Exploring a novel turbulence model: The Chi-square/inverse Gamma approach for enhanced free space optics (FSO) communication

The manuscript introduces a novel turbulence model for free space optics (FSO) communication, constructed through the amalgamation of two distinct statistical models, rooted in the scintillation theory. A closed-form expression for the probability density function (PDF) and cumulative distribution function (CDF) of the turbulence channel, specifically the Chi-square/inverse Gamma distribution, was deduced. Further the influence of zero boresight pointing errors on the performances of FSO transmission over the obtained atmospheric turbulence channel has been considered. To delve into the intricacies of the channel, an examination of the average bit error rate (ABER) was undertaken as an evaluative metric for the transmitted signal’s quality. The ABER analysis was specifically conducted within the framework of IM/DD (intensity modulation and direct detection) and OOK (on-off keying), considering diverse sets of system parameters and across various turbulence scenarios. In the same manner, ABER analysis has been carried out for the subcarrier intensity modulation (SIM) with differential phase-shift keying (DPSK).