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Proceedings of Czech and Slovak Technical Universities

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December 2002, Volume 11, Number 4

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V. Zalud [references] [full-text] [Download Citations]
Wireless Cellular Mobile Communications

In this article is briefly reviewed the history of wireless cellular mobile communications, examined the progress in current second generation (2G) cellular standards and discussed their migration to the third generation (3G). The European 2G cellular standard GSM and its evolution phases GPRS and EDGE are described somewhat in detail. The third generation standard UMTS taking up on GSM/GPRS core network and equipped with a new advanced access network on the basis of code division multiple access (CDMA) is investigated too. A sketch of the perspective of mobile communication beyond 3G concludes this article.

  1. ZALUD, V. Modern radioelectronics. Praha: BEN, 2000 (inCzech).
  2. REDLl, S.M., WEBER, M. K., OLIPHANT, M. W. GSM andPersonal Communications Handbook. Artech House, Inc.Boston - London. 1998.
  3. WANG, J., Ng, T-S. Advances in 3G EnhancedTechnologies for Wireless Communications. Artech House,2002.

J. Sykora [references] [full-text] [Download Citations]
MIMO Spatial Diversity Communications - Signal Processing and Channel Capacity

This paper derives an equivalent discrete channel model for MIMO spatial diversity communications generally considering multidimensional spatial branch symbols and arbitrary path delays. This model is subsequently used for the information capacity evaluation under various special cases.

  1. SYKORA, J. Theory of Digital Communication (in Czechlanguage). Publishing company of Czech Technical University,Prague, 2002.
  2. KAY, S. M. Fundamentals of Statistical Signal Processing(Vol I: estimation theory). Prentice Hall, 1993.
  3. COVER, T. M., THOMAS, J. A. Elements of InformationTheory. John Wiley & sons, 1991.
  4. SYKORA,J. Self-noise MIMO space-time coded systems withimperfect symbol timing. In Proceedings of IEEE PIMRC 2002.Lisbon (Portugal), 2002, pp. 838-842.
  5. TELATAR, I. E. Capacity of Multi-antenna Gaussian Channels.Tech. report, Lucent Technologies, 1995,
  6. FLETCHER, R. Practical Methods of Optimization. 2nd ed.John Wiley & sons, 1987.

L. Burget, P. Motlicek, F. Grezl, P. Jain [references] [full-text] [Download Citations]
Distributed Speech Recognition

This article discusses possibilities of integrating speech technology into wireless technology, allowing voice input for wireless devices. Distributed speech recognition concept and activities related to its standardization are presented. First ETSI DSR MFCC based standard is described. Work on its extension to improve robustness resulting in new standard is also presented.

  1. Gold B., Morgan N. Speech and Audio Signal Processing. NewYork, 1999.
  2. L. Rabiner L., Juang B. H. Fundamentals of speechrecognition. Signal Processing. Prentice Hall, Engelwood cliffs,NJ, 1993.
  3. Davis S. B., Mermelstein P. Comparison of parametricrepresentation for monosyllabic word recognition incontinuously spoken sentences. IEEE Trans. on Acoustics,Speech & Signal Processing, vol. 28, no. 4, 1980, pp. 357-366.
  4. Young S. Acoustic Modeling for Large Vocabulary ContinuousSpeech Recognition. In Computational Models of SpeechPattern Processing, Berlin, 1999, pp. 19-39.
  5. Young S. The HTK Book. Entropics Ltd. 1999.
  6. Hermansky H., Morgan N. RASTA processing of speech. IEEETrans. on Speech & Audio Processing, vol. 2, no. 4, 1994, pp.578-589.
  7. Hirsch H. G., Pearce D. The AURORA ExperimentalFramework for the Performance Evaluations of SpeechRecognition Systems under Noisy Conditions. ISCA ITRWASR2000, September 18-20, 2000.
  8. Pearce D. Enabling New Speech Driven Services for MobileDevices: An overview of the ETSI standards activities forDistributed Speech Recognition Front-ends, AVIOS2000, SanJose, May 2000.
  9. Jain P., Hermansky H., Kingsbury B. Distributed SpeechRecognition Using Noise-Robust MFCC and TRAPSEstimatedManner Features. Proc. of ICSLP 2002, Denver,Colorado, September 2002.
  10. Adami A., Burget L., Dupont S., Garudadri H., Grezl F.,Hermansky H., Jain P., Kajarekar S., Morgan N., Sivadas S.QUALCOMM-ICSI-OGI Features for ASR. In ICSLP, Denver,Colorado, USA, September 2002.
  11. Macho D., Mauuary L., Noe B., Cheng Y. M., Ealey D., JouvetD., Kelleher H., Pearce D., Saadoun F. Evaluation of a NoiserobustDSR Front-end on Aurora Databases. In ICSLP,Denver, Colorado, USA, September 2002.
  12. Jelinek F. Statistical Methods for Speech Recognition. MITPress, 1998.

