EURASIP Journal on Advances in Signal Processing, 2005
Perceptual hash functions provide a tool for fast and reliable identification of content. We pres... more Perceptual hash functions provide a tool for fast and reliable identification of content. We present new audio hash functions based on summarization of the time-frequency spectral characteristics of an audio document. The proposed hash functions are based on the periodicity series of the fundamental frequency and on singular-value description of the cepstral frequencies. They are found, on one hand, to perform very satisfactorily in identification and verification tests, and on the other hand, to be very resilient to a large variety of attacks. Moreover, we address the issue of security of hashes and propose a keying technique, and thereby a key-dependent hash function.
2014 22nd Signal Processing and Communications Applications Conference (SIU), 2014
Özetçe-Bir çok alanda özniteliklerin sayısı oldukça yüksektir. Örnegin tıp alanında kullanılan ol... more Özetçe-Bir çok alanda özniteliklerin sayısı oldukça yüksektir. Örnegin tıp alanında kullanılan olasılıksal uzman sistemlerde semptomların sayısı 1000'ler mertebesindedir. Burada tıbbi tanıya ulaşmak için bütün semptomları sorgulamak pratik olmadıgından sıralama seçimi önem kazanmaktadır. Bu çalışmada, olasılıksal uzman sistemlerde 3 tane soru sıralama stratejisi önerilmekte ve bu stratejilerin yapay veriler üzerindeki başarımları degerlendirilmektedir.
Security analysis of an ultra-lightweight RFID authentication protocol-SLMAP*
Security and Communication Networks, 2011
Computational constraints mostly driven by the cost concerns of radio frequency identification ta... more Computational constraints mostly driven by the cost concerns of radio frequency identification tags only permit to have security schemes that are simple combinations of elementary operations rather than the bullet proven yet computationally intensive cryptographic primitives. As ...
Many RFID authentication protocols have been proposed to preserve security and privacy. Neverthel... more Many RFID authentication protocols have been proposed to preserve security and privacy. Nevertheless, most of these protocols are analyzed and it is shown that they can not provide security against some RFID attacks. Moreover, some of the secure ones are criticized, because they suffer from scalability at the reader/server side as in tag identification or authentication phase they require a linear search depending on number of tags in the system. Recently, new authentication protocols have been presented to solve scalability issue, i.e. they require constant time for tag identification with providing security. In this paper, we analyze two of these new RFID authentication protocols SSM (very recently proposed by Song and Mitchell) and LRMAP (proposed by Ha et al.) and to the best of our knowledge, they have received no attacks yet. These schemes take O(1) work to authenticate a tag and are designed to meet the privacy and security requirements. The common point of these protocols is that normal and abnormal states are defined for tags. In the normal state, server authenticates the tag in constant time, while in the abnormal state, occurs rarely, authentication is realized with linear search. We show that, however, these authentication protocols do not provide untraceability which is one of their design objectives. We also discover that the SSM protocol is vulnerable to a desynchronization attack, that prevents a legitimate reader/server from authenticating a legitimate tag. Furthermore, in the light of these attacks, we conclude that allowing tags to be in different states may give clue to an adversary in tracing the tags, although such a design is preferred to achieve scalability and efficiency at the server side.
2016 39th International Conference on Telecommunications and Signal Processing (TSP), 2016
The level of coconut maturity can be determined by not only observing its shell color but also by... more The level of coconut maturity can be determined by not only observing its shell color but also by applying audio recognition approach from knocking on coconut shell. This knocking sound distinguishes young, fairly mature, and mature coconut. Recognizing the sound characteristic of knocking on coconut is usually performed by the skilled ones who are having extensive experiences and sound sensitiveness of coconut knocking. In order to substitute the skilled ones, the design of coconut maturity prediction device with acoustic frequency detection is invented. The coconut sound signal is tapped by stethoscope which is connected to MAX9814 noise sensor. Arduino Due micro-controller is used to process the signal. The process in processing the signal consists of: conversing analog signal to digital, screening the signal, and finding the average value of sound signal frequency spectrum. The signal screening uses bandpass digital filter, type IIR (Infinite Impulse Response) Elliptic order 7. This filter is utilized in order that the signal that is being processed is not some noise but the signal of knocking sound on coconut. The calculation of average value of sound signal frequency spectrum uses FFT (Fast Fourier Transform) analysis. The maturity prediction is carried out using the classification method of Naive Bayes. The input is three average value of knocking sound frequency and coconut size, and the output is classification of coconut maturity. From this research, it is generated 80% of system success rate.
