陸上移動衛星通信における電波伝搬特性の統計的性質

概要

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The space-earth links in land-mobile satellite communications are frequently cut off as a result of the shadowing and blockage due to roadside trees, buildings, utility poles and other man-made obstacles. Knowledge about the fade statistics is therefore important in designing cost-effective systems. In this paper, propagation measurement results at relatively high elevation angles using a ETS-VI elliptically orbiting satellite are analyzed from the standpoint of whether the propagation channel is in a fade state or a non-fade state. Given a threshold level for the received signal, fade state and non-fade state are determined, and fade duration and non-fade duration are also defined as unavailable duration of communication and as inter-fade-duration, respectively. The statistics of the received signal power, fadeduration and non-fade-duration are investigated in terms of cummulative distribution for elevation angles ranging from 57.9°to 66.5,and for several threshold levels of fade-state (fade margin from 3 to 15 dB). These models of the cummulative distribution have been fitted to log-normal distribution with good agreement.
東海大学の論文