OFDMA Duplicate Transmission Using Orthogonal Codes to Minimize PAPR

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Solution Overview

Problem

Duplicating symbols for transmission in OFDMA signals leads to increased peak-to-average power ratio (PAPR), which restricts transmission power and signal quality due to constructive addition of time-domain crests.

Innovation Solution

Applying phase shifts to symbols using Hadamard matrices to generate duplicate transmissions across multiple resource units, reducing constructive addition in the time domain and minimizing PAPR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If symbols are duplicated for transmission on multiple resource units, then communication reliability is improved, but peak-to-average power ratio increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidpeak-to-average power ratio

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies orthogonal phase shifts (changing the phase parameter) to duplicate symbols before transmission on different resource units. This parameter transformation ensures that while symbols are duplicated for reliability, their phase differences prevent constructive addition in the time domain, thereby controlling the peak-to-average power ratio.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent preemptively applies orthogonal phase shifts to duplicate symbols before transmission to prevent the harmful effect of constructive addition. By introducing this counteracting phase shift in advance, the system avoids the PAPR increase that would otherwise occur from direct duplication, thus maintaining power efficiency while achieving reliability through duplication.

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If symbols are duplicated for transmission on multiple resource units, then data loss is reduced, but transmission power is restricted

Engineering Contradiction:

Improvedata loss reductionVSAvoidtransmission power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

By transforming the phase parameter of duplicate symbols using orthogonal codes, the patent enables reliable transmission without the power restrictions that would result from direct duplication. The phase parameter change ensures that duplicate symbols do not constructively add in the time domain, allowing maximum transmission power to be utilized.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful effect of symbol duplication (which would increase PAPR and restrict power) into a beneficial outcome. By applying orthogonal phase shifts, the duplication that would normally cause harm is transformed into a reliable transmission method that maintains power efficiency, thus turning the harmful PAPR increase into a benefit of improved reliability without power loss.

Inventive Principle:

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

Data Source

PatentEP4648370A1Systems for and methods of frequency domain duplicate mode transmission using orthogonal codes

Publication Date: 2025.11.12 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

Figure 1A~1B
Figure 1C
Figure 1D

AI summary

A system for providing duplicate mode orthogonal frequency-division multiple access transmissions while maintaining a relatively low peak-to-average power ratio. Data to be transmitted is converted to symbols which are duplicated onto a number of resource units. Phase shifts are applied to a number of symbols prior to conversion to the time domain for transmission. The phase shifts can be removed at the receiver prior to decoding the signal to the transmitted data.