Channel Modeling And Simulation Performance Analysis Of MIMO Underwater Wireless Optical Communication System

Since the 21 st century,with the increasing scale of underwater activities such as environmental monitoring,underwater exploration,and real-time underwater positioning,the human demand for underwater high-speed communication systems has increased.Underwater Wireless Optical Communication(UWOC)technology can achieve a high data rate(Gbps order of magnitude)and high bandwidth underwater wireless communication at medium range.Therefore,how to implement UWOC systems has become a hot research topic for researchers.The Bill-Lambert law and the Free Space Optical(FSO)Communication model are the most commonly used methods to describe UWOC systems.However,these methods fail to consider transceiver parameters on the system performance and neglect the scattered beam energy reaching the receiver.This paper designs a simulation program for UWOC systems with adjustable transceiver angle and position using the Monte Carlo method and analyzes the system performance factors.To address the problem that the Beer-Lambert law and the FSO model are inaccurate in describing the UWOC system,this paper investigates the UWOC system model with adjustable transceiver angle and position by the Monte Carlo method.By tracking each photon's motion path in the medium,the case that the photon can still reach the receiver after several scattering events is considered.The model also considers the effects of various transceiver parameters and environmental characteristics on the UWOC system's performance.By comparing the available experimental data,the UWOC channel impulse response data obtained by the Monte Carlo method matches well with the experimental data,which proves the model's feasibility and stability.The proposed model can also calculate the UWOC system characteristics when the transceiver is not strictly aligned,which is a guideline for UWOC system design.For the photon motion path data processing problem,the impulse response of the UWOC channel is calculated by statistical methods in this paper.Ten UWOC channel fitting models are proposed,and the fitting effect of the fitting models on the channel impulse response is compared.The results show that the model has the best fitting effect,the dual Gamma model has the simplest form,and the coefficient of determination of both fitting models is more significant than 0.95.The easily derived channel impulse closure expression is the basis for the performance analysis of the system.For the impact of turbulence on UWOC systems' performance,the exponential-generalized Gamma mixture model(EGG)is proposed.Compared with the log-normal model used to describe atmospheric turbulence,the EGG model is dedicated to describing the effect of underwater turbulence on UWOC.The model has higher goodness of fit for the turbulence-induced fading distribution,and the EGG model integrates the effects of a temperature gradient,bubble density,salinity,etc.,on the system performance.Based on the EGG model,this paper derives a closed expression for the BER of the UWOC system affected by turbulence and inter-code crosstalk using the Gauss-Laguerre orthogonal method and extends the expression to the multiple-input multiple-output(MIMO)case.The simulation results show that the BER closure expression derived in this paper matches well with the accurate value of BER,which indicates the accuracy of the expression.