Multi-band DPD System Using Address Conversion Tables
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Solution Overview
Problem
Existing Digital PreDistortion (DPD) systems are primarily designed for single-band applications and are not suitable for multi-band systems, as they use uniform quantization and a single look-up table for different bands, which limits their effectiveness in handling signals across multiple frequency bands.
Innovation Solution
A DPD system is developed that includes multiple address conversion tables and look-up tables to generate look-up addresses for DPD coefficients, allowing for multi-band processing by combining bit sequences from different bands, enabling efficient DPD processing across various frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If uniform quantization is used for LUT address generation in single-band DPD systems, then the system is simple to implement, but it cannot be applied to multi-band DPD systems
Solution Approach 1:
The patent divides the multi-band signal processing into separate address conversion tables for each band (first address conversion table for first band, second address conversion table for second band, etc.). Each table handles amplitude quantization independently, allowing the system to process multiple bands simultaneously while maintaining the simplicity of uniform quantization within each band.
Solution Approach 2:
The patent extends the single-band LUT address generation to multi-band by adding a new dimension - the band index. Instead of a single amplitude-based address, the system now uses combination addresses formed by concatenating band-specific address sequences. This dimensional extension allows independent quantization tables for each band while maintaining overall system coherence.
2Measurement precision
If a single look-up table is used for multiple bands, then the device complexity is reduced, but the measurement precision and DPD accuracy deteriorate
Solution Approach 1:
The patent applies local quality by creating band-specific address conversion tables where each table is optimized for its particular frequency band's characteristics. The first address conversion table is tailored for the first band's amplitude distribution, the second for the second band, and so on. This allows each band to have locally optimized quantization precision without compromising other bands.
Solution Approach 2:
The patent creates a universal address conversion framework that can handle multiple bands through a standardized process. Each band has its own address conversion table, but they all follow the same structure and methodology. The combination address formation process is universal across bands, allowing the system to maintain consistency while achieving band-specific precision.
3Productivity
If direct truncation of signal amplitude is used for LUT address generation, then the process is simple, but it is unsuitable for multi-band DPD systems
Solution Approach 1:
The patent segments the amplitude truncation process into band-specific operations. Instead of directly truncating the combined multi-band signal amplitude, the system first processes each band's amplitude separately through its own address conversion table, then combines the resulting address sequences. This segmentation maintains the efficiency of direct truncation while enabling multi-band compatibility.
Solution Approach 2:
The patent introduces an intermediary step - the address conversion table - that mediates between the raw signal amplitude and the final LUT address. The address conversion table transforms the amplitude information in a band-specific manner before combination, serving as an intermediary that enables multi-band processing while maintaining processing efficiency through standardized transformation operations.
Data Source
Figure 1~2A
Figure 2B~3
Figure 4A~4B
AI summary
Disclosed is a DPD system. A DPD system provided in an embodiment of the present invention includes a table look-up unit and a DPD processing unit. First to Nth look-up-tables are used to combine two bit sequences of bit sequences obtained according to first to fourth address conversion tables so as to obtain first to Nth table look-up addresses. First to Nth DPD coefficients are found according to the first to Nth table look-up addresses, and one DPD coefficient is obtained via a DPD coefficient combination module, such that the DPD processing unit can perform DPD processing on a signal in first band according to the DPD coefficient. In the embodiment of the present invention, a look-up address is obtained according to four address conversion tables, a DPD coefficient is obtained from a look-up-table according to the look-up address, and then a final DPD coefficient is obtained to perform signal processing. Thereby, a look-up address generation solution is provided for a multi-band DPD system to realize multi-band DPD processing.