Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum

The existing multi-carrier composite modulation recognition methods have failed to effectively integrate inner and outer modulation characteristics, thereby limiting the potential for improving recognition performance under low signal-to-noise ratio (SNR) conditions. To address this issue, this pape...

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Main Authors: Shoubin Wang, Huan Li, Xiaolong Zhang, Hao Jiang, Lei Shen
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/13/4007
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author Shoubin Wang
Huan Li
Xiaolong Zhang
Hao Jiang
Lei Shen
author_facet Shoubin Wang
Huan Li
Xiaolong Zhang
Hao Jiang
Lei Shen
author_sort Shoubin Wang
collection DOAJ
description The existing multi-carrier composite modulation recognition methods have failed to effectively integrate inner and outer modulation characteristics, thereby limiting the potential for improving recognition performance under low signal-to-noise ratio (SNR) conditions. To address this issue, this paper proposes a multi-carrier composite signal modulation recognition algorithm based on a multi-dimensional time-frequency superimposed spectrum (MD-TFSS) with integrated inner and outer features, which can recognize composite modulation signals in the set {BPSK-PM, QPSK-PM, BPSK-QPSK-PM, BPSK-BPSK-PM, QPSK-QPSK-PM}. The proposed method constructs a dual spectrum through multiplying an inner modulation spectrum and a squared spectrum, then combines the inner modulation dual spectrum with the outer modulation time-frequency diagram in dual-channel mode to form MD-TFSS features. Based on the MD-TFSS, a blind recognition algorithm is implemented using the dual-channel input ECA-ResNet18 (DECA-ResNet18) incorporating the ECA attention mechanism. The proposed algorithm first converts the complex features of multi-carrier composite modulation signals into visually interpretable image features (including the quantity and concentration of bright spots and lines) through the MD-TFSS, achieving intuitive representation of multiple modulation characteristics. Meanwhile, the dual-channel input mechanism enables collaborative expression of outer modulation time-frequency diagram and inner modulation dual spectrum features, ensuring tight integration of inner and outer characteristics while avoiding feature isolation issues in traditional multi-diagram concatenation methods. Secondly, the DECA-ResNet18 network dynamically allocates weights through an adaptive regulation mechanism based on input feature differences, autonomously adjusting channel attention levels to effectively capture complementary characteristics from both inner and outer modulation features, thereby enhancing recognition accuracy and generalization capability for multi-carrier composite modulation signals. Theoretical analysis and simulation results demonstrate that, compared with the existing methods that use isolated outer and inner features or conventional multi-feature diagram construction approaches, the proposed algorithm achieves superior recognition performance under low SNR conditions. Additionally, DECA-ResNet18 demonstrates enhanced recognition performance for multi-carrier composite modulated signals compared to the traditional ResNet18.
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spelling doaj-art-5044c2ccb7ec47308a1edac4d0e520b32025-08-20T03:50:17ZengMDPI AGSensors1424-82202025-06-012513400710.3390/s25134007Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed SpectrumShoubin Wang0Huan Li1Xiaolong Zhang2Hao Jiang3Lei Shen4The 36th Research Institute of China Electronics Technology Corporation, Jiaxing 314033, ChinaCollege of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, ChinaCollege of Computer Science and Engineering, Ocean University of China, Qingdao 266100, ChinaThe 36th Research Institute of China Electronics Technology Corporation, Jiaxing 314033, ChinaCollege of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, ChinaThe existing multi-carrier composite modulation recognition methods have failed to effectively integrate inner and outer modulation characteristics, thereby limiting the potential for improving recognition performance under low signal-to-noise ratio (SNR) conditions. To address this issue, this paper proposes a multi-carrier composite signal modulation recognition algorithm based on a multi-dimensional time-frequency superimposed spectrum (MD-TFSS) with integrated inner and outer features, which can recognize composite modulation signals in the set {BPSK-PM, QPSK-PM, BPSK-QPSK-PM, BPSK-BPSK-PM, QPSK-QPSK-PM}. The proposed method constructs a dual spectrum through multiplying an inner modulation spectrum and a squared spectrum, then combines the inner modulation dual spectrum with the outer modulation time-frequency diagram in dual-channel mode to form MD-TFSS features. Based on the MD-TFSS, a blind recognition algorithm is implemented using the dual-channel input ECA-ResNet18 (DECA-ResNet18) incorporating the ECA attention mechanism. The proposed algorithm first converts the complex features of multi-carrier composite modulation signals into visually interpretable image features (including the quantity and concentration of bright spots and lines) through the MD-TFSS, achieving intuitive representation of multiple modulation characteristics. Meanwhile, the dual-channel input mechanism enables collaborative expression of outer modulation time-frequency diagram and inner modulation dual spectrum features, ensuring tight integration of inner and outer characteristics while avoiding feature isolation issues in traditional multi-diagram concatenation methods. Secondly, the DECA-ResNet18 network dynamically allocates weights through an adaptive regulation mechanism based on input feature differences, autonomously adjusting channel attention levels to effectively capture complementary characteristics from both inner and outer modulation features, thereby enhancing recognition accuracy and generalization capability for multi-carrier composite modulation signals. Theoretical analysis and simulation results demonstrate that, compared with the existing methods that use isolated outer and inner features or conventional multi-feature diagram construction approaches, the proposed algorithm achieves superior recognition performance under low SNR conditions. Additionally, DECA-ResNet18 demonstrates enhanced recognition performance for multi-carrier composite modulated signals compared to the traditional ResNet18.https://www.mdpi.com/1424-8220/25/13/4007multi-carrier composite modulationblind recognitionMD-TFSSDECA-ResNet18
spellingShingle Shoubin Wang
Huan Li
Xiaolong Zhang
Hao Jiang
Lei Shen
Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
Sensors
multi-carrier composite modulation
blind recognition
MD-TFSS
DECA-ResNet18
title Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
title_full Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
title_fullStr Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
title_full_unstemmed Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
title_short Blind Recognition Algorithm of Multi-Carrier Composite Modulation Signal Based on Multi-Dimensional Time-Frequency Superimposed Spectrum
title_sort blind recognition algorithm of multi carrier composite modulation signal based on multi dimensional time frequency superimposed spectrum
topic multi-carrier composite modulation
blind recognition
MD-TFSS
DECA-ResNet18
url https://www.mdpi.com/1424-8220/25/13/4007
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AT huanli blindrecognitionalgorithmofmulticarriercompositemodulationsignalbasedonmultidimensionaltimefrequencysuperimposedspectrum
AT xiaolongzhang blindrecognitionalgorithmofmulticarriercompositemodulationsignalbasedonmultidimensionaltimefrequencysuperimposedspectrum
AT haojiang blindrecognitionalgorithmofmulticarriercompositemodulationsignalbasedonmultidimensionaltimefrequencysuperimposedspectrum
AT leishen blindrecognitionalgorithmofmulticarriercompositemodulationsignalbasedonmultidimensionaltimefrequencysuperimposedspectrum