Mehmet Ertuğrul Çelebi | Istanbul Technical University (original) (raw)

Papers by Mehmet Ertuğrul Çelebi

2011 IEEE 19th Signal Processing and Communications Applications Conference (SIU), 2011

Multicasting is a spectrally efficient method for supporting group communication by allowing tran... more Multicasting is a spectrally efficient method for supporting group communication by allowing transmission of packets to multiple destinations using fewer resources. To incorporate cooperative diversity, Cooperative Extended Balanced Space-Time Block Codes (CEBSTBCs) have been proposed providing full diversity when one or more feedback bits are sent back via feedback channel. However, the CEBSTBCs are designed for cooperative unicast communication in the literature. This paper presents a novel wireless multicasting scheme which selects the optimum CEBSTBC for all vehicular users to support wireless multicast. The performance of the proposed scheme is investigated for not only vehicle-to-vehicle communication but also for vehicleto-infrastructure cases. Extensive detailed simulations are performed to show the feasibility of full rate and full diversity multicast service provisioning in vehicular communications.

2007 IEEE 15th Signal Processing and Communications Applications, 2007

... A New Code Design Criterion for Linear Dispersive Space-Time Block Codes Sinan Kahraman, Mehm... more ... A New Code Design Criterion for Linear Dispersive Space-Time Block Codes Sinan Kahraman, Mehmet Ertu˘grul C¸ elebi Elektronik ve Haberlesme Mühendisli˘gi Bölümü ˙Istanbul Teknik ¨Universitesi, ˙Istanbul kahraman@ieee.org, celebi@ehb.itu.edu.tr ¨Ozetçe ...

2014 Australian Communications Theory Workshop (AusCTW), 2014

Polar codes are the first explicit class of codes that are provably capacity-achieving under the ... more Polar codes are the first explicit class of codes that are provably capacity-achieving under the successive cancelation (SC) decoding. As a suboptimal decoder, SC has quasi-linear complexity N (1 + log N) in the code length N. In this paper, we propose a new non-binary SC decoder with reduced complexity N 2 (1 + log N 2) based on the folding operation, which was first proposed in [11] to implement folded tree maximum-likelihood decoding of polar codes. Simulation results for the additive white Gaussian noise channel show that folded SC decoders can achieve the same error performance of standard SC by suitable selecting the folding of the polar code.

IEEE Transactions on NanoBioscience, 2022

Diffusion-based molecular communication system (DBMC) is a system in which information-carrying m... more Diffusion-based molecular communication system (DBMC) is a system in which information-carrying molecules are sent from the transmitter and passively transported to the receiver in a fluid environment. Nanomachines, which are the main part of this system, have limited processing capacity. Besides, at the receiver, high inter-symbol interference (ISI) occurs due to free movement of molecules and the variance of the observation noise is signal dependent. Hence, it is important to design high-performance and low complexity receiver detection methods. In this paper, finite impulse response (FIR) Wiener filter is introduced for the first time, which has considerably less computational complexity compared to the minimum mean square error (MMSE) algorithm proposed in the literature. Moreover, extended Kalman filter is introduced for the first time to DBMC as a receiver detection method. Finally, Viterbi algorithm is modified and used as a benchmark for performance evaluation.

2017 25th Signal Processing and Communications Applications Conference (SIU), 2017

In this paper we propose a two-way spectrum sharing protocol for the overlay cognitive radio netw... more In this paper we propose a two-way spectrum sharing protocol for the overlay cognitive radio network consisting of two primary users (PUs) and two secondary users (SUs). One of the SUs acts as a relay to assist the communication between the PUs while at the same time allowing for two-way transmission with the other SU. The communication process is done in two phases. In the first phase, the PUs and the other SU are allowed to transmit simultaneously. The relay can use successive decoding to decode the message of the SU and then the PUs messages. In the second phase, the relay can use superposition coding to generate a new message composed of the XORed messages of the PUs and a new message for the SU. The performance of the protocol has been analyzed by deriving the outage probabilities of the PUs and SUs. Analytical and simulation results show that the proposed protocol offers efficient spectrum utilization and improved system capacity over the three-phase and two-phase spectrum sharing protocols with one-way SUs transmission in the literature.

2004 IEEE International Joint Conference on Neural Networks (IEEE Cat. No.04CH37541)

W e propose a new method based on the accelerated Expectation Maximization (EM) algorithm to lear... more W e propose a new method based on the accelerated Expectation Maximization (EM) algorithm to learn the unknown image parameters and restoration. Acceleration is provided using Fisher Scoring (FS) optimization in the M step. Only a small number FS iteration is required for each M step. Our proposed algorithm reaches to the local minima in few steps whereas conventional EM needs more iteration. We also estimate the regularization parameter in the same single structure. Thanks to the FS optimization, it is possible to avoid complicated second derivative of the loglikelihood function by using only the gradient values.

