Receiver Design for Close-In Phase Noise and Reciprocal Mixing Compensation

在许多无线通信系统中，接收器需要高度集成、可重构，并且能够在存在许多强干扰阻挡物的拥挤频带中共存。尽管在先进的接收机设计方面取得了重大进展，但减轻振荡器相位噪声的影响仍然是一个主要挑战。相位噪声以两种方式降低期望信号——近相位噪声和互反混频失真。在接近相位噪声失真的情况下，相位噪声频谱本身会扭曲期望的信号，而在互反混合的情况下，相位噪声频谱与附近的干扰阻挡物耦合，从而破坏期望的信号。虽然近相噪声失真的主题已经在文献中得到解决，实际的解决方案，以减轻互反混合的影响几乎是不存在的。目前，减小互反混频器失真的一般方法是用尖锐的片外滤波器来抑制阻塞干扰本身，但代价是增加了复杂性、外形因素和成本，并降低了可重构性。该项目将联合和无缝地补偿近相噪声和互反混频失真，而不需要训练信号或干扰阻挡器的知识。提出的研究的直接影响是引入了一种新的方法来补偿互反混合的影响，这是通信接收器设计中的一个主要问题。此外，由于在拟议的研究中开发的概念和技术是通用的，并且广泛适用于解决电路非理想性的其他来源，因此拟议的研究预计将对未来接收器的设计产生重大影响。PI的研究活动与一项教育计划相结合，该计划描述了研究将如何帮助培养研究生和本科生。拟议研究的多学科性质有望拓宽学生的技术理解。该项目包括本科生的参与，以及通过利用PI所在机构的项目从代表性不足的群体中招募学生。所提出的方法采用中频接收器架构和改进的本振，为接收器前端提供所需的额外自由度，使所需信号跨越不同的矢量空间，而不是由互反混合和近相位噪声失真所跨越的子空间。相位噪声引起的失真可以通过投射到其零空间来消除，这涉及到基带样本的乘法和求和以恢复所需的信号。尽管所提出的相位噪声补偿方法简单，但初步结果表明，由此产生的性能改进是显著的。在电路和算法层面都有重要的研究问题需要解决，以充分实现所提出的补偿方法的好处。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。

In many wireless communication systems, the receiver needs to be highly integrated, reconfigurable, and able to coexist in congested frequency bands in the presence of many strong interfering blockers. Although significant progress has been made in advanced receiver design, mitigating the effects of oscillator phase noise remains a major challenge. Phase noise degrades the desired signal in two ways – the close-in phase noise and reciprocal mixing distortion. In the case of close-in phase noise distortion, the phase noise spectrum distorts the desired signal itself, while in the case of reciprocal mixing, the phase noise spectrum couples with nearby interfering blockers to corrupt the desired signal. While the topic of close-in phase noise distortion has been addressed in the literature, practical solutions to mitigating the effects of reciprocal mixing are nearly non-existent. The general approach to minimizing the distortion from reciprocal mixing today is to suppress the blocking interferers themselves with sharp off-chip filters at the expense of increased complexity, form factor and cost as well as reduced reconfigurability. This project will jointly and seamlessly compensate for both the close-in phase noise and reciprocal mixing distortion without requiring training signals or knowledge of the interfering blockers. The immediate impact of the proposed research is the introduction of a new approach to compensate for the effects of reciprocal mixing, which is a major problem in communication receiver design. Furthermore, as the concepts and techniques developed in the proposed research are general and broadly applicable to address other sources of circuit non-idealities, the proposed research is expected to have a major impact on how future receivers are designed. The PI’s research activities are coupled with an educational plan that delineates how the research will help train both graduate and undergraduate students. The multi-disciplinary nature of the proposed research is expected to broaden the technical understanding of the students involved. The project includes participation of undergraduate students and the recruitment of students from underrepresented groups by leveraging programs at the PI’s institution.The proposed approach employs an IF-receiver architecture with a modified local oscillator to provide the receiver front-end with the additional degrees of freedom necessary for the desired signal to span a different vector space than the subspace spanned by reciprocal mixing and close-in phase noise distortion. The phase noise induced distortion can then be removed by projecting to its null space which involves multiplying and summing of baseband samples to recover the desired signal. Despite the simplicity of the proposed phase noise compensation approach, preliminary results suggest that the resulting performance improvements are significant. There are significant research issues at both the circuit and algorithmic levels that will be addressed to fully realize the benefits of the proposed compensation approach.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.