Communications and Spectrum Management Research Center (ISYAM)

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Browsing Communications and Spectrum Management Research Center (ISYAM) by Author "Karasan, Ezhan"

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    The effect of terrain roughness in the microwave line-of-sight multipath fading estimation based on Rec. ITU-R P.530-15
    (IEEE, 2014-08) Göktas, Polat; Altıntaş, Ayhan; Topçu, Satılmış; Karasan, Ezhan
    Multipath fading is an important constraint on the prediction of path loss for terrestrial line-of-sight microwave links. The International Telecommunication Union - Radiocommunication (ITU-R) Rec. P.530 [1] is one of the most widely used methods providing guidelines for the design of terrestrial line-of-sight links. The purpose of the study presented in this paper is to make an investigation of the effect of both terrain roughness and geoclimatic factor parameters in the path loss characteristics of microwave line-of-sight (LOS) propagation in NATO Band 3+ (1350-2690 MHz) and NATO Band 4 (4440-5000 MHz) frequency ranges. The two parameters led to significantly different results for the link availability due to multipath fading as a function of the fade margin. © 2014 IEEE.
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    Multipath fading effect on terrestrial microwave LOS radio links
    (IEEE, 2015-07) Göktaş Polat; Topçu, Satılmış; Karasan, Ezhan; Altıntaş, Ayhan
    In this paper, the calculation of both the total received power with the effect of the ground reflection and the fade margin to find out the link availability for terrestrial microwave LOS (line-of-sight) radio links is proposed. The expressions are derived from clear-air, rainfall propagation mechanisms and multipath fading due to multipath arising from surface reflection along the defined microwave LOS radio link. We verify the mathematical model by using the ATDI ICS telecom software over sample microwave LOS radio links located in Turkey. © 2015 IEEE.
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    A new approach to diffraction modelling for line-of-sight (LOS) paths
    (IEEE, 2015) Topçu, Satılmış; Göktaş, Polat; Karasan, Ezhan; Altıntaş, Ayhan
    In this paper, we present a new knife-edge diffraction method based on Bullington method for the terrestrial line-of-sight (LOS) paths. The diffraction loss of our new knife-edge diffraction method is compared with the results obtained from the Delta-Bullington method and the measurement data existing in the literature for sample fixed terrestrial microwave line-of-sight (LOS)/ non line-of-sight (NLOS) radio links. The revised Bullington method is shown to perform significantly better than the Delta-Bullington method for both overland and coastal/overwater radio links.
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    Short-term propagation measurements and modeling for terrestrial line-of-sight links
    (IEEE, 2016) Göktaş, Polat; Topçu, Satılmış; Karasan, Ezhan; Altıntaş, Ayhan
    This paper presents a propagation prediction technique to predict propagation mechanisms for fixed terrestrial line-of-sight (LOS) radio links, especially proposed for rural environments. We report the results of a short-term propagation measurement campaign carried out in the area of Ankara, Turkey. The field measurements were performed at the frequency of 2.536 GHz for a period of three months in summer 2015. It is observed that the difference between measurement data and predicted mean received power is smaller than the standard deviation value provided by Recommendation ITU-R P. 1546.