# September 2010, Volume 19, Number 3

**V. Sedenka, Z. Raida**
[references] [full-text]

Critical Comparison of Multi-objective Optimization Methods: Genetic Algorithms versus Swarm Intelligence

The paper deals with efficiency comparison of two global evolutionary optimization methods implemented in MATLAB. Attention is turned to an elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) and a novel multi-objective Particle Swarm Optimization (PSO). The performance of optimizers is compared on three different test functions and on a cavity resonator synthesis. The microwave resonator is modeled using the Finite Element Method (FEM). The hit rate and the quality of the Pareto front distribution are classified.

- LUKES, Z., RAIDA, Z. Multi-objective optimization of wire antennas: genetic algorithms versus particle swarm optimization. Radioengineering, 2005, vol. 14, no. 4, p. 91-97.
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- BANDYOPADHYAY, S., SAHA, S., MAULIK, U., DEB, K. A simulated annealing-based multiobjective optimization algorithm: AMOSA. IEEE Transactions on Evolutionary Computation, 2008, vol. 12, no. 3, p. 269-283.
- ZITZLER, E., DEB, K., THIELE, L. Comparison of multiobjective evolutionary algorithms: Empirical results. Evolutionary Computation, 2000, vol. 8, no. 2, p. 173-195.
- GROŞAN, C., DUMITRESCU, D. A comparison of multiobjective evolutionary algorithms. Acta Universitatis Apulensis, 2002, vol. 4.
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- DEB, K., PRATAP, A., AGARWAL, S., MEYARIVAN, T. A fast and elitist multi-objective genetic algorithm-NSGA-II. KanGAL Report. 2000, no. 2000001. [Online] Available at: http://www.iitk.ac.in/kangal/papers/tech2000001.ps.gz.
- KENNEDY, J., EBERHART, R. C. Particle swarm optimization. IEEE Conference on Neural Networks. Perth (Australia), 1995, p. 1942-1948.
- REYES-SIERRA, M., COELLO COELLO, C. A. Multi-objective particle swarm optimizers: A survey of the state-of-the-art. International Journal of Computational Intelligence Research, 2006, vol. 2, no. 3, p. 287-308. [Online] Available at: http://www.softcomputing.net/ijcir/vol2-issu3-paper5.pdf
- JOHNSON, J. M., RAHMAT-SAMII, Y. Genetic algorithms in engineering electromagnetics. IEEE Antennas and Propagation Magazine, 1997, vol. 39, no. 4, p. 7-21.
- SILVESTER, P. P., FERRARI, R. L. Finite Elements for Electrical Engineers. 3rd ed. Cambridge: Cambridge University Press, 1996.
- CHEN, L. F., ONG, C. K., NEO, C. P., VARADAN, V. V., VARADAN, V. K. Microwave Electronics: Measurement and Materials Characterization. John Wiley and Sons, 2004.
- GEUZAINE, C., REMACLE, J. F. Gmsh Reference Manual. 233 pages. [Online] Cited 2010-01-05. Available at: http://www.geuz.org/gmsh/doc/texinfo/gmsh.pdf.
- ROBINSON, J., RAHMAT-SAMII, Y. Particle swarm optimization in electromagnetics. IEEE Transactions on Antennas and Propagation, 2004, vol. 52, no. 2, p. 397-407.
- JIN, Y., OKABE, T., SENDHOFF, B. Solving three-objective optimization problems using evolutionary dynamic weighted aggregation: Results and analysis. [Online] Available at: http://www.soft-computing.de/moo3D.pdf.

Keywords: Multi-objective optimization, binary genetic algorithm, particle swarm optimization, Pareto front, finite element method.

**S. Rupcic, V. Mandric, S. Rimac-Drlje**
[references] [full-text]

Fabrication Errors Influence on the Sperical Array Radiation Pattern

The paper studies fabrication errors influence on the radiation pattern of a spherical antennas array. The developed Moment Method (MoM) program analyzes a particular influence of an azimuth and elevation position and local angle errors of antenna elements as well as model dimension errors on the radiation pattern. The spectral domain approach to the analysis of the spherical antenna arrays is applied here. Finally, results obtained from the theoretical investigation are verified by comparison with measured results.

