In wireless OFDM systems, the coexistence of direct current (DC) offset and carrier frequency offset (CFO) will severely degrade the transmission performance. This problem was only partially solved by pilot-aided approaches, at the expense of bandwidth. In this paper, we analyze the subspace structure of the received OFDM signal after coarse DC offset cancellation by time-domain average. Then, a novel blind estimator, which is able to estimate both CFO and DC offset in the absence of the pilot, is proposed. The validity of the proposed estimator is demonstrated by simulation results.
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