EARS: Enhanced Spectrum Availability and MU-MIMO Coordination for High Spatial-Spectral Efficiency

William Marsh Rice University, Houston TX

Investigators

Abstract

Astounding spectral efficiencies exceeding 40 bits per second per Hertz have already been achieved in multi-user MIMO systems. Unfortunately, the coordination needed to facilitate transmissions in space, frequency, and time can severely limit efficiency. Moreover, many spectral bands are today deemed unavailable even if no active receiver is nearby and hence resources cannot be used at all. This project fuses three integrated thrusts towards achieving high spectral-spatial efficiency (bits per second per Hertz per square meter) with high spectrum availability (permission to transmit in a particular band at a particular location). First, this project enables a new mode of spectrum availability by exploiting smart primary receivers. The key idea is that a typical primary spectrum transmitter such as a TV broadcaster does not have active receivers in all locations. This thrust realizes an architecture and algorithms for smart primary receivers to inform a controller of their usage, creating vast new dynamically available spatial-spectral resources. Second, this project overcomes fundamental limits in the coordination that is today required for spectrum access. This thrust considers channel sounding and user-state coordination to be a foundational resource of system design that must itself be allocated. An integrated suite of new methods for coordination limited MU-MIMO protocols is developed. The final thrust provides an implementation and measurement study. This thrust yields the first demonstration of spectrum access enhanced by smart primary users and the first multi-user MIMO diverse spectrum system enhanced by coordination limited protocol mechanisms. The platform targets "at scale" experiments via use of maximally amplified signals and real-word scenarios spanning from tower-to-user to indoor WLAN.