High data rate underwater optical wireless communication systems with ICSM codes within green spectrum

Abstract Underwater Optical Wireless Communication (UOWC) is emerging as a promising technology for high-speed data transmission in marine environments. This paper introduces a new UOWC system that integrates Optical Code Division Multiple Access (OCDMA) using Identity Shift Column Matrix (ICSM) codes, specifically designed to enhance communication capacity. For generating the relevant optical signals for the ICSM code sequences, Laser Diodes (LDs) sources are utilized, operating in the green spectrum ranging from 532 to 538.4 nm, known for their low attenuation in UOWC environments, to achieve extended transmission ranges. The performance of the proposed system is rigorously evaluated across five distinct water types—Pure Sea (PS), Clear Ocean (CL), Coastal Sea (CS), Harbor I (HI), and Harbor II (HII)—which exhibit varying absorption and scattering coefficients. The key performance metrics are investigated including eye diagrams, Bit Error Rate (BER), Underwater (UW) transmission distances, and Quality Factor (Q-factor). The obtained results indicate that the system can achieve an overall capacity of 30 Gbps with a maximum UW transmission distance of 50 m in PS water, characterized by the lowest extinction coefficient, while the shortest effective range of 5.2 m is observed in HII water, with the highest extinction coefficient. These ranges are achieved below the threshold value of BER (3.8 $$\times 10^{ - 3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>×</mml:mo> <mml:msup> <mml:mn>10</mml:mn> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ).