Spectral Weighting Orthogonal Matching Pursuit Algorithm for Enhanced Out-of-Band Digital Predistortion Linearization

Abstract

This paper presents a new variant of the orthogonal matching pursuit (OMP) algorithm for reducing the computational complexity of the digital predistortion (DPD) behavioral model in the forward path. The proposed spectral weighting OMP (SW-OMP) algorithm focuses on selecting the most relevant basis functions to compensate for the out-of-band residual distortion which may eventually be masked by the dominant in-band residual error. This basis selection is carried out in an off-line process that does not affect the computational complexity of the real-time closed-loop DPD but, on the contrary, reduces its complexity while enhancing the robustness. Experimental results show that by selecting the DPD coefficients with the SW-OMP, the inherent ACLR and NMSE degradation suffered when reducing the number of coefficients is mitigated under strong nonlinear operation, when compared to using the basis functions selected by the classical OMP algorithm.

Digital Predistorters Go Multidimensional: DPD for Concurrent Multiband Envelope Tracking and Outphasing Power Amplifiers

“…8-right shows the dual-band output spectra of a hybrid outphasing PA before and after 3-D DPD linearization where again, dimensionality reduction techniques are applied to keep the number of coefficients below 100. On the one hand, to select the most relevant basis of the DPD function in the forward path, a greedy algorithm such as for example the orthogonal matching pursuit (OMP) [30], [44] can be used; on the other hand, feature extraction techniques such as the principal component analysis (PCA) [45] or the partial least squares (PLS) [30] can be used to reduce the number of basis in the adaptation subsystem. Fig.…”

Digital Signal Recovery With Transmitter Nonlinear State Tracking for Satellite Communications

“…I N order to enhance the efficiency of space-borne power amplifiers (PAs) while maintaining good linearity of the transmitted signal, PA linearization techniques such as digital pre-distortion (DPD) [1]- [6] methods based on the memory polynomial (MP) model have been widely used. Owing to the fact that it neither increases complexity nor power consumption of the satellite system, digital post-distortion (DPoD) [7]- [9] methods which correct the nonlinear distortion of the signal received at the receiver side is more appealing for satellite to ground communications.…”