Browsing by Author "Yapici,A.C."

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An algorithm for passive RFID based location estimation;
(IEEE Computer Society, 2014) Ozyurt,E.; Aydin,E.; Yapici,A.C.
In this study, an indoor localization system is developed for the mobile robots. The localization system consists of a passive RFID tag and a reader. The passive RFID tag is placed on the robot and reader antennas are spatially dispersed into the room. For the localization, Selective Adaptive Weighted Centroid Localization (SAWCL) algorithm is used. Performance of the localization system is evaluated for the different tags. © 2014 IEEE.
Citation - Scopus: 1
Indoor Location Finding Algorithms for Mobile Robots Carrying Passive Rfid Tags
(2012) Özyurt,E.; Aydin,E.; Yapici,A.C.
Precise localization of mobile robots is critical issue in military, industrial and show business applications. In the literature, several localization techniques has been proposed, in which reader is carried by the mobile object. But in this study a passive Radio Frequency Identification (RFID) tag is attached to mobile robot and the reader antennas being dispersed around the environment. This novelty protects the mobile robot from an increase of weight and results in saving in battery consumption. Also by this way, an increase in mobile object requires a mere increase in low cost passive RFID tags in the navigation system. We have applied a signal pattern matching algorithm, Weighted Centroid Localization (WCL) and Selective Adaptive Weighted Localization (SAWCL) algorithms to locate the tag via Received Signal Strength Indicator (RSSI) and we compare the results. In this study a pilot application is implemented and a prototype is developed to show the proof of concept of the system. © 2012 IEEE.
Reducing the Intermodulation Distortion in Ofdm Systems by Feedforward Linearization Technique
(2009) Yapici,A.C.; Çiflikli,C.
This study presents a feedforward linearizer, in order to reduce the intermodulation distortion (IMD) caused by the nonlinear properties of the radio frequency (RF) power amplifier (PA) in orthogonal frequency-division multiplexing (OFDM) systems. The design procedure and validation of OFDM system and feedforward linearizer have been carried out by Agilent-ADS. In order to evaluate the performance of the feedforward linearizer, sweeping back-off power has been used. Adjacent channel power ratio (ACPR) levels versus back-off power results are investigated to evaluate the performance of the linearization technique. Efficiency improvement is figured out by investigating the power added efficiency (PAE) versus back-off power. Simulation results have been shown that ACPR improvements were acceptable for OFDM system when the PA is utilized together with feedforward linearizer. © 2009 IEEE.