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Belgrade, Serbia

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 | 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.

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.

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.

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