OFDM Frequency Synchronizations

Hello all,

I'm a student working on a problem about frequency synchronization for
OFDM. I just wonder if the Moose's approach (using repeat training
symbols) is the best way to this issue. 

Besides Moose's and Schmidl's approachs, is there any other pilot-based
approach?

Also, I have an immature new idea to estimate the frequency offset but it
can only estimate half the range. Is it still practical? Or may I assume
the frequency offset of the the OFDM signal can be bounded within +/-25%
of subcarrier spacing?

I appreciate any advice. Thanks.

Eric