Simulation parameters for multipath

[Mityan]

For a given frequency, range to transmitter and velocity of the receiver how to determine the time interval at which the multipath environment may be assumed as constant, stable? I.e. when there are no even fast fading, when the number of paths and their delays and amplitudes dont change?

Thanks.

 

[David83]

For a given frequency, range to transmitter and velocity of the receiver how to determine the time interval at which the multipath environment may be assumed as constant, stable? I.e. when there are no even fast fading, when the number of paths and their delays and amplitudes dont change?

Thanks.

The time over which a channel is considered constant is called the coherence time. Roughly speaking, coherence time is inversely proportional to the Doppler spread.

 

[Mityan]

So for 5 GHz and 200 m/s this time will be lambda/2/v = 0.06/400. This is a great time.
Thanks.

 

[David83]

If you consider realistic speeds like 120 Km/h, it will be greater. Because of this most RF channels are assumed to be block fading.