Free-space optical communication systems over fading channels

Fan Yang
2015
Free-space optical (FSO) communication systems can provide larger bandwidth and rapid deployment for communication links. Such systems do not interfere with existing radio frequency (RF) systems and can make communication more secure. However, the performance of FSO communication systems is highly dependent on its channel conditions. The atmospheric channels can impose attenuation and scintillation effects on the communication link, and these effects can hinder the correct detection of
more » ... tection of information on receiver side. In this thesis, we focus on the performance analysis of terrestrial FSO systems over atmospheric fading channels. One successful channel model to fit the experiment data is the lognormal-Rician model, but its widely adoption is impeded by its analytically intractable probability density function (PDF). Therefore we use Padé approximants method to obtain accurate approximations of the PDF, cumulative density function, and moment generating function of lognormal-Rician distribution. Simple closed-form bit-error rate (BER) expression are obtained for binary phase-shift keying (BPSK) modulation with maximum ratio combining (MRC) reception and for binary differential phase-shift keying (DPSK) with selection combing (SC) reception. Asymptotic error rate analysis for BPSK and DPSK is also presented to reveal the performance behavior in large signal-to-noise ratio regimes. The pointing error effects in FSO systems can also contribute to channel impairments. In order to study the influence of pointing error on system performance, we propose a statistical model for pointing error with nonzero boresight error, which takes into account of laser beamwidth, detector aperture size, and jitter variance. A novel closed-form PDF is derived for this pointing error model. Furthermore, we obtain closed-form PDF and series PDF, respectively, for the composite lognormal and Gamma-Gamma turbulence channels with nonzero boresight pointing errors. We conduct error rate analysis of on-off keying signaling with intensity modulati [...]
doi:10.14288/1.0223437 fatcat:fm5fh3vawncuhn3mslbrvpijia