Full-duplex in a hand-held device — From fundamental physics to complex integrated circuits, systems and networks: An overview of the Columbia FlexICoN project

Full-duplex wireless is an exciting emerging wireless communication paradigm that also poses tremendous challenges at virtually every layer: from the antenna interface and integrated circuits (ICs) and systems to the network layer. This paper covers recent advances at Columbia University across all these dimensions. Several potential full-duplex system architectures that are appropriate for different application spaces are discussed. Specific research advances include (i) a novel integrated CMOS non-reciprocal circulator that utilizes time-variance to break Lorentz reciprocity, (ii) a polarization-based antenna cancellation technique that achieves very wideband isolation that can be reconfigured as the environment changes, (iii) several generations of RF and analog self-interference cancellation circuits that combat noise, distortion and bandwidth limitations, (iv) higher-layer resource allocation algorithms that evaluate full-duplex rate gains given realistic physical layer models, and (v) demonstrations of full-duplex operation using realistic IC-based nodes.