On spatial power gradients

The variation of the instantaneous power versus distance for a narrowband c hannel is an important parameter in modern digital systems, relevant for va riations during a burst and for power control algorithms, This paper gives the statistical distribution for the power gradient, both in decibels and i n natural units for a Rayleigh fading channel. The former has been known fo r some time to be Student's t distributed, and the latter has a Laplacian d istribution, a new result. Both results are proven here. They are in varian ce with an approximation given in a recent publication.