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

合作研究：具有波束成形能力的新型太赫兹相控阵无线发射机，可实现点对点50 Gbps数据速率先进蜂窝和无线数据通信的普及继续为公众带来新的可能性。由此产生的应用需要越来越宽的带宽。在30千兆赫（GHz）以下非常拥挤的频谱上，对更宽带宽的需求不断增长，这就需要新的范式转变，以实现频谱高效通信。仅通过将调制方案的复杂性增加到256-QAM（正交调幅）或更高来提高频谱效率预计会趋于平稳，因为它施加了严格的设计要求，而在无线系统中，由于功率预算的限制，这是不可能实现的。另一方面，太赫兹（THz）频段（通常指300 GHz到3太赫兹的频段）的频谱利用率非常低，这促使研究人员研究未来的无线系统，这些系统可能达到每秒10千兆位（Gbps）以上的数据速率，通常只能在有线（铜或光）链路中实现。太赫兹波段宽频谱的可用性还解决了与传统无线链路相关的一个具有挑战性的要求，即需要适应非常复杂的调制方案，以提高频谱效率，以便最好地利用较低无线电频率（即30 GHz及以下）已经拥挤的频段。这个跨学科研究项目的主要目标是研究、设计和实现新的集成相控阵无线发射机架构，该架构适合频率缩放，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研究小组在硅基太赫兹集成电路设计以及多天线无线通信理论领域建立的先前经验和知识。本提案将开发克服上述挑战的新型相控阵发射机架构。具体来说，我们提出了一种基于锁相环的相控阵，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，我们利用前端三倍器的非线性，在天线辐射高数据率信号之前，将三流低带宽中频数据合并。我们建议研究模拟波束形成和模拟/数字混合波束形成方法，这些方法可以根据本项目提出的特定相控阵结构进行微调，从而提供有效的自适应波束引导。这显然需要电路和通信专家之间的密切合作来应对许多挑战。作为概念验证，我们将设计并实现一个300 ghz的16元相控阵发射机。在成功制造和时间/光谱测量后，我们将扩展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.