Digital Pre-Distortion Feedback Training for Multi-Antenna Power Amplifiers
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Solution Overview
Problem
Current digital pre-distortion methods for power amplifiers in wideband multi-carrier wireless communication systems face challenges in achieving high linearity and efficiency, particularly due to high transmission power and peak-to-average power ratio, leading to significant out-of-band interference and inefficient power amplifier operation.
Innovation Solution
A digital pre-distortion processing method and apparatus that transmits a specific training signal to radio frequency front-end devices, acquires and updates DPD coefficients, allowing for periodic or non-periodic training without real-time operation, enabling efficient compensation of nonlinearity and accommodating multi-antenna applications without increasing apparatus volume or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If power amplifier operates at high transmission power to improve system capacity, then productivity increases, but linearity deteriorates causing out-of-band interference
Solution Approach 1:
The patent applies digital pre-distortion technology that performs preliminary compensation of nonlinear distortion before the signal enters the power amplifier. By pre-modifying the input signal to anticipate and counteract the amplifier's nonlinear behavior, the system can operate at high power while maintaining linearity and reducing out-of-band interference.
Solution Approach 2:
The patent implements a feedback mechanism where the output signal from the power amplifier is captured, processed, and used to update the pre-distortion coefficients. This closed-loop feedback allows the system to continuously adapt and optimize the pre-distortion parameters based on actual amplifier behavior, improving linearity while maintaining high transmission power.
2Object-generated harmful factors
If power back-off is applied to maintain linearity, then out-of-band interference reduces, but efficiency of power amplifier drops below 10%
Solution Approach 1:
Instead of reducing input power (power back-off), the patent applies preliminary digital pre-distortion to the input signal. This allows the power amplifier to operate at full power with high efficiency while the pre-distortion preprocessing compensates for nonlinear effects, eliminating the need for power back-off and its associated efficiency losses.
3Measurement precision
If separate DPD feedback channels are provided for each antenna to improve linearity, then measurement precision increases, but device complexity and volume increase
Solution Approach 1:
The patent merges the feedback channels of multiple antennas into a single shared feedback path. The output signals from multiple power amplifiers are combined and fed back through a common analog-to-digital converter and processing chain, enabling DPD coefficient training for multiple antennas without requiring separate feedback hardware for each antenna, thus reducing device complexity and volume.
Solution Approach 2:
The patent implements a universal feedback processing system that handles multiple antenna signals through a single feedback channel. The shared analog-to-digital converter and processing infrastructure serve multiple antennas simultaneously, providing multi-functionality that reduces hardware requirements while maintaining the ability to train DPD coefficients for each antenna.
Data Source
AI summary
This invention discloses a for digital pre-distortion processing method and apparatus, the method including that: training signals are sent to at least one radio frequency front-end device as needed (201); the output training signals of the radio frequency front-end devices are collected through a feedback channel as needed (202); digital pre-distortion (DPD) coefficients of the radio frequency front-end devices are trained as needed (203); after the coefficient training is completed, the DPD coefficients of the corresponding radio frequency front-end devices are updated as needed. There is no need to track the variation of the signals all the time and to compare the signals with a long-time statistical signal template to trigger the training in the invention. The invention can accommodate a multi-antennas application without configuring a corresponding digital pre-distortion feedback channel and coefficient training module separately for each antenna, thereby when the antennas are increased, the volume and cost are not increased and the invention can be of good feasibility from the perspective of commercialization.