Array Transmitter Predistortion for Power Amplifier Nonlinearity
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Solution Overview
Problem
Power amplifiers in wireless communication systems become non-linear when driven close to saturation, leading to significant distortion in output signals, which affects power efficiency and causes in-band and out-of-band interference.
Innovation Solution
Implementing a digital predistorter (DPD) that predistorts the input signal based on predistortion coefficients to cancel out the non-linear distortion of the power amplifier, allowing the amplifier to operate closer to saturation while reducing distortion, using either a separate DPD for each antenna or a shared DPD optimized for the entire antenna array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power amplifiers are driven close to saturation for power efficiency, then power efficiency is improved, but non-linear distortion increases significantly
Solution Approach 1:
The patent applies preliminary action by implementing a digital predistorter that pre-compensates the input signal before it reaches the power amplifier. The predistorter applies inverse non-linear characteristics to the input signal, so that when the signal passes through the non-linear power amplifier, the distortion is canceled out. This allows the PA to operate close to saturation for power efficiency while maintaining signal integrity.
Solution Approach 2:
The patent implements preliminary anti-action by introducing a predistorter that generates an opposing non-linear distortion before the signal enters the power amplifier. The predistorter applies coefficients that create distortion opposite in nature to the PA's non-linearity, effectively neutralizing the harmful distortion effects while allowing high-power operation.
2Power
If separate power amplifiers are used for each antenna in the array, then transmission power capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies merging by combining multiple separate predistortion functions into a single shared digital predistorter for the entire antenna array. Instead of implementing individual DPD circuits for each PA, one predistorter processes signals for all antennas, significantly reducing device complexity and cost while maintaining the power capability of multiple PAs.
Solution Approach 2:
The patent implements universality by designing a single digital predistorter that serves multiple power amplifiers across the antenna array. This universal predistorter structure performs the same distortion compensation function for all PAs simultaneously, reducing overall system complexity while preserving the transmission power capabilities of the multi-antenna configuration.
3Manufacturing precision
If separate predistortion systems are implemented for each antenna, then distortion compensation accuracy is improved, but cost and complexity increase significantly
Solution Approach 1:
The patent applies merging by consolidating multiple independent predistortion systems into a single shared digital predistorter that serves the entire antenna array. This unified approach reduces complexity and cost by eliminating redundant circuits while maintaining effective distortion compensation through centralized coefficient management and signal processing.
Data Source
AI summary
In certain aspects of the present disclosure, a method for wireless communication comprises predistorting a first signal based on a set of coefficients to generate a first predistorted signal, outputting the first predistorted signal for a first transmission to a receiving device, and receiving a first feedback signal from the receiving device, wherein the first feedback signal provides feedback of a first receive signal at the receiving device corresponding to the first transmission. The method also comprises determining whether to store the set of coefficients in a memory based on the received first feedback signal, and storing the set of coefficients in the memory based on the determination.