Digital Predistortion Bandwidth Limiting for Ultra-Wideband Feedback
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Solution Overview
Problem
Existing digital predistortion models face challenges in ultra-wideband systems due to bandwidth limitations, leading to inaccuracies in predistortion parameters and increased costs for high bandwidth and sampling rate requirements in feedback channels.
Innovation Solution
The method involves performing non-linear processing on input signals, applying bandwidth limitation to obtain higher-order output signals within a preset bandwidth, and calculating corresponding coefficients for superposition to ensure predistortion accuracy while reducing the required bandwidth and sampling rate of the feedback channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If polynomial-based DPD models (e.g., fifth-order MP model) are used to ensure predistortion accuracy, then predistortion accuracy is improved, but the required output sampling signal bandwidth becomes five times the input signal bandwidth, which cannot be implemented in ultra-wideband systems
Solution Approach 1:
The patent segments the DPD model into multiple sub-models with different polynomial orders, each handling specific frequency bands or signal components. This allows the system to achieve high predistortion accuracy for the target bandwidth without requiring the full bandwidth expansion that a single high-order model would demand
Solution Approach 2:
The patent applies different polynomial orders and model parameters to different frequency regions or signal characteristics. By tailoring the model complexity locally to match the actual distortion characteristics in each region, the system achieves accurate predistortion where needed while avoiding unnecessary bandwidth requirements
2Measurement precision
If the bandwidth and sampling rate of the feedback channel are increased to match the DPD model requirements, then predistortion accuracy is improved, but predistortion cost increases
Solution Approach 1:
The patent implements partial action by collecting only the necessary portion of the output signal bandwidth that is required for accurate predistortion parameter calculation. Instead of collecting the full bandwidth that a traditional high-order model would require, the system collects only the relevant frequency components, reducing feedback channel requirements and cost while maintaining accuracy
3Quantity of substance
If the bandwidth and sampling rate of the feedback channel are reduced to lower predistortion cost, then predistortion cost is reduced, but predistortion accuracy cannot be ensured
Solution Approach 1:
The patent changes the parameters of the DPD model, specifically using lower polynomial orders and adjusting model coefficients to match the actual collected signal bandwidth. This allows the system to achieve accurate predistortion with reduced feedback channel bandwidth and sampling rate, lowering cost while maintaining accuracy through optimized model parameters
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AI summary
A predistortion correction method, a predistortion correction apparatus, a transmitter, and a base station are provided. The method includes: performing, based on a digital predistortion model, non-linear processing on an input transmit signal to obtain higher-order distortion time-domain signals; and obtaining, after performing processing on the higher-order distortion time-domain signals, a predistortion signal to be input to a power amplifier, where a process of converting the higher-order distortion time-domain signals to the predistortion signal includes bandwidth limitation processing, so that the predistortion signal to be input to the power amplifier is a predistortion signal within a preset bandwidth. Embodiments of the present invention can ensure predistortion accuracy, and can also reduce a requirement for a bandwidth and a sampling rate of a feedback channel, thereby reducing a predistortion cost.