Iterative Frequency-Domain Channel Estimation and Equalization for Single-Carrier Transmissions without Cyclic-Prefix

Compared to the conventional time-domain methods, frequency-domain equalization (FDE) and frequency-domain channel estimation (FDCE) present computationally-efficient methods for the reception of single carrier (SC) transmissions. In this paper, we consider iterative FDE (IFDE) with explicit FDCE for non-cyclic-prefixed SC systems. First, an improved IFDE algorithm is presented based on soft iterative interference cancellation. Second, a new adaptive FDCE (AFDCE) algorithm based on per-tone Kalman filtering is proposed to track and predict the frequency-domain channel coefficients. The AFDCE algorithm employs across-tone noise reduction, exploits time-correlation between successive blocks, and adaptively updates the auto-regressive (AR) model coefficients, bypassing the need for priori knowledge of channel statistics. Finally, a block overlapping idea is proposed which facilitates the joint operation of IFDE and AFDCE. Simulation results show that, compared to other existing IFDE and adaptive channel estimation schemes, the proposed scheme offers lower mean-square-error (MSE) in channel prediction, lower bit error rate (BER) after decoding, and robustness to relatively fast fading channels.