孔径接收下各向异性海洋湍流UWOC系统误码分析

Bit error rate analysis of anisotropic ocean turbulence UWOC system with aperture reception

为了研究孔径接收对各向异性海洋湍流条件下水下无线光通信(UWOC)系统误比特率的影响,系统采用高斯光束传输,接收端通过孔径接收,在脉冲位置调制方式下通过各向异性海洋湍流信道。引入各向异性海洋湍流结构常数,通过对闪烁的形成原理和各向异性海洋湍流条件下闪烁系数的分析,数值模拟得到了在不同接收孔径和各向异性因子下,海洋湍流参量、传输距离、雪崩光电二极管(APD)平均增益和调制阶数对系统误比特率的影响。结果表明,相同各向异性因子和海洋湍流参量下,大孔径接收能有效提升系统误比特率性能;相同孔径直径和海洋湍流参量下,各向异性因子越大,系统通信性能越好;均方温度耗散率、温度和盐度对海洋功率谱变化贡献的比值较小,湍流动能耗散率、动力粘度较大以及传输距离越短,系统误码性能越好;APD增益为100或150时,系统通信性能最佳;调制阶数M=8时,系统通信性能最佳,M>64时,系统误比特率变化程度几乎饱和。该研究为UWOC系统平台搭建和性能估计提供了参考。

In order to study the effect of aperture reception on the bit error rate of underwater wireless optical communication(UWOC)system under the condition of anisotropic ocean turbulence,Gaussian beam transmission was adopted to pass through an anisotropic ocean turbulence channel under pulse position modulation.The signal was then received though the apertureby the acceptor,the effects of ocean turbulence parameters,transmission distance,average gain of avalanche photodiode(APD),and modulation order on the bit error rate of the system under different receiving aperture and anisotropy factor were numerically simulatedby introducing the anisotropic ocean turbulence structure constant and analyzing the formation principle of scintillation and scintillation index under the condition of anisotropic ocean turbulence.The results show that under the same anisotropy factor and ocean turbulence parameters,the bit error rate performance of the system can be effectively improved by large aperture receiver.The larger the anisotropy factor,the better the system communication performance for the same aperture diameter and ocean turbulence parameters.The bit error rate performance of the system becomes better when the ratios of mean square temperature dissipation rate,temperature,and salinity contribution to the variation of ocean power spectrum are smaller,while the turbulent kinetic energy dissipation rate and kinetic viscosity are larger and the transmission distance is shorter.The performance of system communication is optimal when the APD gain is 100 or 150.The optimal system communication performance is achieved when the modulation order M=8,and the degree of system bit error rate variation is almost saturated when M>64.This study provides a reference for UWOC system platform construction and performance estimation.