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- GOOSSENS, R., BOGAERT, I., ROGIER, H. Phase-mode processing for spherical antenna arrays with a finite number of antenna elements and including mutual coupling. IEEE Trans. on Antennas and Propagation, 2009, vol. 57, no. 12, p. 3783-3790.
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- LEIJON, R. Radiation from mobile phone antennas close to the human body. Technical Report No.270L, Department of Microwave Technology, Chalmers University of Technology, Gothenburg, 1997.
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- SIPUS, Z., RUPCIC, S., LANNE, M., JOSEFSSON, L. Analysis of circular and spherical array of waveguide elements covered with radome. In Proceedings of IEEE International Symposium on Antennas and Propagation. Boston (USA), 2001, p. 350-353.
- RUPCIC, S. Circular waveguide antenna arrays on spherical structures. PhD dissertation, University of Zagreb, Faculty of Electrical Engineering and Computing, Zagreb, 2009.
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Keywords: Radiation pattern, antenna array, aperture antenna, spherical array, fabrication errors, experimental model errors

**A. E. Yilmaz**
[references] [full-text]

Fine-Tuning on the Effective Patch Radius Expression of the Circular Microstrip Patch Antennas

In this study, the effective patch radius expression for the circular microstrip antennas is improved by means of several manipulations. Departing from previously proposed equations in the literature, one of the most accurate equations is picked up, and this equation is fine-tuned by means of Particle Swarm Optimization technique. Throughout the study, impacts of other parameters (such as the definition of the fitness/objective function, the degree-of-freedom in the proposed effective patch radius expression, the number of measured resonant frequency values) are observed in a controlled manner. Finally, about 3% additional improvement is achieved over a very accurate formula, which was proposed earlier.

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Keywords: Circular microstrip patch antenna, Closed-form expression, Effective patch radius, Particle swarm optimization, Resonant frequency.

**P. Vagner, M. Kasal**
[references] [full-text]

A Novel Bandpass Filter Using a Combination of Open-Loop Defected Ground Structure and Half-Wavelength Microstrip Resonators

This paper deals with a defected ground structure (DGS) open-loop resonator analysis and bandpass filter design, using coupled DGS and microstrip resonators. The combination of DGS and microstrip resonators allows using top and bottom sides of the microwave substrate, therefore the resonators can partially overlap and a desired coupling coefficient can be easily achieved. The open-loop DGS resonator properties are investigated, as well as coupling types between the resonators. Finally, two bandpass filters are designed and simulated. The sixth order filter is fabricated and the results are compared with measurement. The introduced structure represents an alternative to a conventional parallel-coupled half wavelength microstrip resonator bandpass filter.

- ABDEL-RAHMAN, A., ALI, A. R., AMARI, S., OMAR, A. S. Compact bandpass filters using defected ground structure (DGS) coupled resonators. In Microwave Symposium Digest, 2005 IEEE MTT-S International, 12-17 June 2005.
- ALI, A. R., ABDEL-RAHMAN, A., AMARI, S., OMAR, A. S. Direct and cross-coupled resonator filters using defected ground structure (DGS) resonators. In Proceedings of the European Microwave Conference 2005, 4-6 October 2005.
- VAGNER, P. Microstrip filters using defected ground structure. Dissertation Thesis, Brno University of Technology, Faculty of Electrical Engineering and Communication, Brno 2008. 108 pages (in Czech).
- HONG, J. S., LANCASTER, M. J. Microstrip Filters for RF/Microwave Applications. John Wiley & Sons, Inc. 2001. 460 pages. ISBN 0-471-38877-7.

