NSF-SNSF: ULTRA: Ubiquitous Large InTelligent ArRAys

毫米波(毫米波)和太赫兹(THz)频率下的大量可用带宽正引起人们对下一代通信和传感系统越来越大的兴趣。在这些频率下，多天线收发机(TRX)阵列是克服高路径损耗和提高信噪比的关键，而信噪比是保持强大通信的关键。与单天线系统不同，由于(I)失配和非理想，以及(Ii)大量的控制参数，设计大型多天线阵列需要巨大的挑战。现有的阵列大多依赖于查找表(LUT)和离线补偿。然而，这种静态解决方案既不能捕获所有可能的操作模式，也不能提供对传播条件和通信/感测任务的实时适应性。这项与瑞士苏黎世理工学院研究人员合作的研究项目将产生具有高度可重新配置的140 GHz前端的新型智能大规模多天线阵列架构。与今天的系统不同，这些系统对阵列中的不平衡和失配视而不见，或者只进行静态校正，使用检测器和自适应阵列校准/波束形成将导致自适应阵列，从而随着条件的变化表现得更好，并降低校准大型阵列的成本。这项研究将直接影响Beyond-5G和6G通信、亚毫米波雷达和下一代卫星/卫星间链路的应用。为了传播研究成果，该项目将提供对阵列模型、阵列校准/波束形成代码和阵列演示测量的开放访问。该项目旨在通过联合考虑毫米波电子学、天线阵列、数字基带处理和校准算法的整体方法来应对大型阵列设计挑战。主要目标是设计D波段140 GHz的大型可扩展阵列体系结构，具有智能校准和自适应场内波束形成功能。这项工作分为几个方面，包括大型可扩展阵列中非理想情况的分析和行为建模、将可重构D频段前端设计为性能调节“旋钮”、设计非侵入式D频段前端性能“传感器”、盲阵列校准和波束形成算法以及超140 GHz阵列系统集成和演示。将对与波束无关的非理想(例如，相位/增益/功率失配)和与波束相关的非理想(例如，天线耦合/串扰)进行建模。对于阵列天线的负载补偿，将研究一种可重构的负载调制平衡放大器发射机和一种具有非福斯特终端的Marchand Balun接收机。还将探索D频段正交调相/增益调谐块。非侵入式现场实功率和阻抗检测器将用于检测天线失配/耦合(与波束相关的非理想性)。发射机/接收机(TX/RX)环回将测量阵列单元中的增益/相位/功率失配(与波束无关的非理想性)。信号处理和机器学习算法将用于盲阵列校准和剩余损伤补偿。使其关键参数适应瞬时信道条件的数字波束形成方法和校准/波束形成算法将在现场可编程门阵列(FPGA)原型板上实施，以与D波段TRX阵列对接，以实现ULTRA系统的离线/在线闭环操作。这一美国-瑞士合作项目得到了美国国家科学基金会(NSF)和瑞士国家科学基金会(SNSF)的支持，NSF为美国的研究人员提供资金，SNSF为瑞士的合作伙伴提供资金。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 massive amount of available bandwidth at millimeter-wave (mm-wave) and terahertz (THz) frequencies is gaining increasing interest for next-generation communications and sensing systems. At these frequencies, multi-antenna transceiver (TRX) arrays are key in overcoming the high path-loss and boosting the signal-to-noise ratio, critical for maintaining robust communications. Unlike single-antenna systems, designing large multi-antenna arrays entails significant challenges due to (i) mismatches and non-idealities, and (ii) the large number of control parameters. Existing arrays mostly rely on look-up-tables (LUTs) and offline compensation. Such static solutions, however, can neither capture all possible operation modes nor provide real-time adaptivity to the propagation conditions and communications/sensing tasks. This collaborative research project with Swiss researchers at ETH Zürich will result in novel intelligent large-scale multi-antenna array architectures with highly reconfigurable 140 GHz frontends. Unlike today's systems that are blind to imbalances and mismatches in the array, or only make static corrections, employing detectors and adaptive array calibration/beamforming will result in an adaptive array, thus performing better as conditions evolve, and lowering the cost to calibrate a large array. The research will directly impact applications in beyond-5G and 6G communications, sub-mm-wave radar, and next-generation satellite/intersatellite links. To disseminate research results, the project will provide open access to the array models, array calibration/beamforming codes, and array demonstration measurements.The ULTRA (Ubiquitous Large inTelligent arRAys) project aims at addressing large-array design challenges with a holistic approach that jointly considers mm-wave electronics, antenna arrays, digital baseband processing, and calibration algorithms. The main objective is to design large and scalable array architectures at D-band 140GHz with intelligent calibration as well as adaptive in-field beamforming. The work is divided in several thrusts, including Analytical and Behavior Modeling of Non-idealities in Large Scalable Arrays, Designing Reconfigurable D-Band Frontends as Performance Tuning "Knobs", Designing Non-Intrusive D-Band Frontends Performance "Sensors", Blind Array Calibration and Beamforming Algorithms, and ULTRA 140-GHz Array System Integration and Demonstration. Both beam-independent non-idealities (e.g., phase/gain/power mismatches) and beam-dependent non-idealities (e.g., antenna coupling/crosstalk) will be modeled. For array antenna load compensation, a reconfigurable load-modulated-balanced-amplifier transmitter and a Marchand balun receiver with non-foster terminations will be investigated. D-band orthogonal phase/gain tuning blocks will also be explored. Non-intrusive in-situ real-power and impedance detectors will be used to detect antenna mismatches/coupling (beam-dependent non-idealities). Transmitter/receiver (TX/RX) loopbacks will measure gain/phase/power mismatches (beam-independent non-idealities) in array elements. Signal processing and machine learning algorithms for blind, on-the-fly array calibration and residual impairment compensation will be pursued. Digital beamforming methods that adapt their key parameters to the instantaneous channel conditions and calibration/beamforming algorithms will be implemented on field-programmable gate array (FPGA) prototyping boards to interface with the D-band TRX array for offline/online close-loop operation of the ULTRA system. This collaborative U.S.-Swiss project is supported by the U.S. National Science Foundation (NSF) and the Swiss National Science Foundation (SNSF), where NSF funds the U.S. investigator and SNSF funds the partners in Switzerland.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.