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

University Of California-Davis, Davis CA

Investigators

Abstract

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