Keywords: Defected ground structure (DGS), bandpass filter, DGS resonator, slot resonator, open-loop resonator, half-wavelength microstrip resonator, Chebyshev prototype filter

**P. Kejik, S. Hanus**
[references] [full-text]

Admission Control Techniques for UMTS System

Universal mobile telecommunications system (UMTS) is one of the 3rd generation (3G) cell phone technologies. The capacity of UMTS is interference limited. Radio resources management (RRM) functions are therefore used. They are responsible for supplying optimum coverage, ensuring efficient use of physical resources, and providing the maximum planned capacity. This paper deals with admission control techniques for UMTS. An own UMTS simulation program and several versions of proposed admission control algorithms are presented in this paper. These algorithms are based on fuzzy logic and genetic algorithms. The performance of algorithms is verified via simulations.

- ROMERO, J., SALLENT, O., AGUSTI, R., DIAZ-GUERRA, M. Radio Resources Management Strategies in UMTS. Wiley & Sons, 2005, 345 p. ISBN 978-0-470-02277-1.
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- CAPONE, A., REDANA, S. I3E: A novel call admission control scheme for W-CDMA systems. Wireless Personal Communication. Springer Netherlands, Oct. 2006, vol. 39, no. 1, p. 81-97. ISSN 1572-834X.
- LIU, D., ZHANG, Y., HU, S. Call admission policies based on calculated power control setpoints in SIR-based power-controlled DS-CDMA cellular networks. Wireless Networks, Springer Netherlands, 2004, vol. 10, no. 4, p. 473-483. ISSN 1572-8196.
- MALARKKAN, S., RAVICHANDRAN, V. Performance analysis of call admission control in WCDMA systems with adaptive multi class traffic based on fuzzy logic. IJCSNS International Journal of Computer Science and Network Security, Nov. 2006, vol. 6, no. 11.
- SHEN, S., CHANG, C., HUANG, C., BI, Q. Intelligent call admission control for wideband CDMA cellular systems. IEEE Transactions on Wireless Communications, Sept. 2004, vol. 3, no. 5.
- YENER, A., ROSE, C. Genetic algorithms applied to cellular call admission problem: Local policies. IEEE Transactions on Vehicular Technology, Feb. 1997, vol. 46, p. 72-79.
- KARABUDAK, D., HUNG, C., BING, B. A call admission control scheme using genetic algorithms. In Proceedings of the 2004 ACM symposium on Applied Computing, 2004. ISBN 1-58113-812-1.
- BAIK, S., BALA, J., HADJARIAN, A., PACHOWICZ, P. Genetic evolution approach for target movement prediction. In Lecture Notes in Computer Science. Springer, Heidelberg, vol. 3037/2004, p. 678-681. ISBN 978-3-540-22115-9.
- AYYAPPAN, K., KUMAR, R. Service utilization based call admission control (CAC) scheme for WCDMA network. International Journal of Research and Reviews in Computer Science (IJRRCS), June 2010, vol. 1, no. 2, p. 66-70. ISSN 2079- 2557.
- CHANG, CH., KUO, L., CHEN, Y., SCHEN, S. Neural fuzzy call admission and rate controller for WCDMA cellular systems providing multirate services. In Proceedings of the 2006 International Conference on Wireless Communications and Mobile Computing. Canada, p. 383-388. ISBN 1-59593-306-9.
- LO, J., BRITO, A., CORREIA, L., CORREIA, A. Simulation of call admission control, load control, handover and power control algorithms for enhanced UMTS. SEACORN Project. [Online] Cited 2009-11-19. Available at http://seacorn.cs.ucy.ac.cy/eumtssim/.

Keywords: UMTS, CDMA, admission control, fuzzy logic, genetic algorithms

**I. Develi, K. Kockaya**
[references] [full-text]

BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA) is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER) performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature.

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Keywords: BER performance simulation, Generalized MC DS-CDMA system, Blackman chip waveform

**L. Krulikovska, J. Filanova, J. Pavlovic**
[references] [full-text]

Evolution Strategies in the Multipoint Connections Routing

Routing of multipoint connections plays an important role in final cost and quality of a found connection. New algorithms with better results are still searched. In this paper, a possibility of using the evolution strategies (ES) for routing is presented. Quality of found connection is evaluated from the view of final cost and time spent on a searching procedure.

