Performance Analysis Of Alamouti Scheme In Turbulence Induced Fading With Pointing Errors

Free Space Optics (FSO) communication technology with Multi-input and Multi-output (MIMO) and subcarrier intensity modulation (SIM) has captivated interests in research due the diversity gain offered by MIMO. Atmospheric turbulence and pointing errors are the major challenges that affect the FSO system performance. In this work, the FSO based 2x1 Alamouti scheme employing SIM and Q-PSK is analyzed and compared without using Alamouti scheme with Gamma-Gamma (GG) fading channel considering pointing error effects. We derived the closed form expressions for symbol error rate (SER) with Alamouti scheme under the effect of different atmospheric turbulence and pointing errors using moment generating function (MGF). As a result, the proposed system could achieve a high signal-to-noise ratio(SNR) gain of 27 dB over the without Alamouti scheme under moderate and strong turbulence regime.