Reduced-Length Cancellation Pulses for Low-Complexity CFR
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Solution Overview
Problem
Current crest factor reduction (CFR) algorithms are complex, require significant processing power, and increase the error vector magnitude (EVM) of transmitted signals, while conventional techniques for reducing peak-to-average power ratio (PAPR) often result in peak regrowth and out-of-band emissions.
Innovation Solution
Implementing a CFR technique that uses cancellation pulses with a reduced length, reducing the sample length of the cancellation pulse to less than the number of taps in a corresponding channel filter, and performing peak cancellation in a single iteration to minimize processing complexity and EVM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional CFR algorithms are used to reduce PAPR, then peak-to-average power ratio is reduced, but processing complexity and error vector magnitude increase
Solution Approach 1:
The patent extracts only the essential portion of the cancellation pulse by truncating it to a reduced length (e.g., 64 samples instead of 512 samples). This extraction of the core functional part maintains PAPR reduction effectiveness while eliminating unnecessary processing operations, thereby reducing computational complexity and EVM.
Solution Approach 2:
The patent changes the length parameter of the cancellation pulse from the conventional full length (matching channel filter taps) to a reduced length that is significantly shorter. This parameter change optimizes the balance between PAPR reduction performance and processing complexity, achieving effective peak cancellation with fewer computations.
2Strength
If conventional CFR algorithms are used to reduce PAPR, then peak-to-average power ratio is reduced, but error vector magnitude increases
Solution Approach 1:
By extracting only the most critical portion of the cancellation pulse (the truncated reduced-length version), the patent achieves effective peak cancellation while minimizing distortion to the transmitted signal. This selective extraction reduces EVM by avoiding unnecessary processing of less important signal components.
Solution Approach 2:
The patent applies partial action by using a truncated cancellation pulse that covers only the essential time window needed for peak cancellation. This partial approach is sufficient to reduce PAPR effectively while minimizing the excessive processing that would otherwise increase EVM.
3Strength
If full length cancellation pulses are used, then PAPR reduction is achieved, but processing power requirements increase
Solution Approach 1:
The patent extracts the essential functional portion of the cancellation pulse by truncating it to a reduced length. This extraction maintains the core PAPR reduction capability while eliminating computationally expensive operations on the full-length pulse, thereby significantly reducing processing power requirements.
Solution Approach 2:
The patent changes the length parameter of the cancellation pulse from full length to reduced length, which directly reduces the number of multiplications and additions required in the CFR algorithm. This parameter optimization achieves PAPR reduction with lower processing power consumption.
4Strength
If conventional PAPR reduction techniques are used, then peak-to-average power ratio is reduced, but peak regrowth and out-of-band emissions occur
Solution Approach 1:
By extracting and applying only the truncated reduced-length cancellation pulse, the patent achieves effective peak cancellation without introducing the artifacts that cause peak regrowth and out-of-band emissions. The truncation removes unnecessary components that would otherwise create harmful spectral leakage.
Data Source
AI summary
Techniques are disclosed for the use of Crest Factor Reduction (CFR) technique that utilizes a cancellation pulse signal having a reduced length. The CFR technique may be applied to a signal to be transmitted, which may comprise a composite signal having one or more carrier signals. Each carrier signal of the composite signal may be filtered via a respective channel filter and then recombined to form the signal to be transmitted, on which the CFR operations are then applied. The length of the cancellation pulse signal is less than the number of taps of the channel filter with the largest number of taps. This reduction in cancellation pulse signal length significantly reduces the processing power required to perform the CFR operations while maintaining regulatory emissions compliance.