Beam-Oriented Digital Predistortion for Side Lobe Distortion Control
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Solution Overview
Problem
Traditional digital predistortion technologies are inefficient for 5G or Massive MIMO systems due to high resource consumption and inability to suppress non-linear distortion of side lobes, leading to interference and reduced coverage.
Innovation Solution
A digital predistortion method that redistributes predistortion components using weighting coefficients determined by the digital baseband signal and synthesized signals in the main lobe direction, minimizing non-linear distortion in other directions while maintaining signal quality in the main lobe direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional digital predistortion is applied to each power amplifier in 5G or Massive MIMO systems, then each power amplifier can be linearized, but calculating and hardware resource consumption becomes unacceptable, increasing equipment volume and power
Solution Approach 1:
The patent segments the predistortion function by direction rather than by power amplifier. It divides the beam space into main lobe direction and other directions, applying different predistortion strategies to each segment. This segmentation allows the system to focus computational resources only where needed (main lobe) while using simpler processing for other directions, thereby reducing overall hardware resource consumption while maintaining linearization performance.
Solution Approach 2:
The patent applies local quality by implementing direction-specific predistortion processing. The main lobe direction receives full predistortion processing to ensure high signal quality for users, while other directions use simplified processing. This localized approach optimizes resource allocation by providing high-quality predistortion only where it matters most (main lobe) rather than uniformly across all directions, reducing overall computational complexity.
2Device complexity
If beam-oriented digital predistortion is used to save hardware resources, then resource consumption is reduced and main lobe signal quality is guaranteed, but non-linear distortion of side lobe cannot be suppressed and may even deteriorate, affecting coverage and generating interference
Solution Approach 1:
The patent introduces weighting coefficients as an intermediary mechanism to balance predistortion application across different directions. These weighting coefficients act as mediators that control the strength of predistortion applied to each direction, allowing the system to suppress side lobe distortion while maintaining main lobe performance. The weighting coefficients enable fine-grained control over predistortion distribution, preventing the deterioration of side lobe signals that occurs in conventional beam-oriented approaches.
Solution Approach 2:
The patent dynamically adjusts the weighting coefficients based on signal characteristics and direction. By changing the parameter values of weighting coefficients, the system can adaptively control the predistortion strength for different directions. This parameter adjustment allows suppression of side lobe non-linear distortion while maintaining optimal main lobe signal quality, resolving the contradiction between resource efficiency and distortion suppression.
3Device complexity
If beam-oriented digital predistortion is applied, then hardware resource consumption is reduced, but interference between stations and users increases due to unsuppressed side lobe distortion
Solution Approach 1:
The weighting coefficients serve as intermediaries that control the spatial distribution of predistortion effects. By carefully designing these weighting coefficients, the system can suppress side lobe distortion that causes interference to other stations and users, while maintaining resource efficiency. The weighting coefficients mediate between the conflicting requirements of resource conservation and interference reduction, enabling both goals to be achieved simultaneously.
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AI summary
The disclosure discloses a digital predistortion (DPD) device and method. The DPD device comprises a predistorter configured to obtain a predistortion component from a digital baseband signal using a predistortion parameter and output the predistortion component; and a weighting unit configured to: obtain one or more weighted predistortion components by applying the predistortion component to one or more weighting coefficients, and obtain one or more predistortion correction signals by combining the digital baseband signal and the one or more weighted predistortion components, wherein the one or more weighting coefficients are determined based on the digital baseband signal, the predistortion component, and a synthesized signal in a main lobe direction obtained by combining radio frequency signals from a beamforming array.