Hector E. Nistazakis

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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(More)
In this paper, we derive mathematical expressions for the evaluation of the average (ergodic) capacity of free-space optical (FSO) communication systems. Atmospheric turbulence conditions are modeled using the I-K distribution. Our newly derived expressions provide an efficient tool to assess the spectral efficiency of FSO communication systems. Numerically(More)
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(More)
We study the asymptotic behavior of complex discrete evolution equations of Ginzburg-Landau type. Depending on the nonlinearity and the data of the problem, we find different dynamical behavior ranging from global existence of solutions and global attractors, to blow up in finite time. We provide estimates for the blow up time, depending not only on the(More)
The free space optical communication systems are attracting great research and commercial interest due to their capability of transferring data over short distances, with high rate and security, low cost demands and without licensing fees. However, their performance depends strongly on the atmospheric conditions in the link's area. In this work, we(More)
We consider vector solitons of mixed bright-dark types in quasi-one-dimensional spinor ͑F =1͒ Bose-Einstein condensates. Using a multiscale expansion technique, we reduce the corresponding nonintegrable system of three coupled Gross-Pitaevskii equations ͑GPEs͒ to an integrable Yajima-Oikawa system. In this way, we obtain approximate solutions for(More)
In this paper, an exact unitary transformation is examined that allows for the construction of solutions of coupled nonlinear Schrödinger equations with additional linear field coupling, from solutions of the problem where this linear coupling is absent. The most general case where the transformation is applicable is identified. We then focus on the most(More)
The dynamics of dark matter-wave solitons in elongated atomic condensates are discussed at finite temperatures. Simulations with the stochastic Gross-Pitaevskii equation reveal a noticeable, experimentally observable spread in individual soliton trajectories, attributed to inherent fluctuations in both phase and density of the underlying medium. Averaging(More)
Optical wireless communication (OWC) systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. OWC facilitates rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. Nevertheless, the performance of this new technology depends strongly on the atmospheric(More)
We study spin-polarized states and their stability in the antiferromagnetic phase of spinor ͑F =1͒ quasi-one-dimensional Bose-Einstein condensates. Using analytical approximations and numerical methods, we find various types of polarized states, including patterns of the Thomas-Fermi type, structures featuring a pulse in one component inducing a hole in the(More)