Low-Complexity Sub-band Digital Predistortion for Spurious Emission Suppression in Noncontiguous Spectrum Access

TL;DR

This paper introduces a low-complexity sub-band digital predistortion method tailored for noncontiguous spectrum access, effectively suppressing unwanted emissions in low-cost radio transmitters with adaptive parameter learning.

Contribution

It presents a novel sub-band DPD approach that targets specific spurious emissions, reducing computational complexity and enabling adaptive tracking in practical scenarios.

Findings

Effective suppression of spurious emissions demonstrated in simulations and RF tests.

Reduced complexity in parameter estimation compared to traditional methods.

Successful application to LTE-Advanced PA in real-world conditions.

Abstract

Noncontiguous transmission schemes combined with high power-efficiency requirements pose big challenges for radio transmitter and power amplifier (PA) design and implementation. Due to the nonlinear nature of the PA, severe unwanted emissions can occur, which can potentially interfere with neighboring channel signals or even desensitize the own receiver in frequency division duplexing (FDD) transceivers. In this article, to suppress such unwanted emissions, a low-complexity sub-band DPD solution, specifically tailored for spectrally noncontiguous transmission schemes in low-cost devices, is proposed. The proposed technique aims at mitigating only the selected spurious intermodulation distortion components at the PA output, hence allowing for substantially reduced processing complexity compared to classical linearization solutions. Furthermore, novel decorrelation based parameter learning solutions are also proposed and formulated, which offer reduced computing complexity in parameter estimation as well as the ability to track time-varying features adaptively. Comprehensive simulation and RF measurement results are provided, using a commercial LTE-Advanced mobile PA, to evaluate and validate the effectiveness of the proposed solution in real world scenarios. The obtained results demonstrate that highly efficient spurious component suppression can be obtained using the proposed solutions.