Frequency-Dependent Pathloss in the Ultrawideband Indoor Channel

The frequency-dependent pathloss characteristics of an indoor radio channel are investigated over the FCC-allocated ultrawideband (UWB) frequency range (3.1¿10.6 GHz). Complex channel transfer functions are measured under a variety of propagation conditions. The dispersion index is introduced as a measure of the frequency-dependence pathloss and is estimated for each measured channel response. Its first order statistics exhibit significant deviation from the nominal value. The small-scale spatial analysis of the dispersion index reveals a periodic structure for vertically polarized channels. Fractional calculus is used to demonstrate the impact of this dispersion on system performance, and the consequent signal waveform distortion is evaluated.