A vector coding scheme with improved spectral efficiency for OFDM with frequency error

Abstract

This study proposes a subspace-based inter-carrier interference (ICI) cancellation scheme for orthogonal-frequency-division-multiplexing (OFDM) systems. Conventional ICI cancellation methods suffer from the loss of spectral efficiency, and cannot handle the ICI incurred by a large frequency error. To improve the spectral efficiency, the proposed approach uses a subspace-based precoder that maps at most L−1 data symbols to a group of L consecutive subcarriers. At the receiver, the proposed approach first coarsely estimate the frequency bias through a set of nulling filters each defined on a dedicated spectral bin. Then, based on the estimate of the frequency bias, the proposed approach uses subcarrier-combiners to eliminate intra-group interference. Computer simulations show that in addition to achieving a high spectral efficiency proportional to the precoder order, the proposed approach can effectively eliminate the ICI caused by a large-frequency-error.