Investigation of Underwater Wireless Optical Communications Links With Surface Currents and Tides for Oceanic Signal Transmission

Abstract

This report investigated underwater wireless optical communication (UWOC) links in the presence of surface currents and tides. The scenario of surface currents and tides was generated by a sea water tank, a water pipe, and a water pump of different flow rates. It built the oceanic channel of UWOC varied with the salinity and flow rate in the UWOC transmission. The data rate of UWOC links based on a 520-nm laser diode and none-return-to-zero on-off keying (NRZ-OOK) modulation can achieve 3.4 Gb/s at a bit error rate (BER) of 3.78×10 −4 in 1.8 m long sea water tank when a flow rate reached 1.08 m/s. The BER, eye-diagrams, and received signal optical power measurements showed that both the increasing salinity and flow rate cause the UWOC channel attenuation, thus degrade the performance of UWOC links.

High-Efficiency 4 × 4 × 10 Gbps Orbital Angular Momentum Modes Incorporated into Satellite–Ground–Underwater Optical Wireless System under Diverse Turbulences

“…The authors of [15] further investigated the effect of vehicle motion on a turbulence model by using experimental measurements at a 40 C temperature gradient. The UWOC system in [16] transmits information over a 1.8 m distance in a sea water tank at 3.4 Gbps. Orthogonal frequency division multiplexing over 10 m distance in shallow water is demonstrated in [17].…”

Water-Wave Effect on the Encryption and Deep-Learning-Based Recognition of a Speech Signal Transmitted Over a Wireless Optical Communication Channel

“…The authors measured BER, power, and loss rate as a function of (tap) water-wave level. In [17], the authors showed how salinity and flow rate of sea water induced turbulence in UWOC links, and they used a 520-nm laser. In [18], the authors investigated the effect of (tap) water-waves heights on the received optical power.…”

“…The perpendicular rulers shown positioned in Figs. 1b and 1c allow to evaluate the amplitudes of the sinus and pulse waveforms, similarly to [16], [17] as discussed below. Fig.…”

“…The BC was calculated between the normalized histogram, 𝑃 of the transmitted encrypted signal and the normalized histogram, 𝑄 of the received encrypted signal in the following cases: above-still-water case; above-wavy-water case; and under-wavy-water case. The BC can be calculated between two histograms having M bins from the following equation [49]: (17) 𝐵𝐶(𝑃, 𝑄) = ∑ √𝑃 𝑛 𝑄 𝑛 𝑀 𝑛=1…”

Diffraction deep neural network based orbital angular momentum mode recognition scheme in oceanic turbulence

“…[1][2][3][4] UWOC has many applications in military, civilian, and commercial, such as submarines, underwater unmanned vehicles, and deep-sea resource exploration. [5][6][7][8] In 1992, Allen et al exhibited that a vortex beam can carry orbital angular momentum (OAM). [9] The wavefront of the OAM beam has a helical phase and its electric field complex amplitude contains a term of exp [iℓθ ], where ℓ can be an arbitrary integer named topological charge or azimuthal index, representing the number of 2π phase shifts across the beam, and θ is the azimuthal angle.…”