KEYWORDS: Free space optics, Turbulence, Receivers, Lithium, Optical engineering, Monte Carlo methods, Error analysis, Signal to noise ratio, Telecommunications, Systems modeling
Two approximate closed-form probability density function expressions for the sum of lognormal-Rician random variates (RVs) and the sum of square root of lognormal-Rician RVs are obtained. The proposed expressions are shown to provide high accuracy over a wide range of channel conditions according to Kolmogorov–Smirnov goodness-of-fit statistical tests results. Also, the analysis of the approximation error is presented to indicate that a higher approximation accuracy can be achieved for larger r or smaller variance σz2. To reveal the importance of the proposed approximation, new approximate closed-form expressions of the ergodic capacity, average bit error rate for the intensity-modulation direct-detection (IMDD), and coherent multiple-input multiple-output (MIMO) free-space optical (FSO) systems with equal gain combining diversity technique over lognormal-Rician turbulence channels are developed. It is observed that MIMO technology can offer a significant improvement in system performance and the performance of coherent FSO systems outperforms that of IMDD systems. The Monte Carlo simulation results are further utilized to illustrate the accuracy of the proposed approach.
KEYWORDS: Modulation, Turbulence, Free space optics, Signal to noise ratio, Optical communications, Telecommunications, Lithium, Error analysis, Receivers, Signal detection
Various approaches have been put forward to reduce impairments affected by turbulence fading in free-space optical(FSO) communication systems. In this paper ,We study the ASEP (average slot error probability )and APEP(average packet error probability) performance of PPMs approximately in optimal detection threshold while channel state information(CSI) is best estimated in receiver. In our framework , We mainly focus the weak turbulence with log normal fading and these two probability(ASEP and APEP) are calculated by the method proposed by Holzman. Furthermore, ASEP and APEP are simulated to study how the performance metrics are affected by the atmospheric conditions and other PPMs parameters such as modulation order M , numbers of slots m, pulses q parameters and numbers for information bits N.
This paper investigates the aperture-averaged angle-of-arrival variance for a Gaussian wave propagating through the weak anisotropic non-Kolmogorov atmospheric turbulence along a horizontal path. A heuristic model is deduced from the results of plane and spherical waves under the geometrical optics approximation. The mathematical expression include the spectral power law value, the anisotropic factor and other essential optical parameters of a Gaussian wave.
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