Method for applying combined algorithm to combined learning structure digital predistortion system

Abstract

The invention discloses a method for applying a combined algorithm to a combined learning structure digital predistortion system. Through combination of a classic crest factor restriction (CFR) technology and a digital predistoriton (DPD) technology, a combined learning structure design digital predistoriton system combining an indirect learning structure and a direct learning structure is provided according to advantages and disadvantages of the direction learning structure and the indirect learning structure; then according to advantages of an LMS algorithm, an RLS algorithm and a variable step size LMS, namely, NLMS algorithm, a combined algorithm combining RLS and NLMS is provided for estimating and updating parameters of a digital predistorter. The combined algorithm has the characteristic of rapid convergence of the RLS algorithm and also simplifies computation amount. CFR and DPD are sequentially performed on an input peak average ratio signal, then the processed signal is sent to a power amplifier, so that ideal linear output is obtained, and in-band distortion and out-band spectrum expansion caused by power amplifier non-linear are effectively relieved. Through adoption of the method, performance degradation of a broadband power amplifier caused by memory effect is relieved, furthermore, the linearity and efficiency of the broadband power amplifier are improved.

Description

technical field [0001] The invention relates to a linearization technology of a transmitting end power amplifier of a broadband digital communication system, in particular to a digital self-adaptive predistortion method. Background technique [0002] The power amplifier is an important component of the wireless communication system, and it is also one of the most important nonlinear devices. The nonlinearity of the power amplifier causes the signal to generate in-band and out-of-band distortion through the power amplifier, resulting in an increase in the bit error rate and interference to adjacent channels, thereby reducing the performance of the communication system. [0003] There are two ways to improve the linearity of the power amplifier, one is power back, the operating point of the power amplifier is back to the linear region, but the efficiency of the power amplifier is very low; the other is that the power amplifier is still working in the nonlinear region, the sign...

AI Technical Summary

Problems solved by technology

[0005] Currently, the indirect learning structure widely used in digital pre-distortion technology, in practice, the output signal of the power amplifier fed back to the adaptive algorithm module will be polluted by the quantization noise brought by the A / D converter, which will reduce the performance of the system; in addition, The current adaptive algorithms LMS algorithm and RLS algorithm have certain limitations.

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