Browsing by Author "Macit, Mustafa Can"

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Citation Count: 3
Detection of Trojans in integrated circuits
(IEEE, 2012) Özmen, Atilla; Güçlüoğlu, Tansal; Özmen, Atilla; Alsan, Hüseyin Fuat; Macit, Mustafa Can
This paper presents several signal processing approaches in Trojan detection problem in very large scale integrated circuits. Specifically wavelet transforms spectrograms and neural networks are used to analyze power side-channel signals. Trojans in integrated circuits can try to hide themselves and become almost invisible due to process and measurement noises. We demonstrate that our initial results with these techniques are promising in successful detection. Discrete wavelet transforms and spectrograms can provide clear visual assistance in detecting Trojans by catching the time-scale differences and time-frequency activities introduced by the Trojans. Furthermore neural networks with sufficient training are also used and simulation results show that correct decisions are possible with a very high success rate. © 2012 IEEE.
Citation Count: 4
Performance Investigation of IEEE 802.11af Systems Under Realistic Channel Conditions
(IEEE, 2015) Şenol, Habib; Erküçük, Serhat; Erküçük, Serhat
As the analog TV broadcasting channels have become less frequently used in the last decade there has been a great interest in these frequency bands for the deployment of metropolitan local and personal area networks. Among them the local area network standard IEEE 802.11af defines PHY and MAC layer implementation of such networks in these unused frequency bands also named television white space (TVWS). According to the standard the systems may use contiguous or non-contiguous channels during their operation depending on the channel availability. In this paper we investigate in detail the performance of different operation modes of these systems under realistic channel conditions. While the perfect knowledge of channel would result in similar system performances as the number of in-between-bands occupying the non-contiguous modes is increased the channel estimation performance degrades drastically which is quantified in this study. In addition it is shown that determining the true locations of multipaths heavily relies on the selected channel resolution and has a significant effect on the system performance. Numerical examples are given to demonstrate the effects of both the non-contiguous operation modes and the selected channel resolution.
Performance of ieee 802.11af systems under realistic channel conditions
(Kadir Has Üniversitesi, 2016) Erküçük, Serhat; Erküçük, Serhat
As the analog TV broadcasting channels have become less frequently used in the last decade there has been a great interest in these frequency bands for the deployment of regional local and personal area networks. Among them the local area network standard iEEE 802.11af denes PHY and MAC layer implementation of such networks in these unused frequency bands also named television white space (TVWS). According to the standard the systems may use contiguous or non-contiguous channels during their operation depending on the channel availability. Unlike perfectly known channel condition of iEEE 802.11af based systems used in the literature we investigate in detail the performance of different operation modes of these systems under realistic channel conditions. Accordingly we implement and compare the performances of perfectly known channel linear minimum mean-square error (LMMSE) estimator and a matching pursuit (MP) based channel estimator. MP based estimator being the more practical estimator compared to the others we assess how its performance approaches the other methods. According to simulation results MP-based channel estimation performance is found to be only 1-2 dB inferior compared to LMMSE-based estimation with known delays in low and medium SNR regions. Also the efects of guard interval rate channel resolution and separation of in-between bands in non-contiguous modes are tested in different scenarios. The results of thesis are important for practical implementation of iEEE 802.11af based systems.
Citation Count: 3
Realistic Channel Estimation of IEEE 802.11af Systems in TV White Space
(Institute of Electrical and Electronics Engineers Inc., 2020) Şenol, Habib; Erküçük, Serhat; Şenol, Habib; Erküçük, Serhat
This work investigates the realistic performance of IEEE 802.11af systems released for the efficient spectrum utilization of TV white space (TVWS). These systems are operated over many contiguous or non-contiguous channels based on the TVWS frequency band availability. Accordingly, we consider realistic channel estimation for TVWS system and analyze the corresponding system performance of linear minimum mean square error (LMMSE) and orthogonal matching pursuit (OMP) algorithms. While LMMSE estimates channel path gains assuming perfectly known tap delay locations, OMP estimates both channel path gains and delays. Owing to the realistic implementation and estimating the full channel state information (CSI) of sparse channels, we mainly assess the OMP performance together with the LMMSE estimation for comparison in terms of channel reconstruction and symbol detection errors. To address the channel estimation performance, Bayesian Cramer-Rao bound is derived theoretically for both perfect and imperfect CSI, and confirmed with the simulations. Simulation results demonstrate that the realistic OMP-based symbol detection performance is found to be only 1-2 dB inferior compared to the near-optimal LMMSE-based estimation with known delays in low and medium signal-to-noise-ratio regions, where communication mainly occurs in practice. In addition, the effects of channel multipath number, channel resolution and operation modes on the system performance are studied for different scenarios. The results of this work are important for the practical implementation of IEEE 802.11af-based systems.