L. Dobos, J. Goril [references] [full-text] [Download Citations]
Call Admission Control in Mobile Wireless

Some problems related to wireless network access are discussed in the article. Special attention is paid to Medium Access Control and Call Admission Control. Both have direct impact on communication link accession. While the first one dictates how to, the second one decides who can access the link. The problems with wireless medium access are mentioned and requirements on MAC protocols are named. Also need for CAC algorithms is illustrated and simple functional example is proposed. Finally, the reasons for future enhancements are shortly discovered.

  1. DOSHI, B. T., DRAVIDA, S., MAGILL, P. D., SILLER, C. A.,SRIRAM, K. A Broadband Multiply Access Protocol for STM,ATM and Variable Length Data Services on Hybrid Fiber-CoaxNetworks. Bell Labs Technical Journal, summer 1996, p. 36-65.
  2. ALEGRIA, C. A., LEE, H. J., ZOCCOLILLO, R. Current Trendsin Access and Transport Architecture for Business Customers.Bell Labs Technical Journal, summer 1996, p. 79-87.
  3. FELDMANN, A. Thesis Summary: On-Line Call AdmissionControl for High-Speed Networks. School of ComputerScience, Carnegie Mellon University, Pittsburgh (USA),September 1995.
  4. HAVINGA, P. J. M. Mobile Multimedia Systems. Ph.D. Thesis,Faculty of Computer Science, University of Twente(Netherlands), 2000.
  5. CIZMAR, A., DOBOS, L., PALITEFKA, R. Mobile ATMNetworks. Elfa, Kosice (Slovakia), 1999. ISBN 80-88964-08-3
  6. PAVOL, S.: CAC Algorithms for Mobile ATM Networks.Diploma Work, Technical University of Kosice, Faculty ofElectrical Engineering and Informatics, Dept. of Electronicsand Multimedia Telecommunications, Kosice (Slovakia), 2001.
  7. BARDOS, I.: CAC Algorithms for 3-rd Generation MobileCommunication Systems. Diploma Work. Technical Universityof Kosice, Faculty of Electrical Engineering and Informatics,Dept. of Electronics and Multimedia Telecommunications,Kosice (Slovakia), 2002.
  8. DZIJAK, M.: Mobile Ad-Hoc Networks. Diploma Work.Technical University of Kosice, Faculty of ElectricalEngineering and Informatics, Dept. of Electronics andMultimedia Telecommunications, Kosice (Slovakia), 2001.
  9. 802. IEEE Standard for Local and Metropolitan AreaNetworks: Overview and Architecture. IEEE, 2002.
  10. 802. IEEE Standard for Local and Metropolitan AreaNetworks, Part 11: Wireless LAN Medium Access Control(MAC) and Physical Layer (PHY) Specifications. IEEE, 1999.
  11. GANZ, Z. Media Access Control (MAC) Design Considerationsfor Future Multimedia Wireless LANs. Online at:
  12. EOM, D. S., SUGANO, M., MURATA, M., MIYAHARA, H.: CallAdmission Control for QoS Provisioning in MultimediaWireless ATM Networks. IEICE TRANS., 1998.

J. Novikmec, L. Dobos [references] [full-text] [Download Citations]
Mobile Access to the Internet

In this paper various aspects of mobile access to Internet are discussed. We mention general Internet protocols and mobile enhancements and also future models that will be used in near future.

