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Journal of Telecommunications and Information Technology (JTIT) - Wyniki wyszukiwania

1/2016 Sławomir Kula and Piotr Zwierzykowski
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1/2016 Valery Tikhvinskiy, Grigory Bochechka and Andrey Gryazev
QoS Requirements as Factor of Trust to 5G Network
Trust to modern telecommunications networks plays an important role as a driver of technological and market success of any technology or telecommunication services. Most of the technological approaches to this problem are focused only on network security and do not include such a factor as the quality of service (QoS), which also plays an important role in the formation of trust both from the consumers and the regulator. The future 5G mobile technology will be the engine of development of telecommunications until 2020 and the formation of trust to the 5G networks is one of the main tasks for developers. The authors present the view on the trust to 5G networks in the plane of QoS requirements formation and QoS management. QoS requirements to 5 G networks were determined on the basis of three main business models of services: xMBB, M-MTC and U-MTC and the need to ensure user trust to networks. Infrastructure requirements for QoS control and spectrum management network entities which are based on Network Function Virtualization (NFV) principles have been formed.
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1/2016 Przemysław Gilski and Jacek Stefański
Digital Audio Broadcasting or Webcasting: A Network Quality Perspective
In recent years, many alternative technologies of delivering audio content have emerged, with different advantages and disadvantages. In this paper pros and cons of digital audio broadcasting and webcasting transmission techniques in a network quality perspective are described. A case study of user expectations with respect to currently available services is analyzed, and the perceived quality of real digital broadcasted and webcasted radio stations is examined.
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1/2016 Grzegorz Wilczewski
Monitoring of a Cloud-Based Environment for Resilient Telecommunication Services
This article depicts insights and in-depth presentation of a new tool, specifically designed for Data Center resources monitoring purpose. It enables physical and virtual resources monitoring and is capable of performing advanced analysis on the resulting, measured data. Here in presented are exemplary scenarios conducted over the proprietary Data Center unit, delivering specific information on the behavior of the analyzed environment. Presented results create a base layer for a high level resiliency analysis of telecommunication services.
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1/2016 Kais Rouis, Mikołaj Leszczuk, Lucjan Janowski, Zdzisław Papir and Jamal Bel Hadj Tahar
Study of No-Reference Video Quality Metrics for HEVC Compression
The paper proposes a No-Reference (NR) quality assessment measurement originally developed for H.264, used for High Efficiency Video Coding (HEVC). In particular, authors present an investigation of NR metrics to objectively estimate the perceptual quality of a set of processed video sequences. The authors take into account typical distortions introduced by the block-based coding approaches like HEVC codec. The underlying processing used for the quality assessment considers the blockiness caused by the boundaries of each coded block and the blurring as a lack of spatial details. The correlation between the NR quality metrics and the well-known and most widely used objective metric, the Video Quality Model (VQM), is performed to validate the quality prediction accuracy based on the provided scores. The Pearson correlation coefficients obtained stand for promising results for different types of videos.
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1/2016 Christian Hoppe, Robert Manzke, Marcus Rompf and Tadeus Uhl
Quantifying the Suitability of Reference Signals for the Video Streaming Analysis for IPTV
IP networks are indispensable nowadays and they are some of the most efficient platforms. The constantly growing number of users and new services in these networks – the largest being the Internet – require a satisfactory quality of service from any application they use. So, determining the QoS in real-time services is particularly important. This work shows how to quantify the suitability of reference signals for analyzing the quality of video streaming in IPTV. The assessment relies on two different algorithms: PEVQ and VQuad-HD. Three different reference signals – two real ones and an artificial one – are used in this study, and a numerical measurement system is used, which simulates mean network impairments. These measurements provide valuable information for determining the QoS of actual IPTV services in practice.
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1/2016 Sławomir Hanczewski and Damian Kmiecik
Properties of the Multiservice Erlang's Ideal Gradings
The design and optimization process of modern telecommunications networks is supported by a range of appropriate analytical models. A number of these models are based on the Erlang’s Ideal Grading (EIG) model, which is a particular case of non-full-availability groups. A possibility of the application of the EIG model results from the fact that telecommunications systems show properties and features distinctive to non-full-availability systems. No detailed studies that would decisively help determine appropriate conditions for the application of the EIG model for modeling of other non-full-availability groups, that would be models corresponding to real telecommunications systems, have been performed. Therefore, this article attempts to find an answer to the following question: what are the prerequisite conditions for the application of the EIG model and when the model can be reliably used?
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1/2016 Ioannis D. Moscholios, Michael D. Logothetis, Anthony C. Boucouvalas and Vassilios G. Vassilakis
Call Blocking Probabilities of Multirate Elastic and Adaptive Traffic under the Threshold and Bandwidth Reservation Policies
This paper proposes multirate teletraffic loss models of a link that accommodates different service-classes of elastic and adaptive calls. Calls follow a Poisson process, can tolerate bandwidth compression and have an exponentially distributed service time. When bandwidth compression occurs, the service time of new and in-service elastic calls increases. Adaptive calls do not alter their service time. All calls compete for the available link bandwidth under the combination of the Threshold (TH) and the Bandwidth Reservation (BR) policies. The TH policy can provide different QoS among service-classes by limiting the number of calls of a service-class up to a predefined threshold, which can be different for each service-class. The BR policy reserves part of the available link bandwidth to benefit calls of high bandwidth requirements. The analysis of the proposed models is based on approximate but recursive formulas, whereby authors determine call blocking probabilities and link utilization. The accuracy of the proposed formulas is verified through simulation and found to be very satisfactory.
