SBIR Phase II: Large Arrays for 5G MU-MIMO Wireless Access Operating in mm-wave Frequency Bands

The broader impact/commercial potential of this project focuses on the development of a patented radio front-end supporting multi-user MIMO capability for the 5G mm-wave infrastructure market that would enable cost efficient, high data rate access wirelessly as opposed to cost prohibitive fiber-based data connectivity. Cellular and Wi-Fi networks are hitting a spectrum bottleneck in terms of their ability to offer higher data rates to densely populated areas and the same in a cost-efficient manner to remote rural areas. Advent of 5G cellular networks with new bands in the mm-wave frequency spectrum (between 28-70 GHz) alleviates these issues. RF Pixels' innovative mm-wave radio front-end will enable spectrum efficient communication through frequency re-use to spatially separated users at a fraction of the cost compared to known solutions. Thousands of mobile internet users can enjoy high data rates simultaneously without being starved of spectrum. Data heavy paradigms connecting consumer devices and the cloud, such as wireless virtual reality headsets and robotic personal assistants can be implemented with ease. Virtual and augmented reality based remote educational programs, online health care, smart cities, smart transportation and other new low-latency services will be enhanced delivering major economic and societal impact. This Small Business Innovation Research Phase II project proposes a revolutionary tile architecture that enables massive multi-user MIMO techniques for mm-wave radio systems, without the hardware and power consumption costs of full digital solutions. The radio can efficiently reuse the spectrum between spatially diverse users with active beamforming. Multitude of tiles will be used in a large array making it crucial to achieve excellent power efficiency at the tile level. Tile-to-tile variations hamper accurate beamforming requiring calibration. Beam discovery, refinement and tracking of multiple mobile users simultaneously requires investigation. In Phase I feasibility of a tile architecture that achieves multi-user MIMO and scale to large element arrays was proven. This project will investigate clock generation and coherent distribution to every tile in a large array for accurate beamforming and interference cancellation. Turnkey approach for packaging and antenna array design will be investigated. Impact of tile-to-tile variations on beamforming accuracy and calibration algorithms to mitigate variations will be studied. New algorithms will aim to achieve low-sensitivity to post-calibration errors without much downtime. Beam management algorithms for accurate tracking of mobile users compatible with guidelines of 5G NR standard will be developed. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.