In this work, the performance improvement due to prefiltering of inputs in model-based frequency ... more In this work, the performance improvement due to prefiltering of inputs in model-based frequency estimators is investigated based on simulation experiments. Initial estimates on the tone frequency locations, which are obtained via DFT peak picking type preanalysis, are used to design a prefilter to remove noise and interference. The simulations indicate that prefiltering can improve the accuracy of Pisarenko and AR frequency estimators and MUSIC and KT frequency estimators with low subspace order significantly. The SNR thresholds of model-based frequency estimators are lowered by prefiltering. Additionally, interesting trade-offs between prefiltering gain and the gain due to subspace noise filtering have been investigated.
Host-based intrusion detection by monitoring windows registry accesses
Proceedings of the IEEE 12th Signal Processing and Communications Applications Conference, 2004.
... Bu sistemin zararli yanlimlan tcspit etmekte ~ ok verimli oldugu ve yanlr~ alarm oraninin Fok... more ... Bu sistemin zararli yanlimlan tcspit etmekte ~ ok verimli oldugu ve yanlr~ alarm oraninin Fok d8$iik oldugu gBriilmiigtiir. ... yemi belli programlarm rararli olup olmad~giru anlamak ipin bap dizili~ine ya da yarilimda gbmiilii dizgilere bakar [4,13]. ...
2013 21st Signal Processing and Communications Applications Conference (SIU), 2013
ABSTRACT Denial of Service (DoS) and Distributed Denial of service (DDoS) attacks are common plac... more ABSTRACT Denial of Service (DoS) and Distributed Denial of service (DDoS) attacks are common place in today's computer networks. There are different types of attacks among which Flood based attacks are the major ones. Attacks detection mechanisms usually rely on statistical information of the traffic. As regards of the fact that statistical properties of DoS and DDoS attacks are very similar to those in legitimate traffics, in this paper we characterize the frequency domain of denial of service attacks instead of time domain. We consider the number of packets arriving to the node of victim as a random process which is acquired by sampling the packets number every 1 milli-second. Having created the process we find the normalized spectrum of the sampled data. The results show that the main energy of DoS and DDoS attacks are distributed in high and low frequencies respectively while energy is spread evenly through all range of frequencies in Normal TCP traffic.
Spectrum-Aware Dynamic Frequency Reuse (SADFR) for SON-based OFDM a HetNets
2014 IEEE Wireless Communications and Networking Conference (WCNC), 2014
Mobile network traffic is expected to increase dramatically with the proliferation of smart and d... more Mobile network traffic is expected to increase dramatically with the proliferation of smart and diverse wireless devices. Moreover, pervasive and complex services such as mobile cloud, device-to-device communications and mobile multimedia consumption will require higher bandwidth and better network coverage. Hence, more spectrum and capacity with small cells and self-organization of heterogeneous networks are posed as vital solutions to address this burgeoning demand. In this paper, we propose a novel distributed self-organization algorithm for single frequency reuse scheme of OFDMA based heterogeneous networks for improving network capacity with self-configuration and self-optimization. Our approach, namely Spectrum-Aware Dynamic Frequency Reuse (SADFR), enables deployment of single frequency network by mitigating interference while increasing capacity in OFDMA HetNets. Moreover, we provide a comparative performance evaluation of our algorithm and elaborate on interference management issues in these systems.
