Soft interference cancellation receiver for SC-FDMA uplink in LTE

In this paper, a new soft interference cancellation (SIC) receiver is proposed for the single-carrier frequency-division multiple access (SC-FDMA) multiple-input multiple-output (MIMO) uplink in the Long Term Evolution (LTE) and LTE-Advanced (LTE-A) systems. The receiver works in an iterative fashion between the equalizer and decoder, by using the feedback from the decoder to cancel interfering spatial streams. In addition, the receiver also cancels inter-symbol interference of the desired stream caused by frequency selective fading channel, which reduces the well known “noise enhancement” effect in SC-FDMA. Two types of structures, parallel SIC (P-SIC) and serial SIC (S-SIC) are presented, and an iterative channel estimation method is introduced to further improve the performance of the SIC receiver. Feedback reliability metrics are defined and applied during equalization to avoid catastrophic error propagation. Simulation results demonstrate that with proper reliability metrics, hard slicing on feedback symbol generation can be used to save computational complexity with very small performance loss compared to soft slicing.