Browsing by Author "Erkucuk,S."

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Citation Count: 0
Atmosferik Türbülans Altinda Orbital Açisal Momentum Tabanli Haberleşme Sistemleri Orbital Angular Momentum Based Communication Systems under Atmospheric Turbulence;
(Institute of Electrical and Electronics Engineers Inc., 2020) Sheikh,A.A.A.; Basaran,M.; Erkucuk,S.
Orbital Angular Momentum (OAM) may be a candidate for future communication systems due to its advantages in terms of high data rates and effective frequency utilization. OAM can provide a solution where a beam is transformed into multiple beams within itself and becomes independent streams of data (pertaining to the principle of orthogonality) to be transferred when properly utilized. However, the free space contains atmospheric turbulence which interferes with the beam propagation of OAM and as a result the photons in the light beam are affected as well as the independence of each OAM mode. Therefore, the data stream suffers crosstalk. In this study, weak and strong atmospheric turbulences and how they affect a variety of OAM modes as they propagate through free space are investigated, and important OAM implementation issues are discussed. © 2020 IEEE.
Citation Count: 4
Performance investigation of IEEE 802.11af systems under realistic channel conditions
(Institute of Electrical and Electronics Engineers Inc., 2015) Macit,M.C.; Senol,H.; Erkucuk,S.
As the analog TV broadcasting channels have become less frequently used in the last decade, there has been a great interest in these frequency bands for the deployment of metropolitan, local and personal area networks. Among them, the local area network standard IEEE 802.11af defines PHY and MAC layer implementation of such networks in these unused frequency bands, also named television white space (TVWS). According to the standard, the systems may use contiguous or non-contiguous channels during their operation, depending on the channel availability. In this paper, we investigate in detail the performance of different operation modes of these systems under realistic channel conditions. While the perfect knowledge of channel would result in similar system performances, as the number of in-between-bands occupying the non-contiguous modes is increased the channel estimation performance degrades drastically, which is quantified in this study. In addition, it is shown that determining the true locations of multipaths heavily relies on the selected channel resolution and has a significant effect on the system performance. Numerical examples are given to demonstrate the effects of both the non-contiguous operation modes and the selected channel resolution. © 2015 IEEE.