OFDM Signal PAPR Reduction via Modified Pilot Tones

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Solution Overview

Problem

Orthogonal Frequency Division Multiplexing (OFDM) signals suffer from high Peak-to-Average Power Ratio (PAPR), limiting their application in telemetry systems and requiring effective reduction techniques to enhance bandwidth efficiency.

Innovation Solution

The introduction of modified pilot tones to cancel peaks in OFDM symbols, reducing PAPR without introducing signal distortion, by using Tone Reservation methods that modify and combine pilot tones with the original OFDM signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If OFDM modulation is used to improve bandwidth efficiency and data rates, then spectral efficiency is improved, but PAPR increases limiting practical application

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoidPAPR

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful high PAPR characteristic of OFDM signals into a benefit by using Tone Reservation techniques. Reserved tones are deliberately introduced to cancel out peak values in the time-domain signal, transforming the PAPR problem into a controlled signal processing task that reduces peak power while maintaining the bandwidth efficiency of OFDM modulation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If Tone Reservation is used to reduce PAPR, then PAPR is reduced, but bandwidth is wasted due to reserved subcarriers

Engineering Contradiction:

ImprovePAPRVSAvoidbandwidth

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent makes the reserved tones multi-functional by using them for dual purposes: PAPR reduction and channel estimation. The reserved subcarriers serve both to cancel peak values and to provide pilot signals for channel tracking, thereby converting what would be wasted bandwidth into a useful resource that performs multiple functions simultaneously

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If signal clipping is used to reduce PAPR, then PAPR is reduced, but signal distortion is introduced

Engineering Contradiction:

ImprovePAPRVSAvoidsignal quality

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent introduces reserved tones as an intermediary element that mediates between the transmitted signal and the amplifier. These reserved tones act as a buffer that absorbs peak excursions without distorting the actual data-carrying subcarriers, thereby reducing PAPR while preserving signal quality and avoiding the distortion problems associated with direct clipping

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11824700B2Systems and methods for peak-to-average power ratio (PAPR) reduction in OFDM signals

Publication Date: 2023.11.21 MORGAN STATE UNIVERSITY

AI summary

Systems and methods are provided for reducing peak-to-average power ratio (“PAPR”) in an orthogonal frequency division multiplexing (“OFDM”) signal having reference tones by introducing modified pilot tones to cancel peaks in OFDM symbols in the OFDM signal array. The modified pilot tones are added to the original OFDM signal, which in turn conditions the OFDM symbols of the signal to effectively reduce the PAPR. Such systems and methods provide PAPR reduction for OFDM signals generated by an OFDM Signal Processor through the addition of tone reservation PAPR reduction methods, which use reserved tones such as pilot tones to improve PAPR. Such methods offer an advantage of improving the PAPR without introducing distortion to the signal.