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1/2016 Alexander Pechinkin and Rostislav Razumchik
Estimation of Network Disordering Eff ects by In-depth Analysis of the Resequencing Bu ffer Contents in Steady-state
The paper is devoted to the analytic analysis of resequencing issue, which is common in packet networks, using queueing-theoretic approach. The authors propose the mathematical model, which describes the simplest setting of packet resequencing, but which allows one to make the first step in the in-depth-analysis of the queues dynamics in the resequencing buffer. Specifically consideration is given to N-server queueing system (N > 3) with single infinite capacity buffer and resequencing, which may serve as a model of packet reordering in packet networks. Customers arrive at the system according to Poisson flow, occupy one place in the buffer and receive service from one of the servers, which is exponentially distributed with the same parameter. The order of customers upon arrival has to be preserved upon departure. Customers, which violated the order are kept in resequencing buffer which also has infinite capacity. It is shown that the resequencing buffer can be considered as consisting of n, 1 ≤ n N −1, interconnected queues, depending on the number of busy servers, with i-th queue containing customers, which have to wait for i service completions before they can leave the system. Recursive algorithm for computation of the joint stationary distribution of the number of customers in the buffer and servers, and each queue in resequencing buffer are being obtained. Numerical examples, which show the dynamics of the characteristics of the queues in resequencing buffer are given.
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1/2016 Maciej Piechowiak, Krzysztof Stachowiak and Tomasz Bartczak
Multicast Connections in Wireless Sensor Networks with Topology Control
The article explores the quality of multicast trees constructed by heuristic routing algorithms in wireless sensor networks where topology control protocols operate. Network topology planning and performance analysis are crucial challenges for wire and wireless network designers. They are also involved in the research on routing algorithms, and protocols for these networks. In addition, it is worth to emphasize that the generation of realistic network topologies makes it possible to construct and study routing algorithms, protocols and traffic characteristics for WSN networks.
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1/2016 Marziyeh Barootkar, Akbar Ghaffarpour Rahbar and Masoud Sabaei
LDAOR - Location and Direction Aware Opportunistic Routing in Vehicular Ad hoc Networks
Routing in Vehicular Ad hoc Networks (VANETs) has found significant attention because of its unique features such as lack of energy constraints and high-speed vehicles applications. Besides, since these networks are highly dynamic, design process of routing algorithms suitable for an urban environment is extremely challenging. Appropriate algorithms could be opportunistic routing (OR) where traffic transmission is performed using the store-carry-forward mechanism. An efficient OR mechanism, called Location and Direction Aware Opportunistic Routing (LDAOR), is proposed in this paper. It is based on the best neighbor node selection by using vehicles positions, vehicles directions, and prioritization of messages from buffers, based on contact histories and positions of neighbor nodes to destination. In LDAOR, when multiple nodes make contact with a carrier node, the closest neighbor node to destination is selected as the best forwarder. However, when only one node makes contact with the carrier node, the message is delivered to it if it moves toward the destination. Using the ONE simulator, the obtained performance evaluation results show that the LDAOR operates better than conventional OR algorithms. The LDAOR not only increases delivery rate, but also reduces network overhead, traffic loss, and number of aborted messages.
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1/2016 Thanh Tung Khuat and My Hanh Le
A Novel Technique of Optimization for the COCOMO II Model Parameters using Teaching-Learning-Based Optimization Algorithm
Software cost estimation is a critical activity in the development life cycle for controlling risks and planning project schedules. Accurate estimation of the cost before the start-up of a project is essential for both the developers and the customers. Therefore, many models were proposed to address this issue, in which COCOMO II has been being widely employed in actual software projects. Good estimation models, such as COCOMO II, can avoid insufficient resources being allocated to a project. However, parameters for estimation formula in this model have not been optimized yet, and so the estimated results are not close to the actual results. In this paper, a novel technique to optimize the coefficients for COCOMO II model by using teaching-learning-based optimization (TLBO) algorithm is proposed. The performance of the model after optimizing parameters was tested on NASA software project dataset. The obtained results indicated that the improvement of parameters provided a better estimation capabilities compared to the original COCOMO II model.
