ECE PhD Proposal Review: Carlos Bocanegra

PhD Proposal Review: A Systems Approach to Spectrum Sharing and Multi-antenna Operation for Emerging Networks

Carlos Bocanegra

Location: TBD

Abstract: The demands on wireless connectivity and sensing are ever-increasing, fueled by both emerging applications and an exponential growth in the number of connected devices. Availability of new spectrum in the sub-6GHz bands is limited, which motivates research on innovative ways to utilize the current available spectrum and explore the use of additional spectrum beyond the 6GHz threshold.
This thesis explores three promising techniques with focus on the Physical (L1) and Link (L2) layers. Approach 1 concerns spectrum sharing in the sub-6GHz band, where wireless standards are granted opportunistic access within unlicensed spectrum to increase their usable bandwidth. Approach 2 concerns the design of massive multi-antenna systems, through which devices can benefit from beamforming gains at transmission and diversity gains at reception. Approach 3 concerns the use of very high frequency bands (VHFB), or so called millimeter-wave bands. Each of these approaches, however, has its own set of challenges, such as fairness in channel access, interference management, and optimal beamforming user-specified quality-of-service, respectively.
For spectrum sharing as described in Approach 1, this thesis presents E-Fi, an interference-evasion mechanism that allows Wi-Fi devices to survive opportunistic in-band LTE transmissions. The main contribution is to achieve this without any cooperation between these two, using Almost Blank Subframes (ABS). E-Fi ensures fair channel access while reusing existing Wi-Fi standards, i.e., Wi-Fi Direct, and thus incurring minimal deployment costs.
For Approach 2, this thesis introduces two multi-antenna frameworks, a decentralized one for cellular- and a centralized one for IoT-oriented applications, respectively. For the former, it presents NetBeam, a reconfigurable system of distributed 3D beamformers (3DBF). While NetBeam uses 3DBF to tackle multi-user interference in 3D multi-user deployments, it enforces Machine Learning and efficient antenna selection strategies to deliver the individual required SINR levels to users. As a centralized multi-antenna system, it presents RFGo, a privacy-preserving self-checkout system using passive Radio Frequency ID (RFID) tags. RFGo achieves fast tag discovery using a custom-built RFID reader, which simultaneously decodes a tag’s response from multiple carrier-level synchronized antennas. RFGo achieves reliable tag detection by means of a neural network that accurately discriminates products within the checkout area from those laying outside of it.
In the proposed work that covers Approach 3, this thesis describes an outline of an algorithmic framework for millimeter-wave communications that efficiently allocates antenna elements from Base Stations (BS) to users for hybrid beamforming, while considering their individual traffic demands. We propose to trade-off flexible array geometries (that allows to limit interference to specific regions) versus the irregularity that results in the sidelobes.
In summary, this thesis tackles complex challenges in the future 5G and beyond wireless networks through a combination theory, algorithm design and experimental implementation.