3Time Jitter Influence on the Performance of PPM or PAM SIMO FSO Links over M-Turbulence Channels

Abstract

FSO communications has become more and more popular in the last decade due to its unprecedented benefits, which allows both low cost and high data rates. Nevertheless, the performance of such communication systems is unavoidably delimited due to many factors, primarily including the influence of scintillation and time jitter. The former effect is induced by atmospheric turbulence, which in turn depends on the current weather conditions of the atmospheric channel, causing rapid fluctuations in the received signal strength. At the receiver, the latter effect is due to the misdetection of optical pulses, causing further damage to the received signals, especially the high-rate ones, because of their short pulse time slot. However, both effects can be modeled by appropriate, already proposed, statistical distributions. Here, the turbulence effect is treated by the Málaga distribution, while the newly proposed generalized Gaussian distribution is employed for the time jitter influence. Also, the remarkable receiver’s diversity technique appears to be a promising solution to improve the performance of the FSO communications. In this work, new accurate mathematical expressions are derived for the estimation of the average BER of PPM or PAM FSO links with optimal combining diversity schemes at the receivers’ side. Additionally, the corresponding numerical results are presented for realistic system cases.