2002/4

Browse

Recent Submissions

Now showing 1 - 5 of 10
  • Thumbnail Image
    Item
    Mobile Access to the Internet
    (Společnost pro radioelektronické inženýrství, 2002-12) Novikmec, J.; Dobos, L.
    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.
  • Thumbnail Image
    Item
    Distributed Speech Recognition
    (Společnost pro radioelektronické inženýrství, 2002-12) Burget, L.; Motlicek, P.; Grezl, F.; Jain, P.
    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.
  • Thumbnail Image
    Item
    Indoor Propagation Measurement for WLAN Systems Operating in 2.45 GHz ISM Band
    (Společnost pro radioelektronické inženýrství, 2002-12) Valek, M.; Zvanovec, S.; Pechač, Pavel
    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.
  • Thumbnail Image
    Item
    Mutual Interference Models for CDMA Mobile Communication Networks
    (Společnost pro radioelektronické inženýrství, 2002-12) Wieser, V.; Hrudkay, K.
    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.
  • Thumbnail Image
    Item
    MIMO Spatial Diversity Communications - Signal Processing and Channel Capacity
    (Společnost pro radioelektronické inženýrství, 2002-12) Sykora, J.
    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.