Peak Windowing for OFDM PAPR Reduction Without Peak Regrowth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High Peak to Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) signals leads to inefficient power amplifier usage, causing distortion and increased power consumption due to the need for back-off schemes and high-end hardware, which are costly and inefficient.
Innovation Solution
The method involves applying peak windowing after clipping, which includes calculating the absolute value of the input signal, subtracting a clipping threshold, smoothing the signal, adding it back, and multiplying by the inverse of the clipping threshold to reduce PAPR, utilizing a smoothing scheme that includes Low-Pass Filtering to generate a bandwidth-reduced envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If clipping technique is applied to reduce PAPR, then PAPR is reduced, but nonlinear distortion is caused requiring additional filtering which generates peak regrowth
Solution Approach 1:
The patent introduces a smoothing window function as an intermediary between the clipping operation and the output signal. This window function gradually transitions the clipped signal back to its original form, mediating the harsh transition caused by clipping and preventing the generation of peak regrowth while maintaining signal integrity
Solution Approach 2:
The patent applies smoothing windowing as a preliminary action after clipping but before final signal output. By pre-smoothing the clipped signal envelope, the method prevents the formation of sharp transitions that would cause peak regrowth, addressing the distortion issue before it manifests in the final transmitted signal
2Reliability
If back-off scheme is used to maintain linear operating range, then distortion is reduced, but power consumption increases
Solution Approach 1:
The patent changes the signal parameters by applying a smoothing window function that modifies the envelope of the clipped signal. This parameter transformation allows the signal to maintain higher average power levels while still operating within the linear range of the power amplifier, thereby reducing power consumption without sacrificing linearity
3Loss of energy
If repeated clipping and filtering is applied to suppress peak regrowth, then peak regrowth is reduced, but device complexity and processing time increase
Solution Approach 1:
The patent extracts the essential smoothing function from the complex repeated clipping and filtering process. By isolating and applying a single smoothing window operation, the method achieves peak regrowth suppression without requiring multiple iterative clipping and filtering stages, thereby reducing device complexity and processing time
Data Source
AI summary
A method and apparatus for reducing a Peak to Average Power Ratio (PAPR) using peak windowing is provided. In the apparatus, an absolute value calculator calculates an absolute value of an input signal, a subtractor subtracts a predetermined clipping threshold level from the absolute value, a smoothing unit performs smoothing on the subtracted signal according to a predetermined smoothing scheme and outputs a first smoothed signal, an adder adds the first smoothed signal to the clipping threshold level, an inverse calculator outputs a second smoothed signal by multiplying the clipping threshold level by an inverse of the added signal, and a multiplier outputs a final PAPR-reduced signal by multiplying the input signal by the second smoothed signal. The method and apparatus address an overcompensation problem while processing signals having a large bandwidth and a high data rate without delay, thereby minimizing the clipping influences on Bit Error Rate (BER) and Adjacent Channel Leakage Ratio (ACLR) performances.