In mobile radio propagation theory, fading is classified into four orthogonal categories based on the relationship between signal bandwidth and coherence bandwidth (frequency flat vs. frequency selective) and symbol duration versus coherence time (slow vs. fast). This classification relies on multipath dispersion parameters—specifically RMS delay spread ($\sigma_\tau$), mean excess delay, and maximum Doppler shift—to determine whether a channel preserves spectral characteristics or induces intersymbol interference, as well as the statistical distribution of received signal envelopes such as Rayleigh or Rician distributions. These mechanisms define the theoretical boundaries for wireless communication system design regarding distortion management, diversity techniques (spatial, temporal, frequency), and equalization requirements within stochastic process modeling of time-varying channels.
In mobile radio propagation theory, fading is classified into four orthogonal categories based on the relationship between signal bandwidth and coherence bandwidth (frequency flat vs. frequency selec…