Doubly selective channel estimation for subband OFDMA using basis expansion models

This letter considers the channel estimation for subband orthogonal frequency division multiple access （OFDMA） operating over highly time-frequency selective （i.e., doubly selective） channels. Based on general basis expansion model, two expectation maximization-type channel estimation methods are proposed for subhand OFDMA in order to overcome channel time-frequency selectivity. The proposed method is compared with conventional approach and is shown to be superior to the conventional one.