Semiblind turbo equalization scheme for LTE uplink receiver

An advanced receiver scheme for long-term evolution (LTE) uplink is proposed. The scheme combines semiblind channel estimation and turbo equalization and is based on an approximate expectation-maximization (EM) algorithm. The receiver iterates between demodulation of the data symbols using frequency-domain soft interference cancelation, turbo decoding, and semiblind channel estimation that utilizes the soft symbols extracted from the turbo decoder output. It is shown that, using the proposed scheme, one can replace most of the dedicated pilots used in the current LTE scheme with data information and obtain significantly better performance with the same bandwidth. Moreover, an efficient implementation of the proposed algorithm utilizing the discrete/fast Fourier transform (DFT/FFT) properties used in the single-carrier orthogonal frequency-division multiplexing (SC-OFDM) scheme is presented.