Papers by Selcuk Tascioglu
Communications Faculty of Sciences University of Ankara. Series A2-A3: physics, engineerigng physics, electronic engineering and astronomy, Dec 30, 2022
Quadrature mixing is widely used in wireless communication receivers since it provides a solution... more Quadrature mixing is widely used in wireless communication receivers since it provides a solution for image signal problem with low-cost implementations. Image signal is caused by phase and amplitude mismatches between in-phase (I) and quadrature (Q) paths of the receiver. This problem is known as I/Q imbalance and degrades the communication performance if not compensated. In this study, the impact of I/Q imbalance compensation on wireless communication performance is evaluated through experiments and simulations. Simulation results demonstrate that significant communication performance improvement can be achieved in terms of bit error rate (BER) and symbol error rate (SER) by compensating the I/Q imbalance properly. In the experiments, compensation is applied to the signals captured using a software defined radio with zero-IF architecture. Experimental results demonstrate that wireless transmission success rate for the zero-IF receiver is increased by compensating I/Q imbalance.
Eurasip Journal on Wireless Communications and Networking, Feb 23, 2009
We investigate the autocorrelation properties of timing synchronization waveforms that are genera... more We investigate the autocorrelation properties of timing synchronization waveforms that are generated by embedded frequency domain pilot tones in orthogonal frequency division multiplex (OFDM) systems. The waveforms are composed by summing a selected number of OFDM subcarriers such that the autocorrelation function (ACF) of the resulting time waveform has desirable sidelobe behavior. Analytical expressions for the periodic and aperiodic ACF sidelobe energy are derived. Sufficient conditions for minimum and maximum aperiodic ACF sidelobe energy for a given number of pilot tones are presented. Several useful properties of the pilot design problem, such as invariance under transformations and equivalence of complementary sets are demonstrated analytically. Pilot tone design discussion is expanded to the ACF sidelobe peak minimization problem by including various examples and simulation results obtained from a genetic search algorithm.
Search for OFDM synchronization waveforms with good aperiodic autocorrelations
Page 1. SEARCH FOR OFDM SYNCHRONIZATION WAVEFORMS WITH GOOD APERIODIC AUTOCORRELATIONS Oktay Uret... more Page 1. SEARCH FOR OFDM SYNCHRONIZATION WAVEFORMS WITH GOOD APERIODIC AUTOCORRELATIONS Oktay Ureten', Selpuk Tascioglu', Nur Serinken', Mumtaz Yilmaz* Communications Research Centre 3701 Carling Avenue PO Box 11490, Stn. ...
Dicle üniversitesi mühendislik fakültesi mühendislik dergisi, Apr 4, 2018
Bu çalışmada, kimlik tespiti amacıyla kablosuz vericilerin radyo frekansı (RF) parmak izlerinin p... more Bu çalışmada, kimlik tespiti amacıyla kablosuz vericilerin radyo frekansı (RF) parmak izlerinin polinom uydurma yaklaşımıyla elde edilebildiği gösterilmiştir. Polinom uydurma işlemi, vericilerin geçici rejim işaretlerinin anlık genlik karakteristiklerine uygulanmış ve RF parmak izleri, polinom katsayılarının normalize edilmesiyle oluşturulmuştur. Geçici rejim işaretleri Bayesçi bir sinyal algılama yaklaşımıyla tespit edilmiş ve bu işaretlerden elde edilen RF parmak izleri olasılıksal sinir ağı sınıflandırıcısı ile sınıflandırılmıştır. Polinom uydurma yaklaşımına dayalı RF parmak izlerinin verici kimlik tespiti başarımı ve algoritmanın hesaplama süresi WiFi vericilerine ait deneysel verilerle değerlendirilmiştir. Geçici rejim işaret karakteristiklerine uydurulan polinom derecesi, sınıflandırma başarımı kriteri esas alınarak belirlenmiştir. Kullanılan veri seti için en iyi sınıflandırma başarımı ikinci dereceden polinom katsayılarıyla elde edilmiştir. Bu katsayılardan oluşturulan parmak izleri kullanılarak gerçekleştirilen sınıflandırma işleminin hesaplama süresinin, anlık genlik değerlerinin doğrudan kullanıldığı duruma kıyasla daha düşük olduğu gösterilmiştir. Çalışmada elde edilen bulgular, polinom uydurma yaklaşımına dayalı RF parmak izleriyle kablosuz vericilerin kimlik tespitinde hızlı ve başarılı sonuçlar elde edilebildiğini göstermiştir.
