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Cisar P.,Telekom Srbija | Bosnjak S.,University of Sfax | Cisar S.M.,Subotica Technology
International Journal of Computers, Communications and Control | Year: 2010

Intrusion detection is used to monitor and capture intrusions into computer and network systems which attempt to compromise their security. Many intrusions manifest in changes in the intensity of events occuring in computer networks. Because of the ability of exponentially weighted moving average (EWMA) control charts to monitor the rate of occurrences of events based on their intensity, this technique is appropriate for implementation in control limits based algorithms. The paper also gives a review of a possible optimization method. The validation check of results will be performed on authentic network samples. © 2006-2010 by CCC Publications.


Radosav A.,University of Novi Sad | Cisar P.,Telekom Srbija
International Journal of Computers, Communications and Control | Year: 2011

This study was carried out to observe, measure and analyze the effects of using software visualization in teaching programming with participants from two institutions of higher educations in Serbia. Basic programming learning is notorious for complex for many novice students at university level. The visualizations of examples of program code or programming tasks could help students to grasp programming structures more easily. This paper describes an investigation about the possibilities of enhancement of learning Java using the visualization software Jeliot. An analysis of 400 students' test results indicates that a significant percentage of students had achieved better results when they were using a software visualization tool. In the experience of the authors Jeliot may yield the best results if implemented in with students who are new to the art of programming. © 2006-2011 by CCC Publications.


Cisar P.,Telekom Srbija
Acta Polytechnica Hungarica | Year: 2010

The available literature is not completely certain what type(s) of probability distribution best models network traffic. Thus, for example, the uniform, Poisson, lognormal, Pareto and Rayleigh distributions were used in different applications. Statistical analysis presented in this paper aims to show how skewness and kurtosis of network traffic samples in a certain time interval may be criterions for selection of appropriate distribution type. The creation of histogram and probability distribution of network traffic samples is also discussed and demonstrated on a real case.


Cisar P.,Telekom Srbija
SISY 2011 - 9th International Symposium on Intelligent Systems and Informatics, Proceedings | Year: 2011

Digital forensics is essential for the successful opposition of computer crime. It is associated with many challenges, including rapid changes in computer and digital devices, and more sophisticated attacks on computer systems and networks and the rapid increase in abuse of ICT systems. For a forensic investigation to be performed successfully there are a number of important steps that have to be considered and taken. Since digital forensics is a relatively new field compared to other forensic disciplines, there are ongoing efforts to develop examination standards and to provide structure to digital forensic examinations. This paper attempts to address the diversity of methodologies applied in digital forensic investigations. © 2011 IEEE.


Stojanovic M.D.,University of Belgrade | Vukasinovic M.M.,Telekom Srbija | Djogatovic V.M.R.,University of Belgrade
2015 12th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, TELSIKS 2015 | Year: 2015

Previously dominating research on the Internet Quality of Service (QoS), focused on network performance, has now been shifted towards the customer experience. This paper addresses Quality of Experience (QoE) management issues in the future Internet. We provide a brief overview of QoE metrics and assessment methodologies, and discuss potential relationships between the QoE and network performance parameters. Further, we discuss open technical issues in achieving the inter-provider QoS, including large scale end-To-end measurements. User-centric management assumes a layered approach that includes network infrastructure, network performance, and the user awareness. Business opportunities for service providers in the context of QoE management are also emphasized. We conclude the paper with a list of the most important directions for further research in the area. © 2015 IEEE.


Djordjevic A.R.,University of Belgrade | Tosic D.V.,University of Belgrade | Zajic A.G.,Georgia Institute of Technology | Nikolic M.M.,University of Belgrade | And 2 more authors.
IEEE Antennas and Propagation Magazine | Year: 2012

Temporal leakage occurs when the time-domain response of a linear electromagnetic system is computed from frequency-domain data using the inverse discrete Fourier transform. Although the temporal leakage occurs in most practical cases, this phenomenon is not recognized in the literature covering electromagnetics, antennas, and microwaves. The purpose of the paper is to demonstrate and explain the temporal leakage. © 2012 IEEE.


Miskovic B.,Telekom Srbija | Lutovac M.D.,Singidunum University
2012 Mediterranean Conference on Embedded Computing, MECO 2012 | Year: 2012

Systems for digital television signals transmission, as the most broadband transmission systems, use orthogonal frequency-division multiplexing (OFDM). Multipath propagation problem, characteristic of wireless transmission, can be efficiently solved using a cyclic prefix (CP), which is transmitted during the guard interval (G). Temporary symbols extension, to the removal of CP in the receiver, disturbs orthogonality and introduces interference between subcarriers. Matlab model of OFDM transmitter and receiver for the first and the second generation digital terrestrial television broadcasting system is implemented. Guard interval using effect is observed. Frequency characteristics are analyzed, and quantified with bit error rate (BER) in receiver. © 2012 MANT.


Cisar P.,Telekom Srbija | Cisar S.M.,Subotica Technology
Acta Polytechnica Hungarica | Year: 2011

Many intrusions which attempt to compromise the security of computer and network systems manifest themselves in changes in the intensity of events. Because of the ability of exponentially weighted moving average (EWMA) statistics to monitor the rate of occurrences of events based on their intensity, this technique is appropriate for implementation in control limits based algorithms. The research has shown that the usual application of this algorithm on computer network traffic, as applied in industrial processes, does not provide acceptable results. The paper also gives a review of possible optimization methods.


Kolaric B.,Telekom Srbija
2011 19th Telecommunications Forum, TELFOR 2011 - Proceedings of Papers | Year: 2011

In today's modern business environment, e-business is gaining stronger role and application. Electronic communication becomes an everyday unavoidable part of business processes in many organizations, regardless of their activity and size. That also implies the creation and expansion of efficient external electronic communication with consumers, as well as strengthening the internal electronic communication among the employees. This study is an attempt to investigate the efficiency of applying the intranet in the public companies in Serbia. The facts that Serbia is a country in transition and that market liberalization largely reflects itself on public services' operation, point out to the significance of subject research. © 2011 IEEE.


Bojovic Z.,Telekom Srbija | Secerov E.,University of Novi Sad | Delic V.,University of Novi Sad
Computer Science and Information Systems | Year: 2010

This paper describes a testing conducted on a private IP/MPLS network of a Telecom operator during service introduction. We have applied DiffServ and E-LSP policies for bandwidth allocation for predefined classes of service (voice, video, data and VPN). We used a traffic generator to create the worst possible situations during the testing, and measured QoS for individual services. UML considerations about NGN structure and packet networks traffic testing are also presented using the deployment, class and state diagrams. Testing results are given in tabular and graphical forms, and the conclusions derived will be subsequently used as a basis for defining the stochastic traffic generator/simulator.

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