Elektrik Elektronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/411
Browse
4 results
Search Results
Conference Object Citation - Scopus: 2Associativity Tick Averaged Associativity Based Routing (Ataabr) for Real Time Mobile Networks(2009) Převeze, B.; Preveze, Barbaros; Şafak, A.; Elektrik-Elektronik MühendisliğiThis study proposes a long lived routing method which is also based on Associativity such as ABR (Associativity Based Routing) for real time applications. The main purpose of our work is improving the ABR algorithm in order to reduce the outage of the nodes and decreasing the number of reconstructions required to keep the nodes in communication. The performance of ABR is compared with other long-lived relay selection algorithms for real-time applications.Article Citation - WoS: 88Citation - Scopus: 87Correlation and Structure Functions of Hermite-Sinusoidal Laser Beams in a Turbulent Atmosphere(Optical Soc Amer, 2004) Baykal, YTo study the performance of atmospheric optical links by using Hermite-sinusoidal-Gaussian laser beam sources, we derive the log-amplitude and the phase correlation and structure functions of such beams in a turbulent atmosphere. Our formulations correctly reduce to the known higher-order mode correlation and structure functions, which in turn reduce to the fundamental-mode (TEM00-mode) results. Several special cases of our formulation are presented, among which the case involving Hermite-cosh-Gaussian dependence is especially noted, since this case is of interest to us owing to the nature of cosh dependence exhibiting the concentration of the energy in the outer lobes of the beam. (C) 2004 Optical Society of America.Conference Object Citation - WoS: 1Citation - Scopus: 1Effects of Laser Multimode Content on the Angle-Of Fluctuations in Free Space Optics Access Systems(Spie-int Soc Optical Engineering, 2004) Eyyuboglu, HT; Baykal, YThe effects of the multimode content in a laser beam on the angle-of-arrival fluctuations are examined for free space optics (FSO) access systems. Multimode excitation is represented by coherent addition of Hermite-Gaussian higher order modes. Root mean square angle-of-arrival fluctuations are formulated using the previously reported multimode phase structure function, which is valid in weak atmospheric turbulence. Results are found for practical FSO links operating at 1550 nm and 850 nm wavelengths and for link spans of up to 5 km. In choosing the mode content, various sequential grouping of all possible mode combinations are used up to a certain order (n,m) mode. We start with the single fundamental mode (TEM00) and span up to the highest order (n = 10, m = 10) mode. In this manner, different degrees of source coherence are also taken into account. Angle-of-arrival fluctuations are found to be in the range of several tens of muradians and almost insensitive to the mode content except for the cases when the mode group terminates with an odd mode. In such instances, the fluctuations rise to a few hundreds of murad. Comparing our results with the field of view of a practical FSO receiver, which is several mrad, we conclude that the-angle-of arrival fluctuations due to multimode excitation will not influence the FSO link performance to a major extent.Article Citation - WoS: 38Citation - Scopus: 45Propagation of Modified Bessel-Gaussian Beams in Turbulence(Elsevier Sci Ltd, 2008) Eyyuboglu, Halil Tanyer; Hardalac, FiratWe investigate the propagation characteristics of modified Bessel-Gaussian beams traveling in a turbulent atmosphere. The source beam formulation comprises a Gaussian exponential and the summation of modified Bessel functions. Based on an extended Huygens-Fresnel principle, the receiver plane intensity is formulated and solved down to a double integral stage. Source beam illustrations show that modified Bessel-Gaussian beams, except the lowest order case, will have well-like shapes. Modified Bessel-Gaussian beams with summations will experience lobe slicing and will display more or less the same profile regardless of order content. After propagating in turbulent atmosphere, it is observed that a modified Bessel-Gaussian beam will transform into a Bessel-Gaussian beam. Furthermore it is seen that modified Bessel-Gaussian beams with different Bessel function combinations, but possessing nearly the same profile, will differentiate during propagation. Increasing turbulence strength is found to accelerate the beam transformation toward the eventual Gaussian shape. (c) 2007 Elsevier Ltd. All rights reserved.