This paper presents the WSN-FSO (wireless sensor network-free-space optics) system based on CCR (corner cube retroreflector) and modeled with Gamma-Chi-square distribution. The expressions of ABER (average bit error rate) for the received signal under conditions of different levels of atmospheric turbulence are calculated. Numerical results are presented in the form of graphs, and the results are confirmed by the Monte Carlo simulation. Graphs are presented for different Rician factor values, link lengths, and different levels of atmospheric turbulence. The obtained results are compared with the existing results for other FSO channel distribution models. After thorough consideration we conclude that Gamma-Chi-square gives a better system performance in terms of ABER.