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1/2016 Łukasz Łopaciński, Marcin Brzozowski, Rolf Kraemer, Steffen Buechner and Jörg Nolte
100 Gb/s Data Link Layer - from a Simulation to FPGA Implementation
In this paper, a simulation and hardware implementation of a data link layer for 100 Gb/s terahertz wireless communications is presented. In this solution the overhead of protocols and coding should be reduced to a minimum. This is especially important for high-speed networks, where a small degradation of efficiency will lower the user data throughput by several gigabytes per second. The following aspects are explained: an acknowledge frame compression, the optimal frame segmentation and aggregation, Reed-Solomon forward error correction, an algorithm to control the transmitted data redundancy (link adaptation), and FPGA implementation of a demonstrator. The most important conclusion is that changing the segment size influences the uncoded transmissions mostly, and the FPGA memory footprint can be significantly reduced when the hybrid automatic repeat request type II is replaced by the type I with a link adaptation. Additionally, an algorithm for controlling the Reed-Solomon redundancy is presented. Hardware implementation is demonstrated, and the device achieves net data rate of 97 Gb/s.
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1/2016 Adil Elabboubi, Fouzia Elbahhar, Marc Heddebaut and Yassin Elhillali
DS-UWB and TH-UWB Energy Consumption Comparison
The energy consumption of the wireless communication systems is starting to be unaffordable. One way to improve the power consumption is the optimization of the communication techniques used by the communication networks and devices. In order to develop an energy efficient UWB multi-user communication system, the choice of modulation and multi access technique is important. This paper compares two Ultra-wideband multi-user techniques, i.e. the DS-UWB and the TH-UWB in the case of the Nakagami-m fading channel. For the DS-UWB technique, the orthogonal (T-OVSF, ZCD) and non-orthogonal (Kasami) codes are used. For TH-UWB, authors consider different modulations (PPM, PSM, PAM). This comparison allows choosing the best solution in terms of energy consumption, data rate and communication range. Two different studies are realized to find the most efficient technique to use. In the first study, the same number of users for the different type of codes (data rate values) is chosen and the total energy consumption for several distances and path-loss coefficient is computed. In the second one, the multiusers effects (same data rate) for various values of distances and path-loss are evaluated.
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1/2016 Ryota Negishi, Shuichiro Haruta, Chihiro Inamura, Kentaroh Toyoda and Iwao Sasase
Monetary Fair Battery-based Load Hiding Scheme for Multiple Households in Automatic Meter Reading System
Automatic Meter Reading (AMR) system is expected to be used for real time load monitoring to optimize power generation and energy efficiency. Recently, it has been a serious problem that user’s lifestyle may be revealed by a tool to estimate consumer’s lifestyle from a real-time load profile. In order to solve this issue, Battery-based Load Hiding ( BLH ) algorithms are proposed to obfuscate an actual load profile by charging and discharging. Although such BLH algorithms have already been studied, it is important to consider multiple households case where one battery is shared among them due to its high cost. In this paper, a monetary fair BLH algorithm for multiple households is proposed. In presented scheme, the core unit calculates the difference between the charged amount and discharged one for each household. If the difference is bigger than the predefined threshold (monetary unfair occurs), the most disadvantageous and advantageous households are given priority to discharge and charge the battery and other households should charge to achieve monetary fairness. The efficiency of the scheme is demonstrated through the computer simulation with a real dataset.
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2/2016 Ewa Niewiadomska-Szynkiewicz, Ioan Salomie
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2/2016 Michał Karpowicz and Piotr Arabas
Server Workload Model Identification: Monitoring and Control Tools for Linux
Server power control in data centers is a coordinated process carefully designed to reach multiple data center management objectives. The main objectives include avoiding power capacity overloads and system overheating, as well as fulfilling service-level agreements (SLAs). In addition to the primary goals, server control process aims to maximize various energy efficiency metrics subject to reliability constraints. Monitoring of data center performance is fundamental for its efficient management. In order to keep track of how well the computing tasks are processed, cluster control systems need to collect accurate measurements of activities of cluster components. This paper presents a brief overview of performance and power consumption monitoring tools available in the Linux systems.
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2/2016 Mariusz Kamola, Ewa Niewiadomska-Szynkiewicz, Piotr Arabas and Andrzej Sikora
Energy-saving Algorithms for the Control of Backbone Networks: A Survey
The rapid growth of energy demand by wired IP networks can be mitigated on hardware and software levels. While upgrading to more efficient transmission media still brings biggest savings, we take a look here at power-saving algorithms that combine the capability of setting networking equipment in arbitrary energy states which, combined with profound knowledge of the network traffic matrix, leads to considerable complex optimization problem formulations. Alternatively, lightweighted heuristic approaches are presented, built on much simpler network model but still capable to perform energy-efficient traffic engineering.
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2/2016 Andrzej Karbowski and Przemysław Jaskóła
New Developments in a Two-criteria Approach to Dynamic Power Management in Energy-aware Computer Networks
In the paper authors continue the development of a model of dynamic power management in energy-aware computer networks, where two criteria: energy consumption and the quality of service are considered. This approach is appropriate when the routing problem with fixed demands is inadmissible. The formulation introducing edge indices is modified and tests on problems of different sizes are performed.
