BER performance analysis of coherent SIMO FSO systems over correlated non-Kolmogorov turbulence fading with nonzero boresight pointing errors

In this paper, the effects of nonzero boresight pointing errors on the average bit-error rate (BER) performance of coherent single-input multiple-output (SIMO) free-space optical (FSO) communication systems applying maximal ratio combining (MRC) over correlated non-Kolmogorov turbulence fading are investigated. The non-Kolmogorov turbulence fading is modeled using Gamma-Gamma distribution. Novel closed-form expression is derived for evaluation of the average BER performance for the system under consideration. Analytical results are provided to evaluate the average BER performance with the presence of correlated Gamma-Gamma channels and nonzero boresight pointing errors. It is worth noting that there exist an optimum radius of the ring where all the receivers are located to achieve the minimum BER for a given average signal-to-noise ratio value. The validity of the obtained mathematical expression is illustrated by Monte Carlo simulations. This work will help with further investigation of the fading correlation and the design of FSO communication systems.