CAZAC Reference Sequence PAPR Reduction in Radio Transmission

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Solution Overview

Problem

The use of constant amplitude zero auto-correlation (CAZAC) sequences in radio communication systems leads to degradation in peak to average power ratio (PAPR) due to discontinuous boundaries between data and training signals, which existing systems fail to effectively mitigate without changing the modulation method.

Innovation Solution

A transmission device that obtains and transmits a reference sequence with a symbol sequence length equal to or smaller than the modulation order, using a CAZAC sequence with specific formulas to ensure constant amplitude in both time and frequency domains, thereby minimizing PAPR degradation without altering the modulation method.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a CAZAC sequence is periodically inserted as a training sequence between modulated signals, then frequency response estimation accuracy is improved, but the peak to average power ratio (PAPR) of the waveform degrades due to discontinuous boundaries between data and training signal

Engineering Contradiction:

Improvefrequency response estimation accuracyVSAvoidPAPR degradation

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent combines the training sequence and data sequence into a single continuous CAZAC sequence by applying the CAZAC sequence to both training and data portions. This merging eliminates the discontinuous boundaries between separate sequences, thereby maintaining constant amplitude properties and reducing PAPR degradation while preserving frequency response estimation accuracy.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The CAZAC sequence serves dual functions: it acts as both a training sequence for frequency response estimation and a data sequence for information transmission. By making the CAZAC sequence universal for both purposes, the patent eliminates the need for separate training and data sequences, thereby avoiding boundary discontinuities and PAPR degradation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If a CAZAC sequence is applied to an information sequence, then the constant amplitude property is maintained, but the boundaries between sequences become discontinuous, degrading the PAPR

Engineering Contradiction:

Improveconstant amplitude propertyVSAvoidPAPR degradation

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent ensures continuous application of the CAZAC sequence across both training and data portions without interruption or boundary discontinuities. By maintaining the continuous nature of the CAZAC sequence throughout the entire transmission, the constant amplitude property is preserved and PAPR degradation is minimized.

Inventive Principle:

Principle #20Continuity of useful action

3Object-generated harmful factors

If the modulation method is changed to minimize PAPR degradation, then PAPR is improved, but the radio communication system conformity to existing radio standards is compromised

Engineering Contradiction:

ImprovePAPR degradationVSAvoidradio standard conformity

Core Design Contradiction:

Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent changes the parameter of sequence application rather than modulation method. By applying the CAZAC sequence to both training and data sequences and making the data sequence itself a CAZAC sequence, the patent achieves PAPR reduction while maintaining the same modulation method, thus preserving compatibility with existing radio standards.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20230080783A1Transmission device, reception device, radio communication system, control circuit, and storage medium

Publication Date: 2023.03.16 MITSUBISHI ELECTRIC CORP

AI summary

A transmission device includes: a reference sequence obtaining unit that obtains a reference sequence having a symbol sequence length equal to or smaller than a modulation order in a modulation method used for data transmission, the reference sequence having a constant amplitude in a time domain and a frequency domain; and a multiplexing unit that transmits a signal including the reference sequence.