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2/2016 Sergiy Yu. Fialko and Filip Zeglen
Preconditioned Conjugate Gradient Method for Solution of Large Finite Element Problems on CPU and GPU
In this article the preconditioned conjugate gradient (PCG) method, realized on GPU and intended to solution of large finite element problems of structural mechanics, is considered. The mathematical formulation of problem results in solution of linear equation sets with sparse symmetrical positive definite matrices. The authors use incomplete Cholesky factorization by value approach, based on technique of sparse matrices, for creation of efficient preconditioning, which ensures a stable convergence for weakly conditioned problems mentioned above. The research focuses on realization of PCG solver on GPU with using of CUBLAS and CUSPARSE libraries. Taking into account a restricted amount of GPU core memory, the efficiency and reliability of GPU PCG solver are checked and these factors are compared with data obtained with using of CPU version of this solver, working on large amount of RAM. The real-life large problems, taken from SCAD Soft collection, are considered for such a comparison.
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2/2016 Paweł Szynkiewicz
A Novel GPU-Enabled Simulator for Large Scale Spiking Neural Networks
The understanding of the structural and dynamic complexity of neural networks is greatly facilitated by computer simulations. An ongoing challenge for simulating realistic models is, however, computational speed. In this paper a framework for modeling and parallel simulation of biological-inspired large scale spiking neural networks on high-performance graphics processors is described. This tool is implemented in the OpenCL programming technology. It enables simulation study with three models: Integrate-andfire, Hodgkin-Huxley and Izhikevich neuron model. The results of extensive simulations are provided to illustrate the operation and performance of the presented software framework. The particular attention is focused on the computational speed-up factor.
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2/2016 Thanh Tung Khuat, Quang Chanh Le, Bich Loan Nguyen and My Hanh Le
Forecasting Stock Price using Wavelet Neural Network Optimized by Directed Arti ficial Bee Colony Algorithm
Stock prediction with data mining techniques is one of the most important issues in finance. This field has attracted great scientific interest and has become a crucial research area to provide a more precise prediction process. This study proposes an integrated approach where Haar wavelet transform and Artificial Neural Network optimized by Directed Artificial Bee Colony algorithm are combined for the stock price prediction. The proposed approach was tested on the historical price data collected from Yahoo Finance with different companies. Furthermore, the prediction result was found satisfactorily enough as a guide for traders and investors in making qualitative decisions.
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2/2016 Agnieszka Jakóbik
A Cloud-aided Group RSA Scheme in Java 8 Environment and OpenStack Software
In this paper a RSA based security system enabling the group of users to upload the single masked message to the cloud environment is proposed. Data stored are encrypted using RSA algorithm. The data receiver is able to encrypt the message retrieved from the cloud environment using private key. Two different separate RSA systems are used. The presented approach is divided into three parts. First, an RSA key is generated for each sender. Then masking the message by newly chosen mask proposed individually by every member, additionally encrypted by individual RSA private key of each member is proceed. Next, encrypting the gathered message inside the cloud environment, using the public key of the receiver is executed. In the third step, the message is decrypted by the receiver using his private RSA key. The scheme reduces the computational load on users side and transfers calculations and storage effort to the cloud environment. The proposed algorithm was developed for storing and sending the data that originally are produced by a group of users, but the receiver of the data is single. It was implemented using Java 8 and OpenStack software. Numerical test of different key length for RSA are presented.
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2/2016 Hudan Studiawan, Supeno Djanali and Baskoro Adi Pratomo
Graph-based Forensic Analysis of Web Honeypot
Honeypot still plays an important role in network security, especially in analyzing attack type and defining attacker patterns. Previous research has mainly focused on detecting attack pattern while categorization of type has not yet been-comprehensively discussed. Nowadays, the web application is the most common and popular way for users to gather information, but it also invites attackers to assault the system. Therefore, deployment of a web honeypot is important and its forensic analysis is urgently required. In this paper, authors propose attack type analysis from web honeypot log for forensic purposes. Every log is represented as a vertex in a graph. Then a custom agglomerative clustering to categorize attack type based on PHP-IDS rules is deployed. A visualization of large graphs is also provided since the actual logs contain tens of thousands of rows of records. The experimental results show that the proposed model can help forensic investigators examine a web honeypot log more precisely.
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2/2016 Youness Jouihri, Zouhair Guennoun, Youssef Chagh and Driss Zahi
Network Function Virtualization: Mitigating the Impact of VoLTE on the Policy and the Charging System
Needless to say that telecommunications’ operators are showing increasing interests toward solving the dilemma of optimizing network resources while offering state-of-the-art quality of service. Recently, operators have shown an increasing interest to investigate solutions for better control on network utilization, service usage and monetization. They also noticed a significant growth in Diameter signaling and more specifically in signaling related to policy management. A massive introduction of Voice over LTE (VoLTE) service will have a significant impact on the systems handling policy signaling, as VoLTE will reshape the landscape of Long Term Evolution (LTE) policies and completely change the way policy management works. However, this massive approach is meant to provide significant competitive advantages for operators offering LTE services and still require circuit-switched network to provide voice service. The biggest challenge for those operators is to find an appropriate solution, scalable enough to handle the unpredictable growth of Diameter signaling. In this paper, a model, based on Network Function Virtualization (NFV) technology is proposed, able to address the challenges of massively introducing VoLTE, without impacting existing services and without jeopardizing current revenues. In presented approach, the standard VoLTE call flows, referenced user’s behavior and latest experiments’ results on NFV technology are used.