IEEE Signal Processing and Communications Applications, 2005

In this work, a closed form solution in the M step of the Expectation Maximization (EM) algorithm... more In this work, a closed form solution in the M step of the Expectation Maximization (EM) algorithm is investigaed for learning of unknown image and blur parameters. Cholesky factorization is used to find autoregressive image model parameters. Moreover, the regularization parameter is estimated in the same single structure. The restored image is obtained simultaneously using the regularized version of the

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007

Page 1. The 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communi... more Page 1. The 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC&amp;#x27;07) 1-4244-1144-0/07/$25.00 ©2007 IEEE. DIVERSITY ENHANCEMENT WITH COOPERATIVE BALANCED SPACE-TIME BLOCK CODINGł ...

2010 IEEE 18th Signal Processing and Communications Applications Conference, 2010

SÕnÕrlÕ geribeslemeli kablosuz haberleúme sistemlerinde kod seçimi ve verici anten seçimi yaygÕn ... more SÕnÕrlÕ geribeslemeli kablosuz haberleúme sistemlerinde kod seçimi ve verici anten seçimi yaygÕn olarak kullanÕlÕr. E÷er vericideki bir antenin kanal kazancÕ di÷er antenlerin kanal kazançlarÕna göre çok büyükse verici anten seçimi kullanmak alÕcÕdaki Sinyalin Gürültüye OranÕnÕ (SNR) artÕrÕr. Buna karúÕlÕk, vericideki antenlerin kanal kazançlarÕ birbirlerine yakÕn de÷erlerde ise kod seçimi kullanmak alÕcÕdaki SNR`Õ arttÕrÕr. Bu makalede, alÕcÕdaki SNR´Õ arttÕrmak için uyarlamalÕ kod ve anten seçimi önerilmiútir. Bu teknikte, fazladan bir bitlik geribesleme kullanÕlarak verici anten seçimine ve kod seçimine göre alÕcÕda daha iyi bir SNR de÷eri elde edilir. DetaylÕ benzetimler göstermiútir ki, üç verici anten için uyarlamalÕ kod ve anten seçiminde kullanÕlacak 4 bitlik geribesleme, kod seçimi olarak kullanÕlan Geniúletilmiú Dengeli Uzay-Zaman Blok KodlamanÕn ideal geribesleme baúarÕmÕnÕ elde etmektedir. ødeal geribesleme ise kanal durum bilgisinin vericide tam olarak bilinmesini gerektirir.

2008 IEEE 16th Signal Processing, Communication and Applications Conference, 2008

Page 1. Hız Kontrollü Doğrusal Dağılımlı Uzay-Zaman Kodları Rate Controlled Linear Dispersive Spa... more Page 1. Hız Kontrollü Doğrusal Dağılımlı Uzay-Zaman Kodları Rate Controlled Linear Dispersive Space-Time Codes Sinan Kahraman1, M. Ertuğrul Çelebi2 1. UEKAE TÜBİTAK sinankahraman@ uekae.tubitak.gov.tr 2. Elektronik ve Haberleşme Mühendisliği Bölümü, İ.T.Ü. ...

2007 IEEE 15th Signal Processing and Communications Applications, 2007

In this paper, balanced space-time block code selection schemes with four and five feedback bits ... more In this paper, balanced space-time block code selection schemes with four and five feedback bits are proposed for wireless communication systems using four transmit antennas, by increasing the number of transmission matrices. It is shown by computer simulations that the diversity gain is further increased by these new schemes compared to those given in (M. E. Celebi et al., 2007).

2009 IEEE 17th Signal Processing and Communications Applications Conference, 2009

In this paper, it is shown that orthogonal space-time block code (OSTBC) matrices designed for re... more In this paper, it is shown that orthogonal space-time block code (OSTBC) matrices designed for real signal transmission can be used for the transmission of complex signals when limited feedback bits are available from receiver to transmitter. This approach simplifies the maximum likelihood (ML) decoding at the receiver while making full rate, full-diversity transmission of complex signals possible using 4

2012 IEEE 13th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2012

This paper considers a two-way relay network in which two source nodes exchange messages during t... more This paper considers a two-way relay network in which two source nodes exchange messages during two time slots with the help of a half-duplex amplify-and-forward relay node. Closed form expressions of source and relay node powers are obtained by solving an optimization problem which aims to minimize system total power by constraining source nodes' received signal-to-noise ratios (SNR), thus satisfying the minimum quality of service (QoS). Furthermore, the variation of optimum powers versus the parameter which gives information about the channel qualities is investigated for symmetric and asymmetric QoS at the source nodes. In addition, assuming equal channel and noise variances, the effect of variance on the proposed and equal power allocation is illustrated. Numerical results show that the optimum power allocation outperforms the equal power allocation scheme in terms of total power for various variance values and QoS demands.

