Browsing by Author "Dupuy, Florian"

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    Wideband channel characterization : simulation and measurements analysis
    (Helsinki University of Technology, 2008) Dupuy, Florian; Lostanlen, Yves; D.Sc.; Department of Radio Science and Engineering; Radiotieteen ja -tekniikan laitos; Faculty of Electronics, Communications and Automation; Elektroniikan, tietoliikenteen ja automaation tiedekunta; Icheln, Clemens; Prof. (pro tem)
    The development of wireless telecommunication requires higher speed data rates. Wideband MIMO systems are a possible answer to that need. Both wideband and MIMO characteristics enhance multipath propagation, and require a precise knowledge of the channel to properly exploit their capabilities. The extraction of the channel parameters can be done from the measurements, but also from simulations. In the frame of this thesis, the possibility to use ray tracing to derive capacity coverage prediction is studied, based on the comparison with measurements. First the radio channel models are discussed, from the MIMO channel model to the ray tracing methods. Then the measurements methods and the algorithms extracting the channel parameters are presented, before focusing on a measurement campaign to compare prediction from ray tracing and measurements-based SAGE algorithm. Key parameters for capacity –delay spread and angular spread– were first compared, then capacity itself is introduced and a capacity comparison is conducted. Polarization influence on capacity is also studied, and different methods of emulating polarization on ray tracing are studied. Last but not least, the desired capacity coverage prediction is achieved on a wide area around the measurement streets. The simulation results with the ray tracing software are promising. The multipath components were predicted well enough by ray tracing to compute capacity. Then the polarization emulating methods gave interesting results: polarization influences capacity, and the derived capacity values were close enough to those computed from measurement to launch a capacity coverage calculation, first step toward a cellular planning based on MIMO capacity. However, some uncertainties are still left, due to computation time and models approximations.