A statistical characterization of point-to-point microwave links using biased Rayleigh distributions

A multipath fading model has been used to examine the characteristics of a point-to-point microwave radio channel. The new attributes of this model that differ from other multipath models enable the incorporation of the ideas of fading severity and time variability. This is achieved by the use of a biased Rayleigh-distributed second (interfering) ray. The biasing constant determines the fading severity, while the Rayleigh cutoff frequency determines the rate-of-change of the channel. For point-to-point microwave radio channels, this model provides narrow-band fading signal-level distributions that completely replicate the Norton or Nakagami-Rice distributions while at the same time providing signal level distributions that replicate those obtained from broad-band measurements. Thus, this model unifies the narrow-band and broadband multipath fading models. Using this model, nondiversity and diversity system operation is investigated and the concept of a broad-band correlation coefficient introduced. The distributions of notch speed are also investigated. Software simulation results are compared with some hardware simulation results and field measurements.