Array Signal Processing Techniques for Terahertz Communications and Sensing

由于现有应用的流行和新应用的出现，对无线吞吐量和连接的需求继续以前所未有的速度增长，例如增强现实、自动驾驶汽车、全息游戏或数据阵雨。虽然在5G网络中使用毫米波频率将有助于克服当前的频谱短缺，但这些较新的应用要求在数据速率、设备连接和延迟方面进一步增强。意识到这些局限性，研究人员现在正将他们的注意力转向太赫兹(THz)通信，范围从0.1到10THz，作为未来6G网络的使能技术。由于可用的频谱范围很广，太赫兹通信天生就可以达到远高于100 Gbps的数据速率。太赫兹信号的短波长提供了几个优点，特别是可以在很小的占地面积上打包数百个天线单元。进而，这允许形成具有非常高方向性的发射/接收波束，并利用超大规模多输入多输出(UM-MIMO)技术显著提高网络容量。实现太赫兹通信的全部潜力最终将取决于先进的信号处理技术的可用性，这些技术利用了太赫兹传播和收发设备的基本物理机制。拟议研究的长期目标是开发、性能评估和应用太赫兹通信和传感的新信号处理技术，重点是使用超大规模天线阵列在中短距离链路上进行UM-MIMO传输。短期目标围绕三个途径阐述：(1)开发新的算法和训练协议，用于估计太赫兹频率下的UM-MIMO信道参数，包括到达角度和到达时间差，并赋予这些算法在移动性条件下的应用跟踪能力；(2)设想混合模拟-数字(HAD)UM-MIMO THz收发机的新设计方法，以最大限度地提高数据速率，同时确保对信道和硬件损伤的稳健性，并研究智能反射面(IRS)与HAD收发机相结合以克服阻塞的使用；(3)通过利用多个接入点的视线(LOS)测量，开发新的THz发射机室内定位和跟踪的协作算法，并利用多个IRS提供的分集将这些算法扩展到非视距(NLOS)场景。这一研究计划将为研究生和博士级别的HQP培训提供关键机会，同时主要研究成果将在国际会议上公布，并在高度精选的期刊上发表。

The demand for wireless throughput and connectivity continues to grow at unprecedented rates, boosted by the popularity of existing applications and the emergence of new ones, such as augmented reality, autonomous vehicles, holographic gaming, or data showers. While the use of mm-wave frequencies in 5G networks will help overcome current spectrum shortage, these newer applications call for further enhancements in data rate, device connectivity, and latency. Aware of these limitations, researchers are now turning their attention to terahertz (THz) communications, within the range from 0.1 to 10THz, as an enabling technology for future 6G networks. Due to the availability of wide swaths of spectrum, THz communications can innately achieve data rates well in excess of 100 Gbps. The short wavelengths of THz signals offer several advantages, especially the possibility to pack several hundreds antenna elements over a small footprint area. In turn, this allows to form transmit/receive beams with very high directivity, and exploit ultra-massive multiple-input multiple-output (UM-MIMO) techniques to significantly improve network capacity. Achieving the full potential of THz communications will ultimately depend on the availability of advanced signal processing techniques that exploit the underlying physical mechanisms of THz propagation and transceiver devices. The long-term goal of the proposed research is the development, performance evaluation and application of new signal processing techniques for THz communications and sensing, with focus on the use of very large-scale antenna arrays for UM-MIMO transmissions over short to medium range links. The short-term objectives are articulated around three avenues: (1) To develop new algorithms and training protocols for estimation of UM-MIMO channel parameters at THz frequencies, including angles of arrival and time differences of arrival, and endow these algorithms with tracking capabilities for applications under mobility conditions; (2) To conceive new design methods for hybrid analog-digital (HAD) UM-MIMO THz transceivers that maximize data rate while ensuring robustness against channel and hardware impairments, and to investigate the use of intelligent reflecting surfaces (IRSs) in combination with HAD transceivers to overcome blockage; (3) To develop new cooperative algorithms for indoor localization and tracking of THz transmitters by exploiting line-of-sight (LoS) measurements from multiple access points, and extend these algorithms to non-LoS (NLoS) scenarios by taking advantage of the diversity provided by multiple IRSs. This program of research will provide key opportunities for HQP training at the MEng and PhD levels, while the main findings will be presented at international conferences and published in highly selective journals.