Gradient-Adaptive 2-D LUT Method for 6G Flexible-Duplex

In this letter, we propose a novel self-interference (SI) cancellation solution for asymmetric in-band full-duplex (IBFD) systems, where the downlink (DL) signals are noncontiguously aggregated within the available band. The method builds on a Hammerstein model with parallel spline-interpolated 2-D lookup tables (LUTs), together with efficient gradient-descent parameter learning rules. The provided RF measurement results harnessing a GaN Doherty power amplifier (PA) at 3.5 GHz demonstrate digital SI cancellation levels up to 35 dB, with substantially reduced processing complexity compared with the reference polynomial model. These methods and results pave the way toward enhanced duplexing capabilities and flexibility in the emerging 6G era.