Investigation of Beam-Level Nonlinear Equalization in Digital Phased Arrays

Interest in nonlinear equalization (NLEQ) techniques has been growing as a means to reduce nonlinear distortion through digital signal processing rather than more expensive and power-hungry high-linearity analog components. This is especially relevant to element-level digital arrays where there is no spatial filtering before the nonlinear receiver chain. While element-level NLEQ has shown encouraging performance improvements, an NLEQ implementation at the beam level would be more efficient, requiring less power consumption and a smaller footprint. This work investigates the feasibility of a beam-level approach and compares beam-level NLEQ to more conventional element-level NLEQ. Simulation and analysis demonstrates beam-level NLEQ is effective when the signals of interest arrive from the same angle, but degrades when signals are spatially diverse. Future techniques may combine beam-level NLEQ and adaptive digital beamforming to efficiently reduce nonlinear distortion in arbitrary signal environments.