SWIFT: Interference Mitigation using Spatial and Frequency Nulling for Wideband mm-Wave Transceivers

SWIFT：使用宽带毫米波收发器的空间和频率归零来减轻干扰

• 批准号: 2128558
• 负责人: Ali Niknejad
• 金额: $ 75万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2128558&HistoricalAwards=false
• 关键词: SWIFT; Interference; Mitigation; using; Spatial

Currently deployed fifth generation (5G) solutions operate in frequency bands, mostly below 6 GHz, and to a limited extent at 28/39 GHz, and expansion to other emerging frequency bands is under consideration. When operating at 28 GHz or 39 GHz, hundreds of antennas are needed to boost the power of the transmitted signal to form a focused beam to increase the communication range. On the receiver, there is a unique opportunity to take advantage of the many antenna elements to also cancel out or attenuate interference from unwanted directions. This proposal seeks to understand the most power efficient and optimal means of achieving interference cancellation. Furthermore, as the transition of high-speed applications starts to occur from sub-6 GHz frequency bands to higher frequencies, especially at 28/39 GHz, traditional means of cancelling unwanted interference operating in other frequency bands (other “channels”) using high quality acoustic resonators does not seem viable. As such, this project will explore the application of filters that are electronically tunable and take advantage of the switching properties of modern digital devices as a means of overcoming these limitations. While addressing the coexistence issue is a major hurdle for commercial radios, many other radios are also in danger of losing functionality and sensitivity if steps are not taken to address the problem of interference. Many important sensors, such as weather radars and radio astronomy telescopes, may cease to function if interference levels increase as expected. It is therefore imperative to protect such radios by directly collaborating with the radio astronomy community. This research will also lead to the training of students in the engineering of modern communications systems and wireless communications. Future generation of radios utilize broader band millimeter-wave (mm-wave) front-ends, higher channel bandwidths (1 GHz or more), and beamforming. Multi antenna array signal processing techniques naturally provide some spatial filtering of unwanted signals. By placing nulls in the antenna pattern to purposefully “zero-out” interference, one can improve signal-to-distortion ratio, achieve better spectrum utilization, and realize more robust radios. While all these benefits can be realized using digital signal processing, the wide dynamic range requirements on the analog-to-digital converter make the hundred element array radio high power and even unfeasible. Furthermore, out-of-band interference will likely pose an issue when the mm-wave spectrum is more crowded. Traditional ways of removing interference using sharp filters based on high-Q resonators is not viable above 10 GHz. To address these issues, interference cancellation will be explored in several locations in the receiver, at the radio frequency itself (using tunable electronic notch filters), at the boundary between radio frequency blocks and analog blocks (spatial notch), as well as inside the analog-to-digital converter itself. In this way, interference will be rejected before (or during) quantization, which will reduce the dynamic range requirements of the receiver greatly. This is especially important at wider channel bandwidths proposed in 5G and future generation radios. Cancellation of interference, though, requires knowledge of the location and frequency of the interfering signal. Digital and baseband tracking loops will be explored to identify the properties of the interfering signal and feedback loops will then allow interference cancellation to be performed in the various forms. Application of these techniques for the protection of passive radio sensors, such as radio astronomy telescopes, will be studied and techniques for interference tracking from the radio astronomy community will be investigated.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.

目前部署的第五代（5G）解决方案在频带中运行，大多数低于6 GHz，在有限程度上在28/39 GHz，并且正在考虑扩展到其他新兴频带。 当工作在28 GHz或39 GHz时，需要数百个天线来提高发射信号的功率，以形成聚焦波束，从而增加通信范围。 在接收器上，有一个独特的机会可以利用许多天线元件来抵消或衰减来自不需要方向的干扰。 该提议寻求理解实现干扰消除的最功率有效和最佳的手段。 此外，随着高速应用开始从6 GHz以下频带过渡到更高频率，特别是在28/39 GHz处，使用高质量声学谐振器消除在其他频带（其他“信道”）中操作的不想要的干扰的传统手段似乎不可行。 因此，本项目将探索电子可调滤波器的应用，并利用现代数字设备的开关特性作为克服这些限制的手段。 虽然解决共存问题是商业无线电的主要障碍，但如果不采取措施解决干扰问题，许多其他无线电也有失去功能和灵敏度的危险。许多重要的传感器，如气象雷达和射电天文望远镜，如果干扰水平如预期的那样增加，可能会停止运作。因此，必须通过与射电天文学界直接合作来保护这些无线电。 这项研究还将导致现代通信系统和无线通信工程的学生的培训。下一代无线电利用更宽频带的毫米波（mm波）前端、更高的信道带宽（1 GHz或更高）和波束成形。 多天线阵列信号处理技术自然地提供对不想要的信号的一些空间滤波。 通过在天线方向图中放置零点以有目的地“归零”干扰，可以提高信号失真比，实现更好的频谱利用率，并实现更鲁棒的无线电。虽然所有这些优点都可以使用数字信号处理来实现，但是对模数转换器的宽动态范围要求使得百元件阵列无线电高功率甚至不可行。 此外，当毫米波频谱更拥挤时，带外干扰可能会造成问题。使用基于高Q谐振器的锐滤波器消除干扰的传统方法在10 GHz以上是不可行的。 为了解决这些问题，将在接收器中的多个位置、射频本身（使用可调电子陷波滤波器）、射频块和模拟块之间的边界（空间陷波）以及内部探索干扰消除。模数转换器本身。以这种方式，在量化之前（或期间）将拒绝干扰，这将大大降低接收机的动态范围要求。这在5G和下一代无线电中提出的更宽信道带宽下尤为重要。 然而，干扰的消除需要知道干扰信号的位置和频率。 将探索数字和基带跟踪环路以识别干扰信号的特性，然后反馈环路将允许以各种形式执行干扰消除。 将研究这些技术在保护无源无线电传感器（如射电天文望远镜）方面的应用，并调查射电天文学界的干扰跟踪技术。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。