synchronisation of ofdm symbol

[shameem]

hi,
Can anybody please explain me how we can calculate the fine frequency offset by doing autocorelation b/w cyclik prefix and the corresponding part of the ofdm symbol in time domain?

thanks
regards
shameem

 

[janath]

Cyclic prefix is a repetition of symbols.


For example at the prefix if x symbol is there there will be the same signal at T duration.


Thta is for E,g.


...x......x(o) x(1)..........x

time difference between two xs is T (1/T =frequency osperation)...

hence phase offset is =2*pi*(frequency error)*T


this will be the same for all x in the cyclic prefix.
Hence correlation is done. Phase error will be the constant term. Hence, from that phase you can extimate the frequency offset.

Janath