Modeling And Analysis Of Mixed RF-UWOC System

Due to the broadcasting of Radio Frequency(RF)link and the scarcity of spectrum resources,RF link is extremely vulnerable to signal interference,facing security risks and destroying system performance.These factors can seriously affect system performance.Underwater Wireless Optical Communication(UWOC)namely means data transmission in water environment by laser,which can provide greater transmission bandwidth and higher transmission rate with higher security.However,it is not suitable for long-distance communication due to the influence of environmental factors.Therefore,the research of mixed RF-UWOC system has become one of the cross-research hotspots.The system can not only save spectrum resources,but also be suitable for long-distance transmission,more in line with the actual needs of military,ocean exploration and other fields.Based on mixed RF-UWOC system,through mathematical modeling,general performance analysis is carried out first,and then the security performance of the system is studied in combination with physical layer security.The main research contents are as follows:1.Conduct mathematical modeling and theoretical analysis on the performance of mixed RF-UWOC system.The cumulative distribution function and probability density function of the signal-to-noise ratio are derived respectively,and then the accurate and asymptotic closed analytical formula of the outage probability and average bit error rate are derived.The correctness of the simulation and calculation is verified by Monte Carlo Method.The results show that the system performance under Amplify-and-Forward(AF)strategy is better than that under Decode-and-Forward(DF)strategy.Heterodyne Detection(HD)is better than Intensity Modulation/Direct Detection(IM/DD).In terms of bit error rate,the modulation effect of Binary Phase Shift Keying(BPSK)is better than that of On-Off Keying(OOK).2.Carry out mathematical modeling and theoretical analysis on the physical layer security of mixed RF-UWOC system.For mixed RF-UWOC system,eavesdropping nodes with random distribution exist in RF links.Using the random geometry theory,the exact closed analytical formula of security outage probability is derived under AF and DF forwarding strategies.The correctness of the simulation and calculation is verified by Monte Carlo Method,and the results showed that under the condition of certain parameters such as channel gain and detection method,the temperature and bubble level would affect the system by changing the environmental parameters.In terms of relay strategy,AF forwarding strategy is better than DF.Compared with IM/DD,HD detection method is better.