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2/2016 Witold Gruszczyński and Piotr Arabas
Application of Social Network Inferred Data to Churn Modeling in Telecoms
The subject of this work is the use of social network analysis to increase the effectiveness of methods used to predict churn of telephony network subscribers. The social network is created on the basis of operational data (CDR records). The result of the analysis is customer segmentation and additional predictor variables. Proposed hybrid predictor employs set of regression models tuned to specific customer segments. The verification was performed on data obtained from one of the Polish operators.
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2/2016 Pulipati Srilatha and Ramakrishnan Manjula
Similarity Index based Link Prediction Algorithms in Social Networks: A Survey
Social networking sites have gained much popularity in the recent years. With millions of people connected virtually generate loads of data to be analyzed to infer meaningful associations among links. Link prediction algorithm is one such problem, wherein existing nodes, links and their attributes are analyzed to predict the possibility of potential links, which are likely to happen over a period of time. In this survey, the local structure based link prediction algorithms existing in literature with their features and also the possibility of future research directions is reported and discussed. This survey serves as a starting point for beginners interested in understanding link prediction or similarity index algorithms in general and local structure based link prediction algorithms in particular.
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2/2016 Denis A. Vedenkin, Yuri E. Sedelnikov and Aydar R. Nasybullin
Antenna Arrays Focused on Broadband Signals
Broadband and ultra-wideband signals are increasingly used in modern radio systems. Traditional performance of evaluation antennas operating with narrowband signals are not always adequately reflect the characteristics of broadband antennas, at least in view of the frequency dependence of the antenna pattern. Accounting for broadband signals the antennas becomes important in the low-frequency range of the spectrum. Systems using these types of signals may include control of the atmosphere and measuring its frequency-selective properties in the range meter and decameter wavelengths. Possibility of spatial selection based on focusing of broadband signals in this case promises to implement a number of additional features. Therefore, it is important to evaluate the properties of antennas based on the spectral content of the signal, as well as taking into account the ways of its processing in the receiving equipment. Consideration features of functioning the antenna array, focused on broadband signal is devoted to this article.
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2/2016 Oleg G. Morozov, Aydar R. Nasybullin, Denis A. Vedenkin and Timur A. Agliullin
Radio Photonic Systems for Measurement of Instantaneous Radio Frequency with Amplitude-phase Modulation of Optical Carrier
In this article questions related to the development instantaneous radio frequency measurement system based on application in them original ways of the amplitude-phase modulation transformation of single-frequency optical carrier by a radio signal in symmetric two-frequency and measuring “frequency-amplitude” transformation in fiber Bragg grating with special profile are considered. Such systems have broad prospects for use in telecommunications, military systems and for environmental monitoring.
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2/2016 V. Sudharsan and B. Yamuna
Support Vector Machine based Decoding Algorithm for BCH Codes
Modern communication systems require robust, adaptable and high performance decoders for efficient data transmission. Support Vector Machine (SVM) is a margin based classification and regression technique. In this paper, decoding of Bose Chaudhuri Hocquenghem codes has been approached as a multi-class classification problem using SVM. In conventional decoding algorithms, the procedure for decoding is usually fixed irrespective of the SNR environment in which the transmission takes place, but SVM being a machinelearning algorithm is adaptable to the communication environment. Since the construction of SVM decoder model uses the training data set, application specific decoders can be designed by choosing the training size efficiently. With the soft margin width in SVM being controlled by an equation, which has been formulated as a quadratic programming problem, there are no local minima issues in SVM and is robust to outliers.
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2/2016 P. Salija and B. Yamuna
An Efficient Early Iteration Termination for Turbo Decoder
Turbo code finds wide applications in mobile communication, deep space communication, satellite communication and short-range communication despite its high computational complexity and iterative nature. Realizing capacity approaching turbo code is a great achievement in the field of communication systems due to its efficient error correction capability. The high computational complexity associated with the iterative process of decoding turbo code consumes large power, introducing decoding delay, and reducing the throughput. Hence, efficient iteration control techniques are required to make the turbo code more power efficient. In this paper, a simple and efficient early iteration termination technique is introduced based on absolute value of the mean of extrinsic information at the component decoders of turbo code. The simulation results presented clearly show that the proposed method is capable of reducing the average number of iterations while maintaining performance close to that of fixed iteration termination. The significant reduction in iteration achieved by the method reduces decoding delay and complexity while maintaining Bit Error Rate performance close to standard fixed iteration turbo decoder.