International Conference on Electrical and Electronics Engineering, Nov 1, 2017
In this paper, effect of sampling rate on the performance of transmitter identification system us... more In this paper, effect of sampling rate on the performance of transmitter identification system using transient-based RF fingerprints is considered. Two different existing RF fingerprinting techniques have been employed to investigate the performance of a transmitter identification system by using experimental data collected at a high sampling rate. Decimation was carried out to analyze the effect of lower sampling rates. It has been shown that transient-based RF fingerprinting methods can be effectively used for identification of wireless transmitters at low sampling rates.
Bilişsel radyo ağları için değişim noktası analizine dayalı geniş bant spektrum algılama
Bu tezde, radyo iletisim sinyalleri icin yeni bir genis bant spektrum algilama yaklasimi onerilme... more Bu tezde, radyo iletisim sinyalleri icin yeni bir genis bant spektrum algilama yaklasimi onerilmektedir. Onerilen yaklasimda, gozlenen radyo frekans (RF) spektrumunun parcali sabit bir fonksiyon olarak modellenebilecegi varsayilir ve RF guc spektrumu, model parametrelerinin sonsal ornekleri ile olusturulan sinyal spektrumu gerceklestirimlerinin beklenen degeri olarak kestirilir. Elde edilen kestirim, spektrumun kaba bir gosterimi olup algilama basarimini artirmak icin bu kestirimden ayrintili tarama parametreleri cikarilabilir. Kullanici frekanslari, bant genislikleri ve sinyal guc seviyeleri hakkindaki onsel bilgiye ihtiyac duymayan yontem, ilgilenilen genis bandin duzensiz parcali ve heterojen yapida oldugu bilissel radyo sistemleri icin uygundur. Elde edilen spektrum karakteristikleri hesaplama karmasikligini azaltmak ya da sonraki veriler icin kestirim ve ongorum dogrulugunu artirmak icin kullanilabilir. Onsel bilginin iyilestirilmis basarim icin kullanilabiliyor olmasi, bilissel radyo aginin calistigi ortam hakkinda onsel bilginin bir radyo ortam haritasi ile saglanabildigi durumda, cekici bir ozelliktir.Onerilen genis bant spektrum algilama yontemini degerlendirmek ve benzetimlerle basarimini olcmek icin cesitli metrikler tanimlanmistir. Benzetim sonuclari, geleneksel FFT-tipi spektrum analizi tekniklerine gore onerilen yontemin, cozunurluk ve/veya tepki suresi acisindan avantajlar sundugunu gostermektedir. Ayrica, gurultu belirsizliginin yontemin algilama basarimina etkisi degerlendirilmis ve yontemin, belirsizlik durumunda da dayanikli bir genis bant spektrum algilama yontemi olarak kullanilabilecegi gosterilmistir.Abstract In this thesis, a novel wideband spectrum sensing approach is proposed for the detection of radio communication signals. In the proposed approach, it is assumed that the monitored RF spectrum can be modeled as a piece-wise flat function and RF power spectrum is estimated as the posterior expectation of the realizations of the underlying signal spectrum obtained through the simulated samples drawn from the joint posterior distribution of the model parameters. The obtained estimation is a coarse description of the spectrum that can be further utilized to extract fine scanning parameters to improve sensing performance. The technique doesn’t rely on a priori knowledge of user frequencies, bandwidths and power levels; therefore it is suitable for cognitive radio systems where the wideband spectrum of interest is likely to be fragmented and heterogeneous. On the other hand, the technique allows the utilization of acquired spectral characteristics to reduce the computational complexity or to improve the accuracy of estimations and predictions for future data. The fact that the proposed technique can utilize prior knowledge for improved performance is an attractive feature for cognitive radio networks for which a radio environment map (REM) can provide prior knowledge about the environment the network operates. Several metrics have been defined for the assessment of the proposed technique and the performance has been evaluated through simulations. The simulation results show that the proposed technique offers advantages over the conventional FFT-type spectrum analysis methods in terms of resolution and/or latency. The impact of the noise uncertainty on the detection performance has also been evaluated and it is shown that the technique can be used as a robust wideband spectrum sensing tool even under noise uncertainty.
