SpecEES: Trusted Frequency-Agile Transceiver Architectures for Secure and Energy-Efficient Communication

对无线通信日益增长的需求造成了频谱短缺。结合波束成形和大规模多输入多输出（MIMO）技术，高度可编程的软件定义无线电（SDR）可以实现跨多个平台的无线通信，从而提高众多用户之间频谱共享的效率。然而，集成的高分辨率宽带MIMO收发器需要通过数字信号处理来获取和传输复杂的信号，需要消耗大量的功率。与此同时，由于无线设备与网络的连接为干扰和窃听等恶意攻击提供了新的切入点，因此出现了与频谱共享相关的关键安全挑战。不受持续监控的无线设备和传感器尤其需要全面的保护，以确保频谱共享安全。先进的加密和编码方案在计算上是昂贵的，并且需要更宽的带宽和更高的载波频率。该项目提出了一种超低功耗频率敏捷收发器架构，可与可信MIMO系统集成，以实现动态频谱接入、管理有害干扰和识别授权设备。这项研究将对社会和国家做出重大贡献和影响，这些社会和国家迫切需要安全的频谱接入和共享，包括服务不足的人群。此外，该项目将提供一个独特的机会，教育不同层次的学生（K-12，本科生和研究生）在无线通信系统的安全和能源效率的实际方面。该项目的目标是开发一种可重构的宽带MIMO系统，该系统结合了干扰抑制、高效波束成形和嵌入式射频（RF）签名，可应用于多种类型的无线系统，包括短距离无授权通信和远程有授权通信。为了减少干扰和噪声，将开发具有自适应幅度文件夹的非线性可重构射频接收器，以便在保持感兴趣的弱信号的完整性的同时，将有害干扰器立即推到更高的频率。该项目将使用带有嵌入式n路滤波器组的可编程噪声整形环路，进一步抑制宽带干扰，去除折叠干扰器，并在超低功耗的情况下在大频谱上实现可扩展的宽动态范围。为了以最小的功率和面积增加实现最大的可编程性，将采用组合固有器件特性作为调谐元件来构建滤波器组和文件夹，以快速适应动态和计划外的电磁环境。为了获得更好的功率效率，将开发用于n路MIMO天线阵列的频率敏捷功率放大器（PAs），通过使用联合负载牵引和可选的离散包络跟踪，在整个SDR带宽内保持高功率效率。该项目将利用功率放大器固有的非线性功能和记忆效应，实现颠覆性射频法医指纹科学技术。基于增强PA非线性的时变射频指纹轮询和基于基站后失真解码的射频签名识别将提高无线通信的安全性。每个设备的这些独特签名将使攻击者难以通过预编码数据符号来伪造签名。该奖项反映了美国国家科学基金会的法定使命，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。

The increasing demand for wireless communication creates a spectrum shortage. Combining with beamforming and massive multiple-input-multiple-output (MIMO) technologies, a highly programmable software-defined radio (SDR) that enables wireless communications across multiple platforms can increase the efficiency of spectrum sharing among a multitude of users. However, the integrated high-resolution wideband MIMO transceivers would consume significant power to acquire and transmit complex signals with digital signal processing. Meanwhile, critical security challenges associated with spectrum sharing arise because the connection of wireless devices to networks represents new entry points for malicious attacks, such as jamming and eavesdropping. Wireless devices and sensors not under constant surveillance especially need comprehensive protection for secured spectrum sharing. Advanced encryption and coding schemes are computationally expensive and require wider bandwidths and higher carrier frequencies. This project proposes an ultra-low-power frequency-agile transceiver architecture that can be integrated with trusted MIMO systems to achieve dynamic spectrum access, manage harmful interference, and identify authorized devices. This research will have significant contributions and impacts to the society and nation in critical need of secured spectrum access and sharing among all users including underserved populations. In addition, the project will provide a unique opportunity to educate students of different levels (K-12, undergraduate, and graduate) on practical aspects of wireless communication systems' security and energy efficiency.The goal of this project is to develop a reconfigurable wideband MIMO system incorporating interference suppression, efficient beamforming, and embedded radio frequency (RF) signatures that can be applied to many types of wireless systems including short-range unlicensed communications and long-range licensed communications. For interference and noise mitigation, reconfigurable RF receivers using nonlinearity with adaptive amplitude folders will be developed to instantaneously push harmful jammers to higher frequencies while preserving the integrity of weak signals of interest. The project will use a programmable noise-shaping loop with embedded N-path filter banks to further suppress wideband interference, remove folded jammers, and achieve a scalable wide dynamic range over a large frequency spectrum while consuming ultra-low power. To achieve maximum programmability with minimum increase of power and area, combinatorial intrinsic device characteristics will be adopted as tuning elements to build filter banks and folders for rapid adaptation to a dynamic and unplanned electromagnetic environment. To achieve better power efficiency, frequency-agile power amplifiers (PAs) for N-path MIMO antenna array will be developed to maintain high power efficiency over the entire SDR bandwidth through the use of joint load-pulling and optionally discrete envelope tracking. The project will utilize inherent nonlinear functions and memory effects of power amplifiers to enable disruptive RF forensic fingerprinting science and technology. The time-varying RF fingerprint polling from the augmented PA nonlinearities and the RF signature identification through base-station post-distortion decoding will enhance the wireless communication security. These unique signatures of each device will make it difficult for adversaries to fake the signatures through precoding the data symbols.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.