EAGER: Proof-of-Concept of a New MIMO Transceiver for Addressing Beam Squint in Wideband High-Dimensional Arrays

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Proposal no. 1546604: EAGER: A New System Architecture for Addressing the Fundamental Beam-Squint Problem in Wireless Communication with Wideband High-Dimensional Antenna Arrays Wireless technology is poised for a radical transformation. New systems operating at centimeter-wave (10-30GHz) and millimeter-wave (30-300GHz) frequencies are the focus of intense current research to meet the exploding wireless data traffic demands. Two factors make such high frequencies attractive: i) order-of-magnitude larger chunks of available spectrum, and ii) high-dimensional antenna arrays enabled by the small wavelengths. The resulting large number of degree of freedom can be exploited for a number of critical capabilities, including highly directional communication with narrow high-gain beams, and spatial reuse of the spectrum by simultaneous wideband transmissions to multiple users through multiple beams. However, the hardware complexity of the beamforming front-end and the computational complexity of the back-end digital processing challenge the current "digital" paradigm and require a fresh look at the design of the high-dimensional analog-digital interface. One fundamental problem whose impact on performance can no longer be ignored in emerging mmW and cmW systems is the well-known ``beam-squint'' problem - the beam direction changes as a function of frequency. Traditional solutions are far too complex to be realized in practice. The objective of this two-year EAGER project is to provide proof-of-concept of a new multi-beam system architecture that promises to deliver near-optimal performance with dramatically reduced complexity compared to conventional designs. The project will provide an invaluable research and training opportunity for graduate and undergraduate students at the cutting edge of wireless communications, including basic theory and prototype-based experimentation. A patent has been filed on the new architecture and it is expected to play an important role in the conception and development of emerging wideband multi-antenna technology for cmW and mmW applications. The technology could also impact radar applications. The proposed research draws on tools from communication theory, signal processing, optimization, harmonic analysis, antenna design, and physics of propagation. It is prompted by promising initial results that revisit the beam-squint problem from a new perspective, quantify its significant impact on performance, and suggest the new multi-beam system architecture for effectively dealing with it. The new perspective is offered by a beamspace theory, pioneered by the PI, for the design and analysis of multiple input multiple output (MIMO) wireless systems that employ multi-antenna arrays. An integrated theoretical-experimental research plan is being pursued with two overall objectives: i) development of basic theory for the new system architecture, and ii) proof-of-concept validation using a prototype at 10GHz. The development of basic theory will characterize the new multi-beam (MB) MIMO transceivers in all point-to-point system configurations. It will enable a more complete quantification of the performance gains of the proposed wideband MB-MIMO transceivers relative to conventional phased array-based systems, as well as the performance-complexity tradeoffs offered by them. The proof-of-concept demonstration will use a prototype with a lens antenna for analog beamforming. The results of this project will provide a definitive proof-of-concept of the new MB-MIMO architecture for performance-complexity optimization in wideband high-dimensional MIMO systems in which beam-squint is a significant problem. The findings of this project are expected to lead to new research in the critical emerging area of wireless communication and sensing with wideband high-dimensional arrays.