  1. Cellular IP: Overview.
  2. PERKINS, CH. IP Mobility Support. Internet RFC 2002,October 1996.
  3. VALKO, A., CAMPBELL, A. T., GOMEZ, J. Cellular IP, Internetdraft, November 1998.
  4. VALKO, A. Cellular IP: A new approach to Internet host mobility.November 1998.
  5. CAMPBELL, A. T., GOMEZ, J., SANGYHO, K., BILL, P., VALKO,A., TURANYI, Z. A cellular IP testbed demonstrator
  6. NTT Communications' IPv6 Activities
  7. IIJ (Internet Initiative Japan)

P. Pomenka [references] [full-text] [Download Citations]
Wireless Local Area Networks: A Comprehensive Guide

Nowadays the demand on exchange of information is higher and higher. During recent years rapid development of radio communication, both mobile and non-mobile has been experienced. Because of need of wider frequency range and expansive number of services using "the air" as the medium, higher frequencies have to be applied. This paper deals mainly with wireless LAN using license-free band such as 2.4GHz (ISM) or 5.2GHz.

  1. IEEE Wireless Standard Zone,
  2. Wi-Fi Alliance,
  3. ETSI Telecom Standard,

V. Wieser, K. Hrudkay [references] [full-text] [Download Citations]
Mutual Interference Models for CDMA Mobile Communication Networks

Nowadays we are witnesses of a huge development one of the most progressive communication technology - mobile networks. The main problem in these networks is an elimination of the mutual interference, which, mainly in non-orthogonal CDMA networks, is the principal obstacle for reaching high transmission rates The aim of this contribution is to give simplified view to mutual interference models for orthogonal and non-orthogonal CDMA networks. The contribution is intended mainly for PhD. students to help them to obtain an orientation in such a complicated areas, as the interference models for CDMA networks are.

  1. VITERBI, A. J. CDMA. Principles of Spread SpectrumCommunication. New York: Addison-Wesley PublishingCompany, 1996.
  2. PRASAD, R.: CDMA for Wireless Personal Communications.London: Artech House, 1996.
  3. GILHOUSEN, K. S., JACOBS, I. M., PADOVANI, R., VITERBI,A. J., WEAVER, L. A., WHEATLEY III, CH. E. On the Capacityof a Cellular CDMA System. IEEE Transactions on VehicularTechnology. 1991, vol. 40, no. 2, p. 303 - 312.
  4. LEE, W. C. Y. Overview of Cellular CDMA. IEEE Transactionson Vehicular Technology. 1991, vol. 40, no. 2, p. 291-302.
  5. WHIPPLE, D. P. North American Cellular CDMA. HewlettPackard Journal. 1993, p. 90 - 97.
  6. GEJJI, R. R. Forward - Link - Power Control in CDMA CellularSystems. IEEE Transactions on Vehicular Technology. 1992,vol. 41, no. 4, p. 532 - 536.
  7. WIESER, V. Analysis of System Methods for Minimization ofMutual Interference in Mobile Microcellular Systems DS-CDMA(in Slovak). Habilitation work. 1999, VA Liptovsky Mikulas.

K. Hrudkay, V. Wieser [references] [full-text] [Download Citations]
Power Control Imperfection in CDMA Systems with Adaptive Antennas

This paper deals with a simulation of cellular CDMA system using base station adaptive antennas. The model assumes two tiers area, four types of antennas, lognormal shadowing corresponding to three types of environments and perfect power control or two values of power control error, respectively. The capacity of system in up-link is evaluated by a number of mobile stations with higher signal to interference ratio than threshold with given outage probability.

