Performance Analysis of FSO Array Receivers in Presence of Atmospheric Turbulence

We evaluate the performance of a free space optical link using an array of direct detection receivers in terms of the bit error rate (BER) under the influence of various atmospheric conditions and turbulence strengths. The expression for BER is derived by modeling the turbulence as a gamma-gamma distribution. The effect of weather conditions is incorporated using Beer-Lambert's law. Results show that increasing the number of detectors reduces the BER as expected. In addition, the diversity gain increases with the increasing turbulence strength but remains almost constant for a fixed value of the turbulence strength and the number of detectors over various atmospheric conditions such as very clear air, drizzle, haze, fog, and so forth.