FR2 Multi-Antenna Digital Pre-Distortion With a Single LUT
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Solution Overview
Problem
Power amplifiers in wireless communication systems, particularly in frequency range 2 (FR2), exhibit inherent non-linearity causing in-band distortion and degradation of signal quality, which is exacerbated by the use of multiple transmit antennas, necessitating improved digital pre-distortion (DPD) techniques.
Innovation Solution
A method for DPD in FR2 systems with multiple antennas involves generating a single look-up-table (LUT) by combining loop-back signals from all antenna paths, determining PA polynomials, and applying a single LUT to compensate for non-linearity, using dual power DPD training to improve performance across all power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate LUTs are used for each antenna path to compensate for PA non-linearity, then the EVM performance for each antenna is improved, but the storage requirements and system complexity increase significantly
Solution Approach 1:
The patent combines loop-back signals from multiple antenna paths to generate a single combined signal, then determines a single set of PA polynomials and generates one LUT that compensates for PA non-linearity across all antenna paths. This merging approach maintains EVM performance while significantly reducing storage requirements compared to maintaining separate LUTs for each antenna.
Solution Approach 2:
The single generated LUT serves as a universal compensation table for all antenna paths in the FR2 system. By designing the DPD block to consider PA characteristics of all antennas through the combined signal approach, one LUT performs the pre-distortion function for multiple antennas, eliminating the need for antenna-specific LUTs.
2Measurement precision
If multiple separate LUTs are used for each antenna path, then the EVM performance is improved, but the system implementation becomes more complex
Solution Approach 1:
The patent merges the DPD processing for multiple antennas into a unified approach where a single LUT is generated and applied to all antenna paths. This simplifies software implementation by eliminating the need for separate LUT management, memory allocation, and processing logic for each antenna, while still achieving effective PA non-linearity compensation.
3Device complexity
If traditional DPD methods are used without considering multiple antenna characteristics, then the implementation is simpler, but the EVM performance degrades in FR2 systems
Solution Approach 1:
The patent employs a feedback mechanism where loop-back signals from multiple antenna paths are captured and combined. This feedback information is used to determine PA polynomials that accurately characterize the non-linearity across all antennas, enabling the generation of an LUT that improves EVM performance while maintaining a relatively simple implementation structure.
Data Source
AI summary
Methods and devices are provided in which a processor of a user equipment (UE) combines loop-back signals from a plurality of antenna paths of the UE to generate a combined signal. The loop-back signals are based on a signal transmitted over the antenna paths. The processor determines power amplifier (PA) polynomials based on a comparison of the combined signal to the signal transmitted over the antenna paths. The processor generates a single look-up table (LUT) for the PA polynomials. The processor applies the single LUT to a transmitted signal of the UE to compensate for PA non-linearity.