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通信系统的信噪比与信道状态和收发电路噪声有关。通过对大气湍流指数与光强方差的分析,基于光强度调制建立了湍流大气Rytov指数与无线光通信系统接收信噪比之间的关系。分析了由光强闪烁引入乘性噪声的情况下,无线光通信系统接收信噪比与接收光强方差之间的关系;讨论了大气湍流乘性噪声常用的两种概率密度函数及其对接收光强信号的影响,得到了Rytov指数与光强方差、系统接收信噪比之间的关系。最后采用不同天气条件下测得的实验数据验证了结果。研究表明:在弱湍流环境下,光强方差与Rytov指数满足线性关系,相应的接收信噪比随着Rytov指数的增大而降低;在中强湍流环境下,光强方差趋近饱和,系统信噪比趋近于稳定值。
The signal-to-noise ratio of the communication system is related to the channel state and the transceiver circuit noise. Based on the analysis of atmospheric turbulence index and light intensity variance, the relationship between the Rytov exponent of turbulent atmosphere and the received signal-to-noise ratio of wireless optical communication system is established based on light intensity modulation. The relationship between the received signal-to-noise ratio and the variance of received light intensity in wireless optical communication system is analyzed under the condition that the multiplicative noise is introduced by the flicker of light intensity. Two kinds of probability density functions commonly used in atmospheric turbulence multiplicative noise are discussed, Light intensity signal, the relationship between the Rytov index and the variance of light intensity and the received signal-to-noise ratio of the system is obtained. Finally, the experimental data obtained under different weather conditions verify the results. The results show that the variance of light intensity and Rytov index satisfy the linear relationship in weak turbulence environment, and the corresponding received signal-to-noise ratio decreases with the increase of Rytov index. In moderate turbulence environment, the light intensity variance approaches to saturation, and the system The signal-to-noise ratio approaches a stable value.