Digital Post-Distortion for MIMO Receiver Linearization Under Strong Same-Frequency Interference

Paper i proceeding, 2026

This work investigates receiver linearization in a four-antenna multiple-input multiple-output (MIMO) system operating in the presence of a strong blocker. The received signals are first spatially combined using either maximal ratio combiner (MRC) or zero-forcing combiner (ZFC), followed by a dual-input digital post-distortion (DI-DPoD) stage that compensates for nonlinear distortion generated by low-noise amplifiers (LNAs) driven into compression. The DI-DPoD model is derived from a prior calibration of the receiver's nonlinear behavior and leverages both the desired and blocker components at the combiner output. Measurement-based results show that DI-DPoD reduces distortion-induced error power by approx. 20 dB beyond the combiner output, achieving nearly identical normalized mean squared error (NMSE) performance for both ZFC and MRC-based front ends across varying blocker powers, signal-to-noise ratio (SNR) levels, and angles of arrival. The findings highlight the importance of jointly exploiting spatial selectivity and calibrated nonlinear modeling for robust wideband receiver linearization.