Electronics, Oct 16, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Bayesian Wideband Spectrum Segmentation for Cognitive Radios
Abstract A novel approach for wideband spectrum segmentation is proposed. The proposed method, ca... more Abstract A novel approach for wideband spectrum segmentation is proposed. The proposed method, called segmented periodogram, is based on the posterior expectation of the piece-wise flat realizations of the underlying signal spectrum, which is obtained through the ...
Performance Analysis of Transmitter Identification Based on I/Q Imbalance Estimation
Performance of a transmitter identification method based on I/Q imbalance estimation is analyzed ... more Performance of a transmitter identification method based on I/Q imbalance estimation is analyzed for different modulation types in this work. This analysis is considered on the basis of the constellation structure of proper and improper modulation signals. The effect of impropriety of complex signals on the features obtained from I/Q imbalance is analyzed. Simulation results show that transmitters can be identified with a high accuracy for proper communication signals even at low SNR, whereas the identification performance degrades for improper communications signals, especially at low SNR.
Communications Faculty of Sciences University of Ankara. Series A2-A3: physics, engineerigng physics, electronic engineering and astronomy, 2015
In this paper, the problem of signal-to-noise ratio (SNR) estimation of noisy transient signals i... more In this paper, the problem of signal-to-noise ratio (SNR) estimation of noisy transient signals is considered. The SNR estimation is performed based on the average energy of the transient and noise signals. The performance of the SNR estimator is evaluated in terms of normalized mean square error and normalized bias. It is shown by simulations that the SNR estimation method exhibits good estimation performance for the SNRs encountered in many practical applications. Besides, the effect of the estimation of the transient starting point on the performance of the SNR estimation is investigated
The objective of this work is to investigate the impact of noise uncertainty on the performance o... more The objective of this work is to investigate the impact of noise uncertainty on the performance of a wideband spectrum segmentation technique. We define metrics to quantify the degradation due to noise uncertainty and evaluate the performance using simulations. Our simulation results show that the noise uncertainty has detrimental effects especially for low SNR users.
A technique to determine number and locations of frame synchronization pilot carriers in pilot-based OFDM systems
Proceedings of the IEEE 12th Signal Processing and Communications Applications Conference, 2004.
Bu calismada, parametrik CUSUM (cumulative sum) algoritmasinin degisim noktasi kestirim basarimi ... more Bu calismada, parametrik CUSUM (cumulative sum) algoritmasinin degisim noktasi kestirim basarimi analiz edilmistir. Veriye ait dagilimin bilindigi durumda kullanilabilen bu parametrik yontem, calisma kapsaminda Gauss rasgele surecinin ortalamasindaki ani bir degisimin yerinin kestirilmesi amaciyla kullanilmistir. Yontemde kullanilan log-olabilirlik oranina dayali esitlikler Gauss gurultu modeli icin turetilmis ve yontemin temel calisma ilkesi orneklerle anlatilmistir. Sinyal parametrelerinin bilinmedigi durumlarda kullanilan kismi en iyi (suboptimal) cozumler ele alinarak, pratikte yontemin basariminin en iyi (optimal) cozume kiyasla ne olcude azalacagi incelenmistir. Calisma kapsaminda ele alinan CUSUM algoritmasinin turevleri icin degisim noktasi kestirim basarimlari benzetimler yoluyla karsilastirmali olarak sunulmustur. Kismi en iyi yaklasimlarda sinyal parametreleri icin yapilan kestirimlerin ve bu parametreler hakkindaki onsel bilginin (a priori information) dogrulugunun, degi...
