Statistical modeling of small-scale fading in directional radiochannels

摘要

After a review of the known description of time-variant channelsnby means of system and correlation functions, a consistent extension ofnthis description to directional time-variant channels is described. Thisnextension allows a clear distinction between time- and space-variantneffects in directional mobile radio channels. The major intention of thendescribed directional extension however is the derivation of anstatistical modeling approach for small-scale fading effects inntime-variant wideband directional channels, which can be regarded as anconsistent extension of the well established Rayleigh or Rice-fadingnapproach for nondirectional time-variant narrowband channels. Thenapproach, which is based on the time and aperture-variant transfernfunction, appears to be preferable to the frequently used statisticalnmodeling of the time-variant angle-resolved impulse response for severalnreasons. The major advantage is that the approach can cope with thendemand for a great number of superimposing components as the basis fornstatistical modeling. The correlation between adjacent values isnproposed to be achieved by filtering with appropriate directionalnscattering functions. The description of the modeling approach, as donenin the present paper, is intended to be general and universal; for thenapplication on certain channel types statistical distribution functionsnand parameters to be used with the approach can readily be determinednfrom appropriate measurements