Baseband Predistortion Using Adaptive Nonlinear Filter Selection
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Solution Overview
Problem
Existing methods for improving the linearity of power amplifiers in 3G and B3G mobile communication systems, such as pre-distortion of base-band digital signals, are inefficient due to the need for specific nonlinear function designs that are not universally applicable, leading to low transmitter efficiency and complexity in implementation.
Innovation Solution
A device and method for pre-distorting base-band digital signals using an adaptive parameter calculation unit and a pre-distorter that selects nonlinear filter parameters based on the characteristics of the power amplifier and input signals, allowing for improved efficiency and universality across different wireless communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pre-distortion method with fixed nonlinear function is used, then the implementation is simple, but the method cannot be universally applied to different applications and power amplifier characteristics
Solution Approach 1:
The patent implements a dynamic parameter selection mechanism where the pre-distorter switches between different nonlinear filter parameter sets based on the instantaneous power level of the input signal. The parameter selection unit selects parameters from multiple stored sets corresponding to different power ranges, enabling the system to adapt to varying signal conditions and power amplifier characteristics without requiring complex real-time calculation
2Reliability
If feed forward scheme is used to improve power amplifier linearity, then linearity is improved, but the device complexity increases due to additional analogy radio frequency devices and high complexity in implementation
Solution Approach 1:
The patent replaces the complex analog feed-forward architecture with a digital signal processing approach. Instead of using additional analog radio frequency devices and complex analog adjustment networks, the invention implements pre-distortion through digital filtering and parameter selection in the baseband domain, significantly reducing device complexity while maintaining linearity improvement
Solution Approach 2:
The patent introduces a parameter selection unit as an intermediary between the input signal and the pre-distorter. This unit selects appropriate nonlinear filter parameters based on signal power statistics, acting as a mediator that adapts the pre-distortion characteristics without requiring complex real-time computation or additional analog components
3Productivity
If traditional pre-distortion method is used, then the base-band digital signal is preprocessed, but the transmitter efficiency remains low due to inability to adapt to different power amplifier characteristics
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing multiple sets of nonlinear filter parameters corresponding to different power ranges and power amplifier characteristics. These parameter sets are prepared in advance and stored in memory, allowing the system to quickly switch between them based on current operating conditions without performing complex real-time calculations, thus maintaining both high processing speed and adaptability
Data Source
AI summary
A device and method for pre-distorting a base-band digital signal. The device includes an adaptive parameter calculation unit and a pre-distorter. The adaptive parameter calculation unit is adapted to calculate nonlinear filter parameters in accordance with samples of a base-band digital signal and a feedback signal of a radio frequency channel, and output a calculation result to the pre-distorter. The pre-distorter is adapted to store and update the nonlinear filter parameters, perform power statistics of the base-band digital signal, select nonlinear filter parameters corresponding to a result of the power statistics, pre-distort the base-band digital signal, and output the pre-distorted base-band digital signal. With the method, the non-linearity of a power amplifier may be improved, different non-linearity inverse models may be selected according to different input signals and power amplifier characteristics, and the efficiency of a base station transmitter may be improved.