Digital Radio Link: Multipath Fading on a 7 GHz Line-of-Sight Link (Digital Radiolaenk: Flervaegsfaedning pa en 7 GHz-Laenk av Frisiktstyp)

摘要

The major part of the results from propagation measurements on a 7 GHz, 34 Mb/s LOS-link are presented in terms of a comprehensive summary. The main purpose with the measurements, during May to September 1983-1984, were to characterize the radio channel with suitable models during multipath propagation causing frequency selective or flat fading within the actual bandwidth. From the narrow band sweep measurements, the propagation parameters, corresponding to frequency selective events, are extracted by a minimum square fit of a modelled 3-way transfer function to observed transfer functions. The statistical distribution of measured wide band fade depth are estimated for an unprotected and a space diversity channel using antenna separation of 8 m. In addition to the distribution of wide band fade levels, the statistical distribution of the durations of deep fades are estimated. Finally, the optimal choice of vertical antenna separation is discussed, concerning the ability to combat severe frequency selective fading.