2013 21st Signal Processing and Communications Applications Conference (SIU), 2013

This paper investigates single relay selection strategies in two-way relay network and analog net... more This paper investigates single relay selection strategies in two-way relay network and analog network coding (ANC) setting, in terms of sum-power minimization given signal to noise ratio (SNR) constraints. Firstly, the energy-efficient single relay selection and power allocation (EE-SRS-PA) scheme is introduced where the optimality is proven under gain requirements. Secondly, the best-worst relay selection and power allocation (BWRS-PA) scheme is introduced where the best relay is selected according to the widely known best-worst relay selection criterion along with optimum power allocation at the sources. Simulation results are presented to show the merits of the proposed schemes compared to similar work in the literature.

2012 20th Signal Processing and Communications Applications Conference (SIU), 2012

Abstract In this work, we introduce a method for fast decoding of silver codes that is dimensiona... more Abstract In this work, we introduce a method for fast decoding of silver codes that is dimensionality reduced method on search tree of the sphere decoder. In the recent works, it is known that the fast decoding method for the silver code has the worst-case complexity of m 2. By the use of proposed method, silver code has only m 1.5 decoding complexity in worst-case. In this case, the error performance of the proposed method for the silver codes has limited loss about 1 dB in the receiver unit.

2007 9th International Symposium on Signal Processing and Its Applications, 2007

Abstract In a previous work, we have proposed to use a generalized Gaussian Mixture (GM) distribu... more Abstract In a previous work, we have proposed to use a generalized Gaussian Mixture (GM) distribution for modelling the sea clutter. In this work, we analyze the performance of the proposed method for the CFAR and non-CFAR cases. In order to evaluate the ...

2007 IEEE 15th Signal Processing and Communications Applications, 2007

In this paper, a trellis coded balanced space-time block code selection scheme (TC/BSTBCS) which ... more In this paper, a trellis coded balanced space-time block code selection scheme (TC/BSTBCS) which is obtained by using balanced space-time block code selection (BSTBCS) with super-orthogonal space-time trellis coding (SOSTTC) is proposed for wireless communication. As a result of using the transmission matrices of BSTBCS - instead of Alamouti code in SOSTTC - at states of trellis structures with various

IEEE Signal Processing and Communications Applications, 2004

The totally blind image restoration problem is solved using an expectation maximization (EM) base... more The totally blind image restoration problem is solved using an expectation maximization (EM) based learning technique. A new formulation on simultaneous recursive image and blur parameter identification and image restoration is given in a dynamic Bayesian network (DBN) framework. This technique incorporates optimal Kalman smoothing equations for maximum likelihood (ML) parameter identification and state estimation. Because of the computationally heavy

IEE Proceedings - Communications, 2006

We propose full rate balanced space-time block codes which achieve full diversity for arbitrary n... more We propose full rate balanced space-time block codes which achieve full diversity for arbitrary number of transmit antennas, provided that one or a few feedback bits are sent to the transmitter denoting the relative state information of the channels. Moreover, all transmitted symbols can be decoded separately at the receiver, as in the case of orthogonal space-time block coding; thus the decoding complexity is linear. It is shown by computer simulations that the new approach provides signal-to-noise ratio improvement, and it is more resilient to feedback errors, compared to the transmit antenna selection technique, on the basis of same number of feedback bits.

IEEE Transactions on Neural Networks, 2000

The key point in design of radial basis function networks is to specify the number and the locati... more The key point in design of radial basis function networks is to specify the number and the locations of the centers. Several heuristic hybrid learning methods, which apply a clustering algorithm for locating the centers and subsequently a linear leastsquares method for the linear weights, have been previously suggested. These hybrid methods can be put into two groups, which will be called as input clustering (IC) and input-output clustering (IOC), depending on whether the output vector is also involved in the clustering process. The idea of concatenating the output vector to the input vector in the clustering process has independently been proposed by several papers in the literature although none of them presented a theoretical analysis on such procedures, but rather demonstrated their effectiveness in several applications. The main contribution of this paper is to present an approach for investigating the relationship between clustering process on input-output training samples and the mean squared output error in the context of a radial basis function netowork (RBFN). We may summarize our investigations in that matter as follows: 1) A weighted mean squared input-output quantization error, which is to be minimized by IOC, yields an upper bound to the mean squared output error. 2) This upper bound and consequently the output error can be made arbitrarily small (zero in the limit case) by decreasing the quantization error which can be accomplished through increasing the number of hidden units.