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering
Quadrature mixing is widely used in wireless communication receivers since it provides a solution... more Quadrature mixing is widely used in wireless communication receivers since it provides a solution for image signal problem with low-cost implementations. Image signal is caused by phase and amplitude mismatches between in-phase (I) and quadrature (Q) paths of the receiver. This problem is known as I/Q imbalance and degrades the communication performance if not compensated. In this study, the impact of I/Q imbalance compensation on wireless communication performance is evaluated through experiments and simulations. Simulation results demonstrate that significant communication performance improvement can be achieved in terms of bit error rate (BER) and symbol error rate (SER) by compensating the I/Q imbalance properly. In the experiments, compensation is applied to the signals captured using a software defined radio with zero-IF architecture. Experimental results demonstrate that wireless transmission success rate for the zero-IF receiver is increased by compensating I/Q imbalance.
Electronics
In this paper, a sequential transient detection method for radio frequency (RF) fingerprinting us... more In this paper, a sequential transient detection method for radio frequency (RF) fingerprinting used in the identification of wireless devices is proposed. To the best knowledge of the authors, sequential detection of transient signals for RF fingerprinting has not been considered in the literature. The proposed method is based on an approximate implementation of the generalized likelihood ratio algorithm. The method can be implemented online in a recursive manner with low computational and memory requirements. The transients of wireless transmitters are detected by using the likelihood ratio of the observations without the requirement of any a priori knowledge about the transmitted signals. The performance of the method was evaluated using experimental data collected from 16 Wi-Fi transmitters and compared to those of two existing methods. The experimental test results showed that the proposed method can be used to detect the transient signals with a low detection delay. Our propose...
MIMO Detection Algorithms – Deep Learning Based and Traditional Methods
2022 International Conference on Electrical, Computer and Energy Technologies (ICECET)
Performance Analysis of Transmitter Identification Based on I/Q Imbalance Estimation
2019 11th International Conference on Electronics, Computers and Artificial Intelligence (ECAI), 2019
Performance of a transmitter identification method based on I/Q imbalance estimation is analyzed ... more Performance of a transmitter identification method based on I/Q imbalance estimation is analyzed for different modulation types in this work. This analysis is considered on the basis of the constellation structure of proper and improper modulation signals. The effect of impropriety of complex signals on the features obtained from I/Q imbalance is analyzed. Simulation results show that transmitters can be identified with a high accuracy for proper communication signals even at low SNR, whereas the identification performance degrades for improper communications signals, especially at low SNR.
2017 10th International Conference on Electrical and Electronics Engineering (ELECO), 2017
In this paper, effect of sampling rate on the performance of transmitter identification system us... more In this paper, effect of sampling rate on the performance of transmitter identification system using transient-based RF fingerprints is considered. Two different existing RF fingerprinting techniques have been employed to investigate the performance of a transmitter identification system by using experimental data collected at a high sampling rate. Decimation was carried out to analyze the effect of lower sampling rates. It has been shown that transient-based RF fingerprinting methods can be effectively used for identification of wireless transmitters at low sampling rates.
IEEE Access, 2019
Radio frequency (RF) fingerprinting is considered as one of the promising techniques to enhance w... more Radio frequency (RF) fingerprinting is considered as one of the promising techniques to enhance wireless security in the Internet of Things (IoT) applications. In this paper, a low-complexity RF fingerprinting method for classification of wireless IoT devices is proposed. The method is based on the energy spectrum of the transmitter turn-on transient signals from which unique characteristics of wireless devices are extracted. The number of spectral components to be used is determined through a proposed approach based on the estimated transient duration value. Transient duration estimation is achieved from the smoothed versions of the instantaneous amplitude characteristics of transmitter signals, which are obtained through a sliding window averaging method. Classification performance of the proposed spectral fingerprints is assessed using experimental data and described by a confusion matrix. The discrimination effectiveness of the spectral fingerprints is quantified by a class separability criterion and evaluated for different noise levels through Monte Carlo simulations. It is demonstrated that the proposed fingerprints outperform the classification performance of two existing fingerprints especially at low signal-to-noise ratio. Additionally, computational complexity analysis of the classifier using the proposed fingerprints is provided. INDEX TERMS Internet of Things (IoT) security, radio transmitter turn-on transient, RF fingerprinting, transient energy spectrum, wireless device identification.
