N. Lohse

Technische Universität Dresden, Dresden, Saxony, Germany

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Publications (9)0 Total impact

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    N. Lohse, M. Bronzel, G. Fettweis
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    ABSTRACT: Channel modelling today has to address time-variant systems with multiple antennas at the transmitter and at the receiver, the so-called MIMO (multiple input multiple output) systems. In order to describe this time-variant channel with spatially distributed antennas by a simple space-time filter, spatial system functions are defined, which are based on a space-time analogy of Bello's (1963) "physical-intuitive" systems functions. In addition, the paper in hand considers space-time correlation functions and introduces the corresponding space-time filter approach.
    MIMO: Communications Systems from Concept to Implementations (Ref. No. 2001/175), IEE Seminar on; 01/2002
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    ABSTRACT: IBMS is a concept for future mobile communication systems to provide a large range of data rates with different degrees of mobility. The integration of heterogeneous services and communication systems requires a common Network Access and Connectivity CHannel (NACCH) for basic signaling to provide permanent network access. Smart Antennas are utilized to adaptively enable a trade-off between mobility and data rate.
    12/2001: pages 35-48;
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    N. Lohse, J. Hbner, M. Bronzel
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    ABSTRACT: Appropriate channel models are needed in order to determine the performance of new emerging space time processing techniques. This paper investigates several properties of the mobile space-time channel, which can be modeled by stochastic parameters of the time-variant azimuth-delay-power-spectrum (ADPS). The raw characteristics of the ADPS are determined from ray tracing methods using the Radiowave Propagation Simulator (RPS). A simple mobility model has been integrated into the simulation tool, which assumes a mobile user moving with constant velocity along specified corridors within the selected scenarios.
    10/2001;
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    ABSTRACT: This paper summarizes the achievements of Subworkinggroup 2.1 (SWG2.1) of the COST259 initiative. A common approach for modelling the time-variant wideband angular-dispersive radio channel for link-level simulations is derived and the main parameters are described. The basic modelling philosophy is a stochastic signal description where deter-ministic a-priori information about the environment enters the model. The model is a generalization of the well-known COST207 models in three respects: (i) the directions of arrival both at the base station and the mobile station are in-cluded, (ii) not only macrocells, but also micro-and picocells are envisaged, (iii) large scale variations are modelled. To allow efficient simulations while still including large-scale variations, we have to distinguish between external, global, and local parameters. As part of the external parameters, a set of radio environments has been defined each of which is capable of generating several propagation scenarios. Global parameters tune the statistics of the local parameters and the actual realization. The relation between directional and non-directional models is touched by means of the wide-sense stationary uncorrelated-scattering (WSSUS) concept.
    01/2000;
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    ABSTRACT: The simulation of space-time receivers for wireless communication systems requires a spatial channel model which reasonably characterizes the time-variant effects of the mobile radio channel. This paper describes a space-time vector channel model with stochastic fading simulation and its effective implementation for bit-level simulations. Measurements have been analyzed in order to verify the assumptions of the channel model
    Vehicular Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th; 02/1999
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    ABSTRACT: In the recent years, the field of mobile communication has been vastly growing due to the introduction of new detection techniques. The latest innovation is the use of smart antennas in order to increase the capacity of mobile communication systems. As an impact of this new technology, the modem design has to be reviewed. New requirements of design criteria are formulated. The need for new channel models, that are dependent on the direction of arrival (DoA), is pointed out. Only a comprehensive view of the total modem including the smart antennas guarantees the development of effective algorithms for channel estimation in time and space, equalization, detection etc. Smart antennas have an inherent capability to increase the capacity of a mobile communication system, but not only to serve more users and to cover a larger region, but also to increase the data rate. This new aspect has been investigated both theoretically and by measurements. It is especially important in future mobile communication systems since there is an emerging demand for higher data rates.
    Wissenschaftliche Zeitschrift der Technischen Universität Dresden. 01/1998;
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    ABSTRACT: Bei der Analyse und dem Design drahtloser Kommunikationssysteme spielt die Modellierung und Simulation der Signalausbreitungswege eine immer wichtigere Rolle. Im Zusammenhang mit adaptiven Empfängerkonzepten für zukünftige Mobilfunksysteme sind dabei die räumlichen Ausbreitungseigenschaften auf dem Funkkanal von besonderem Interesse. Aus der Literatur sind verschiedene Modellierungsansätze bekannt, die im Rahmen der Arbeit diskutiert werden. Eine Verifizierung der Modelle kann praktisch ausschließlich anhand gemessener Kanalparameter erfolgen. Zu diesem Zweck sind mit dem RUSK ATM Channel Sounder richtungsaufgelöste Kanalmessungen im HIPERLAN-Frequenzband durchgeführt worden. Erste Meßergebnisse werden vorgestellt und diskutiert. Diese zeigen eine gute Übereinstimmung mit den Ergebnissen von Kanalsimulationen unter Verwendung abgeleiteter Modellparameter.
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    ABSTRACT: Investigations on novel space-time transceivers have driven a redesign of space-time channel models, which compute spatial and temporal correlated radio signals jointly. A low complex space-time-channel-filter is presented in this paper, which enables a direct modelling of this joint correlated channel process. It is realized by the Karhunen-Lóeve-Transform (KLT), which is based on separate knowledge of temporal fading processes and the spatial correlation. The spatial correlation and its corresponding measure, the coherence distance, were analysed for real scenarios. A narrowband realisation of the repre-sented channel modelling approach was implemented and tested for a unified linear array with 8 antenna elements.
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    ABSTRACT: In this paper a new spatial model for the mobile radio channel is introduced, which allows performance analysis of smart antenna receivers. In order to validate this model real-time measurements in the Hiperlan frequency range have been carried out using a recently developed vector channel sounder. The main features of this device and first measurement results are presented. These results reveal a promising match between the measurements and the channel parameters derived from the model.