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3/2016 Krzysztof Borzycki
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3/2016 Priya Mishra, Charu Gandhi and Buddha Singh
Link Quality and Energy Aware Geographical Routing in MANETs using Fuzzy Logics
In literature, varieties of topology and geographical routing protocols have been proposed for routing in the MANETs. It is widely accepted that the geographical routings are a superior decision than topological routings. Majority of geographical routing protocols assume an ideal network model and choose the route that contains minimum number of hops. However, in reality, nodes have limited battery power and wireless links are additionally unreliable, so they may highly affect the routing procedure. Thus, for reliable data transmission, condition of the network such as link quality and residual energy must be considered. This paper aims to propose a novel multi-metric geographical routing protocol that considers both links-quality and energy metric along with progress metric to choose the next optimal node. The progress is determined by utilizing greedy as well as compass routing rather than pure greedy routing schemes. To combine these metrics, fuzzy logics are used to get the optimal result. Further, the protocol deals with “hole” problem and proposes a technique to overcome it. Simulations show that the proposed scheme performs better in terms of the packet delivery ratio, throughput and residual energy than other existing protocols.
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3/2016 Grzegorz Zalewski and Włodzimierz Ogryczak
Comparison of Selected Fair-optimization Methods for Flow Maximization between Given Pairs of Nodes in Telecommunications Network
Dimensioning of telecommunications networks requires the allocation of the ows (bandwidth) to given trac demands for the source-destination pairs of nodes. Unit ow allocated to the given demand is associated with revenue that may vary for di erent demands. Problem the decision-making basic algorithms to maximize the total revenue may lead to the solutions that are unacceptable, due to "starvation" or "locking" of some demand paths less attractive with respect to the total revenue. Therefore, the fair optimization approaches must be applied. In this paper, two fair optimization methods are analyzed: the method of ordered weighted average (OWA) and the reference point method (RPM). The study assumes that ows can be bifurcated thus realized in multiple path schemes. To implement optimization model the AMPL was used with general-purpose linear programming solvers. As an example of the data, the Polish backbone network was used.
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3/2016 Paweł Białoń
A Practical Approach to Trac Engineering using an Unsplittable Multicommodity Flow Problem with QoS Constraints
The paper presents a practical approach to calculating intra-domain paths within a domain of a content-aware network (CAN) that uses source routing. This approach was used in the prototype CAN constructed as a part of the Future Internet Engineering project outcome. The calculated paths must satisfy demands for capacity (capacity for a single connection and for aggregate connections using the given path are considered distinctly) and for a number of path-additive measures like delay, loss ratio. We state a suitable variant of QoS-aware unsplittable multicommodity ow problem and present the solving algorithm. The algorithm answers to the needs of its immediate application in the constructed system: a quick return within a short and fairly predictable time, simplicity and modi ability, good behavior in the absence of a feasible solution (returning approximately-feasible solutions, showing how to modify demands to retain feasibility). On the other hand, a certain level of overdimensioning of the network is explored, unlike in a typical optimization algorithm. The algorithm is a mixture of: (i) shortest path techniques, (ii) simpli ed reference-level multicriteria techniques and parametric analysis applied to aggregate the QoS criteria (iii) penalty and mutation techniques to handle the common constraints. Numerical experiments assessing various aspects of the algorithm behavior are given.
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3/2016 Mateusz Krzysztoń and Ewa Niewiadomska-Szynkiewicz
Heavy Gas Cloud Boundary Estimation and Tracking using Mobile Sensors
This paper addresses issues concerned with design and managing of monitoring systems comprised of mobile wireless sensing devices (MANETs). The authors focus on self-organizing, cooperative and coherent networks that maintain a continuous communication with a central operator and adopt to changes in an unknown environment to achieve a given goal. The attention is focused on the development of MANET for heavy gas clouds detection and its boundary estimating and tracking. Two strategies for constructing the MANET are described, in which sensors explore the region of interest to detect the gas cloud, create temporary network topology and finally, cover the cloud boundary, and track the moving cloud. The utility and efficiency of the proposed strategies has been justified through simulation experiments.
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3/2016 Saleh Seyedzadeh, Majid Moghaddasi and Siti B. A. Anas
Variable-Weight Optical Code Division Multiple Access System using Different Detection Schemes
In this paper a Variable Weight OCDMA (VWOCDMA) system using KS code with Direct Decoding (DD), Complementary Subtraction (CS) and AND subtraction detections is proposed. System performance is analyzed using mathematical approximation and software simulation. In mathematical analysis, the effects of Phase-Induced Intensity Noise, shot noise and thermal noise are taken into account. Bit Error Rate of different users is plotted as a function of received optical power per chip with varying the bit rates and number of active users. It has been shown that for different bit rates and number of users, system using DD has better performance than the system applying CS and AND detection. Using DD scheme, the number of active users are 100 while this value is 27 and 25 in case of using CS and AND detection, respectively, when the received optical power per chip is –10 dBm.
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3/2016 Janusz H. Klink, Maria J. Podolska and Tadeus Uhl
Concept for a Measurement Management System for Access Service to the Internet
This paper describes the problems associated with the provision of quality of service over an access connection to the Internet, i.e. the Internet Access Service (IAS). The paper has something of an overview character. Following a comprehensive introduction to the subject of “Changing Network Technologies” the paper focuses on the topic “Quality of IAS” in the light of regulatory directives of the European Parliament and the latest recommendations of ITU-T and ETSI. The focus will then shift to “Measurement Points and Measurement Scenarios for Determining QoS”. This topic will be described in detail and illustrated with several graphics. The final chapter has a pronounced scientific character and contains, among other things, a suggestion for a so-called Measurement Management System (MMS) to aid the design, execution and evaluation of efficient, automatic QoS measurements in networks.
