Iterative channel estimation method for long-term evolution downlink transmission

Long-term evolution (LTE) standard employs orthogonal frequency division multiplexing (OFDM) for downlink (DL) data transmission. As pilot subcarriers are non-uniformly and sparsely spaced in the OFDM DL transmission, more complicated channel estimation methods may have to be adopted in the mobile devices to ensure adequate performance. An iterative approach is proposed for the channel estimation task, in which an inverse fast Fourier transform and fast Fourier transform pair is iteratively used to smooth channel estimates provided by decision feedback. The performance of this approach is compared with two two-dimensional interpolation methods and one discrete Fourier transform-based estimation method that have been proposed for the LTE DL transmission. Simulation results show that the performance of the proposed method surpasses all the other methods except at high signal-to-noise ratio, and moreover, not a single estimation method consistently performs better than the proposed method for all the channel models considered. Thus, the proposed method is the best among the considered methods for LTE DL transmission.