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An Interference-Cancellation Scheme for Carrier-Frequency Offsets Correction in OFDMA Systems Recently, orthogonal frequency-division multiplexing (OFDM), with clusters of subcarriers allocated to different subscribers (often referred to as OFDMA), has gained much attention for its ability to enable multiple-access wireless multimedia communications. In such systems, carrier-frequency offsets (CFOs) can destroy the orthogonality among subcarriers. As a result, multiple-user interference, along with significant performance degradation, can be induced. In this paper, we present a scheme to compensate for the CFOs at the base station of an OFDMA system. In the proposed scheme, circular convolutions are employed to generate the interference after the discrete Fourier transform processing, which is then removed from the original received signal to increase the signal-to-interference ratio (SIR). Both SIR analysis and simulation results will show that the scheme can significantly improve system performance.
Date of Publication: Jan. 2005