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3/2016 Andrzej Wilczyński, Agnieszka Jakóbik and Joanna Kołodziej
Stackelberg Security Games: Models, Applications and Computational Aspects
Stackelberg games are non-symmetric games where one player or specified group of players have the privilege position and make decision before the other players. Such games are used in telecommunication and computational systems for supporting administrative decisions. Recently Stackleberg games became useful also in the systems where security issues are the crucial decision criteria. In this paper authors briefly survey the most popular Stackelberg security game models and provide the analysis of the model properties illustrated in the realistic use cases.
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3/2016 Paweł Kobojek and Khalid Saeed
Application of Recurrent Neural Networks for User Verification based on Keystroke Dynamics
Keystroke dynamics is one of the biometrics techniques that can be used for the verification of a human being. This work briefly introduces the history of biometrics and the state of the art in keystroke dynamics. Moreover, it presents an algorithm for human verification based on these data. In order to achieve that, authors’ training and test sets were prepared and a reference dataset was used. The described algorithm is a classifier based on recurrent neural networks (LSTMand GRU). High accuracy without false positive errors as well as high scalability in terms of user count were chosen as goals. Some attempts were made to mitigate natural problems of the algorithm (e.g. generating artificial data). Experiments were performed with different network architectures. Authors assumed that keystroke dynamics data have sequence nature, which influenced their choice of classifier. They have achieved satisfying results, especially when it comes to false positive free setting.
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3/2016 Mateusz Trokielewicz and Ewelina Bartuzi
Cross-spectral Iris Recognition for Mobile Applications using High-quality Color Images
With the recent shift towards mobile computing, new challenges for biometric authentication appear on the horizon. This paper provides a comprehensive study of cross-spectral iris recognition in a scenario, in which high quality color images obtained with a mobile phone are used against enrollment images collected in typical, near-infrared setups. Grayscale conversion of the color images that employs selective RGB channel choice depending on the iris coloration is shown to improve the recognition accuracy for some combinations of eye colors and matching software, when compared to using the red channel only, with equal error rates driven down to as low as 2%. The authors are not aware of any other paper focusing on cross-spectral iris recognition is a scenario with near-infrared enrollment using a professional iris recognition setup and then a mobile-based veri cation employing color images.
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3/2016 Michał Wroński
Faster Point Scalar Multiplication on Short Weierstrass Elliptic Curves over Fp using Twisted Hessian Curves over Fp2
This article shows how to use fast Fp2 arithmetic and twisted Hessian curves to obtain faster point scalar multiplication on elliptic curve ESW in short Weierstrass form over Fp. It is assumed that p and #ESW(Fp) are different large primes, #E(Fq) denotes number of points on curve E over field Fq and #Et SW (Fp) Fp), where Et is twist of E, is divisible by 3. For example this method is suitable for two NIST curves over Fp: NIST P-224 and NIST P-256. The presented solution may be much faster than classic approach. Presented solution should also be resistant for side channel attacks and information about Y coordinate should not be lost (using for example Brier-Joye ladder such information may be lost). If coefficient A in equation of curve ESW : y2 =x3+Ax+B in short Weierstrass curve is not of special form, presented solution is up to 30% faster than classic approach. If A=−3, proposed method may be up to 24% faster.
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3/2016 Rudy Yuwono, Endah Budi Purnomowati and Mohamad Yasir Amri
Curved-Pentagonal Planar Monopole Antenna for UHF Television Broadcast Receiving Antenna
A planar monopole antenna is an aerial, which the radiating element is perpendicular to the ground plane. It has five equal curvy sides and works at Ultra High Frequency (UHF) band of terrestrial broadcast 478–806 MHz. The curvy sides are made of five equal trimmed ellipses and separated 72o each ellipse to another, form pentagonal shape. Optimizations are obviously necessary to gain the antenna performance at the desired frequency range. The dimensions to optimize this antenna performance are the length of the sides, the offset of curvature, the antenna height from the ground plane, and the ground plane size. Optimization process is done by simulating the proposed antenna with calculated designs using Computer Simulation Technology (CST) Studio Suite 2015 software. The optimized antenna design then fabricated with a 75 W coaxial line fed, measured, and results: Voltage Standing Wave Ratio (VSWR) range of 1.05–1.28, antenna gain at 600 MHz is 15.33 dBi, elliptical polarized, and omnidirectional. With these features, this antenna should satisfy the requirements of UHF television broadcasting.
