Average bit error rate (BER) performance of on-off keying (OOK) modulation in a free space optical (FSO) system, which is based on adaptive threshold technique under atmospheric turbulence described by exponentiated Weibull (EW) distribution, is studied and compared with that of using fixed threshold technique. In order to solve the adaptive threshold, the equation is simplified by using the generalized Gauss-Laguerre polynomial function, which significantly improves the operational efficiency. The simulation results show that the adaptive threshold varies with the average transmitted power under different noise variances, receiving aperture sizes and turbulence conditions. Compared with the fixed threshold technique, the adaptive threshold technique can greatly improve the BER performance of FSO communication system.
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