Specific Objectives:
Our project advances the concepts of MU-MIMO by demonstrating the successful operation of our protocol on custom MIMO SDR front-end platforms. Specifically, we explore the regimes in which our opportunistic channel sounding protocol pushes the performance gains of MU-MIMO closer to those predicted by prior theoretical works. Our platform also enabled the first characterization of mobile multi-user channels in UHF bands.
Significant Results: The project has resulted in the design and fabrication of a custom MIMO SDR front-end for the WARPv3 SDR platform and a novel framework to enable experiments in the UHF bands. This platform enables the first characterization of mobile multi-user UHF channels, enabling evaluation of opportunistic sounding even in the presence of STA or environmental mobility. The design simplifies high-power UHF-band 8×8 MIMO experiments and improves synchronous clocking over previous SDR testbeds. We obtained experimental radio licenses WH2XJV and WJ9XFF to operate our experimental equipment on UHF channels in Houston, TX and performed a series of indoor and outdoor measurement campaigns in various mobility scenarios to analyze MU-MIMO beamforming capacity with respect to CSIT overhead.
The project has also produced a multiuser UHF MU-MIMO, the first system to achieve UHF band full-rank uplink multi-user capacity in a fully distributed and scalable manner without a control channel. The project’s multiuser, multi-antenna transmission scheme is for UHF, a portion of the radio spectrum that is traditionally reserved for television broadcasts. Based on over-the-air experiments in a range of indoor and outdoor operating environments, the team found that UHF-band multiuser MIMO compared
favorably and produced high spectral efficiency as well as low-overhead wireless access.