Erküçük, Serhat

Erküçük, Serhat

Name Variants

Erküçük, Serhat
S.,Erküçük
S. Erküçük
Serhat, Erküçük
Erkucuk, Serhat
S.,Erkucuk
S. Erkucuk
Serhat, Erkucuk
Erküçük, S.
Erküçük,S.

Job Title

Prof. Dr.

Email Address

Serkucuk@khas.edu.tr

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Scholarly Output

66

Articles

19

Citation Count

0

Supervised Theses

9 Scholarly Output Search Results

Now showing 1 - 10 of 64

Citation Count: 5
Comparison of Compressed Sensing Based Algorithms for Sparse Signal Reconstruction
(IEEE, 2016) Çelik, Safa; Başaran, Mehmet; Erküçük, Serhat; Çırpan, Hakan Ali
Compressed sensing theory shows that any signal which is defined as sparse in a given domain can be reconstructed using fewer linear projections instead of using all Nyquist-rate samples. In this paper we investigate basis pursuit matching pursuit orthogonal matching pursuit and compressive sampling matching pursuit algorithms which are basic compressed sensing based algorithms and present performance curves in terms of mean squared error for various parameters including signal-tonoise ratio sparsity and number of measurements with regard to mean squared error. In addition accuracy of estimation performances has been supported with theoretical lower bounds (Cramer-Rao lower bound and deterministic lower mean squared error). Considering estimation performances compressive sampling matching pursuit yields the best results unless the signal has a non-sparse structure.
Citation Count: 2
Noncoherent Ultra Wideband Wireless Sensor Networks for Primary User Detection
(IEEE Computer Society, 2016) Sabucu, Yağmur; Erküçük, Serhat
As a result of increasing demand for new technologies unlicensed usage of available spectrum has become very essential to provide an efficient usage of spectrum. For that reason sensor networks may be a reliable option to decide on the absence/presence of licensed users and to communicate without causing much interference as a secondary user network. These networks consist of two communication links for primary user detection. One link is between the primary user and the sensors and the other link is between the sensors and the fusion center. In this study we consider an IEEE 802.15.4a based ultra wideband (UWB) network with a noncoherent receiver structure for the first link. For the second link binary pulse position modulation is implemented to convey primary user information to the fusion center. Numerical expressions for probabilities of false alarm and detection for the overall system are obtained and validated by simulations where the performance of the system improves with number of sensors and the reliability of the first link. The results obtained from this study can be used for improving the primary user detection performance of UWB based wireless sensor networks in noncoherent operation mode. © 2016 IEEE.
Citation Count: 1
Busy Tone Based Power Control for Coordination of Iffy 802.11af and 802.22 System
(IEEE, 2017) Ülgen, Oğuz; Erküçük, Serhat; Karatalay, Onur; Baykas, Tuncer
In this paper, a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies, in addition to both 802.11af access point and clients listening to the busy tone, they also adjust their communication power according to the location information and use hopping for communication, if needed Acccordingly, interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards.
Citation Count: 0
Primary User Detection in Ieee 802.15.4a Based Wireless Sensor Networks
(IEEE, 2013) Sabucu, Yağmur; Erküçük, Serhat
Ultra wideband impulse radio (UWB-IR) technology has been defined in the IEEE 802.15.4a standard for location and ranging applications. In this paper UWB-IR sensors are considered in wireless sensor networks (WSNs) with two different IEEE 802.15.4a based signalling
Citation Count: 17
Channel Estimation for TDS-OFDM Systems in Rapidly Time-Varying Mobile Channels
(Institute of Electrical and Electronics Engineers Inc., 2018) Basaran,M.; Şenol,H.; Erküçük,S.; Çirpan,H.A.
This paper explores the performance of time-domain synchronous orthogonal frequency-division multiplexing (TDS-OFDM) systems operated under rapidly time-varying mobile channels. Since a rapidly time-varying channel contains more unknown channel coefficients than the number of observations, the mobile channel can conveniently be modeled with the discrete Legendre polynomial basis expansion model to reduce the number of unknowns. The linear minimum mean square error (LMMSE) estimate can be exploited for channel estimation on inter-block-interference-free received signal samples owing to transmitting pseudo-noise (PN) sequences. In conventional TDS-OFDM systems, the channel estimation performance is limited due to estimating channel responses only from the beginning part of the channel. Therefore, a new system model named "partitioned TDS-OFDM system" is proposed to improve the system performance by inserting multiple PN sequences to the middle and end parts of the channel as well. In addition to providing the reconstruction error performance, Bayesian Cramer-Rao lower bound is derived analytically. Also, the LMMSE-based symbol detection is employed. To alleviate the negative effects of inter-carrier-interference (ICI) occuring in mobile channels, ICI cancellation is applied to enhance the detection performance. The simulation results demonstrate that the proposed TDS-OFDM system is superior to the conventional system and its corresponding performance is able to approach the achievable lower performance bound. © 2018 IEEE.
Citation Count: 0
Rapidly Varying Sparse Channel Tracking With Hybrid Kalman-Omp Algorithm
(Springer, 2019) Büyükşar, Ayşe Betül; Şenol, Habib; Erküçük, Serhat; Cirpan, Hakan Ali
