A Simple Approximation of FSO Link Distribution and its Applications

We consider a wireless free space optical (FSO) communication system. The FSO link is assumed to follow the gamma-gamma distribution. It is shown in literature that the probability density function (PDF) of the gain of FSO link has complicated form, it is in the form of modified bessel function. Due to its complicated nature, the analytical expressions of FSO communication system has very high computational complexity. In this paper, for a FSO link, an approximate expression in terms of series expansion for PDF of the gain of FSO link is derived. Further, it is shown that the derived approximate expression is accurate and easy to deal. The performance analysis of the FSO based communication system is performed in terms of bit error rate by using the derived PDF expression.