OFDM PAR Reduction with Iterative Weighting Against Peak Regrowth
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Solution Overview
Problem
Conventional PAR reduction techniques for HD Radio signals, such as clipping, lead to regrowth of signal peaks in subsequent processing, and existing methods are inefficient in reducing peak-to-average power ratio (PAR) effectively.
Innovation Solution
A PAR reduction algorithm that iteratively clips and weights signal peaks, varying the weight across iterations to mitigate regrowth, while preserving signal integrity and reducing out-of-band emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional clipping is used to attenuate signal peaks, then signal peaks are reduced to acceptable levels, but signal peaks reoccur in subsequent processing
Solution Approach 1:
The patent applies preliminary weighting to the clipped signal components before they are added back to the original signal. By pre-weighting the difference signal (original minus clipped) with a factor less than 1, the method anticipates and prevents peak regrowth before it occurs in subsequent processing stages
Solution Approach 2:
The patent implements an iterative feedback mechanism where the output of each iteration is fed back as input to the next iteration. The weighting factor is adjusted based on the convergence behavior observed in previous iterations, allowing the system to learn from and correct the peak regrowth issue progressively
2Object-affected harmful factors
If iterative PAR reduction algorithms are applied, then PAR reduction is achieved, but computational complexity increases
Solution Approach 1:
The patent changes the parameter of the weighting factor from a fixed value to a dynamically adjusted value that varies with iteration number. This parameter change allows the algorithm to converge faster by using different weighting strategies at different stages of the iteration process, reducing the total number of iterations required
Solution Approach 2:
The patent applies partial clipping by using a weighting factor less than 1, which means not all clipped components are fully restored. This partial action approach achieves sufficient PAR reduction without requiring excessive iterations, balancing computational efficiency with performance
Data Source
AI summary
A method comprises performing iterations of a peak-to-average ratio (PAR) reduction algorithm on a modulated OFDM symbol, each of the iterations including: clipping the modulated OFDM symbol to produce a clipped modulated OFDM symbol; subtracting the clipped modulated OFDM symbol from the modulated OFDM symbol to produce a difference signal; weighting the difference signal using a weight that varies across the iterations, to produce a weighted difference signal that varies across the iterations; subtracting the weighted difference signal from the modulated OFDM symbol to produce a modified modulated OFDM symbol; and performing further PAR reduction operations on the modified modulated OFDM symbol to produce a PAR-reduced OFDM symbol for use in a next iteration.