It is expected from future communication standards that channel estimation algorithms should be able to operate over very fast varying frequency selective channel models. Therefore in this study autoregressive (AR) modeled fast varying channel has been considered and tracked with Kalman filter over one orthogonal frequency division multiplexing (OFDM) symbol. Channel sparsity is exploited which decreases the complexity requirements of the Kalman algorithm. Since Kalman filter is not directly applicable to sparse channels orthogonal matching pursuit (OMP) algorithm is modified for AR modeled sparse signal estimation. Also by using windows sparsity detection errors have been decreased. The simulation results showed that sparse fast varying channel can be tracked with the proposed hybrid Kalman-OMP algorithm and windowing method offers improved MSE results.
Citation Count: 7
Detection of Interdependent Primary Systems Using Wideband Cognitive Radios
(Elsevier GMBH Urban & Fischer Verlag, 2013) Yılmaz, Burak; Erküçük, Serhat
Cognitive radios (CRs) may be sharing multiple frequency bands with primary systems if the CR is a wideband or an ultra wideband (UWB) system. In that case the CR should ensure all the coexisting primary systems in these bands are detected before it can start data transmission. In this work we study the primary system detection performance of a wideband CR assuming that there are multiple coexisting primary systems and that these primary systems may be jointly active. Accordingly we consider the implementation of energy detection scheme in multiple bands followed by two detection methods: (i) a maximum-a-posteriori (MAP) based detection (i.e. joint detection) that takes into account the statistics of simultaneously operating systems in independent bands and (ii) a Neyman-Pearson (NP) test based detection that optimizes the threshold values independently in each band (i.e. independent detection). For a simpler implementation of the independent detection we show that the threshold values obtained from joint detection can be used in order to achieve the optimum NP test based independent detection results. In addition to quantifying the gain of joint detection over independent detection in terms of probabilities of false alarm and detection for practical scenarios we also present the operation capability of CRs in terms of the fractions of time the CR can access the channel without interfering with the primary systems. The results are important for the practical implementation of multiband detection when the primary systems are known to be interdependent. (C) 2013 Elsevier GmbH. All rights reserved.
Citation Count: 0
A Novel Indoor Channel Model for Tvws Communications Based on Measurements
(IEEE, 2018) Hashir, Syed Muhammad; Erküçük, Serhat; Baykaş, Tunçer
In this paper we present an indoor measurement campaign for TV white space bands inside a university building. The measurement results are compared with different indoor propagation models in the literature. We observed large estimation errors for the total path loss value from all existing models. Consequently we are proposing a new indoor propagation model for TVWS frequencies which concatenates the effects of frequency dependent path loss with penetration losses due to walls and windows. Performance comparison with existing models show that the proposed model achieves superior performance compared to existing models in terms of Root-Mean-Squared Error (RMSE).
Primary User Detection in Ultrawide-Band Based Wireless Sensor Networks
(Kadir Has Üniversitesi, 2013) Sabucu, Yağmur; Erküçük, Serhat
In this thesis ultra-wideband (UWB) based wireless sensor networks (WSNs) are considered for the detection of a primary user. Different from earlier works (i) both uplink and downlink information of the primary user are assessed for the primary user detection and (ii) iEEE 802.15.4a standard is considered for the implementation of each secondary user. Specifically the worked focused on the comparison of the two iEEE 802.15.4a based signalling namely binary pulse position modulation (BPPM) and combined BPPM/ binary phase shift keying (BPPM/BPSK) and the implementation of noncoherent receivers at the fusion center for reduced complexity. Accordingly the sensor-fusion center link is investigated in detail considering practical implementation conditions. Some suggestions have been provided based on the primary user detection performance results of the UWB based WSNs. -- Abstract'tan.
Citation Count: 3
Evaluation of Noise Distributions for Additive and Multiplicative Smart Meter Data Obfuscation
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Khwaja, Ahmed S.; Erkucuk, Serhat; Anpalagan, Alagan; Venkatesh, Bala
In this paper, we compare and analyze light-weight approaches for instantaneous smart meter (SM) data obfuscation from a group of consumers. In the literature, the common approach is to use additive Gaussian noise based SM data obfuscation. In order to investigate the effects of different approaches, we consider Gaussian, Rayleigh, generalized Gaussian and chi-square distributions to achieve either additive or multiplicative data obfuscation. For each type of obfuscation approach, we calculate the required parameters to achieve obfuscation such that 50% of the obfuscated data fall outside an interval equalling twice the mean of the instantaneous SM measurements. We also calculate the minimum number of SMs required to estimate the mean of the actual SM measurements, such that the estimate varies within only 0.5% of the actual mean with a 99.5% probability. Simulation results are used to verify the calculations, and it is shown that multiplicative Rayleigh and generalized Gaussian noise require the least number of SMs, which is 90% less than the traditional approach of additive Gaussian noise-based SM data obfuscation.