A Co-Frequency Nonlinear Interference Correction Scheme for Direct RF Sampling Receivers

In direct radio frequency (RF) sampling receivers, the nonlinear harmonics and crossmodulation distortions (XMDs) generated by high-power signals after the low-noise amplifier (LNA) may overlap with the target signal frequency and cause blocking. In this letter, a nonlinear postcorrection scheme with a novel harmonics and crossmodulation memory polynomial (HXMP) model is proposed. The postcorrection scheme uses a threshold filter to blindly extract a reference signal from the received signal. The HXMP model characterizes the harmonics and XMD introduced by multiple high-power interferences. Experimental results demonstrate that when nonlinear interference overlaps in frequency with the target signal, the proposed method can effectively enhance the target signal quality. Compared with other existing models, the HXMP model achieves higher fitting accuracy for XMD.