Energy-Efficient Chip-Scale Sensing of CrowdedWide Spectrum

不断增长的无线应用需求导致了前所未有的射频(RF)频谱短缺，但频谱接入将成为我国经济增长和技术领先地位的日益重要的基础。一种动态共享频谱接入方案有望显著提高频谱效率。共享频谱接入的关键使能技术是实时传感器，它可以监控非常宽和拥挤的频谱。不幸的是，使用现有技术实时访问广泛而拥挤的频谱需要极其耗电的高速模数转换器，因此不适用于能源受限的移动应用。该项目将通过融合基于射频声谐振器的设备、无线电路和稀疏信号处理的最新创新，开发新一代节能和低成本的频谱传感系统。如果成功，这一新的芯片级负担得起的系统将实现一种变革性的功能--实时对密集占用的宽频进行能效感知--使我们能够通过动态频谱访问大幅提高频谱效率。此外，计划开展的活动将确保该项目在从教育到工业、从电磁频谱政策到外展等多个重要方面产生长期影响。最近的工作证明，利用压缩传感或稀疏傅里叶变换，通过中速模数转换器以低于奈奎斯特的速率采集GHz宽信号是可能的。然而，所有这些系统都要求频谱稀疏，当频谱被密集占用时会出现不足。与现有的将每个通道的整个带宽数字化的频谱感知方法不同，该项目利用了一种新的想法，即只监控一小部分通道带宽就足以进行占用检测。基于这一概念，该项目将利用一种新颖的泛音微电子机械系统(MEMS)射频谐振器，在GHz宽频谱上创建许多非常窄、尖锐和等间距的通带。最终结果是泛音滤波器通过抑制每个信道内用于占用检测的冗余频谱内容来稀疏频谱。这种由滤波产生的稀疏性允许利用稀疏傅里叶变换算法和中速模数转换器来实现高能效的频谱感知。在具有足够数量的滤波器通带的情况下，所提出的高能效频谱传感器可以捕获所有信道，并且不会遗漏任何占用信息。该项目还将通过滤波器-电路联合设计开发一个宽调谐范围的RF泛音过滤微系统，以支持多频段操作和通过扫描感测多GHz宽带。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The ever-increasing demand for wireless applications has resulted in an unprecedented radio frequency (RF) spectrum shortage, yet access to spectrum will be an increasingly important foundation for our nation's economic growth and technological leadership. A dynamically shared spectrum access scheme is expected to significantly boost the spectrum efficiency. The key enabling technology for the shared spectrum access is a real-time sensor that can monitor a very wide and crowded spectrum. Unfortunately, real-time access to a wide and crowded spectrum using existing technologies requires extremely power-hungry high-speed analog-to-digital converters and hence is not practical for energy-constrained mobile applications. This project will develop a new generation of energy-efficient and low-cost spectrum sensing systems by fusing recent innovations in RF acoustic-resonator-based devices, wireless circuits, and sparse signal processing. If successful, this new chip-scale affordable system will enable a transformative functionality -- energy-efficient sensing of densely occupied wide spectrum in real time -- that allows us to substantially enhance spectrum efficiency via dynamic spectrum access. In addition, activities are planned to ensure that this project will have long-lasting effects in a number of important dimensions, from education to industry, and from electromagnetic spectrum policy to outreach.Recent work has demonstrated the possibility of acquiring GHz-wide signals with moderate-speed analog-to-digital converters at a sub-Nyquist rate by leveraging compressive sensing or sparse Fourier transform. However, all these systems require the spectrum to be sparse and fall short when the spectrum is densely occupied. In contrast to existing spectrum sensing approaches that digitize the entire bandwidth of each channel, this project harnesses a new idea that monitoring only a small fraction of the channel bandwidth is sufficient for occupancy detection. Based on this concept, the project will leverage a novel overtone micro-electro mechanical-system (MEMS) RF resonator to create many very narrow, sharp, and equally spaced passbands across the GHz-wide spectrum. The end result is that the overtone filter sparsifies the spectrum by suppressing, within every channel, the redundant spectrum content for occupancy detection. This filtering-created sparsity allows the utilization of sparse Fourier transform algorithm and moderate-speed analog-to-digital converters to achieve spectrum sensing with high energy efficiency. With a sufficient number of filter passbands, the proposed energy-efficient spectrum sensor captures all channels and does not miss any occupancy information. This project will also develop a wide-tuning-range RF overtone filtering microsystem through a filter-circuit co-design to support multi-band operations and sensing of multi-GHz wide spectrum via scanning.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.