Hector E. Nistazakis

Average Capacity of Optical Wireless Communication Systems Over Atmospheric Turbulence Channels

The optical wireless communication systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. These systems facilitate rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. On the other hand, the performance of this new technology depends strongly on the atmospheric conditions and the parameters of the link such as the length and the operation wavelength. In this work, we extract closed form mathematical expression for the evaluation of the average (ergodic) capacity of such a system, using the log-normal and gamma-gamma distribution, in order to model the atmospheric turbulence conditions and we study the influence of the above parameters on it.

Performance analysis of free-space optical communication systems over atmospheric turbulence channels

Turbulence fading is one of the main impairments affecting the operation of free-space optical (FSO) communication systems. The authors study the performance of FSO communication systems, also known as wireless optical communication systems, over log-normal and gamma-gamma atmospheric turbulence-induced fading channels. These fading models describe the atmospheric turbulence because of its very good agreement with experimental measurement data. Closed-form expressions for the average (ergodic) capacity and the outage probability are derived for both statistical models. Another contribution of this work is a study of how the performance metrics are affected by the atmospheric conditions and other parameters such as the length of the link and the receivers aperture diameter. The derived analytical expressions are verified by various numerical examples and can be used as an alternative to time-consuming Monte-Carlo simulations.

Capacity analysis of dual amplify-and-forward relayed free-space optical communication systems over turbulence channels with pointing errors

This paper elaborates on the end-to-end capacity of dual-hop free-space optical (FSO) communication systems employing amplify-and-forward (AF) relaying, assuming channel state information is only known at the receiving terminals. The relay is assumed to either possess perfect channel state information or have a fixed gain. The performance of the considered system is affected by the combined effects of atmospheric turbulence-induced fading, pointing errors (i.e., misalignment fading), and path loss. Atmospheric turbulence conditions are modeled using the gamma-gamma distribution. For the system under consideration, accurate analytical approximations as well as upper bounds to the ergodic capacity are derived. In addition, bound approximations in the high signal-to-noise ratio regime are deduced that provide valuable insights into the impact of model parameters on the capacity of AF FSO dual-hop relaying systems. Numerically evaluated and computer simulation results are further provided to demonstrate the validity of the proposed mathematical analysis.

Bright-dark soliton complexes in spinor Bose-Einstein condensates

We consider vector solitons of mixed bright-dark types in quasi-one-dimensional spinor

Dual-hop relaying communications over generalized-K (KG) fading channels

(F=1)

Average capacity of optical wireless communication systems over I-K atmospheric turbulence channels

Bose-Einstein condensates. Using a multiscale expansion technique, we reduce the corresponding nonintegrable system of three coupled Gross-Pitaevskii equations (GPEs) to an integrable Yajima-Oikawa system. In this way, we obtain approximate solutions for small-amplitude vector solitons of dark-dark-bright and bright-bright-dark types, in terms of the

Bayesian and frequentist estimation of the performance of free space optical channels under weak turbulence conditions

{m}_{F}=+1,\ensuremath{-}1,0

Families of matter-waves in two-component Bose-Einstein condensates

spinor components, respectively. By means of numerical simulations of the full GPE system, we demonstrate that these states indeed feature soliton properties, i.e., they propagate undistorted and undergo quasielastic collisions. It is also shown that in the presence of a parabolic trap the bright component(s) is (are) guided by the dark one(s) and, as a result, the small-amplitude vector soliton as a whole performs quasiharmonic oscillations. The oscillation frequency is found as a function of the spin-dependent interaction strength for both small-amplitude and large-amplitude solitons.

Capacity estimation of optical wireless communication systems over moderate to strong turbulence channels

In this paper, a study on the end-to-end performance of dual-hop non-regenerative relaying over independent generalized-K (KG) fading channels is presented. Using a suitable upper bound for the end-to-end signal-to-noise ratio (SNR), novel closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF) and the moments of this bounded SNR are derived. These results can be afterwards used to obtain important performance metrics of the considered system such as the outage probability and the error performance of digital modulation schemes. In the case of independent but non-necessarily identical fading channels, lower bounds for the average bit error probability (ABEP) for different modulation schemes are determined by using the Pade approximants method. For the case of identical fading channels, closed-form lower bounds for the ABEP are derived. Various numerical and computer simulation results illustrate the proposed analysis.

Stabilizing soliton transmission by third-order dispersion in dispersion-compensated fibre links

The optical wireless communication systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. These systems facilitate rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. On the other hand, the performance of this new technology depends strongly on the atmospheric conditions and the parameters of the link such as the length and the operation wavelength. In this work, we extract closed form mathematical expression for the evaluation of the average (ergodic) capacity of such a system, using the log-normal and gamma-gamma distribution, in order to model the atmospheric turbulence conditions and we study the influence of the above parameters on it.