Performance Analysis for Cooperative Communication System in Optical IoUT Network With HDAF Strategy

In this work, a cooperative optical Internet of Underwater Things (IoUT) system with hybrid decode-amplify-forward (HDAF) strategy is first proposed and investigated over the aggregated underwater wireless optical communication (UWOC) channel. The impacts of absorption, scattering and the misalignment caused by spatial spreading in the sea, which are modeled by the beam spread function (BSF), as well as the oceanic turbulence on the underwater optical links are all included to describe the practical channel characteristics. With the help of Gauss-Hermite and Gauss-Legendre quadrature numerical methods, the closed-form expressions of the average bit error ratio (ABER) and outage probability for this cooperative optical HDAF-IoUT system are derived and verified by the Monte Carlo (MC) simulations. Furthermore, numerical analyses are offered to explore the effects of water type, turbulence strength, relay location and power allocation scheme on this HDAF-IoUT system. The performance of this optical system over the mixture Exponential Generalized Gamma (EGG) channel is also given for comparison. The obtained results indicate that the optical HDAF-IoUT system is superior to the IoUT system with fixed amplify-and-forward (FAF) strategy, and has a better performance when the relay is close to the middle position for a fixed power allocation scheme. This work is beneficial for the cooperative system design in IoUT network.