Multi-Band Crest Factor Reduction for Balanced Clipping Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio frequency units face challenges in efficiently processing signals across multiple frequency bands, leading to increased signal processing effort and potential degradation in performance due to crest factor reduction and clipping limitations.
Innovation Solution
The implementation of a dual-band and multi-band crest factor reduction (CFR) technique that utilizes a preview signal to balance clipping noise between RF bands, reducing the need for high sampling rates and maintaining performance without increasing the peak-to-average power ratio (PAR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wideband CFR is used to process multi-band signals, then crest factor reduction is achieved, but signal processing effort increases significantly
Solution Approach 1:
The patent divides the wideband signal into multiple frequency bands (e.g., low band and high band) and processes each band separately. This segmentation allows the CFR algorithm to operate on narrower bandwidths, reducing the computational complexity and processing effort while maintaining effective crest factor reduction in each band
Solution Approach 2:
The patent transforms the time-domain CFR problem into a frequency-domain problem by applying FFT to convert time-domain signals into frequency-domain representations. This allows independent processing of different frequency bands, reducing the overall processing effort compared to direct time-domain wideband processing
2Reliability
If clipping is applied to reduce peak power, then crest factor is reduced, but clipping noise is generated and distributed unevenly across bands
Solution Approach 1:
The patent applies clipping separately to each frequency band rather than to the combined wideband signal. This segmentation ensures that clipping noise is generated independently in each band and can be controlled separately, preventing excessive clipping noise in any single band while maintaining overall peak power control
Solution Approach 2:
The patent adjusts clipping thresholds and parameters individually for each frequency band based on the specific characteristics of that band. This local optimization ensures that clipping is applied appropriately in each band, minimizing clipping noise generation while achieving the required crest factor reduction
3Measurement precision
If high sampling rates are used for multi-band CFR processing, then processing accuracy is maintained, but hardware resource requirements increase
Solution Approach 1:
The patent processes each frequency band at its own appropriate sampling rate rather than using a single high sampling rate for the entire wideband signal. This allows the system to maintain processing accuracy for each band while significantly reducing the overall hardware resource requirements, as the sampling rate can be optimized independently for each band
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method comprising: obtaining a first radio signal and a second radio signal, determining a first envelope signal based on the first radio signal and a second envelope signal based on the second radio signal, determining a preview envelope signal based on the first envelope signal and the second envelope signal, determining a common clipping gain signal based on the preview envelope signal, determining a first clipping gain signal based on the common clipping gain signal and a first weighing factor, determining a second clipping gain signal based on the common clipping gain signal and a second weighing factor, performing a first crest factor reduction for the first radio signal utilizing the first clipping gain signal, and performing a second crest factor reduction for the second radio signal utilizing the second clipping gain signal.