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无线光通信(OWC)系统采用大气通道作为传输媒介,而大气湍流效应引入了与信号强度有关的乘性噪声。为了消除乘性噪声所引起的信号衰落,分析并给出了基于最小均方(LMS)自适应滤波器的判决门限更新算法和稳态的抽头权系数相关矩阵算法。通过理论分析和计算机仿真,讨论了最小均方滤波器及其参数对无线光通信接收性能的影响。结果表明,采用非因果滤波器的无线光通信系统对湍流噪声具有明显的抑制作用。在弱湍流情况下,基于自适应最小均方滤波器的系统误码率(BER)低于10-8,可以满足网络通信的要求。通过分析不同滤波器阶数对误码率的影响表明,所采用的255阶的非因果结构的最小均方滤波器是最优的结构。
The Wireless Optical Communication (OWC) system uses the atmospheric channel as the transmission medium, and the atmospheric turbulence effect introduces the multiplicative noise related to the signal strength. In order to eliminate signal fading caused by multiplicative noise, a decision threshold updating algorithm based on Least Mean Square (LMS) adaptive filter and a steady-state tap weight coefficient correlation matrix algorithm are given. Through theoretical analysis and computer simulation, the influence of the minimum mean square filter and its parameters on the reception performance of wireless optical communication is discussed. The results show that the wireless optical communication system with non-causal filter has a significant inhibitory effect on turbulent noise. In the case of weak turbulence, the system BER (bit error rate) based on the adaptive minimum mean square filter is less than 10-8, which can meet the requirements of network communication. By analyzing the influence of different filter order on bit error rate, it is shown that the 255-order non-causal minimum-mean-square filter is the optimal structure.