doppler shift correction for OFDM

[aaron_do]

Hi all,


suppose I have an OFDM signal coming from a source moving towards me at high speed. The symbols will be compressed in the time-domain resulting in an upwards shift in the center frequency, and a broadening of the signal bandwidth. The question is, can I correct this by simply using a higher frequency reference crystal on the receiver side?


thanks,
Aaron

 

[vfone]

This dynamic multipath equalization can be done only in DSP.

 

[aaron_do]

thanks for the reply. Lets say there's no multipath, strictly only doppler effect. I'm thinking that doppler is just compressing the signal in time, so if I speed up the "time" of the receiver, then doppler corrected. Any thoughts?

additional question: suppose I have a satellite link sending an 20-MHz OFDM (64 pt) signal at 6 GHz, and travelling at 50000 km/hr. So the doppler shift is about 300 kHz, while the signal is compressed by about 1 kHz. Given the carrier spacing is around 300 kHz, this 1 kHz seems rather insignificant, while the 300kHz offset can be corrected using a mixer. Does that sound right or am I missing something?

thanks,
Aaron