Crest Factor Reduction Device for Multi-Carrier Signals
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Solution Overview
Problem
Current Crest Factor Reduction (CFR) techniques for Orthogonal Frequency Division Multiplexing (OFDM) systems face challenges in reducing Peak to Average Power Ratio (PAPR) efficiently, particularly in multi-carrier signals, due to high computational complexity and peak leakage issues, which affect power amplifier efficiency and error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR).
Innovation Solution
A device comprising a peak detector, multiple peak cancellation signal generators, and a subtractor, which detects peaks in a sampled multi-carrier signal, generates and adjusts cancellation signals within specific frequency bands, and subtracts them from the original signal to reduce PAPR, utilizing a multi-stage approach with varying filter lengths to combine the advantages of Noise Shaping CFR and Peak Cancellation CFR algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Noise Shaping CFR algorithm is used to guarantee elimination of all peaks, then PAPR performance is improved, but computational complexity increases significantly
Solution Approach 1:
The invention segments the multi-carrier signal into multiple independent carrier components and processes peaks for each carrier separately using individual peak cancellation signal generators. This segmentation allows the system to achieve reliable peak elimination through multiple parallel processing paths while managing complexity by distributing the processing load across multiple simpler units rather than one complex sequential processor.
Solution Approach 2:
The invention applies partial action by using multiple peak cancellation signal generators that each handle specific carriers, rather than applying a single complex noise shaping filter to the entire signal. This approach provides sufficient peak elimination for each carrier component while reducing the overall computational burden compared to comprehensive noise shaping of the complete multi-carrier signal.
2Device complexity
If Peak Cancellation CFR algorithm is used to reduce complexity, then device complexity is reduced, but peak leakage occurs leading to high PAPR risk
Solution Approach 1:
The invention merges the advantages of both Noise Shaping and Peak Cancellation CFR algorithms by combining multiple peak cancellation signal generators (providing low complexity) with a resource allocation mechanism that prioritizes high peak detection and cancellation (providing reliability). The merging of these approaches allows the system to achieve both low complexity and high reliability simultaneously.
Solution Approach 2:
The invention implements feedback through the resource allocation mechanism that monitors peak detection results and dynamically allocates resources among multiple peak cancellation signal generators. This feedback loop ensures that high peaks are prioritized for cancellation, preventing peak leakage while maintaining low computational complexity through efficient resource management.
3Reliability
If cascaded clipping scheme with multiple CFR stages is applied to improve PAPR performance, then PAPR is reduced, but device complexity increases
Solution Approach 1:
The invention segments the multi-carrier signal processing into multiple parallel carrier-specific processing paths, each handling a specific carrier frequency. This segmentation allows effective PAPR reduction for each carrier while avoiding the need for multiple sequential cascaded stages, thereby reducing overall device complexity while maintaining effective PAPR control.
4Reliability
If multiple peak cancellation signal generators are used to handle multiple carriers, then PAPR reduction effectiveness is improved, but resource allocation complexity increases
Solution Approach 1:
The invention implements self-service through autonomous peak detection and resource allocation mechanisms where each peak cancellation signal generator independently detects peaks in its assigned carrier and autonomously generates cancellation signals. This self-service approach improves PAPR reduction effectiveness across multiple carriers while minimizing resource allocation complexity by eliminating the need for centralized resource management.
Data Source
AI summary
The present disclosure provides a device (300) of crest factor reduction for a multi-carrier signal. The device (300) includes: a peak detector (320) adapted to receive a sampled representation of the multi-carrier signal, detect a peak from the sampled representation and obtain a value and a time domain location of a cancellation peak for cancelling the peak; a plurality of peak cancellation signal generators (330) each corresponding to a carrier of the multi-carrier signal and adapted to generate a peak cancellation signal within a frequency band of its corresponding carrier based on the value and time domain location of the cancellation peak; and a subtractor (350) adapted to subtract the peak cancellation signals from the sampled representation after being delayed. The present disclosure also provides another device of crest factor reduction, a multi-stage crest factor reduction circuit and a peak detector.