
290 Simulation Technologies in Networking and Communications
A more sophisticated approach has to be followed when we intend to perform a more realistic
and accurate simulation of the digital communications system. This so-called dynamic or time-
variant approach requires simulating the time variation of the channel. This is done by taking into
account the Doppler spectrum of the channel, which is introduced through an additional lter that
shapes the originally white signals according to either the classical or the uniform Doppler spec-
trum. This approach is summarized in Table 10.5 (note that, although Table 10.5 looks very similar
to Table ...