FSO Communications over Doubly Inverted Gamma-Gamma Turbulence Channels with Nonzero-Boresight Pointing Errors

In this paper, the recently proposed doubly inverted Gamma-Gamma (IGGG) turbulence channel model is considered to analyze the performance of a free-space optical communication system. To this end, the probability density function (PDF) and cumulative distribution function (CDF) of the irradiance fluctuations of an optical wave propagating through an IGGG turbulence channel under nonzero-boresight pointing errors are derived. Furthermore, the PDF and CDF under zero-boresight pointing errors are obtained as a special case. To study the impact of nonzero-boresight pointing error parameters and turbulence condition on the system performance, exact closed-form expressions for outage probability, bit error rate, and average capacity under intensity modulation/direct detection are derived. Besides, asymptotic analysis is provided which help us to identify the diversity gain of the system. The analytical analyzes are verified through numerical and Monte-Carlo simulation results.