Alleviation of Jamming in Free Space Optical Communication over Gamma-Gamma Channel with Pointing Errors

In this paper, the groundwork on jamming effect and its alleviation mechanisms in free space optical (FSO) communication are studied over Gamma-Gamma (GG) fading channels along with the pointing error (PE) effects. A closed-form expression of the bit error rate (BER) is evaluated analytically for a single-input single-output (SISO) FSO system in the presence of jammer. The worst case jamming condition for maximization of error is calculated numerically. The jammer channel is considered to be GG distributed. Being the most dominating noise, the jamming signal is acted as the only noise source in the considered FSO set-up. Therefore, this study is performed over additive GG noise channel. The error performances are investigated for different atmospheric turbulence (AT) regimes (weak to strong) and for different PE parameters of jamming noise. Moreover, to combat the jamming effect, a multiple-input single-output (MISO) FSO system is considered. A closed-form expression of the BER of the multiple transmit channels over the GG noise is analytically calculated. The analytical results for both SISO and MISO FSO systems are verified with the help of the simulation results obtained by MATLAB software. It is established that MISO FSO performs better than SISO FSO system in terms of BER performance under the influence of jamming noise. Furthermore, many important observations are made upon the BER performances for different AT and PE parameters for SISO and MISO FSO systems.