Two-Threshold Peak Cancellation for Single-Iteration PAPR Reduction
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Solution Overview
Problem
Conventional peak cancellation Crest Factor Reduction (CFR) techniques require multiple iterations to achieve target PAPR, leading to peak regrowth, increased error vector magnitude (EVM), and algorithm complexity.
Innovation Solution
Implementing a peak cancellation CFR method with two thresholds, where the first threshold is used for peak detection and the second for hard clipping, allowing for peak clustering and single-iteration cancellation with scaled pulses, reducing EVM and algorithm complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional peak cancellation CFR technique is used with multiple iterations, then target PAPR can be achieved, but peak regrowth occurs and EVM increases
Solution Approach 1:
The patent segments the peak cancellation process into two distinct threshold levels: a first threshold for initial peak detection and a second (lower) threshold for final hard clipping. This segmentation allows the system to identify and cancel peaks above the first threshold in a single iteration, then apply hard clipping to any remaining peaks above the second threshold, achieving target PAPR without the need for multiple iterations that cause peak regrowth and EVM degradation.
Solution Approach 2:
The patent changes the parameter of threshold levels by introducing two distinct thresholds instead of using a single threshold repeatedly. The first threshold is set higher to capture significant peaks, while the second threshold is set lower for final compression. This parameter change enables effective PAPR reduction in one iteration while maintaining signal quality, avoiding the peak regrowth issues that occur with conventional single-threshold multi-iteration approaches.
2Manufacturing precision
If multiple iterations are performed in peak cancellation CFR, then PAPR target is reached, but algorithm complexity increases
Solution Approach 1:
The patent segments the peak cancellation process into two distinct threshold levels: a first threshold for initial peak detection and a second (lower) threshold for final hard clipping. This segmentation allows the system to identify and cancel peaks above the first threshold in a single iteration, then apply hard clipping to any remaining peaks above the second threshold, achieving target PAPR without the need for multiple iterations that cause peak regrowth and EVM degradation.
Solution Approach 2:
The patent skips the conventional multi-iteration process by using a two-threshold approach that achieves PAPR reduction in a single iteration. By detecting peaks above the first threshold and canceling them immediately, then applying hard clipping for any remaining peaks above the second threshold, the system rushes through the PAPR reduction process in one pass, avoiding the computational overhead and complexity of multiple iterative cycles.
3Manufacturing precision
If hard clipping is applied to reduce large peaks, then PAPR is reduced, but out-of-band radiation increases due to sharp corners
Solution Approach 1:
The patent applies preliminary peak cancellation before hard clipping by first detecting and canceling peaks that exceed the first threshold. This preliminary action removes the most significant peaks that contribute to high PAPR, allowing the subsequent hard clipping at the lower second threshold to operate on a already-compressed signal with fewer extreme values, thereby reducing the generation of sharp corners and associated out-of-band radiation.
Solution Approach 2:
The patent changes the parameter of threshold levels by introducing two distinct thresholds instead of using a single threshold repeatedly. The first threshold is set higher to capture significant peaks, while the second threshold is set lower for final compression. This parameter change enables effective PAPR reduction in one iteration while maintaining signal quality, avoiding the peak regrowth issues that occur with conventional single-threshold multi-iteration approaches.
Data Source
AI summary
An apparatus and method for performing crest factor reduction (CFR). A peak detection circuit detects peaks from input signal samples based on a first threshold. The first threshold is higher than a second threshold that is determined based on a target peak-to-average power ratio (PAPR). A gain computation circuit determines a gain factor for at least one detected peak. A scaled cancellation pulse generation circuit generates a scaled cancellation pulse for the at least one detected peak based on the gain factor. A combiner circuit combines the scaled cancellation pulse with the input signal samples to generate an output signal. A hard clipping circuit may compress the output signal based on the second threshold. The first threshold is set slightly higher than the second threshold.