Rayleigh fading channels in mobile digital communication systems. I. Characterization

The paper addresses Rayleigh fading, primarily in the UHF band, that affects mobile systems such as cellular and personal communication systems (PCS). The paper itemizes the fundamental fading manifestations and types of degradation. Two types of fading, large-scale and small-scale, are described. Two manifestations of small-scale fading (signal dispersion and fading rapidity) are examined, and the examination involves two aspects: time and frequency. Two degradation categories are defined for dispersion: frequency selective fading and flat fading. Two degradation categories are defined for fading rapidity: fast and slow. A mathematical model using correlation and power density functions is presented. This model yields a symmetry to help view the Fourier transform and duality relationships that describe the fading phenomena.