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- 摘要
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Practical Performance and Prospect of Underwater Optical Wireless Communication
摘要： Underwater optical wireless communication has been merely a theory for a long time because light sources are too weak to use them as emitters for communications. In the past decade, however, underwater optical wireless communications have used laser diodes or light emitting diodes as emitters with visible light in high brightness with low power consumption. Recently, they have become practical. As described in this paper, recent trends of underwater optical wireless communication study, practical modems and prospective uses of underwater optical wireless communication are presented first. Next, optical characteristics of the seawater in various conditions are explained based on the experimental data measured using the profiler for underwater optics produced especially for this study. Then the prototype underwater optical wireless communication modem developed by our team is introduced. It was tested in several sea areas, which confirmed bi-directional communication in the 120 m range at 20 Mbps and a remote desktop connection between under water vehicles at 100 m range. In addition, one modem was set in air; other was set in water. The modems mutually communicated directly through the sea surface.
关键词： UOWC,turbidity,chlorophyll,LD,VLC
更新于2025-09-23 15:23:52
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Dual-Hop Mixed RF-UOW Communication System: A PHY Security Analysis
摘要： In this paper, the secrecy performance of a dual-hop mixed radio-frequency/underwater optical wireless communication (RF-UOWC) system is investigated. The considered system consists of one single antenna source node (S) communicating with one destination node (D), considered as the legitimate receiver, through an amplify-and-forward relay node equipped with multiple antennas for reception. Specifically, the relay receives the incoming signal from S via an RF link, applies maximal-ratio combining technique, amplifies the output combined signal with either a fixed gain or variable gain, and then forwards it to the destination via an UOWC link. The transmission protocol is performed under the eavesdropper’s attempt to overhear the RF link (i.e., S-R). We derive exact closed-form expressions for the system’s average secrecy capacity and the intercept probability in terms of Meijer’s G-function as well as the univariate and bivariate Fox’s H -functions. A complexity analysis is also performed to analyze the evaluation time of the derived analytical formulas as well as Monte Carlo simulation method complexity. Our derived analytical formulas present an efficient tool to depict the impact of some system and channel parameters on the secrecy performance, namely, the number of relay antennas, the number of eavesdropping nodes, relay gain, fading severity of RF links, and water turbulence severity of the UOWC link.
关键词： intercept probability,underwater optical wireless communication (UOWC),dual-hop relaying,physical layer security,performance analysis,Amplify-and-forward,average secrecy capacity
更新于2025-09-23 15:21:01
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Photon-Counting Underwater Wireless Optical Communication by Recovering Clock and Data From Discrete Single Photon Pulses
摘要： To realize a long-distance underwater communication by using low-cost light emitting diode (LED) and single photon avalanche diode (SPAD), we proposed a method for recovering clock and data directly from discrete random pulse sequences output by SPAD. On this basis, a new communication model is established, taking into account not only ?uctuations in photon ?ux and quantum ef?ciency of photon detection in a time-slot, but also the phase difference of the recovered clock caused by it. A photon-counting underwater optical wireless communication (UOWC) system was built. The effects of the system setting parameters such as the number of gating signals, synchronous character length and baud rate on the average bit error rate (BER) were veri?ed by experiments. The experimental results show that under condition of only average 10 photons in one time-slot, photon-counting UOWC with a BER of 3.51 × 10?4 and a baud rate of 1 Mbps can be achieved.
关键词： clock synchronization,Underwater optical wireless communication (UOWC),photon-counting,data recovery
更新于2025-09-11 14:15:04