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 consider performance of a cooperative diversity scheme in Rician fading channel. The analytical results obtained in this paper will be comapred to the simulation results published previously, and it will be shown that the results are in great accordance. Besides that, the influence of the number of relay nodes on the performance of the system will be analysed.
Keywords: Fading channel, network cooperative diversity, outage probability, wireless networks.
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Subject Category: Communication Theory
Page(s): 38-40
This paper presents an analysis of maximum ratio combining (MRC) receiver of quaternary phase-shift keying (QPSK) signals transmitted over a Weibull fading channel. We determine the influence of imperfect cophasing and branches unbalance on bit error rate dependence on average signal-to-noise ratio. The performance dependence on diversity order and fading severity is also observed.
Keywords: Cophasing, Diversity systems, Error probability, Fading.
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Subject Category: Communication Theory
Page(s): 41-44
In this paper, a new approach for a twochannel IIR filter bank based on the frequency-response masking technique is presented. A model filter pair is a double complementary IIR filter pair implemented as a parallel connection of two all-pass filters. Masking filters are linear-phase FIR filters. The resulting overall filter pair is nearly power complementary, and simultaneously achieves high sub-channel selectivity. The approximately linear phase of channel filters is achieved with an IIR model filter pair of an approximately linear phase. Compared to the traditional solution based on FIR filters only, the proposed filter bank exhibits a smaller overall delay and requires a smaller number of multipliers for implementation.
Keywords: complementary filter pairs, digital filters, filter banks, frequency-response masking.
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Subject Category: Signal Processing
Page(s): 45-48
In the article, the Generalized Current Follower Transconductance Amplifier (GCFTA) element for generalized frequency filter design and a novel active element, the Programmable Current Amplifier (PCA) for the realization of the current-mode analog blocks, are presented. The paper also presents a method of general frequency filter design, whereas the basic circuit is a general autonomous circuit using GCFTA, PCA elements and general admittances. The properties of the proposed filter have been verified using PSPICE simulations.
Keywords: Active Filter, CCII+/–, Current-Mode Circuit, Generalized Current Follower Transconductance Amplifier (GCFTA), Multifunctional Filter, Programmable Current Amplifier (PCA).
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Subject Category: Signal Processing
Page(s): 49-52
A higher order large-domain hybrid finite element – method of moments (FEM-MoM) technique is presented. The discretization and solving FEM and MoM parts of the problem and the coupling of the two methods are described. A benchmark example of analysis of a scatterer with pronounced curvature at resonant frequency is given, demonstrating accuracy and robustness of the presented hybrid technique.
Keywords: Electromagnetic analysis, finite element methods, hybrid techniques, method of moments.
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Subject Category: Applied Electromagnetics
Page(s): 53-56
Some practical problems concerning the characterization and modeling of microwave absorbers are discussed in this paper. First, a number of measurement methods are considered for determination of the relative and absolute absorbing ability of the most popular absorbing materials – foams, rubber sheets, coatings and thin films. Next, several more complicated methods for characterization of the complex dielectric parameters of the absorbers are presented and discussed. Finally, examples for modeling of microwave absorbers by 3D simulators are given.
Keywords: absorbing media, permeability measurement, permittivity measurement.
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Subject Category: Applied Electromagnetics
Page(s): 57-60
Power delivery networks (PDNs) in modern printed circuit boards (PCBs) are usually realized using power planes. Since the planes have very low inductance, it is usually believed that such PDNs have the smallest amount of switching noise. However, in reality, the power planes can resonate. The noise at resonant frequencies can be significant and it deteriorates the PDN performance. One of the classical methods for decreasing the noise is bypassing. This paper investigates the behavior of a typical PDN and the effect that real SMD bypass capacitors produce when attached to it.
Keywords: Power-delivery networks, switching noise.
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Subject Category: Applied Electromagnetics
Page(s): 61-64
An overview is given of industrial measurement instruments (transmitters) of pressure and other process parameters. It is followed by a description of the technology used in the current generation of intelligent transmitters featuring two-way digital communication. A recently developed product of IHTM–CMTM, the intelligent pressure transmitter is presented, including a description of the software temperature compensation method for the used pressure sensor. Features and application possibilities of the developed hardware and software platform are discussed, as well as its suitability for the realization of wireless sensors.
Keywords: Measurement, sensor, transmitter.
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Subject Category: Applied Electronics
Page(s): 65-68
Embedded devices need both an efficient and a secure implementation of cryptographic algorithms. In this overview paper we show a typical top-down approach for secure and efficient implementation of embedded systems. We outline the security pyramid by illustrating the five primary abstraction levels in an embedded system. Focusing only on two levels - architecture and circuit level - we show how the design can be implemented to be both efficient and secure.
Keywords: Security, embedded systems, design methods, design pyramid, public key cryptosystems (PKC).
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Subject Category: Applied Electronics
Page(s): 69-72
This paper is aimed at presenting the models and characteristics of two types of inductors designed in LTCC (Low Temperature Cofired Ceramic) technology. We present the physical model of a 3D planar solenoid-type inductor and of a serial planar solenoid-type inductor for the RF (radio frequency) range. To verify the results obtained by using these models, we have compared them with the results obtained by employing the Ansoft HFSS electromagnetic simulator. Very good agreement has been recorded for the effective inductance value, whereas the effective Q factor value has shown a somewhat larger deviation than the inductance.
Keywords: Q factor, Physical model of inductor, Inductance, Planar solenoid inductor.
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Subject Category: Student Paper – Applied Electromagnetics
Page: 73-76