Maximum vehicle speed.

[anwersbh]

Please I want the solution for the question below:

Consider a mobile wireless system, using QPSK modulation at 25 Ksymbols/s, and a carrier frequency of 1900 MHz. What is the fastest speed in km/h that is permissible for a vehicle using such system, if its required that the change in phase due to Doppler spread does not exceed 5 degree/ symbole?

 

[wwfeldman]

if this is a homework question, say so

guidance:
at your symbol rate, what is the time per symbol?

how much time per symbol is a 5 degree shift?

doppler shift:
https://en.wikipedia.org/wiki/Doppler_effect
the radar section

remember that radar requires the return signal, while you do not