rfsystem
Joined: 25 Feb 2002
Posts: 798
Helped: 85
|
 28 Feb 2006 8:53 Re: Doppler Frequency Shift For OFDM |
|
|
|
It makes a frequency shift of the subcarriers. If OFDM is used that is normally corrected within the frequency/phase adjustment. There is only minor effect that the frequency shift is very little less for the lower subcarrier numbers than for the higher numbers.
I remember that a connection to a spacecraft was lost because these difference was not taken into account.
For OFDMA this effect is more important. Then the frequency shifts of interleaved subcarriers from different mobile stations are different. This shifts violate the orthogonality of the subcarriers and the interstation noise increases. I expect that the base stations for 802.16e have mobile station individual frequency corrections.
|
|
