Reduced complexity carrier frequency offset estimation for OFDM systems

In broadband wireless communications, extensive research has been devoted to orthogonal frequency division multiplexing (OFDM) due to its ability in mitigating the multipath effects. In OFDM, however, carrier frequency offsets (CFO) induce the loss of orthogonality among the sub-carriers and this results in significant performance degradation. In this paper, we propose a reduced complexity algorithm for CFO estimation with the aid of sub-carriers. Using only one training OFDM symbol with N sub-carriers, the estimation range of the proposed scheme can be N/2 times larger than conventional CFO estimation schemes As a result, the precision of the oscillators can be significantly-reduced, thus, enabling low cost implementation. This paper will also investigate sub-carrier allocations for the proposed scheme. It will be shown that the allocations should be based upon some specific binary sequences such as the extended m-sequences proposed in this paper.