  1. GILHOUSEN, K. S. et al. On the Capacity of a Cellular CDMASystem. IEEE Transaction on Vehicular Technology. 1991, vol.40, no. 2, pp. 303-312.
  2. PROAKIS, J. G. Digital Communications. 3rd. ed. McGraw-Hill,1995.
  3. LIBERTI, J. C.; RAPPAPORT, T. S. Analytical Results forCapacity Improvement in CDMA. IEEE Transaction onVehicular Technology. 1994, vol. 43, no. 3, pp. 680-690.
  4. KAJIWARA, A. Effects of Cell Size, Directional Antenna,Diversity, and Shadowing on Indoor Radio CDMA Capacity.IEEE Transaction on Vehicular Technology. Feb.1997, pp.265-275.
  5. WIESER, V., HRUDKAY, K. Mutual Interference Models forCDMA Mobile Communication Networks. This issue.
  6. HRUDKAY, K., DUHA, J. Simulation of a Cellular CDMASystem with Adaptive Antennas. In Proceedings of the 10thInternational Conference Radioelektronika 2000. Bratislava(Slovak Republic), 2000.

P. Ledl, P. Pechac [references] [full-text] [Download Citations]
Area Coverage Simulations for Millimeter Point-to-Multipoint Systems Using Building Blockage

Area coverage simulation results for LMDS or PMP systems in millimeter waveband are presented in this paper. Area coverage simulations were performed according to ITU-R P.1410 model, where Rayleigh statistical distribution with g = 7.95 is used to model the building heights. Morphological data of the city of Prague were used to calculate a new set of values g. The model was optimized to local conditions. Area coverage prediction results using the new set of values g are also presented. Accuracy of the model was increased due to suggested modification.

  1. Clark M. P. Wireless Access Networks, Fixed Wireless Accessand WLL Networks - Design and Operation. John Wiley &Sons, Ltd, 2000.
  2. Smith C. LMDS. McGraw-Hill, 2000.
  3. ITU-R P.1410 Propagation data and prediction methodsrequired for design of terrestrial broadband millimetric radioaccess systems operating in a frequency range about 20-50GHz. ITU, Geneva, 2000.
  4. Pechac P., Ledl P., Mazanek M. Signal propagation aspectsfor local multipoint distribution system (LMDS) operating inmillimeter waveband. Radioelektronika, Pardubice, 2001.
  5. Peebles P. Z. Probability, Random Variables and RandomSignal Principles. McGraw-Hill, 1980.

M. Valek, S. Zvanovec, P. Pechac [references] [full-text] [Download Citations]
Indoor Propagation Measurement for WLAN Systems Operating in 2.45 GHz ISM Band

For a planning of indoor Wireless LAN systems working in the ISM band, the signal propagation prediction is needed. In this article, the measurement campaign based on two types of measurements at 2.45 GHz is introduced. The first type of the measurement was a classical narrowband signal level measurement within indoor scenario without presence of people. The aim of this measurement was to find empirical parameters for COST231 Multi-Wall and One-Slope models. In order to statistically describe the time varying nature of the received envelope of the signal, at WLAN 2.45 GHz band, the second part of measurement campaign was accomplished. In this case, the signal level was measured using commercial WLAN PCMCIA cards in two notebooks. Probability density functions and corresponding cumulative distribution functions were set and discussed based on the specific locations and orientation of one of the notebooks. Results from both measurement campaigns were compared and conclusions are drawn for the needs of practical planning of indoor WLAN systems coverage.

  1. IEEE 802.11 Working Group,
  2. SAUNDERS, S. R. Antennas and Propagation for WirelessCommunication Systems. John Willey&Sons, Ltd, 1999.
  3. PARSONS, J. D. The Mobile Propagation Radio Channel. 2ndEdition. John Wiley and Sons, London, 2000.
  4. Digital Mobile Radio towards Future Generation Systems.COST 231 Final Report, Brussels, 1996.
  5. PECHAC, P., KLEPAL, M. Empirical Models for IndoorPropagation in CTU Prague Buildings. Radioengineering, April2000, vol. 9, no. 1, p. 31-36.
  6. PECHAC, P., KLEPAL, M., ZVANOVEC S. Results of IndoorPropagation Measurement Campaign at 1900 MHz.Radioengineering, vol. 10, no. 4, December 2001, pp. 2-4.
  7. ZVANOVEC, S. Pokryti pikobunek signalem GSM, DiplomaThesis, Department of Electromagnetic Field, CTU Prague,January 2002, (in Czech).
  8. Orinoco WLAN Card Specifications,