First, parametrical analysis of results of the ES are discussed and compared with the Prim’s algorithm, which was chosen as a representative of the deterministic routing algorithms.

Second, ways for improving the ES are suggested and implemented. The obtained results are reviewed. The main improvements are specified and discussed in conclusion.

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- KACUR, J., KOROSI, J. An accuracy optimization of a dialog ASR system utilizing evolutional strategies. In Proceedings of the 5th International Symposium on Image and Signal Processing and Analysis. Istanbul (Turkey), 2007, p. 180-184. ISSN 1845-5921, ISBN 978-953-184-116-0.
- POLEC, J., KARLUBIKOVA, T., VARGIC, R. Probabilistic Models in Telecommunications. Bratislava: STU Publishing House, 2007.
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Keywords: Evolution strategies (ES), routing of multipoint connections, optimization

**J. B. Seventline, D. Elizabath Rani, K. Raja Rajeswari**
[references] [full-text]

Ternary Chaotic Pulse Compression Sequences

In this paper method available for generating ternary sequences is discussed. These sequences are useful in many applications but specifically in synchronization of block codes and pulse compression in radar. The ternary sequences are derived from chaotic maps. It is feasible to achieve simultaneously superior performances in detection range and range resolution using the proposed ternary sequences. The properties of these sequences like autocorrelation function, Peak Side Lobe Ratio (PSLR), ambiguity diagram and performance under AWGN noise background has been studied. The generation of these sequences is much simpler, and the available number of sequences is virtually infinite and not limited by the length of the sequence.

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Keywords: Pulse Compression, Autocorrelation, Peak side lobe ratio

**T. Fryza**
[references] [full-text]

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The paper deals with a video compression method based on the multi-dimensional discrete cosine transform. In the text, the encoder and decoder architectures including the deﬁnitions of all mathematical operations like the forward and inverse 3-D DCT, quantization and thresholding are presented. According to the particular number of currently processed pictures, the new quantization tables and entropy code dictionaries are proposed in the paper. The practical properties of the 3-D DCT coding chain compared with the modern video compression methods (such as H.264 and WebM) and the computing complexity are presented as well. It will be proved the best compress properties could be achieved by complex H.264 codec. On the other hand the computing complexity - especially on the encoding side - is lower for the 3-D DCT method.

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Keywords: Video signal processing, data compression, discrete cosine transform, multidimensional coding, digital signal processors.

**R. Stukavec, T. Kratochvil**
[references] [full-text]

Simulation and Measurement of the Transmission Distortions of the Digital Television DVB-T/H Part 2: Hierarchical Modulation Performance

The paper deals with the second part of results of the Czech Science Foundation research project that was aimed into the simulation and measurement of the transmission distortions of the digital terrestrial television according to DVB-T/H standards. In this part the hierarchical modulation performance characteristics and its simulation and laboratory measurements are presented. The paper deals with the hierarchical oriented COFDM modulator for the digital terrestrial television transmission and DVB-T/H standards and possible utilization of this technique in real broadcasting scenarios – fixed, portable and mobile digital TV, all in one TV channel. Impact of the hierarchical modulation on Modulation Error Rate from I/Q constellations and Bit Error Rates before and after Viterbi decoding in DVB-T/H signal decoding are evaluated and discussed.

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Keywords: Hierarchical modulation, high priority path, low priority path, stream, HP, LP, COFDM, DVB-T/H.

**F. Khateb, J. Vavra, D. Biolek**
[references] [full-text]

A Novel Current-Mode Full-Wave Rectifier Based on One CDTA and Two Diodes

Precision rectifiers are important building blocks for analog signal processing. The traditional approach based on diodes and operational amplifiers (OpAmps) exhibits undesirable effects caused by limited OpAmp slew rate and diode commutations. In the paper, a full-wave rectifier based on one CDTA and two Schottky diodes is presented. The PSpice simulation results are included.

