Abstract

Underwater Optical Wireless Communication (UOWC) offers a potential alternative to traditional Radio Frequency (RF) and acoustic methods, which suffer from low speed, short range, and high latency in underwater conditions. Reliability and security are both impacted by signal deterioration brought on by turbidity, scattering, and absorption, which is still a concern in UOWC. This study investigates a key for a UOWC system by combining different modulation formats and Forward Error Correction (FEC) codes with Rivest-Shamir-Adleman (RSA) encryption and tested on a 4m in-house underwater channel. While FEC codes aid in reducing bit errors brought on by the underwater channel, RSA encryption provides additional security for data by preventing eavesdropping. The information is encrypted initially and is then sent to undergo modulation and Forward Error Corrections if needed. The experimental studies of execution size for modulation schemes and FEC were in line with the theoretical value, repeat code (3) file size was thrice the original, repeat code (5) increased the file size by 5 times, OOK-RZ had twice the file size as OOK-NRZ, and PPM file size was 16 times, and so on. Among the various FEC codes and the modulation schemes employed, the results show that using Hamming, Bose–Chaudhuri–Hocquenghem (BCH), and Reed-Solomon codes improves stability and security by almost 1.5 times than that of no FEC when integrated with PPM and DPIM modulation schemes. This approach offers a promising solution for applications in underwater robotics, environmental monitoring, and defence, demonstrating the potential of UOWC as a secure communication system for challenging and dynamic underwater conditions.