Recent Submissions

Now showing 1 - 5 of 11
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    Impact of Ultra Wide Band (UWB) on Macrocell Downlink of DCS-1800 and GSM-900 Systems
    (Společnost pro radioelektronické inženýrství, 2005-04) Taha-Ahmed, Bazil; Calvo-Ramon, Miguel; de Haro-Ariet, Leandro
    The effect of UWB interference on the DCS-1800 and GSM-900 downlink is studied for different UWB power density. For high UWB power density (-70 dBm/MHz), the effect of UWB signals is very high when the distance between UWB transmitter and DCS-1800 receiver is less than 1 m. For low UWB power density (-100 dBm/MHz), the effect of the UWB signals is quasi null even if the distance between the UWB transmitter and the DCS-1800 receiver is 0.5 m. It is found that the spectrum mask proposed by the FCC for indoor application (-53 dBm/MHz in the DCS-1800 band and -41 dBm/MHz in the GSM-900 band) is very high to be tolerated by the two mobile systems and we have to propose another spectrum mask with lower UWB power density.
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    An Efficient and Effective Pilot Space-Time Adaptive Algorithm for Mobile Communication Systems
    (Společnost pro radioelektronické inženýrství, 2005-04) Landqvist, Ronnie; Mohammed, Abbas
    In this paper we present a new adaptive space-time algorithm for mitigating the effects of CCI and ISI and minimizing the probability of error in mobile communication systems, and evaluate its performance for different mobile velocities. The proposed algorithm is computationally efficient and provides better performance than the conventional RLS algorithm.
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    Intelligent FDSS Overlay on GSM System (Uplink Analysis)
    (Společnost pro radioelektronické inženýrství, 2005-04) Taha-Ahmed, Bazil; Calvo-Ramon, Miguel; de Haro-Ariet, Leandro
    The overlay of an intelligent frequency diversity spread spectrum system (FDSS) on the (GSM) system is studied. The uplink capacity of both systems is given using a model of 36 hexagonal macrocells. Performance of GSM and FDSS users is investigated. An original GSM system with 48 users/macrocell can be substituted by a mixed system, which has GSM system capacity of 48 users/macrocell and FDSS system capacity of 128 users/macrocell.
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    Methods for Speech SNR Estimation: Evaluation Tool and Analysis of VAD Dependency
    (Společnost pro radioelektronické inženýrství, 2005-04) Vondrasek, Martin; Pollak, Petr
    The dynamic range of broadband digital system is mostly limited by harmonics and spurious arising from ADC nonlinearity. The nonlinearity may be described in several ways. The distinction between static and dynamic contributions has strong theoretical motivations but it is difficult to independently measure these contributions. A more practical approach is based upon analysis of the complex spectrum, which is well defined, easily measured, and may be used to optimize the ADC working point and to somehow characterize both static and dynamic nonlinearity. To minimize harmonics and spurious components we need a sufficient level of input noise (dither), which destroys the periodicity at multistage pipelined ADC, combined with a careful analysis of the different sources of nonlinearity.
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    Analysis of Rain Rate Spatial Cross-Correlation Coefficients in the Basque Country Area
    (Společnost pro radioelektronické inženýrství, 2005-04) Antonio Romo, Juan; Anitzine, Ignacio F.; Fontan, Fernando P.; Marino, Perfecto
    This paper reports on a study on the spatial characteristics of rain rates recorded in the Basque region in northern Spain. To perform this study a network of eighty raingauges spread throughout the region has been used. Statistical parameters such as the spatial cross-correlation coefficient and the space-time cross-correlation coefficient were calculated and their evolution with separation distance studied. It is hoped that information reported could be useful in better understanding characteristics of rain and in developing countermeasures for terrestrial and satellite radio networks operating at frequencies above 10 GHz.