Digital Pre-Distortion Term Shaping for Out-of-Band Emissions
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Solution Overview
Problem
Existing digital pre-distortion (DPD) techniques are limited in high power and high bandwidth situations, as they often require fixed terms and are inflexible, struggling to meet industry standards for adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) across wide frequency ranges.
Innovation Solution
The implementation of a shaping function that alters DPD coefficients to vary pre-distortion accuracy across frequency bands, using weight values based on electromagnetic emissions and ACLR profile data, converting these into time-domain shaping parameters to modify the pre-distortion function and reduce emissions in out-of-band frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed terms are used in digital pre-distortion, then device complexity is reduced, but manufacturing precision deteriorates because the system cannot meet ACLR and EVM standards across wide frequency ranges
Solution Approach 1:
The patent implements dynamic DPD terms that can be adjusted based on frequency band characteristics. The system transitions from fixed pre-distortion terms to dynamic terms that adapt to different operating conditions, allowing the DPD function to optimize performance across wide frequency ranges while maintaining manageable complexity through controlled adaptability.
Solution Approach 2:
The system changes DPD parameters (terms) based on frequency band and operating conditions. By modifying the pre-distortion function parameters dynamically according to the specific frequency range and signal characteristics, the system achieves high precision ACLR and EVM performance without requiring maximum complexity in all operating modes.
2Manufacturing precision
If pre-distortion accuracy is increased across all frequency bands, then manufacturing precision improves, but use of energy increases due to computational resource consumption
Solution Approach 1:
The patent applies different levels of pre-distortion accuracy to different frequency bands based on their specific requirements. Instead of uniformly high accuracy across all bands, the system optimizes computational resources by applying appropriate precision locally to each frequency range, reducing overall energy consumption while maintaining necessary performance standards.
Solution Approach 2:
The system applies full pre-distortion accuracy only where necessary rather than uniformly across all frequency bands. By using partial action (reduced computational effort) in frequency ranges that tolerate lower precision, the system achieves acceptable overall performance with significantly reduced energy consumption compared to maximum precision applied everywhere.
3Manufacturing precision
If flexible DPD terms are implemented to meet industry standards, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The patent implements dynamic DPD terms that adapt to frequency band and operating conditions. This dynamic approach provides the necessary flexibility to meet ACLR and EVM standards across wide frequency ranges while controlling complexity through systematic adaptation rather than unrestricted flexibility.
Solution Approach 2:
The system modifies DPD function parameters based on operating conditions and frequency band characteristics. By changing parameters dynamically rather than implementing maximum flexibility in the DPD structure, the system achieves compliance with industry standards while maintaining manageable device complexity through controlled parameter adaptation.
Data Source
AI summary
An example apparatus includes: memory having a terminal, the memory to store machine-readable instructions and adjacent channel leakage data; and programmable circuitry having a terminal coupled to the terminal of the memory, the programmable circuitry to execute the machine-readable instructions to: determine a range of out-of-band frequencies responsive to adjacent channel leakage ratio data; generate weight values responsive to electromagnetic emissions within the range of out-of-band frequencies of a first signal; modify a pre-distortion function responsive to the weight values; and apply the modified pre-distortion function to generate a second signal, the second signal to exhibit fewer emissions in the range of out-of-band frequencies than the first signal during transmission.