SBIR-STTR Award

The broader impact/commercial potential of this project will be to develop a scalable framework for increasing the spectral efficiency of wireless Multiple-In, Multiple-Out (MIMO) systems in environments with long channel coherence time by leveraging implicit channel sounding. To date, standards committees and equipment vendors have avoided implicit channel sounding since key technical questions regarding its use remained unanswered. By providing a zero-overhead method for implicit channel sounding, the proposed system will be able to provide rich environment and user mobility data to the Media Access Controller (MAC) and application layer, with strong implications for the future design of rate and group selection for MU-MIMO systems. With commercialization targeted at unlicensed TVWS wireless devices, the proposed 4-antenna system will be able to provide at least a 4-fold increase in network capacity compared to existing single-antenna TVWS solutions, without suffering from protocol overhead congestion typical in existing multi-user MIMO systems. Integral to this approach is the ability to implement the technology on low-cost software-defined radio hardware, placing this technology within the reach of underserved communities looking for low-cost broadband data solutions.

This Small Business Innovation Research (SBIR) Phase I project will demonstrate an innovative implicit beamforming protocol that eliminates channel sounding overhead in TV-band White Space (TVWS) radio channels, enabling efficient and high-speed, last-mile unlicensed wireless network deployments. The project will develop and benchmark practical implicit channel reciprocity calibration for software-defined radio arrays, while utilizing an innovative software-defined radio signal flow that allows the system to be implemented on low-cost commodity system-on-chip hardware. Both approaches represent a departure from existing methods of beamforming in commercial systems, which rely on both overhead-intensive explicit beamforming and real-time parallel hardware for signal processing and beamforming calculation. While shown to be feasible in academic research papers, both key innovations have yet to be validated in an operational system and several known barriers to implementation are investigated in this project. Finally, the proposed implicit beamforming system will be validated on real TVWS channels though trace-driven system emulation. To our knowledge, this is the first time that an implicit beamforming system will be tested on commercial hardware and on real wireless channels.

The broader impact/commercial potential of this project is to provide wireless technology for economic high-speed internet connectivity in under-served rural regions, addressing the needs of 40 million Americans and over 50% of the global population. The technological developments in this project will pave the way for adoption of Massive, or Many-Antenna MIMO technologies in next-generation wireless systems by addressing scalability bottlenecks with innovative hardware and protocol design. The result of this project will be a revolutionary new wireless system for internet service providers addressing an $80 billion fixed wireless systems market and connecting under-served global communities to high-speed internet commerce, communications, education, and entertainment.This Small Business Innovation Research (SBIR) Phase 2 project will develop a production-ready Television White Space (TVWS) Massive MU-MIMO wireless system for IP data traffic, then use it to characterize for the first time diverse, large-scale multi-user TVWS channels. This project will demonstrate the first economically-viable Massive MIMO system, as well as the first point-to-multipoint wireless system capable of non-line-of-sight ranges over 10s of miles with over 2 Gbps of aggregate capacity. The system will be used to measure and characterize TVWS channels at scale in various rural environments, with large beamforming arrays serving tens of clients tens of miles away. In particular, these measurements will explore the effect of range, environment, user separation, and polarization on real-world achievable capacity. The results will be used to guide the design, optimization, and deployment of rural TVWS broadband networks across the world.