接收中的频率复用以及生物启发的自动干扰避免来提高频谱使用效率。射频频谱扫描系统利用了独特设计的射频多带滤波器的超快光调谐和开关能力以及现有光学器件的瞬时响应。信号的同时发送和接收由超宽带自干扰消除系统实现。此外，还将探索一种新的自动干扰避免技术。它的灵感来自于生物学中的一个类比——电鱼属特征鱼（Eigenmannia）的干扰回避反应。该方案提出了一种综合的、跨学科的、创新的方法来解决无线通信中的频谱稀缺问题，同时提高频谱的使用效率。拟议的研究涉及系统设计和实验验证的紧密耦合，因此将产生实验室原型，以展示更有效地使用无线电频谱。

Radio frequency (RF) spectrum is a valuable resource that, if effectively utilized, can boost economic growth, improve our quality of life, and enhance public safety. However, due to growing demand on wireless services, the RF spectrum is becoming overcrowded. Although the spectrum seems to be fully occupied by all kinds of wireless systems, there are many frequencies not actively used and can be dynamically allocated for other users. However, this is challenging even for state-of-the-art electronics, as the search for unused frequencies requires vast amount of computational resources and sophisticated hardware. This proposal aims to overcome this challenge by making use of photonics--an alternative signal processing method that has wider bandwidth and faster speed than its counterpart in electronics. With the proposed photonics techniques, the radio frequency signal is first converted to an optical signal, which can then be processed almost instantaneously. The research effort of this project will be devoted to the fast discovery and efficient use of spectrum resources. This project also proposes a comprehensive education plan closely related to the research effort. It includes developing mobile apps for learning fiber optics, organizing a fiber optics workshop for the local community, developing undergraduate freshman seminar and cross-disciplinary courses, as well as providing research experiences for high school and undergraduate students, especially those from underrepresented groups. The improvement in spectrum usage will benefit many vital wireless services for the society, including mobile communications, remote healthcare, distant learning, and mobile computing.To accommodate the increasing usage of wireless devices, a more effective way to search, find, use, and share the radio frequency spectrum is necessary. The focus of this research is to fundamentally change how spectrum resources can be quickly discovered and used effectively through photonics techniques. Two closely related research themes are proposed: (i) developing a real-time "Scan-and-Find" RF spectrum scanning system based on a tunable/reconfigurable multiband RF filter, and (ii) improving spectrum usage efficiency based on photonics-enabled frequency reuse in simultaneous transmission and reception of signals as well as bio-inspired automatic interference avoidance. The RF spectrum scanning system exploits the ultrafast optical tuning and switching capability of a uniquely designed RF multiband filter as well as the instantaneous response of existing optical devices. The simultaneous transmission and reception of signals is enabled by an ultra-wideband self-interference cancellation system. Furthermore, a novel automatic interference avoidance technique will be explored. It is inspired by an analogy in biology--jamming avoidance response in Eigenmannia, a genus of electric fish. This proposal presents a comprehensive, interdisciplinary, and innovative approach to solve the spectrum scarcity problem while improving spectrum usage efficiency in wireless communications. The proposed research involves a close coupling of system design and experimental validation, and thus will yield laboratory prototypes to demonstrate more effective usage of the radio spectrum.