Causal and semicausal AR image model identification using the EM algorithm
IEEE Transactions on Image Processing, 1993
The method presented by T. Katayama and T. Hirai (1990), who considered the problem of semicausal... more The method presented by T. Katayama and T. Hirai (1990), who considered the problem of semicausal autoregressive (AR) parameter identification for images degraded by observation noise, is extended. In particular, an approach to identifying both the causal and semicausal AR parameters without a priori knowledge of the observation noise power is proposed. The image is decomposed into 1-D independent complex scalar subsystems resulting from the vector state-space model, using the unitary discrete Fourier transform (DFT). Then the expectation-maximization algorithm is applied to each subsystem to identify the AR parameters of the transformed image. The AR parameters of the original image are then identified using the least-square method. The restored image is obtained as a byproduct of the EM algorithm.
VHDL-Ams Design of an Impulse Radio Uwb Transceiver
A report submitted for EE492 senior design project class in partial fulfillment of the requiremen... more A report submitted for EE492 senior design project class in partial fulfillment of the requirements for the degree of Bachelor of Science (Department of Electrical and Electronics Engineering) in Boğaziçi University ... Principal Investigator: Name of the PI Prof. Günhan Dündar ...
Identification of image and blur parameters in frequency domain using the EM algorithm
IEEE Transactions on Image Processing, 1996
We extend a method presented previously, which considers the problem of the semicausal autoregres... more We extend a method presented previously, which considers the problem of the semicausal autoregressive (AR) parameter identification for images degraded by observation noise only. We propose a new approach to identify both the causal and semicausal AR parameters and blur parameters without a priori knowledge of the observation noise power and the PSF of the degradation. We decompose the image into 1-D independent complex scalar subsystems resulting from the vector state-space model by using the unitary discrete Fourier transform (DFT). Then, by applying the expectation-maximization (EM) algorithm to each subsystem, we identify the AR model and blur parameters of the transformed image. The AR parameters of the original image are then identified by using the least squares (LS) method. The restored image is obtained as a byproduct of the EM algorithm.
2018 IEEE 29th Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2018
In this paper, we address the resource allocation problem of device-to-device (D2D) communication... more In this paper, we address the resource allocation problem of device-to-device (D2D) communications underlaying orthogonal frequency division multiple access (OFDMA) based cellular systems by exploiting the efficiency that comes from an ensemble of graph theory and Knapsack problem. It is possible to construct the conflict graph of the D2D pairs by finding the maximal independent sets. Then, we use those independent sets as inputs to Knapsack problem iteratively in order to find D2D groups which allocate the subchannels. In Knapsack problem, we consider a maximum interference level that the base station is exposed at each subchannel. We illustrate that the proposed resource allocation method significantly outperforms graph coloring in terms of average data rate for the high number of underlaying D2D pairs in cellular systems.
Auction-Based Throughput Maximization in Cognitive Radio Networks Under Interference Constraint
Wireless Personal Communications, 2013
ABSTRACT Cognitive radio is an emerging technique to improve the utilization of radio frequency s... more ABSTRACT Cognitive radio is an emerging technique to improve the utilization of radio frequency spectrum in wireless communication networks. That is, spectrum efficiency can be increased significantly by giving opportunistic access of the frequency bands to a group of cognitive users to whom the band has not been licensed. In this paper, as a cross layer application (MAC and physical layers) of graph theory, we consider the problem of throughput maximization of spectrum allocation in cognitive radio networks under interference constraint. We propose a novel auction-based channel allocation mechanism which tries to maximize both total and primary users’ utilities while satisfying signal to interference ratio constraint on primary receivers so that transmitted packets will be successfully received, without controlling secondary user powers. For comparison we discuss a greedy algorithm as well, however, one that does not handle interference issue. In order to compare results of proposed and greedy algorithms, we propose net throughput by taking into account outage probability of primary receiver. Simulation results show that exposing higher SINR (outage) threshold not only decreases total gain and primary users’ utilities but also worsens channel distribution performance. On the other hand adding auction mechanism significantly increases total gain throughput and primary user’ s utility. Particularly, up to SINR threshold values of 20 dBs, auction provides outstanding performance and proposed algorithm has total throughput results close to those of the greedy one even though no interference constraint is applied in the greedy algorithm. Another noticeable point of simulation results is crossover of net throughputs of proposed and greedy algorithms at a SINR threshold level after which results of ABSA-UNIC and NASA-UNIC are much better. This clearly shows superiority of proposed mechanism.
Uploads
Papers by E. Anarim