Elektrik - Elektronik Mühendisliği Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12469/47

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Advanced Signal Processing Algorithms for Wireless Communications
(Springer-Verlag Berlin, 2006) Panayırcı, Erdal; Çırpan, Hakan Ali
Traditional wireless technologies are not well suited to meet the extremely demanding requirements of providing the very high data rates with the ubiquity mobility and portability characteristic of cellular systems. Some fundamental barriers related to the nature of the radio channel as well as the limited bandwidth availability at the frequencies of interest stand in the way. Unique sets of efficient advanced signal processing algorithms and techniques is the one of the primary enablers that will allow lifting these limits primarily due to the impressive advent of low cost and low power digital signal processors. As an application of advanced signal processing techniques we will consider the solution of blind phase noise estimation and data detection problem via a computationally efficient sequential Monte Carlo (SMC) methodology in this paper.
Analysis and Optimization of Matching Networks-I Getting Started With Ads
(Springer-Verlag Berlin, 2008) Şengül, Metin Y.
[Abstract Not Available]
Analysis and Optimization of Matching Networks-Ii Getting Started With Microwave Office
(Springer-Verlag Berlin, 2008) Şengül, Metin Y.
[Abstract Not Available]
Citation - WoS: 4
Citation - Scopus: 5
Broadband Equalizer Design With Commensurate Transmission Lines Via Reflectance Modeling
(IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 2008) Şengül, Metin Y.; Yarman, Sıddık Binboğa
In this paper an alternative approach is presented to design equalizers (or matching networks) with commensurate (or equal length) transmission lines. The new method automatically yields the matching network topology with characteristic impedances of the commensurate lines. In the implementation process of the new technique first the driving point impedance data of the matching network is generated by tracing a pre-selected transducer power gain shape without optimization. Then it is modelled its it realizable bounded-real input reflection coefficient in Richard domain which ill turn yields the desired equalizer topology with line characteristic impedances. This process results in an excellent initial design for the commercially available computer aided design (CAD) packages to generate final circuit layout for fabrication. An example is given to illustrate the utilization of the new method. It is expected that the proposed design technique is employed as it front-end to commercially available computer aided design (CAD) packages which generate the actual equalizer circuit layout with physical dimensions for mass production.
Citation - WoS: 7
Channel Modeling for Visible Light Communications
(Springer-Verlag Berlin, 2016) Miramirkhani, Farshad; Uysal, Murat; Panayırcı, Erdal
In this chapter, we present a novel and realistic channel modeling approach for visible light communications that overcomes the limitations of previous works. In our work, we consider wavelength dependency, effect of realistic light sources as well as different types of reflections such as specular and mixed cases of diffuse and specular. We use nonsequential ray tracing algorithms to calculate the detected power and path lengths from source to detector for each ray. These are then processed to yield the channel impulse responses for various indoor environments. We further present a channel characterization study where channel parameters such as channel DC gain, root mean square delay spread, coherence bandwidth, mean excess delay are calculated for different environments.
Citation - Scopus: 5
Design and Implementation of a Negative Feedback Oscillator Circuit Based on a Cellular Neural Network With an Opposite Sign Template
(2010) Tander, Baran; Özmen, Atilla; Özçelep, Yasin
In this paper explicit amplitude and frequency expressions for a Cellular Neural Network with an Opposite-Sign Template (CNN-OST) under oscillation condition are derived and a novel inductorless oscillator circuit with negative feedbacks based on this simple structure is designed and implemented. The system is capable of generating quasi-sine signals with tuneable amplitude and frequency which can't be provided at the same time in the classical oscillator circuits.
Citation - Scopus: 2
Fuzzy-Neural Networks for Medical Diagnosis
(2010) Şenol, Canan; Yıldırım, Tülay
In this paper a novel fuzzy-neural network architecture is proposed and the algorithm is developed. Using this new architecture fuzzy-CSFNN fuzzy-MLP and fuzzy-RBF configurations were constituted and their performances have been compared on medical diagnosis problems. Here conic section function neural network (CSFNN) is also a hybrid neural network structure that unifies the propagation rules of multilayer perceptron (MLP) and radial basis function (RBF) neural networks at a unique network by its distinctive propagation rules. That means CSFNNs accommodate MLPs and RBFs in its own self-network structure. The proposed hybrid fuzzy-neural networks were implemented in a well-known benchmark medical problems with real clinical data for thyroid disorders breast cancer and diabetes disease diagnosis. Simulation results show that proposed hybrid structures outperform both MATLAB-ANFIS and non-hybrid structures. © 2010 Inderscience Enterprises Ltd.
Joint Data Detection and Channel Estimation for Uplink Mc-Cdma Systems Over Frequency Selective Channels
(Springer, 2007) Panayırcı, Erdal; Doğan, Hakan; Çırpan, Hakan Ali; Fleury, Bernard Henri
This paper is concerned with joint channel estimation and data detection for uplink multicarrier code-division multiple-access (MC-CDMA) systems ill the presence of frequency fading channel. The detection and estimation implemented at the receiver are based on a version of the expectation maximization (EM) algorithm which is very suitable for the the multicarrier signal formats. Application of the EM-based algorithm to the problem of iterative data detection and channel estimation leads to a receiver structure that also incorporates a partial interference cancelation. Computer simulations show that the proposed algorithm has excellent BER end estimation performance.
Citation - WoS: 12
Citation - Scopus: 26
Novel Channel Models for Visible Light Communications
(Spie-Int Soc Optical Engineering, 2015) Miramirkhani, Farshad; Uysal, Murat; Panayırcı, Erdal
In this paper we investigate channel modeling for visible light communications (VLC) using non-sequential ray tracing simulation tools. We create three dimensional realistic simulation environments to depict indoor scenarios specifying the geometry of the environment the objects inside the reflection characteristics of the surface materials as well as the characteristics of the transmitter and receivers i.e. LED sources and photodioes. Through ray tracing simulations we compute the received optical power and the delay of direct/indirect rays which are then used to obtain the channel impulse response (CIR). Following this methodology we present CIRs for a number of indoor environments including empty/furnished rectangular rooms with different sizes and wall/object materials (e.g. plaster gloss paint wood aluminum metal glass) assuming deployment of both single and multiple LED transmitters. We further quantify multipath channel parameters such as delay spread and channel DC gain for each configuration and provide insights into the effects of indoor environment parameters (e.g. size wall/object materials etc.) transmitter/receiver specifications (e.g. single vs. multiple transmitters location rotation etc.) on the channel.
Citation - WoS: 22
Citation - Scopus: 26
On Channel Estimation in Dc Biased Optical Ofdm Systems Over Vlc Channels
(IEEE Computer Society, 2016) Sayli, Osman; Dogan, Hakan; Panayırcı, Erdal
Visible Light Communication(VLC) has been considered as a potential access option for 5G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In (VLC) system illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC Biased optical (DCO)-OFDM has been proposed for VLC systems to provide optically power efficient solution and easy implementation. Wireless communication systems generally require estimating and tracking the fading channel in order to detect transmitted data coherently. In this work comb type pilot arrangement with interpolation and block type pilot arrangement are proposed for the DCOOFDM systems over visible light channels. Simulation results have verified that the proposed block type pilot arrangement based channel estimation has clear BER performance advantages compared with comb type pilot arrangement based channel estimation. © 2016 IEEE.
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.

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