Scalable Single-Input Behavioral Modeling Architecture for MIMO Systems With Crosstalk

The inherent nonlinear behavior exhibited by power amplifiers (PAs) in saturation mode is a major impediment in wireless systems to achieve higher power efficiency, and higher spectral efficiency. Although PA behavioral modeling and digital predistortion (DPD) techniques are widely utilized at transmitter to characterize and linearize such distorted nonlinear output of PAs, the nonlinear distortions with memory effects have become more severe due to simultaneous strong crosstalk between multiple PA branches in multiple-input multiple-output (MIMO) arrays. Furthermore, current multi-input behavioral models suffer from a sharp increase in number of coefficients as the number of transmitter path increases in MIMO. In overcoming these challenges, we propose a decomposed cross-correlation based single-input-single-output (CC-SISO) behavioral modeling architecture. The proposed solution utilizes a low-cost, novel cross-correlation based method to estimate and cancel the simultaneous nonlinear and reverse crosstalk from multiple PA branches. Once the crosstalk is mitigated, the MIMO DPD can be implemented with single-input DPD blocks which significantly reduces the complexity. Furthermore, CC-SISO DPD eliminates the requirement for signal feedback paths before and after the PA, and thus reduces overall hardware implementation complexity. Through simulations, we demonstrate that the proposed CC-SISO architecture can reduce the overall complexity of state-of-art multi-input DPD models for MIMO systems.

Automated summary

The nonlinear distortions with memory effects caused by strong crosstalk between multiple power amplifier (PA) branches in multiple-input multiple-output (MIMO) systems pose challenges for behavioral modeling and linearization techniques. In this study, a decomposed cross-correlation based single-input-single-output (CC-SISO) architecture is proposed to estimate and cancel the simultaneous nonlinear and reverse crosstalk in PAs. This architecture significantly reduces the complexity of MIMO digital predistortion (DPD) models and eliminates the need for signal feedback paths, thus simplifying hardware implementation.