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Esmaeili M.,Isfahan University of Technology | Tadayon M.H.,Iran Telecommunications Research Center | Gulliver T.A.,University of Victoria
AEU - International Journal of Electronics and Communications | Year: 2010

A low-complexity method for constructing a large class of high-rate girth-8 quasi-cyclic low-density parity-check (LDPC) codes with moderate length 1000 < n < 10 000 is presented. This method is based on combining configurations with incidence matrices composed of cyclic permutation matrices and Tanner graph girth at least 8. Shortened lattice codes of length n < 380 and girth 8 are employed as component codes. From the performance perspective, the resulting codes are comparable to their counterparts such as random-like and shortened array LDPC codes. © 2009 Elsevier GmbH. All rights reserved.


Mostafaei H.,Islamic Azad University at Urmia | Esnaashari M.,Iran Telecommunications Research Center | Meybodi M.R.,Amirkabir University of Technology
Applied Mathematics and Information Sciences | Year: 2015

To cover a set of targets with known locations within an area with limited or prohibited ground access using a wireless sensor network, one approach is to deploy the sensors remotely, from an aircraft. In this approach, the lack of precise sensor placement is compensated by redundant de-ployment of sensor nodes. This redundancy can also be used for extending the lifetime of the network, if a proper scheduling mechanism is available for scheduling the active and sleep times of sensor nodes in such a way that each node is in active mode only if it is required to. In this paper, we propose an efficient scheduling method based on learning automata and we called it LAML, in which each node is equipped with a learning automaton, which helps the node to select its proper state (active or sleep), at any given time. To study the performance of the proposed method, computer simulations are conducted. Results of these simulations show that the proposed scheduling method can better prolong the lifetime of the network in comparison to similar existing method. © 2015 NSP Natural Sciences Publishing Cor.


Moaveni B.,Iran University of Science and Technology | Abdollahzadeh H.,Islamic Azad University at Tehran | Mazoochi M.,Iran Telecommunications Research Center
Proceedings - 2011 2nd International Conference on Control, Instrumentation and Automation, ICCIA 2011 | Year: 2012

Zeta converters are the fourth-order DC-DC converters capable of operating in both step-up and step-down modes and do not suffer from the polarity reversal problem. There are many applications which require a variable output voltage commanded by an external reference signal. So, the Zeta converters can be particularly useful for such applications. To achieve a Zeta converter with adjustable output voltage capable of following an external reference signal smoothly and accurately, there will be a need for a suitable control system. Since the Zeta converter model that is used in this paper is nonlinear, we propose a combination scheme of model reference adaptive control (MRAC) with neural networks (NN). In this paper, we propose and design a neural network adaptive model reference controller to control the output voltage of Zeta converter. Simulation results show the effectiveness of the proposed scheme for the Zeta converters with adjustable output voltage. © 2011 IEEE.


Vahidipour S.M.,Amirkabir University of Technology | Meybodi M.R.,Amirkabir University of Technology | Esnaashari M.,Iran Telecommunications Research Center
IEEE Transactions on Systems, Man, and Cybernetics: Systems | Year: 2015

In this paper, an adaptive Petri net (PN), capable of adaptation to environmental changes, is introduced by the fusion of learning automata and PN. In this new model, called learning automata-based adaptive PN (APN-LA), learning automata are used to resolve the conflicts among the transitions. In the proposed APN-LA model, transitions are portioned into several sets of conflicting transitions and each set of conflicting transitions is equipped with a learning automaton which is responsible for controlling the conflicts among transitions in the corresponding transition set. We also generalize the proposed APN-LA to ASPN-LA which is a fusion between LA and stochastic PN (SPN). An application of the proposed ASPN-LA to priority assignment in queuing systems with unknown parameters is also presented. © 2013 IEEE.


Esnaashari M.,Iran Telecommunications Research Center | Meybodi M.R.,Amirkabir University of Technology | Meybodi M.R.,Institute for Studies in Theoretical Physics and Mathematics IPM
IEEE Transactions on Cybernetics | Year: 2015

Cellular learning automaton (CLA) is a recently introduced model that combines cellular automaton (CA) and learning automaton (LA). The basic idea of CLA is to use LA to adjust the state transition probability of stochastic CA. This model has been used to solve problems in areas such as channel assignment in cellular networks, call admission control, image processing, and very large scale integration placement. In this paper, an extension of CLA called irregular CLA (ICLA) is introduced. This extension is obtained by removing the structure regularity assumption in CLA. Irregularity in the structure of ICLA is needed in some applications, such as computer networks, web mining, and grid computing. The concept of expediency has been introduced for ICLA and then, conditions under which an ICLA becomes expedient are analytically found. © 2013 IEEE.