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Keywords: Current-mode rectifier, CDTA.

**R. Sotner, Z. Hrubos, J. Slezak, T. Dostal**
[references] [full-text]

Simply Adjustable Sinusoidal Oscillator Based on Negative Three-Port Current Conveyors

The paper deals with sinusoidal oscillator employing two controlled second-generation negative-current conveyors and two capacitors. The proposed oscillator has a simple circuit configuration. Electronic (voltage) adjusting of the oscillation frequency and condition of oscillation are possible. The presented circuit is verified in PSpice utilizing macro models of commercially available negative current conveyors. The circuit is also verified by experimental measurements. Important characteristics and drawbacks of the proposed circuit and influences of real active elements in the designed circuit are discussed in detail.

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Keywords: Current conveyors, electronic adjusting, sinusoidal oscillator.

**R. Pandey, M. Gupta**
[references] [full-text]

FGMOS Based Voltage-Controlled Grounded Resistor

This paper proposes a new floating gate MOSFET (FGMOS) based voltage-controlled grounded resistor. In the proposed circuit FGMOS operating in the ohmic region is linearized by another conventional MOSFET operating in the saturation region. The major advantages of FGMOS based voltage-controlled grounded resistor (FGVCGR) are simplicity, low total harmonic distortion (THD), and low power consumption. A simple application of this FGVCGR as a tunable high-pass filter is also suggested. The proposed circuits operate at the supply voltages of +/-0.75 V. The circuits are designed and simulated using SPICE in 0.25-µm CMOS technology. The simulation results of FGVCGR demonstrate a THD of 0.28% for the input signal 0.32 V_{pp} at 45 kHz, and a maximum power consumption of 254 µW.

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Keywords: Floating gate MOSFETs, low-voltage, voltage-controlled grounded resistor, Spice.

**M. S. Khan, M. S. Awan, S. Sheikh Muhammad, M. Faisal, Marzuki, F. Nadeem, E. Leitgeb**
[references] [full-text]

Probabilistic Model for Free-Space Optical Links Under Continental Fog Conditions

The error characteristics of a free-space optical (FSO) channel are signiﬁcantly different from the ﬁber based optical links and thus require a deep physical understanding of the propagation channel. In particular different fog conditions greatly inﬂuence the optical transmissions and thus a channel model is required to estimate the detrimental fog effects. In this paper we shall present the probabilistic model for radiation fog from the measured data over a 80 m FSO link installed at Graz, Austria. The fog events are classiﬁed into thick fog, moderate fog, light fog and general fog based on the international code of visibility range. We applied some probability distribution functions (PDFs) such as Kumaraswamy, Johnson SB and Logistic distribution, to the actual measured optical attenuations. The performance of each distribution is evaluated by Q-Q and P-P plots. It is found that Kumaraswamy distribution is the best ﬁt for general fog, while Logistic distribution is the optimum choice for thick fog. On the other hand, Johnson S_{B} distribution best ﬁts the moderate and light fog related measured attenuation data. The difference in these probabilistic models and the resultant variation in the received signal strength under different fog types needs to be considered in designing an efﬁcient FSO system.

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Keywords: Free Space Optics (FSO), optical attenuations, Mie scattering, Probability Density Function (PDF), visibility, channel modeling.

**O. Kucera**
[references] [full-text]

Author's comment on: "Electrical Analogy to an Atomic Force Microscope"

In [1] I used assumptions which proved to be wrong in further research. Corrections are given in this comment.

- KUCERA, O. Electrical analogy to an atomic force microscope. Radioengineering, 2010, vol. 19, no. 1, p. 168 - 171.
- GITTES, F., SCHMIDT, C.F. Thermal noise limitations on micromechanical experiments. European Biophysics Journal, 1998, vol. 27, n. 1, p. 75 - 81.

Keywords: Atomic Force Microscopy, electrical mechanical analogs, circuit theory