4. Broadband propagation

Due to the presence of multiple paths, the radio propagation channel is frequency selective and variable in time and space due to variations in the radio environment. A broadband model models its behavior in a given configuration (frequency, bandwidth, mobility (fixed, pedestrian, car, etc.)) and environment (indoor, outdoor, rural, urban, etc.). It takes into account the temporal dispersion of the impulse response (multipath) caused by the many phenomena involved in the propagation process (reflection, transmission, diffraction, scattering, etc.). It is defined by a function representing the power delay profile (PDP), called the impulse response (h(τ )). This is the response at time t to an impulse emitted at time t - τ (see figure