K分布湍流信道的Gamma近似

Gamma approximation of K-distribution turbulent channel

当无线电波经过大气、太阳风等随机介质时,传输介质折射率的随机起伏会导致无线电波信号产生衰落。尽管K分布可以很好地描述湍流信道模型,但因其表达式十分复杂,很难用于分析包括误码率在内的通信性能。因此,提出了一种Gamma分布近似方法,采用KL散度分析并验证了近似方法的有效性。应用K分布湍流信道的Gamma近似,给出了BPSK调制的误码率闭式表达式,分析了湍流对误码率的影响。数值计算表明,湍流对误码率影响非常明显,特别是信噪比(SNR)较低时,即使是湍流现象较弱时,误码率也比无湍流时高出3~4个数量级。同时,随着α的增加,闪烁指数m减小,误码率得到降低,这就为湍流信道条件下通信系统的设计和分析提供了重要依据。

The random fluctuations in the refractive index of the transmission medium will cause the radio wave signal to fade,when radio waves pass through random media such as the atmosphere and the solar wind.Although the K distribution can describe the turbulent channel model well,it is difficult to analyze the communication performance including bit error rate due to its complicated expression.Therefore,a Gamma distribution approximation method is proposed,and the effectiveness of the approximation method is verified by using KL divergence analysis.Using the Gamma approximation of the K-distributed turbulence channel,the closed-form expression of the bit error rate of BPSK modulation is given,and the influence of turbulence on the bit error rate is analyzed.Numerical calculations show that the effect of turbulence on the bit error rate is very obvious,especially when the signal-to-noise ratio(SNR)is low,even when the turbulence phenomenon is weak,the bit error rate is 3-4 orders of magnitude higher than when there is no turbulence.At the same time,asαincreases,the scintillation index m decreases,and the bit error rate is reduced,which provides an important basis for the design and analysis of communication systems under turbulent channel conditions.