## 4 Conclusions  
This study designs and implements a 10 Mbps UWOC system based on an FPGA. By optimizing the demodulation architecture, introducing MF, BEDF, RS (255,239) encoding, and fully digital AGC technology, the system's anti-interference capability and reliability are significantly enhanced. The system achieves an image transmission with a bit error rate as low as 2 \(\times\) 10\({}^{-8}\) over a 10 m simulated clear seawater and demonstrates stability under three different water quality conditions. The application of beam expansion and collimation techniques enables the system to reach a maximum transmission distance of 111.35 m in clear seawater. This research provides important theoretical and technical references for the design of high-reliability, low-power, and low-latency underwater laser communication systems, with broad application prospects. For instance, it can be deployed in submarine underwater links, underwater node information collection and transmission, information interaction between ships and underwater divers, underwater Internet of Things, and autonomous underwater vehicles (AUVs), among other fields. Additionally, it can be combined with network protocols and relay schemes to establish underwater communication local area networks, enabling multi-point cooperative communication [43, 52]. The optical antenna design adopted by the system provides strong support for long-distance optical communication. The fully digital AGC system, MF, BEDF, and RS code signal processing modules developed in this study are encapsulated as IP cores, enabling seamless future technological upgrades and system migration. However, this experiment also has certain limitations. Firstly, there is a significant difference between the laboratory test environment and actual marine conditions. Complex currents, suspended particles, and biological interferences may all affect the system performance. Secondly, due to the limitations of laboratory conditions, the theoretical transmission distance of 113.5 m remains to be verified. Additionally, the system was powered by a PC during testing, the limited energy capacity of underwater devices and the difficulty of battery replacement make power supply a critical challenge for future applications. It is necessary to further consider the power supply issues in practical applica  
Figure 19: Comparison of RS decoding time. Figure 18: Comparison of resource utilization and performance of RS coding. tions. To overcome these limitations, future research will involve encapsulating the system for communication testing in real-world environments and further optimizing the design based on the results. Concurrently, effective power supply solutions will be explored, including advanced energy harvesting technologies to achieve self-powered systems [37; 53]. Furthermore, integrating machine learning and artificial intelligence could lead to more advanced system reliability designs [54]. Through interdisciplinary collaboration and continuous technological innovation, UWOC systems are poised to achieve significant advancements in reliability, transmission rate, and range of applications, ultimately emerging as a cornerstone of underwater communication and unlocking new possibilities for marine exploration and resource utilization. Conceptualization, T.H. and P.D. ; methodology, Z.R. and N.L. ; software, T.H. and P.D. ; validation, T.H. and P.D. ; formal analysis, Z.Y. and Z.L. ; investigation, T.H. and Z.L. ; writing--original draft preparation, T.H. ; writing--review and editing, Z.Y., Z.W. and Z.R. ; visualization, T.H. and Z.W. ; supervision, Z.Y. and H.S. All authors have read and agreed to the published version of the manuscript. This research was funded by the Suzhou Basic Research Pilot Project (SSD2023003), the Suzhou Science and Technology Innovation Carrier Plan (SZS2022007), and the Suzhou \"Unveiling and Commanding\" Project (SYG2024003). Not applicable.