Browsing by Subject "Received signal strength"
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Item Open Access Cooperative visible light positioning systems(2017-12) Erdem, OsmanLight emitting diode (LED) based visible light positioning (VLP) systems o er an alternative approach to commonly used radio frequency (RF) based positioning systems. In the literature, VLP studies are performed only for noncooperative systems. In this thesis, received signal strength (RSS) based cooperative localization is proposed for visible light systems. The e ects of cooperation on the localization accuracy of visible light positioning systems are illustrated based on a Cram er-Rao lower bound expression. The obtained expression is generic for any three-dimensional con guration and covers all possible cooperation scenarios via de nitions of connectivity sets. In addition, a low-complexity positioning algorithm is proposed for cooperative location estimation. Numerical results are presented to investigate the signi cance of cooperation and to evaluate performance of the proposed algorithm in various scenarios.Item Open Access Effects of cooperation on visible light positioning(IEEE, 2018) Erdem, Osman; Keskin, Musa Furkan; Gezici, SinanIn this paper, cooperative localization is proposed for visible light systems. The effects of cooperation on the localization accuracy of visible light positioning systems are illustrated based on a Cramér-Rao lower bound expression. The obtained expression is generic for any three-dimensional configuration and covers all possible cooperation scenarios via definitions of connectivity sets. Numerical results are presented to investigate significance of cooperation in various scenarios.Item Open Access Fundamental limits on localization in single input multiple output visible light systems(2017-09) Kökdoğan, FurkanVisible light systems have recently been considered as an e ective and promising solution for indoor positioning. In this thesis, a theoretical accuracy analysis is conducted for position estimation in visible light systems based on received signal strength (RSS) measurements. Considering a single light emitting diode (LED) at the transmitter and multiple photo-detectors (PDs) at the receiver, the Cram er-Rao lower bound (CRLB) is derived for both a generic three-dimensional scenario and speci c con gurations of the PDs at the receiver. For the special case in which the height of the receiver is known, a compact expression is derived for the CRLB, considering a uniform circular layout and the same elevation angle for all the PDs. Asymptotic analysis and accuracy of derived compact expression is investigated for this con guration of the system. In addition, the optimal placement of the PDs at the receiver is investigated by taking the e ects of the elevation angle parameter of the PDs into consideration. The optimal values are obtained theoretically and also veri ed by simulations. Numerical examples are presented to illustrate the impacts of system parameters on localization accuracy, namely radius of the uniform circular layout, elevation angle and number of PDs. Finally, theoretical limits are compared against the maximum likelihood estimator (MLE) as a benchmark to evaluate the performance of receiver position estimation.Item Open Access Indoor localization with transfer learning(IEEE, 2022-08-29) Korkmaz, İlter Onat; Özateş, Tuna; Koç, Enes; Aydın, Ege; Kor, Ege; Dilek, Doğaç; Güngen, Murat Alp; Köse, İdil Gökalp; Akman, ÇağlarIndoor positioning methods aim to estimate positions of transmitters where the GPS signals are unavailable. These systems usually employ algorithms explicitly trained for a single location such as fingerprinting method. For that reason, they can only be used in a particular location. This restriction prevents the use of the fingerprint method in tasks such as search and rescue operations where there is no prior knowledge of the place. A fingerprinting system using a trained algorithm with data collected from many places can work in multiple places. This paper proposes an indoor positioning system that uses the parameters of a pre-trained neural network trained with the data obtained from finite difference time domain simulations with transfer learning without collecting large amounts of data. The initial parameters for the model to be trained with the received signal strength (RSS) data collected from real places are used as be the parameters of the artificial neural network trained with the aforementioned simulation data. Performance results of the trained model are comparable to the results of the works in which fingerprinting method is employed in a single environment.Item Open Access SF-Devil: Distributed Bluetooth scatternet formation algorithm based on device and link characteristics(IEEE, 2003-06-07) Pamuk, Canan; Karaşan, EzhanBluetooth has become very popular owing to the fact that it is a promising ad-hoc networking technology for short ranges. Although construction and operation of piconets is well defined in Bluetooth specifications, there is no unique standard for scatternet formation and operation. In this paper, we propose a distributed Bluetooth scatternet formation algorithm based on device and link characteristics (SF-DeviL). SF-DeviL handles energy efficiency using class devices and the received signal strength. SF-DeviL forms scatternets that are robust to position changes and battery depletions. © 2003 IEEE.Item Open Access Theoretical limits on localization in single input multiple output (SIMO) visible light systems(Elsevier, 2018) Kökdoğan,Furkan; Erdem, Osman; Gezici, SinanIn this work, a theoretical accuracy analysis is conducted for position estimation in visible light systems based on received signal strength (RSS) measurements. Considering a single light emitting diode (LED) at the transmitter and multiple photo-detectors (PDs) at the receiver, the Cramér-Rao lower bound (CRLB) is derived for both a generic three-dimensional scenario and specific configurations of the PDs at the receiver. For the special case in which the height of the receiver is known, a compact expression is derived for the CRLB, considering a uniform circular layout and the same elevation angle for all the PDs. In addition, the optimal placement of the PDs at the receiver is investigated by taking the effects of the elevation angle parameter of the PDs into consideration. The optimal values are obtained theoretically and also verified by simulations. Numerical examples are provided to illustrate the impacts of various system parameters on localization accuracy and to compare the theoretical limits against the maximum likelihood estimator (MLE) for the receiver position.