Browsing by Author "Gonendik, E."

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    Fundamental limits on RSS based range estimation in visible light positioning systems
    (IEEE, 2015-12) Gonendik, E.; Gezici, Sinan
    In this study, theoretical limits are obtained for the accuracy of range (distance) estimation in visible light positioning (VLP) systems. In particular, the Ziv-Zakai bound (ZZB) and the weighted Cramer-Rao bound (WCRB) are derived ´ for range estimation based on received signal strength (RSS) measurements. Also, the maximum a posteriori probability (MAP) and the minimum mean-squared error (MMSE) estimators are obtained for RSS based range estimation, and compared against the theoretical limits.
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    Improved lower bounds for ranging in synchronous visible light positioning systems
    (Institute of Electrical and Electronics Engineers Inc., 2016) Keskin, M. F.; Gonendik, E.; Gezici, Sinan
    In this study, the Ziv-Zakai bound (ZZB) is derived for synchronous visible light positioning (VLP) systems. The proposed ZZB extracts ranging information from the prior information, the time delay parameter, and the channel attenuation factor based on the Lambertian pattern. In addition to the ZZB, the Bayesian Cram�r-Rao bound (CRB) and the weighted CRB (WCRB) are calculated for synchronous VLP systems. Furthermore, a closed-form expression is obtained for the expectation of the conditional CRB (ECRB). Numerical examples are presented to compare the bounds against each other and against the maximum a posteriori probability (MAP) estimator. It is observed that the ZZB can provide a reasonable lower limit on the performance of MAP estimators. On the other hand, the WCRB and the ECRB converge to the ZZB in regions of low and high source optical powers, respectively; however, they are not tight in other regions. � 2016 IEEE.
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    Strongly coupled outer squircle-inner circular coil architecture for enhanced induction over large areas
    (Institute of Electrical and Electronics Engineers Inc., 2016) Kilic V.T.; Unal, E.; Gonendik, E.; Yilmaz, N.; Demir, Hilmi Volkan
    This paper reports a newly designed class of strongly coupled planar coil structures for the purpose of enhanced induction over large areas. These new architectures feature a squircle shape at the outer rim with rounded corners and straight sides evolved into a fully circular shape in the inner side, which proves to be essential to achieve high efficiency in arrays and all-surface inductive heating. As a proof-of-demonstration, a simple inductive heating system composed of a pair of side-by-side placed coils was constructed together with a ferrite layer. Experiments were repeated for 0° and 180° phase differences between coil currents. Here, the system efficiency was shown to be increased overall by 37.4% using outer squircle-inner circular coils instead of conventional circular coils. This comparative study indicates that the proposed coil architecture offers the potential for large-area, fast, and phase-insensitive inductive heating with high efficiency.