Many applications that could benefit from the underwater optical wireless communication technique face challenges in using this technology due to the substantial, varying attenuation that affects optical signal transmission through waterbodies. This research demonstrated that convolutional neural networks (CNNs) could readily address these problems. A modified CNN model was proposed to recover the original data of a non-return to zero on–off keying modulated signal transmitted optically through a tank full of Gulf seawater. A comparison between the proposed CNN model and a conventional fixed-threshold decoder (FTD) demonstrates the excellent performance of the proposed CNN model, which improved the bit error ratio (BER), signal-to-noise ratio (SNR), and effective channel length. The BER of the optical signals that are transmitted at powers of 24, 26, and 27 dBm and a bit rate of 10 Mbit/s at a distance of 3 m from the transmitter when FTD is used is 7.826 × 10⁻⁷, 5.049 × 10⁻⁸, and 8.38 × 10⁻¹⁰, respectively. When the CNN decoder is used at the same distance and powers, the BER is 6.23 × 10⁻¹⁴, 1.44 × 10⁻¹⁶, and 2.69 × 10⁻¹⁸, respectively. In conclusion, the BER decreased by about seven orders of magnitude, the effective channel length increased by four times, and the SNR decreased by about 20 dB. The simplicity of the proposed CNN decoder is independent of the prior knowledge of the channel conditions. Furthermore, the magnificent obtained results make the proposed CNN decoder an ideal substitute for ordinary underwater optical wireless communication decoders.

Radio overfree space optics (Ro-FSO) is a modern communication technique that promises a development future. In this paper, WDM Ro-FSO communication system has designed (10 Gbps×8λ) for transmissions 80 Gbps data rate via the largest possible distance under clear air, heavy rain, and heavy fog atmosphere conditions of FSO link, with test the best wavelengths performance of (193.1 to 93.8) THz that each one (wavelength) carry 10 Gbps by employ BER analyzer at receiver channels. The electric signals produced by phase shift keying (PSK) modulation technique modulated the information (10 Gbps) on RF signal (20 GHz). The results of transporting 80 Gbps were 5 km under clear air weather condition, 1.2 km under heavy rain, and 0.2 km under heavy fog condition. Finally, the different wavelengths that carry high-value data rate are tested by measurement of the BER and Q factor for each received channel, and the theoretical model of PSK modulation is analyzed.

In this paper, texts were experimentally transmitted by pulse width modulation (PWM) using an underwater wireless optical communication system (UWOC) in a channel containing water of varying salinity as a result of changes in the concentration of sodium chloride (NaCl). Mathematical equations are used using a MATLAB program to compare theoretical and practical results at different slop angle (θ0). (NaCl) concentration was changed from (0% w/v) to (90% w/v) to achieve different salinity of water (i.e., from clear water to turbid water). A diode laser with a power of 30 mW and a wavelength of 532 nm has been employed in the transmitter. The experimental results show that the extinction coefficient or the overall attenuation C(λ) is equal to (0.083/m) in the water containing a low concentration of (NaCl) which is consistent with pure seawater. Additionally, the obtained optical power (PR) and the signal to noise ratio (S/N) decreases to (27.6) mW and (23.99) dB, respectively. Furthermore, it was found that the water had a maximum total attenuation C(λ) equal to (2.565/m) in the water containing a high concentration of (NaCl) which was compatible with turbid harbour water, as well as the received power and (S/N) decreases to (2.306) mW and (13.2) dB, respectively. The theoretical results were similar to the practical results when the slope angle of the target or detector relative to the optical transmitter was (zero).

In this paper, the BER and losses are inspected experimentally in an underwater optical wireless communication system (UWOC) with different water types. Results show that salt and Maalox content increase BER and power losses.

In this research, texts were sent by pulse width modulation(PWM) in the channel of clean water usingArduino hardware and software for an underwater wireless opticalcommunication system (UWOC). The air bubbles device utilized thedisturbance at different distances from the transmitter source within thechannel of clean water. The total length of the channel is (1) m. In thisstudy, the source of transmitter wavelengths 650 nm was used with thepower of 80mw. The results showed that the received power was 32 mWin the clean water, while when air bubbles pump within the channel ofclean water at 0.2m, 0.5m and 0.8m away from the transmitter source,the received power was 28 mW, 27.5 mW, and 27 mW respectively. Thispaper shows that max. Signal to Noise Ratio (S/N) and min. attenuation(α) in the clean water were (24.637dB) and (3.979dB/m) respectively.The practical results showed that the Symbol Error Rate (SER) in thecase of the air bubbles pump was maximum (0.03) when the value of(S/N) was minimum (23.899).