Turbo equalization for LTE uplink under imperfect channel estimation

Single-carrier frequency division multiple access (SC-FDMA) has appeared to be a promising technique for high data rate communication in Long Term Evolution (LTE) uplink. In this paper, we propose an improved turbo equalizer for multiuser multiple-input multiple-output (MU-MIMO) LTE uplink to enhance the performance as the channel statement information is imperfect at the receiver. we derive the optimal soft-input soft-output (SISO) detector in turbo equalizer based on minimum mean square error (MMSE) criterion under imperfect channel estimation by concerning the statistical characteristic of the channel estimation error. It can be implemented in frequency-domain and almostly cause no increase in computational complexity compared to the conventional turbo equalizer for SC-FDMA. Simulation results for LTE scenario demonstrate that the proposed turbo equalizer yields 0.8-1.0dB gain to the turbo receiver which does not consider the imperfect CSI when channel estimation errors exist.