Collaborative Research: Novel Terahertz Phased-Array Wireless Transmitters with Beamforming Capability Enabling Point-to-Point 50 Gbps Data Rates

合作研究：具有波束形成能力的新型太赫兹相控阵无线发射机，实现点对点50 Gbps数据速率先进的蜂窝和无线数据通信的激增不断为公众带来新的可能性。由这些可能性产生的应用需要越来越宽的带宽。在低于30千兆赫（GHz）的非常拥挤的频谱上对更宽带宽的这种不断增长的需求需要新的范式转变以实现频谱高效的通信。通过仅将调制方案的复杂度增加到256-QAM（正交幅度调制）或更高来提高频谱效率预期达到平稳，因为其施加了在无线系统中给定功率预算约束的情况下不可能实现的严格设计要求。另一方面，太赫兹（THz）频段（通常指300 GHz至3 THz的频段）的频谱利用率极低，这促使研究人员研究未来的无线系统，这些系统可能实现10+千兆比特每秒（Gbps）的数据速率，通常只能在有线（铜或光）链路中实现。THz频带上的宽频谱的可用性还解决了与传统无线链路相关联的挑战性要求，即，需要适应非常复杂的调制方案以增强频谱效率，以便最好地利用在较低无线电频率（即，30 GHz及以下）。这个跨学科研究项目的主要目标是研究，设计和实现新型集成相控阵无线发射机架构，这些架构可以进行频率缩放，并将成为无线基础设施的核心使能模块，可以在20- 50米的链路范围内实现50 Gbps的视距（LOS）无线连接。该项目将利用PI研究小组在硅基THz集成电路设计以及多天线无线通信理论领域建立的经验和知识。 该提案将开发新的相控阵发射机架构，克服上述挑战。具体来说，我们提出了一个锁相环为基础的相控阵，不需要本地振荡器或射频移相器和前端功率放大器。重要的是，我们利用前端频率三倍器的非线性来联合收割机在高数据速率信号被天线辐射之前组合三个较低带宽中频数据流。我们建议研究模拟波束形成和混合模拟/数字波束形成方法，微调到本项目中提出的特定相控阵结构，以提供有效的自适应波束控制。这显然需要电路和通信专家之间的密切合作，以应对许多挑战。作为概念验证，我们将设计和实现一个300 GHz，16元素相控阵发射机。在成功制造和时间/频谱测量后，我们将扩大我们目前的室内无线测试设置，并进行室外无线测试。

Collaborative Research: Novel Terahertz Phased-Array Wireless Transmitters with Beamforming Capability Enabling Point-to-Point 50 Gbps Data RatesThe proliferation of advanced cellular and wireless data communications continues to bring forth new possibilities for the general public. The applications resulting from these possibilities require increasingly broader bandwidth. This ever-increasing need for broader bandwidth over a very crowded spectrum below 30 gigahertz (GHz) necessitates new paradigm shifts to enable spectrally efficient communications. Improving spectral efficiency by only increasing the complexity of modulation schemes to 256-QAM (quadrature amplitude modulation) or higher is expected to plateau, as it exerts stringent design requirements that are impossible to achieve given the power budget constraint in a wireless system. On the other hand, the vastly under-utilized spectrum across the terahertz (THz) band, commonly referred to the frequency band from 300 GHz to 3 THz, has prompted researchers to investigate futuristic wireless systems that can potentially achieve 10+ gigabit-per-second (Gbps) data rates, normally only achievable in wired (copper or optical) links. The availability of wide spectrum over the THz band also addresses a challenging requirement associated with conventional wireless links, that is, the need to accommodate very complex modulation schemes to enhance spectral efficiency so as to best take advantage of an already congested band at lower radio frequencies (i.e., 30 GHz and below). The main objective of this interdisciplinary research project is to study, design, and implement novel integrated phased-array wireless transmitter architectures that are amenable to frequency scaling and will be the core enabling blocks for a wireless infrastructure that can potentially achieve 50 Gbps line-of-sight (LOS) wireless connectivity over a 20-50m link range. The project will leverage prior experience and knowledge established in the PIs' research groups in the areas of silicon-based THz integrated circuits design as well as multi-antenna wireless communication theory. This proposal will develop new phased-array transmitter architectures that overcome the above challenges. Specifically, we propose a phase locked loop based phased-array with no need of local oscillators or radio-frequency phase shifters and front-end power amplifiers. Importantly, we exploit the non-linearity of front-end frequency triplers to combine three streams of lower bandwidth intermediate-frequency data right before the high data rate signal is radiated by the antennas. We propose to study analog beamforming and hybrid analog/digital beamforming methods that are fine-tuned to specific phased-array structures proposed in this project so as to provide efficient adaptive beam-steering. This clearly requires a close collaboration between circuits and communications experts to address many challenges. As proof of concept, we will design and implement a 300-GHz, 16-element phased-array transmitter. Upon successful fabrication and temporal/spectral measurements, we will expand our current indoor wireless testing setup and conduct outdoor wireless testing.