PA (power amplifier) non-linear effect eliminating method based on distorted constellation estimating and modulating

Abstract

The invention provides a PA (power amplifier) non-linear effect eliminating method based on distorted constellation estimating and modulating, which comprises the steps of receiving assisting sequences and data loads with the same modulating mode, and establishing the baseband model of the assisting sequences under the modulating mode, wherein the baseband model is constructed by standard constellation points and PA response functions; establishing distorted amplitude set and additional phase set of the distorted constellation points according to the baseband model; resolving the distorted amplitude set and additional phase set of the distorted constellation points according to the assisting sequences; obtaining the distorted constellation according to the distorted amplitude set and additional phase set of the distorted constellation points and the standard constellation point phases; and modulating the modulating signals of the data loads according to the resolved distorted constellation. The PA non-linear effect eliminating method based on distorted constellation estimating and modulating disclosed by the invention simplifies the design difficulty of a sending end radio frequency element by the digital signal processing of the baseband, and meanwhile, the receiving end only needs lower complexity and is lower in cost.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to a method for eliminating nonlinear influence of PA based on distortion constellation estimation and demodulation. Background technique [0002] In recent years, in order to meet the rapid development of wireless communication services, to achieve greater communication capacity within a limited frequency bandwidth, modulation methods with higher spectral efficiency, such as QAM, have been widely used. However, the signal power of these modulation methods has a large peak-to-average ratio, so there is a high requirement on the linearity of the power amplifier (PA, power amplifier). On the other hand, for high-frequency broadband communication, such as 60GHz, E-band, etc., the design of PA is close to the limit of CMOS technology, which will produce more prominent nonlinear phenomena, including AM-AM distortion and AM-PM distortion. AM-AM distortion is a manifestation of PA ...

AI Technical Summary

Problems solved by technology

However, the nonlinear models of different PAs are diverse, especially for high-frequency broadband communications such as 60 GHz, the PA model has high complexity, so that the predistorter can adjust the response according to the PA model. difficulty of implementation

[0007] (2) RF predistortion and intermediate frequency predistortion. Predistortion is constructed by selecting appropriate devices (such as diodes). This method is difficult to make adaptive adjustments according to the PA model, and it is difficult to make predistortion counteract PA nonlinear distortion. , which is very prominent when the PA nonlinear model is complex

Therefore, the ability of RF predistortion and IF predistortion to improve PA linearity is very limited

[0008] (3) Although baseband digital predistortion is easy to realize adaptive adjustment, its implementation complexity is very high

First of all, the RF signal output by the PA needs to be converted to digital baseband processing through an additional down-converter and ADC, which makes the implementation of the transmitter very expensive

Secondly, since the pre-distortion is implemented through a lookup table, to achieve better pre-distortion performance, a large number of entries need to be stored, which will undoubtedly increase the overhead of the system

In addition, the adaptive adjustment of pre-distortion can only update one entry at a time, so the efficiency is low, and it takes a long training time to store the entries to reach a stable convergence state

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