Hatefi Ardakani H.,Iran Telecommunications Research Center | Rashed-Mohassel J.,University of Tehran | Akbarzadeh Jahromi A.,Iran University of Science and Technology | Khalaj Amirhosseini M.,Iran University of Science and Technology
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

This paper presents new detailed features of microstrip lines on a generic pseudochiral medium. A full-wave analysis is also proposed based on the spectral domain technique to extract the propagation characteristics of the new line in a straightforward way is compared to other methods in the literature. In addition, The Extended Method of Lines (E-MoL) is implemented to validate the results. It is found that the orientation of the Ω particles has significant effects on propagation characteristics of the microstrip line. Several novel characteristics are achieved, which is not the case for conventional microstrip lines. These appealing phenomena may be very promising in realization of new devices in microwave and millimeter-wave integrated circuits. © 2010 IEEE.


Ardakani H.H.,Iran Telecommunications Research Center | Kashani Z.G.,Iran Telecommunications Research Center | Amirkalaee M.K.,Iran Telecommunications Research Center | Rashed-Mohassel J.,University of Tehran
IET Microwaves, Antennas and Propagation | Year: 2013

In this study, a generic multilayer structure containing metals, dielectrics, line sources and graphene sheets is considered and analysed. The spectral domain techniques (SDTs) have been known as an efficient method for analysis of planar structures. However, since existence of graphene sheet imposes a new boundary condition, conventional SDTs cannot deal with it. Therefore a spectral-based method is proposed by applying the two-dimensional Fourier transform to the fields' equations. First, a graphene sheet described by a conductivity tensor is assumed to be placed between two arbitrary dielectric layers. A generalised transformation matrix is then calculated which relates the electromagnetic fields of the top layer in terms of the ones of the bottom layer. It is shown that considering the tangential electric fields as supporting field components makes an easier analysis and results in more simplified expressions. The proposed method is evaluated through some examples of guiding and radiating structures. Some novel characteristics are observed, which are promising in providing new applications. © The Institution of Engineering and Technology 2013.


Eskandari L.,Sharif University of Technology | Yousefi H.,Iran Telecommunications Research Center | Movaghar A.,Iran Telecommunications Research Center | Khansari M.,Sharif University of Technology
Proceedings - 2011 IFIP 9th International Conference on Embedded and Ubiquitous Computing, EUC 2011 | Year: 2011

The main source of energy consumption in the current MAC protocols for wireless sensor networks is idle listening. To mitigate this problem, duty cycling is used. However, it increases data delivery latency. In this paper, we propose an Interference-aware duty-cycle MAC (IMAC) protocol for wireless sensor networks that uses cross-layer information to reserve multiple paths for each source and send data packets along them efficiently. IMAC also handles the existing interference between these paths such that data packets can be delivered in the minimum required number of cycles. Simulation results in ns-2 show that the proposed algorithm has an average reduction of 49% in data delivery latency compared to a current solution called RMAC. © 2011 IEEE.


Ardakani H.H.,Iran Telecommunications Research Center | Kashani Z.G.,Iran Telecommunications Research Center | Amirkalaee M.K.,Iran Telecommunications Research Center | Rashed-Mohassel J.,University of Tehran
2012 6th International Symposium on Telecommunications, IST 2012 | Year: 2012

In this paper, a generic multilayer structure containing metals, dielectrics and graphene sheets is considered and analyzed. The spectral domain techniques (SDTs) have been known as an efficient method for analysis of planar structures. But since the existence of graphene sheet imposes a new boundary condition; the conventional SDTs cannot deal with it. Therefore, a spectral-based method is proposed by applying the two dimensional Fourier transform to the fields equations. First, without loss of generality, a graphene sheet described with a conductivity tensor is assumed to be placed between two arbitrary dielectric layers. A generalized transformation matrix is then calculated where relates the electromagnetic fields of the top layer in terms of the ones of the bottom layer. It is shown that considering the tangential electric fields as supporting field components makes an easier analysis and results in more simplified expressions. The proposed method is evaluated through some examples. Some novel characteristics are observed which are promising in providing new applications. © 2012 IEEE.


Tadayon M.H.,Iran Telecommunications Research Center
International Journal of Security and its Applications | Year: 2016

Network coding is a new method for forwarding network throughput in digital communication systems. In this paper, we introduce an efficient scheme for protecting the source data against wiretapper in linear network coding. The proposed scheme is implemented on the generated data packets in source node. We employ a well-known permutation function called Mobius transformation to transfer the existing data packet to an appropriate interchanged data packet. Then the new data packet can be sent to the intermediate nodes via output links of the source node in network securely. Indeed, the security of the proposed scheme against wiretapper is provided by employing Mobius transformation and interleaver operation on the generated data packet in source node. In the absence of cryptography systems, the proposed method is a light weight security scheme for network coding that can provide a security level easily. © 2016 SERSC.

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