+48 22 5128 100  

Szachowa 1,
04-894 Warszawa

Journal of Telecommunications and Information Technology (JTIT) - 4/2016

Piotr Krawiec
[ Bibtex Plain ]
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.
[ Bibtex Plain ]
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.
[ Bibtex Plain ]
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.
[ Bibtex Plain ]
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).
[ Bibtex Plain ]
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.
[ Bibtex Plain ]
Miloud Frikel, Said Safi and Youssef Khmou
Focusing Operators and Tracking Moving Wideband Sources
In this paper, the localization of wideband source with an algorithm to track a moving source is investigated. To locate the wideband source, the estimation of two directions of arrival (DOA) of this source from two different arrays of sensors is used, and then, a recursive algorithm is applied to predict the moving source’s position. The DOA is estimated by coherent subspace methods, which use the focusing operators. Practical methods of the estimation of the coherent signal subspace are given and compared. Once the initial position is estimated, an algorithm of tracking the moving source is presented to predict its trajectory.
[ Bibtex Plain ]
Marian Kowalewski and Andrzej Pękalski
Implementation of Standardized Cooperation Environment for Intelligent Transport Systems
Many of Intelligent Transport Systems (ITS) solutions are using components that dynamically change in time and space. Among these, there occur changes of location, movement parameters, components configuration, external environment influence, automation use, etc. Standard facilities in ITS communication model are useful base for implementation of the services in such variable environment. Such features have an influence on the implementation of the services and requirements for the lower communication layers.
[ Bibtex Plain ]
Tohari Ahmad and Kharisma Muchammad
L-SCANN: Logarithmic Subcentroid and Nearest Neighbor
Securing a computer network has become a need in this digital era. One way to ensure the security is by deploying an intrusion detection system (IDS), which some of them employs machine learning methods, such as k-nearest neighbor. Despite its strength for detecting intrusion, there are some factors, which should be improved. In IDS, some research has been done in terms of feature generation or feature selection. However, its performance may not be good enough. In this paper, a method to increase the quality of the generated features while maintaining its high accuracy and low computational time is proposed. This is done by reducing the search space in training data. In this case, the authors use distance between the evaluated point and the centroid of the other clusters, as well as the logarithmic distance between the evaluated point and the subcentroid of the respective cluster. Besides the performance, the effect of homogeneity in extracting centroid and subcentroid on the accuracy of the detection model is also evaluated. Based on conducted experiment, authors find that the proposed method is able to decrease processing time and increase the performance. In more details, by using NSL-KDD 20% dataset, there is an increase of 4%, 2%, and 6% from those of TANN in terms of accuracy, sensitivity and specificity, respectively. Similarly, by using Kyoto 2006 dataset, proposed method rises 1%, 3%, and 2% than those of TANN.
[ Bibtex Plain ]
Rupender Singh and Meenakshi Rawat
Closed-form Distribution and Analysis of a Combined Nakagami-lognormal Shadowing and Unshadowing Fading Channel
The realistic wireless channels face combined (time shared) Nakagami-lognormal shadowing and unshadowing fading because of time varying nature of radio channel and mobile user. These channels can be modeled as time-shared sum of multipath-shadowing and unshadowing Rician distributions. These fading create severe problems in long distance wireless systems where multipath fading is superim-posed on shadowing fading (called multipath-shadowing fading). The multipath effect can be modeled using Rayleigh, Rician, Nakagami-m or Weibull distribution and shadowing effect is modeled using lognormal distribution. In this paper, authors present a new closed-form probability distribution function of a Nakagami-lognormal fading channel. Using this result, the closed-form expression of combined Nakagami-lognormal shadowing and unshadowing fading is presented. The obtained closed-form result facilitates to derive the important performance metrics of a communication system such as amount of fading, outage probability, and average channel capacity in closed-form expressions.
[ Bibtex Plain ]
Tomasz Kossek, Dariusz Czułek and Marcin Koba
Long-term Absolute Wavelength Stability of Acetylene-stabilized Reference Laser at 1533 nm
The second harmonic generation process in Periodically Poled Lithium Niobate (PPLN) has been applied in order to measure frequency of reference laser locked to acetylene absorption peak 12C2H2 (P13) (1533 nm) against optical frequency synthesizer. The measurement results have been compared to the results obtained using different techniques for the same reference laser during the past 10 years in other laboratories.
[ Bibtex Plain ]
Anna Warzec, Michał Marszalec and Marzenna Lusawa
Veri fication of Staff Pro ficiency in the Calibration Laboratory on Voltage, Frequency, Resistance and Capacity Measurements
The Laboratory of Electrical, Electronic and Optoelectronic Metrology is accredited by the Polish Center of Accreditation for nearly two decades. Over time, the requirements of proficiency veri fication are growing continuously. In order to satisfy higher and higher of reliability demands the most promising staff pro ficiency veri fication estimators were examined for voltage, frequency, resistance and capacity measurements. The article presents measurement systems used for veri fication, analysis of results or simulations, and shows conclusion for selecting the best solution.
[ Bibtex Plain ]