Bilişsel radyo ağları için değişim noktası analizine dayalı geniş bant spektrum algılama
Bu tezde, radyo iletisim sinyalleri icin yeni bir genis bant spektrum algilama yaklasimi onerilme... more Bu tezde, radyo iletisim sinyalleri icin yeni bir genis bant spektrum algilama yaklasimi onerilmektedir. Onerilen yaklasimda, gozlenen radyo frekans (RF) spektrumunun parcali sabit bir fonksiyon olarak modellenebilecegi varsayilir ve RF guc spektrumu, model parametrelerinin sonsal ornekleri ile olusturulan sinyal spektrumu gerceklestirimlerinin beklenen degeri olarak kestirilir. Elde edilen kestirim, spektrumun kaba bir gosterimi olup algilama basarimini artirmak icin bu kestirimden ayrintili tarama parametreleri cikarilabilir. Kullanici frekanslari, bant genislikleri ve sinyal guc seviyeleri hakkindaki onsel bilgiye ihtiyac duymayan yontem, ilgilenilen genis bandin duzensiz parcali ve heterojen yapida oldugu bilissel radyo sistemleri icin uygundur. Elde edilen spektrum karakteristikleri hesaplama karmasikligini azaltmak ya da sonraki veriler icin kestirim ve ongorum dogrulugunu artirmak icin kullanilabilir. Onsel bilginin iyilestirilmis basarim icin kullanilabiliyor olmasi, bilissel radyo aginin calistigi ortam hakkinda onsel bilginin bir radyo ortam haritasi ile saglanabildigi durumda, cekici bir ozelliktir.Onerilen genis bant spektrum algilama yontemini degerlendirmek ve benzetimlerle basarimini olcmek icin cesitli metrikler tanimlanmistir. Benzetim sonuclari, geleneksel FFT-tipi spektrum analizi tekniklerine gore onerilen yontemin, cozunurluk ve/veya tepki suresi acisindan avantajlar sundugunu gostermektedir. Ayrica, gurultu belirsizliginin yontemin algilama basarimina etkisi degerlendirilmis ve yontemin, belirsizlik durumunda da dayanikli bir genis bant spektrum algilama yontemi olarak kullanilabilecegi gosterilmistir.Abstract In this thesis, a novel wideband spectrum sensing approach is proposed for the detection of radio communication signals. In the proposed approach, it is assumed that the monitored RF spectrum can be modeled as a piece-wise flat function and RF power spectrum is estimated as the posterior expectation of the realizations of the underlying signal spectrum obtained through the simulated samples drawn from the joint posterior distribution of the model parameters. The obtained estimation is a coarse description of the spectrum that can be further utilized to extract fine scanning parameters to improve sensing performance. The technique doesn’t rely on a priori knowledge of user frequencies, bandwidths and power levels; therefore it is suitable for cognitive radio systems where the wideband spectrum of interest is likely to be fragmented and heterogeneous. On the other hand, the technique allows the utilization of acquired spectral characteristics to reduce the computational complexity or to improve the accuracy of estimations and predictions for future data. The fact that the proposed technique can utilize prior knowledge for improved performance is an attractive feature for cognitive radio networks for which a radio environment map (REM) can provide prior knowledge about the environment the network operates. Several metrics have been defined for the assessment of the proposed technique and the performance has been evaluated through simulations. The simulation results show that the proposed technique offers advantages over the conventional FFT-type spectrum analysis methods in terms of resolution and/or latency. The impact of the noise uncertainty on the detection performance has also been evaluated and it is shown that the technique can be used as a robust wideband spectrum sensing tool even under noise uncertainty.
Uploads
Papers by Selcuk Tascioglu