Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission

Providing Optical Wireless Communications (OWCs) is desirable for high data transmission efficiency. Intensity Modulation and Direct Detection (IM/DD) is widely adopted for its simplicity and practicality. Among various modulation schemes, Code Shift Keying (CSK) has demonstrated superior transmissi...

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Main Authors: Nobuyoshi Komuro, Hiromasa Habuchi
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Photonics
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Online Access:https://www.mdpi.com/2304-6732/12/2/166
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author Nobuyoshi Komuro
Hiromasa Habuchi
author_facet Nobuyoshi Komuro
Hiromasa Habuchi
author_sort Nobuyoshi Komuro
collection DOAJ
description Providing Optical Wireless Communications (OWCs) is desirable for high data transmission efficiency. Intensity Modulation and Direct Detection (IM/DD) is widely adopted for its simplicity and practicality. Among various modulation schemes, Code Shift Keying (CSK) has demonstrated superior transmission efficiency compared to On-Off Keying (OOK) and Pulse Position Modulation (PPM). Prior research has shown that CSK performance can be further enhanced through parallel transmission and code concatenation techniques. However, the direct application of concatenated CSK to parallel transmission reduces the number of available code combinations as the concatenation level increases, potentially lowering modulation efficiency. This study proposes an advanced transmission scheme that integrates parallel transmission with a multi-level intensity adjustment mechanism. The proposed method preserves a high number of distinguishable transmission symbols, thereby achieving higher data transmission rates. Analytical derivations for transmission efficiency are provided for single-user scenarios, and numerical simulations validate the effectiveness of the proposed system. The key contributions of this work include mitigating symbol reduction in nonorthogonal CSK with parallel transmission and adjusting the multi-level intensity to enhance overall system performance. The results confirm that the proposed scheme significantly improves the efficiency and scalability of nonorthogonal CSK in OWC applications.
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spelling doaj-art-506859e0795844a3ba0cbdfa099aa7332025-08-20T03:11:22ZengMDPI AGPhotonics2304-67322025-02-0112216610.3390/photonics12020166Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel TransmissionNobuyoshi Komuro0Hiromasa Habuchi1Digital Transformation Enhancement Council, Chiba University, Chiba 263-8522, JapanDepartment of Information and Sciences, Ibaraki University, Hitachi 316-8511, JapanProviding Optical Wireless Communications (OWCs) is desirable for high data transmission efficiency. Intensity Modulation and Direct Detection (IM/DD) is widely adopted for its simplicity and practicality. Among various modulation schemes, Code Shift Keying (CSK) has demonstrated superior transmission efficiency compared to On-Off Keying (OOK) and Pulse Position Modulation (PPM). Prior research has shown that CSK performance can be further enhanced through parallel transmission and code concatenation techniques. However, the direct application of concatenated CSK to parallel transmission reduces the number of available code combinations as the concatenation level increases, potentially lowering modulation efficiency. This study proposes an advanced transmission scheme that integrates parallel transmission with a multi-level intensity adjustment mechanism. The proposed method preserves a high number of distinguishable transmission symbols, thereby achieving higher data transmission rates. Analytical derivations for transmission efficiency are provided for single-user scenarios, and numerical simulations validate the effectiveness of the proposed system. The key contributions of this work include mitigating symbol reduction in nonorthogonal CSK with parallel transmission and adjusting the multi-level intensity to enhance overall system performance. The results confirm that the proposed scheme significantly improves the efficiency and scalability of nonorthogonal CSK in OWC applications.https://www.mdpi.com/2304-6732/12/2/166optical wireless communication (OWC)intensity modulation and direct detection (IM/DD)code shift keyingparallel transmission
spellingShingle Nobuyoshi Komuro
Hiromasa Habuchi
Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
Photonics
optical wireless communication (OWC)
intensity modulation and direct detection (IM/DD)
code shift keying
parallel transmission
title Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
title_full Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
title_fullStr Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
title_full_unstemmed Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
title_short Design and Analysis of Enhanced IM/DD System with Nonorthogonal Code Shift Keying and Parallel Transmission
title_sort design and analysis of enhanced im dd system with nonorthogonal code shift keying and parallel transmission
topic optical wireless communication (OWC)
intensity modulation and direct detection (IM/DD)
code shift keying
parallel transmission
url https://www.mdpi.com/2304-6732/12/2/166
work_keys_str_mv AT nobuyoshikomuro designandanalysisofenhancedimddsystemwithnonorthogonalcodeshiftkeyingandparalleltransmission
AT hiromasahabuchi designandanalysisofenhancedimddsystemwithnonorthogonalcodeshiftkeyingandparalleltransmission