Institute of Electron Technology
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Iterative Algorithm for Threshold Calculation in the Problem of Routing Fixed Size Jobs to Two Parallel Servers, Journal of Telecommunications and Information Technology, 2015, nr 3
Get PDFAt present, solutions of many practical problems require significant computational resources and systems (grids, clouds, clusters etc.), which provide appropriate means are constantly evolving. The capability of the systems to fulfil quality of service requirements pose new challenges for the developers. One of the well-known approaches to increase system performance is the use of optimal scheduling (dispatching) policies. In this paper the special case of the general problem of finding optimal allocation policy in the heterogeneous n-server system processing fixed size jobs is considered. There are two servers working independently at constant but different speeds. Each of them has a dedicated queue (of infinite capacity) in front of it. Jobs of equal size arrive at the system. Inter-arrival times are i.i.d. random variables with general distribution with finite mean. Each job upon arrival must be immediately dispatched to one of the two queues wherefrom it will be served in FCFS manner (no pre-emption). The objective is the minimization of mean job sojourn time in the system. It is known that under this objective the optimal policy is of threshold type. The authors propose scalable fast iterative non-simulation algorithm for approximate calculation of the policy parameter (threshold). Numerical results are given
SAC-OCDMA over Hybrid FTTx Free Space Optical Communication Networks, Journal of Telecommunications and Information Technology, 2015, nr 2
Get PDFThis paper presents an investigation of Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) over hybrid Fiber-to-the-x (FTTx) Free Space Optical (FSO) link under dierent weather conditions. FTTx and FSO are the last mile technologies that complement each other in delivering secure and high speed communication to customers' residence or office. SAC-OCDMA is one of the potential multiplexing techniques that has become a research area of interest in optical communications and considered a promising technique for FTTx access networks. It is based on Khazani-Syed (KS) code with Spectral Direct Decoding (SDD) technique. All the components involved in the network were speciffed according to the available market product in order to simulate the actual environment as close as possible. The result shows that for bit error rate (BER) of 10_9, the network is able to perform with 20 km Single Mode Fiber (SMF) spanning from the central office (CO) and 1.48 km FSO range with transmission rate of 1.25 Gb/s during heavy rain
Uniqueness and Reproducibility of Trac Signatures, Journal of Telecommunications and Information Technology, 2015, nr 4
Get PDFUsable user authentication is an important research topic. The traffic signature-based approach is a new authentication technology that identifies the devices used by online users based on traffic signatures, where the traffic signature is a statistic of the video stream delivered by the authentication server to the user device. This approach has two advantages. First, users need not do any operations regarding the device identification. Second, users need not be sensitive to the privacy loss and computer theft. In this paper, an author evaluates the uniqueness and reproducibility of the sig- nature by introducing a function that quantifies the distance between two signatures. Through number of experiments is demonstrated that the process interference approach has the advantage of generating new signatures that are sufficiently distinguishable from one another
Quaternion Feistel Cipher with an In nite Key SpaceBased on Quaterni on Julia Sets, Journal of Telecommunications and Information Technology, 2015, nr 4
Get PDFIn this paper Quaternion Feistel Cipher (QFC) with an infinite key space based on quaternion Julia sets is proposed. The basic structure of the algorithm is based on the scheme proposed in 2012 by Sastry and Kumar. The proposed algorithm uses special properties of quaternions to perform rotations of data sequences in 3D space for each of the cipher rounds. It also uses Julia sets to form an infinite key space. The plaintext is divided into two square matrices of equal size and written using Lipschitz quaternions. A modular arithmetic was implemented for operations with quaternions. A computer-based analysis has been carried out and obtained results are shown at the end of this paper
New Tool for Investigating QoS in the WWW Service, Journal of Telecommunications and Information Technology, 2015, nr 1
Get PDFThe subject of this paper is the QoS measurement in the World Wide Web (WWW) service. It will begin with a brief presentation of methods currently used to measure QoS in the WWW service before going on to describe in detail the new tool QoSCalc(WWW). Following that, the potential of the new tool will be put to the test in a series of analysis scenarios. The results and insights obtained will then be presented in several diagrams, and interpreted
Techniki informacyjne a rynek i demokracja, Telekomunikacja i Techniki Informacyjne, 2015, nr 1-2
Get PDFArtykuł poświęcony jest krytyce popularnych poglądów odnośnie wpływu nowych technologii, zwłaszcza technik informacyjnych, na rynek i demokrację. Wykazuje, że techniki informacyjne wykorzystane do maksymalizacji zysku prowadzą jednak do wzrostu bezrobocia i rozwarstwienia społecznego, że rynek wysokiej techniki ma charakter oligopolistyczny z ukrytymi zmowami cenowymi oraz często prowadzi do powstania nowych monopoli. Artykuł dowodzi, że osiągnięcia technik informacyjnych są często wykorzystywane nieetycznie, prowadząc do korupcji rynku. Jednocześnie, toczą się ostre walki o to czy techniki informacyjne będą wykorzystane do wzmocnienia demokracji, zwłaszcza demokracji bezpośredniej, czy też posłużą jako argument przeciw demokracji
O perspektywach rozwoju sieciowych usług telewizyjnych. Telekomunikacja i Techniki Informacyjne, 2015, nr 1-2
Get PDFArtykuł opisuje stan rozwoju usług telewizyjnych udostępnianych za pośrednictwem Internetu, w tym telewizji internetowej IPTV, hybrydowej HbbTV oraz bazujących na nich usług takich jak popularna VoD (Video on Demand), podobna do niej OTT TV (over-the-top TV). Przedstawiono prognozę rozwoju tych rozwiązań usług telewizyjnych, zwłaszcza w odniesieniu do polskiego ryku telewizyjnego
Wind farms influence on radiocommunication systems operating in the VHF and UHF bands. Telekomunikacja i Techniki Informacyjne, 2015, nr 1-2
Get PDFThe following paper discusses several aspects connected with the wind farms’ impact on radiocommunication systems. The first part of this article is filled with the analysis of the ITU-R BT.1893 model, originally created for the analysis of the interaction between the wind turbines and digital TV receivers in the UHF band. A measurement campaign carried out by the authors confirmed that this model is also applicable for the lower, maritime VHF band. Utilizing the software implementation of this model, the authors conducted a thorough simulation analysis of the wind turbines’ influence on radio systems working in both VHF and UHF bands. The results of these simulations are presented and discussed in the second part of the paper