Hybrid Look-Up-Tables Based Behavioral Model for Dynamic Nonlinear Power Amplifiers

Abstract

A new look-up table based behavioral model for dynamic nonlinear power amplifiers is proposed. This model labelled as hybrid look-up tables model is based on the combination of a memoryless look-up table sub-model and a nested look-up tables one. It is demonstrated that the proposed model circumvents the computational complexity associated with the parameters identification in analytically defined behavioral models. Moreover, the proposed model reduces the size of the standalone nested look-up tables model by approximately 80% while maintaining its accuracy. Furthermore, a novel slew-rate based trimming and indexing technique to reduce the nested look-up tables model size is developed and corroborated experimentally. Additionally, the two-box structure of the hybrid look-up tables model makes it suitable for bandwidth scalability. Experimental validation using LTE-advanced test signals with up to 120MHz bandwidth demonstrates the ability of the proposed hybrid look-up tables model to be bandwidth scalable with less than 0.5dB degradation in the normalized mean-squared error. INDEX TERMS Behavioral modeling, dynamic distortion, look-up table, memory effects, nonlinear distortions, power amplifier (PA).

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“…However, their memory-less nature forbids its implementation towards the dynamical realistic MIMO PAs driven by a digital baseband processing module. For this purpose, Dalbah et al [95] have taken the impact of MEs for dynamic nonlinear systems in the bandwidth range of 100 MHz by deploying a typical memory-less LUT with a hybrid LUT-based model referred to as nested LUT sub-model. Since the MIMO beam scanning constitutes an impulsive coefficient learning of high data rates and beamforming algorithms, and as a result, the bottlenecks of computational intensiveness hinder the iterative runtime of dense memory depth orders [85], [96].…”

Research on robust adaptive sliding film fault-tolerant control under nonlinear distortion of signal transmission in amorphous flat air-to-ground wireless ad-hoc network system

“…This paper uses the power series model as the nonlinear mathematical model of the power amplifier. In the literature (Dalbah et al , 2020; Wang et al , 2019c; Pérez-Hernández et al , 2021), the baseband equivalent input and output relationship are shown in equation (1): where i denotes the i-th wireless communication transmit link. To make a clarification here, the power amplifier because it is at the transmitting end of the subsystem, i can denote both the i-th subsystem and the transmitting link of the i - th subsystem.…”

“…This paper uses the power series model as the nonlinear mathematical model of the power amplifier. In the literature (Dalbah et al, 2020;Wang et al, 2019c;Pérez-Hern andez et al, 2021), the baseband equivalent input and output relationship are shown in equation ( 1):…”

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“…This model compensates for static distortions but has limited performance in the presence of strong memory effects. Other models that can be considered as suitable candidates for RF digital predistortion are the nested look-up tables based predistorters [23]- [24]. However, these typically require extensive processing to synthesize the nested LUT which usually has a very large size.…”