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3/2016 Ryszard Strużak, Terje Tjelta and José P. Borrego
On Radio-Frequency Spectrum Management
This article review lessons learned from the uses of radio-frequency (RF) spectrum at national and international scales. Its main purpose is to stimulate debate on how to allow new wireless systems to operate, and to reduce the chronic apparent shortage of RF spectrum. The article aims at a better understanding of the mechanisms behind spectrum management and their pertinence to the public interest. The main contributions if the article are:
• Considering RF spectrum management as a construct that structures radio services and, at the same time, distributes wealth and power;
• Highlighting major doctrines of RF spectrum management;
• Promoting spectrum management directly by its users;
• Promoting cooperation and transparency.
The several parts of the paper include the evolution of spectrum exploitation, and a foreseeable future by taking a closer look at major dilemmas and challenges. The paper ends with general comments and conclusions.
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4/2016 Piotr Krawiec
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4/2016 Mohammad R. Abbasi, Ajay Guleria and Mandalika S. Devi
Traffic Engineering in Software Defined Networks: A Survey
An important technique to optimize a network and improve network robustness is traffic engineering. As traffic demand increases, traffic engineering can reduce service degradation and failure in the network. To allow a network to adapt to changes in the traffic pattern, the research community proposed several traffic engineering techniques for the traditional networking architecture. However, the traditional network architecture is difficult to manage. Software Defined Networking (SDN) is a new networking model, which decouples the control plane and data plane of the networking devices. It promises to simplify network management, introduces network programmability, and provides a global view of network state. To exploit the potential of SDN, new traffic engineering methods are required. This paper surveys the state of the art in traffic engineering techniques with an emphasis on traffic engineering for SDN. It focuses on some of the traffic engineering methods for the traditional network architecture and the lessons that can be learned from them for better traffic engineering methods for SDN-based networks. This paper also explores the research challenges and future directions for SDN traffic engineering solutions.
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4/2016 Grzegorz Zalewski and Włodzimierz Ogryczak
Network Dimensioning with Maximum Revenue Efficiency for the Fairness Index
Network dimensioning is a specific kind of the resource allocation problem. One of the tasks in the network optimization is to maximize the total flow on given pairs of nodes (so-called demands or paths between source and target). The task can be more complicated when different revenue/profit gained from each unit of traffic stream allocated on each demand is taken into account. When the total revenue is maximized the problem of starvation of less attractive paths can appear. Therefore, it is important to include some fairness criteria to preserve connections between all the demands on a given degree of quality, also for the least attractive paths. In this paper, a new bicriteria ratio optimization method which takes into account both, the revenue and the fairness is proposed. Mathematical model is built in a form of linear programming. The solutions are analyzed with some statistical measures to evaluate their quality, with respect to fairness and efficiency. In particular, the Gini’s coefficient is used for this purpose.
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4/2016 Paweł Olender
Hybrid Models for the OWA Optimization
When dealing with multicriteria problems, the aggregation of multiple outcomes plays an essential role in fi nding a solution, as it reflects the decision-maker's preference
relation. The Ordered Weighted Averaging (OWA) operator provides a exible preference model that generalizes many objective functions. It also ensures the impartiality and allow to obtain equitable solutions, which is vital when the criteria represent evaluations of independent individuals. These features make the OWA operator very useful in many fields, one of which is location analysis. However, in general the OWA aggregation makes the problem nonlinear and hinder its computational complexity. Therefore, problems with the OWA operator need to be devised in an efficient way. The paper introduces new general formulations for OWA optimization and proposes for them some simple valid inequalities to improve efficiency. A hybrid structure of proposed models makes the number of binary variables problem type dependent and may reduce it signi cantly. Computational results show that for certain problem types, some of which are very useful in practical applications, the hybrid models perform much better than previous general models from literature.
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4/2016 Wojciech Kamieniecki
EVA as a Tool for Estimation of Management Efficiency and Value Creation in Polish Telecom Sector
The paper presents results of empirical study on creation of added value in Polish telecom sector, based on Economic Value Added (EVA) indicator. First, an EVA analysis was performed for publicly traded telecom companies. Next, the effectiveness of EVA itself in management of telecom companies was evaluated. A statistical analysis was made to investigate dependence between EVA and other indicators of company value, confirming that EVA sign and magnitude are in agreement with indicators based on data from financial books. Finally, the effectiveness of using EVA for prediction of market capitalization of telecom companies was investigated. Overall results do not give a clear picture and cannot allow to state that EVA is a better determinant of value of telecom company than financial indicators like Earnings Per Share (EPS).
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4/2016 Krzysztof Bronk, Adam Lipka, Błażej Wereszko, Jerzy Żurek and Krzysztof Żurek
Self-organization and Routing Algorithms for the Purpose of the Sensor Network Monitoring Environmental Conditions on a Given Area
The article describes an implementation of wireless sensor network (WSN) based on the IEEE 802.15.4-2006 standard, which was designed to monitor environmental conditions (e.g. temperature, humidity, light intensity, etc.) on a given area. To carry out this task, a self-organization algorithm called KNeighbors was selected. It exhibits low computational complexity and is satisfactory with respect to energy consumption. Additionally, the authors proposed a novel routing algorithm and some modifications to the MAC layer of the IEEE 802.15.4 standard. The article discusses the selected algorithms and procedures that were implemented in the network.
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