Multi-Band Digital Predistortion with Reduced-Dimension LUTs
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Solution Overview
Problem
Multi-band digital pre-distortion (DPD) systems face impractical complexity and memory requirements due to the exponential growth of multi-dimensional look-up tables (LUTs) and polynomial models, making them challenging to implement effectively for non-linear systems like power amplifiers.
Innovation Solution
The implementation of reduced-dimension look-up tables (LUTs) and polynomial terms, such as 1D or 2D LUTs combined with 1D or 2D polynomial terms, to perform multi-band DPD, reducing computational burden and memory size while maintaining effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-dimensional LUTs or polynomial models are used for multi-band DPD, then linearization effectiveness is improved, but device complexity and memory requirements grow exponentially
Solution Approach 1:
The patent segments the multi-dimensional DPD problem into multiple one-dimensional LUTs, each handling a specific frequency band. Instead of using a single multi-dimensional LUT that would require exponential memory, the system divides the problem into manageable 1D LUTs that can be computed and stored separately, then combines their outputs to achieve the overall DPD effect.
Solution Approach 2:
The patent merges the outputs of multiple 1D LUTs to produce the final DPD result. By combining the results from separate 1D LUTs (each handling different frequency bands), the system achieves multi-band DPD functionality without requiring a multi-dimensional LUT structure, thus reducing computational and memory complexity.
2Measurement precision
If multi-dimensional LUTs are used for multi-band DPD, then linearization accuracy is improved, but memory size becomes impractical
Solution Approach 1:
The patent segments the large multi-dimensional LUT into multiple small 1D LUTs. Each 1D LUT stores only the data necessary for a single frequency band, dramatically reducing total memory requirements compared to a multi-dimensional LUT that would need to store all combinations of frequency band inputs simultaneously.
3Reliability
If high sampling rates are used for multi-band DPD, then linearization performance is improved, but processing speed requirements increase
Solution Approach 1:
The patent segments the high-rate sampling problem into multiple lower-rate 1D LUT operations, one for each frequency band. By processing each band separately at its required rate and combining results, the system achieves high-performance multi-band DPD without requiring a single ultra-high-speed processor to handle all bands simultaneously.
Data Source
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AI summary
A system and method for multi-band digital pre-distortion (DPD) for a non-linear system. The system includes a DPD circuitry configured to perform multi-band DPD on a multi-band input signal to compensate for a non-linearity of a non-linear system. The multi-band input signal includes input signals of multiple frequency bands and the DPD circuitry is configured to perform DPD on an input signal of each frequency band per frequency band. The DPD circuitry is configured to perform the DPD using a combination of a look-up table (LUT) that evaluates a non-linear function and computation of terms of a non-linear polynomial of one or more variables representing the input signals of multiple frequency bands. Both the non-linear function and the non-linear polynomial are in a reduced dimension lower than a dimension of the multi-band input signal.