Hasari Celebi

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Location awareness is one of the essential characteristics of cognitive radios. In this paper, an innovative cognitive positioning system (CPS) that achieves accuracy adaptation in both indoor and outdoor environments is proposed as a step towards realization of location awareness in cognitive radios. The proposed CPS is composed of two modes; bandwidth(More)
Francis E. Retnasothie, M. Kemal Özdemir, Tevfik Yücek, Hasari Celebi, Joseph Zhang, and Ranesh Muththaiah ∗ Logus Broadband Wireless Solutions 845 Progress Ave, Toronto, Canada M1H 2X4 † Logus Broadband Wireless Solutions USA 3803 Corporex Park Plaza Suite 700, Tampa, FL 33619 ‡University of South Florida, Department of Electrical Engineering 4202 E.(More)
Location awareness is an essential characteristic of cognitive radios as well as networks. In this article a location awareness engine architecture is proposed for the realization of location awareness in cognitive radios and networks. The proposed architecture consists of location estimation and/or sensing, seamless positioning and interoperability,(More)
Cognitive Radio (CR) systems with spectrum awareness feature is a promising approach to use spectrum effectively. However, accurate modeling of spectrum utilization is crucial for the development and performance evaluation of such systems. Hence, in this paper, a wideband multidimensional spectrum occupancy measurement campaign is conducted to study the(More)
Opportunistic spectrum access feature of cognitive radio systems is a method to improve frequency underutilization of wireless spectrum. One of the techniques for detecting the unused bands is the energy detection for which selection of the threshold defines detection performance. In this paper, the adaptive threshold method is proposed as an alternative(More)
There are different location estimation approaches in order to determine the position of a mobile users precisely in indoor environments. In this study, in order to determine the position of the mobile user at the shopping malls received signal strength (RSS) RF fingerprint based approaches is considered. Wi-Fi and GSM RSS data has been collected by using(More)
In this letter, fundamental limits on time delay estimation are studied for cognitive radio systems, which facilitate opportunistic use of spectral resources. First, a generic CramerRao lower bound (CRLB) expression is obtained in the case of unknown channel coefficients and carrier-frequency offsets (CFOs) for cognitive radio systems with dispersed(More)
1Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, 06800 Ankara, Turkey 2Department of Electrical and Computer Engineering, Texas A&M University at Qatar, 23874 Doha, Qatar 3Department of Electrical Engineering, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620, USA 4Department of Electrical Engineering,(More)