Performance analysis of a free space optical link using Alamouti type Space Time Block Code with weak turbulent condition

In this paper, we investigate the performance of a free space optical link using Alamouti type Space Time Block Code (STBC) over weak atmospheric turbulence-induced fading channels. An analytical approach is presented to evaluate the bit error rate (BER) performance of a direct detection on-off keying (OOK) free space optical link over a weak atmospheric turbulent condition considering Alamouti type space time block code (STBC) and maximal ratio combining (MRC) at the receiver. The results are evaluated numerically and also by simulation. Results show that there is significant improvement in BER performance at a given BER due to coding and diversity combining at the receiver. The amount of improvement for (M × L ) STBC is of the order of 18 dB, 10 dB and 5 dB for laser source, M=2 and number of photodetector, L= 1, 2 and 4 respectively.