TELFOR is the abbreviation for the Telecommunications Forum, a long lasting scientific, engineering and professional event which started in 1993 in Belgrade, Serbia. Initial idea was to establish a new modest national scientific conference in Telecommunications and related areas. During the years, that idea evolved in such a way that today TELFOR is a huge regional international conference, having also its several other parallel tracks, like special presentations of companies, presentations and papers of invited experts, exhibition of telecommunications hardware, software, systems and services, then seminars, tutorials, round tables, etc. During TELFOR’s existence several thousands of scientific papers were presented and published, quite a number of them being with a considerable quality and important results.
Having such resources at disposal, establishing a new scientific journal, the TELFOR Journal, was a very natural next step for several reasons:
- Authors with favourable TELFOR reviewers’ assessments would have additional chances to improve and expand their initial ideas;
- Editorial board would have a wide set of prospective invited authors;
- After some time of existence, one could expect that TELFOR Journal would attract independent authors to submit their papers to be considered for publishing.
The TELFOR Journal is a brand new journal. The first volume consisting of two issues is scheduled to be published during the TELFOR 2009 conference in November 2009. The first volume of the Journal is intended to present a selection of the best scientific papers presented at Telecommunications Forum 2008.
The TELFOR Journal will be published in the English language, with both electronic and printed versions, minimally two times a year. Having in mind that recent studies have shown that freely available papers are cited very often, Editorial board decided that electronic version will be free of charge.
The TELFOR Journal is an IEEE co-supported publication and it will follow all the IEEE rules, procedures, and consequently the scientific quality.
The large spectrum of TELFOR Journal topics accounts for the rapid convergence through telecommunications towards the information and knowledge society. The Journal provides a medium for exchanging research results and technological achievements accomplished by the scientific community from academia and industry.
Editor-in-Chief
Prof. Dr Đorđe Paunović
In this paper we present comparison analysis for packet scheduling algorithms for HSDPA (High Speed Downlink Packet Networks). In particular, we analyze the round robin, max C/I and FCDS packet scheduling algorithms in HSDPA by comparing the average throughput, delay and fairness of the users, changing the number of the users in pedestrian and vehicular environment. The results have showed that the number of the users in a given coverage area is very important when choosing which packet scheduling algorithm for HSDPA networks. These results will be very useful for choosing the adequate scheduling algorithm in HSDPA network with aim to satisfy the desired quality of service for the mobile users.
Keywords: HSDPA, Mobile Networks, Scheduling.
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Subject Category: Telecommunications Networks
Page(s): 2-5
Low use of licensed spectrum imposes a need for the advanced spectrum management for wise spectrum usage with the release of unneeded frequency bands for the secondary markets and opportunistic access. In this paper we present the possibilities to apply reinforcement learning in WCDMA to enable the autonomous decision on spectrum repartition among cells and release of frequency bands for possible secondary usage. The proposed solution increases spectrum efficiency while ensuring maximum outage probability constraints in WCDMA uplink. We give two possible approaches to implement reinforcement learning in this problem area and compare their behavior. Simulations demonstrate the capability of two methods to successfully achieve desired goals.
Keywords: dynamic spectrum management, reinforcement learning, WCDMA.
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Subject Category: Telecommunications Networks
Page(s): 6-9
Ad-hoc and sensor networks are becoming an increasingly popular wireless networking concepts lately. This paper analyzes and compares prominent routing schemes in these networking environments. The knowledge obtained can serve users to better understand short range wireless network solutions thus leading to options for implementation in various scenarios. In addition, it should aid researchers develop protocol improvements reliable for the technologies of interest.
Keywords: Ad-hoc networks, Sensor networks, AODV, DSDV, Performance analysis.
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Subject Category: Telecommunications Networks
Pag(s): 10-13
In this paper we describe an automated method for testing the influence of selective fading on a radio-relay system and its vital modules in the form of M-curve signatures. Presented method is developed with a goal to make efficient measuremets of different RR devices generations, as well as to enable effective R&D of new RR equipment.
Keywords: Measurement automation, frequencyselective fading, M-curve signature, radio-relay devices.
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Subject Category: Radio Communications
Page(s): 14-17
The paper describes a modified topology of an all-optical network with simultaneous in-node routing and wavelength assignment. The routing process is controlled by the Hopfield neural network. Intensive simulations demonstrate the stability and scalability of proposed algorithm and its capability for dynamic routing.
Keywords: All-optical networks, routing, wavelength conversion, optimization, Hopfield neural network.
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Subject Category: Optical Communications
Page(s): 18-21
In this paper a method for speech quality estimation is evaluated by simulating the transfer of speech over packet switched and mobile networks. The proposed system uses Dynamic Time Warping algorithm for test and received speech comparison. Several tests have been made on a test speech sample of a single speaker with simulated packet (frame) loss effects on the perceived speech. The achieved results have been compared with measured PESQ values on the used transmission channel and their correlation has been observed.
Keywords: Dynamic Time Warping, Mean Opinion Score, Perceptual Evaluation of Speech Quality.
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Subject Category: Multimedia
Page(s): 22-25
In this paper, we present an approach to search result clustering, using partitioning of underlying link graph. We define the notion of "query-induced subgraph" and formulate the problem of search result clustering as a problem of efficient partitioning of a given subgraph into topic-related clusters. Also, we propose a novel algorithm for approximative partitioning of such a graph, which results in a cluster quality comparable to the one obtained by deterministic algorithms, while operating in a more efficient computation time, suitable for practical implementations. Finally, we present a practical clustering search engine developed as a part of this research and use it to get results about real-world performance of proposed concepts.
Keywords: Information Search and Retrieval, Graph Clustering, Randomized Algorithms, Web Measurement.
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Subject Category: Software Tools and Applications
Page(s): 26-29
This paper is about defining special measures within a universal service for potential socially excluded users, as a part of Project on US in Serbia. In the centre of research are people with disabilities, low income households, and welfare institutions in the Republic of Serbia. After analyzing regulations and statistical data, proposals for telecommunications services for these users are analyzed together with the costs of their realizations. At the end preliminary results of research are discussed.
Keywords: special measures, socially excluded users, universal service.
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Subject Category: Telecommunications Services
Page(s): 30-33
The goal of this study was to test the applicability of accelerometer as the sensor for assessment of the walking. We present here the comparison of gait phases detected from the data recorded by force sensing resistors mounted in the shoe insoles, non-processed acceleration and processed acceleration perpendicular to the direction of the foot. The gait phases in all three cases were detected by means of a neural network. The output from the neural network was the gait phase, while the inputs were data from the sensors. The results show that the errors were in the ranges: 30 ms (2.7%) – force sensors; 150 ms (13.6%) – nonprocessed acceleration, and 120 ms (11%) – processed acceleration data. This result suggests that it is possible to use the accelerometer as the gait phase detector, however, with the knowledge that the gait phases are time shifted for about 100 ms with respect the neural network predicted times.
Keywords: accelerometers, force sensing resistor, gait phase, neural network.
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Subject Category: Student Paper – Signal Processing
Page(s): 34-37