A Successive Intercarrier Interference Reduction Algorithm for OFDM Systems

In a rapidly fading environment, Doppler spread caused by user mobility destroys the orthogonality among OFDM subcarriers, resulting in intercarrier interference. In this paper, a low complexity ICI reduction algorithm which can be applied to QAM signal constellations is proposed. A combinatorial optimization problem for ICI suppression is formulated and then relaxed to a quadratic programming problem. A successive method is then utilized to deduce a sequence of reduced-size QP problems, which is solved by limiting the search in the 2- dimensional subspace spanned by its steepest-descent and Newton directions to reduce the computational complexity. Furthermore, a low-bit descent search is employed to enhance the system performance. The proposed algorithm is shown to provide excellent performance with low computational complexity.