Enabling Wireless Communications in the Terahertz Band

近年来，由于当今社会创建、共享和消费信息的方式发生了变化，无线数据流量呈指数级增长。伴随这一变化的是对更高速度无线通信的日益增长的需求。无线每秒太比特的链路有望在未来十年内成为现实。为了实现这一目标，太赫兹频段(0.1-10太赫兹)通信被视为下一个十年的关键无线技术之一。通过提供前所未有的大带宽，太赫兹频段将有助于克服当前无线网络的频谱稀缺问题和容量限制。此外，太赫兹频段通信将实现人们期待已久的大量应用，从Terabit无线个人和局域网中附近设备之间的即时海量数据传输，到5G和小蜂窝以外的移动设备上的超高清内容流。然而，由于太赫兹频段信道具有很高的频率选择性路径损耗和非常有限的距离，这一研究面临着一些挑战，需要创新的解决方案和对无线通信中已有的概念进行修订，该项目将为太赫兹频段超宽带通信的发展铺平道路。太赫兹技术及其应用最近被DARPA确定为具有比互联网本身更广泛的潜在影响的四种技术之一。超宽带通信将极大地增加无线网络的容量，并实现人们期待已久的应用，这是目前的无线技术无法实现的，因此将在社会上发挥重要作用。此外，太赫兹频段还没有受到监管。该项目团队积极参与IEEE 802.15无线个人区域网络太赫兹任务组，其目标是为这一范例创建第一个标准。在这个项目中，一名研究生将得到支持，硕士研究生(作为专题学生)将参与其中，成为这一快速发展领域的专家。研究成果将在重要的、一流的科学会议、期刊和该领域的主要杂志上传播。此外，本项目提出的解决方案可定制并适用于毫米波系统等较低频率，有助于5G蜂窝系统的发展进程。本项目的研究目标是加强太赫兹频段超宽带通信的理论基础，使每秒太比特链路更接近现实一步。我们的目标突破是将无线系统的容量提高到每秒太比特，并克服当前无线网络的频谱稀缺和容量限制。该项目将沿着三大推力做出贡献。首先，基于超大型天线阵列的数千个天线单元，引入了超大质量多输入多输出的概念，以克服距离限制。分析了波束形成、空间复用和两者结合的动态工作模式，以及多频段超大容量多输入多输出的动态工作模式。其次，将建立端到端三维信道和三维超大质量多输入多输出信道的精确模型，为THz频段通信设计提供物理见解和指导方针。第三，通过捕获独特的信道特性，将研究用于太赫兹频段通信的距离自适应资源分配、低采样率和多载波同步方案。

In recent years, wireless data traffic has grown exponentially due to a change in the way today's society creates, shares and consumes information. This change has been accompanied by an increasing demand for higher speed wireless communication. Wireless Terabit-per-second links are expected to become a reality within the next ten years. Towards this aim, the Terahertz Band (0.1-10 THz) communication is envisioned as one of the key wireless technologies of the next decade. The THz band will help to overcome the spectrum scarcity problems and capacity limitations of current wireless networks, by providing an unprecedentedly large bandwidth. In addition, THz-band communication will enable a plethora of long-awaited applications ranging from instantaneous massive data transfer among nearby devices in Terabit Wireless Personal and Local Area Networks, to ultra-high-definition content streaming over mobile devices in 5G and beyond small cells. Nevertheless, there are several research challenges from the very-high and frequency-selective path loss of the THz-band channel and the very limited distance, which require innovative solutions and the revision of well-established concepts in wireless communication.This project will contribute to pave the way for the development of ultra-broadband communication in the THz band. THz technology and its applications has been recently identified by DARPA as one of the four with a potential broader impact larger than the Internet itself. Ultra-broadband communication will play a major role in the society by drastically increasing the capacity of wireless networks and enabling long-awaited applications not possible with current wireless technologies. In addition, the THz band is not yet regulated. The project team is actively involved in IEEE 802.15 Wireless Personal Area Network Terahertz Task Group, whose objective is to create the first standard for this paradigm. In this project, one graduate student will be supported, and master students (as special topic students) will be involved, to become experts in this fast evolving field. The research results will be disseminated in important, first rate scientific conferences, journals and premier magazines in the field. Moreover, the proposed solutions in this project can be tailored and are useful for the lower frequencies such as the millimeter-wave systems, which can help the development progress of 5G cellular systems.The research objective of this project is to strengthen the theoretical foundations of ultra- broadband communications in the THz band and bring the Terabit-per-second links one-step closer to reality. Our targeted breakthrough is to increase the capacity of wireless systems to reach Terabit-per-second and overcome the spectrum scarcity and capacity limitations of current wireless networks. This project will make contributions along three major thrusts. First, the concept of ultra-massive multiple-input-multiple-output is introduced to overcome the distance limitation, based on the use of the very large antenna arrays with thousands of antenna elements. The dynamic operation modes that include beamforming, spatial multiplexing and a combination of both, as well as the multi-band ultra-massive multiple-input-multiple-output will be analyzed. Second, accurate models for the three-dimensional end-to-end channel, and the three-dimensional ultra-massive multiple-input-multiple-output channel will be developed, which will provide physical insights and the guidelines for the THz band communication design. Third, by capturing the unique channel peculiarities, distance-adaptive resource allocation, and low-sampling-rate and multi-carrier synchronization schemes will be investigated for THz band communications.