Abstract—Compared to conventional time-domain equalization, frequency-domain equalization (FDE) presents a computationally ef�cient alternative for the reception of single carrier (SC) transmissions. In this paper, we consider iterative FDE (IFDE) with explicit frequency-domain channel estimation (FDCE) for non-cyclic-pre�xed SC systems. First, an improved IFDE algorithm is presented based on soft iterative interferencecancellation. Second, a new adaptive FDCE (AFDCE) algorithm based on per-tone Kalman �ltering is proposed to track and predict the frequency-domain channel coef�cients. The AFDCE algorithm employs across-tone noise reduction, exploits temporal correlation between successive blocks, and adaptively updates the auto-regressive model coef�cients, bypassing the need for prior knowledge of channel statistics. Finally, block-overlapping is used to facilitate the joint operation of IFDE and AFDCE. Simulation results show that, compared to related IFDE and adaptive channel estimation schemes, the proposed schemes offer lower mean-square error (MSE) in channel prediction, lower bit error rate (BER) after decoding, and robustness to non-stationary channels. Index Terms—Iterative frequency-domain equalization, frequency-domain channel estimation, Kalman �lter, MMSE, single carrier, time-varying frequency-selective channels.

Wireless communication systems targeting at broadband and mobile data trans-missions commonly face the challenge of fading channels which are both time and frequency selective. Therefore, the design of effective equalization and estimation algorithms for such channels becomes a fundamental problem of communication sys-tems. On one hand, multi-carrier transmission systems demonstrate prominent po-tential to combat the doubly selective fading, however, several factors may retard their applications, such as: high peak-to-average power ratio, sensitivity to phase noise, etc. On the other hand, single carrier transmission is a conventional approach and has important applications, such as HDTV broadcasting systems, underwater acoustic communication systems. In this dissertation, we focus on receiver design for effective and efficient reception of single-carrier transmissions through doubly se-lective channels. Our target is to design and develop a group of channel estimation and equalization algorithms in the frequency-domain, which enable high performance reception of single-carrier transmission with low computational complexity. Motivated by

Abstract—Carrier frequency synchronization is critical to the quality of signal reception in OFDM systems. This paper presents an approximate maximum-likelihood (ML) carrier frequency offset (CFO) estimation scheme based on time-domain channel estimates which retain the CFO information in the form of phase rotation. The proposed ML CFO estimate is investigated under static as well as time-varying fading channels. Statistical properties of the estimator are examined and Cramer-Rao lower bound (CRLB) is derived. Theoretical analysis and numerical simulations show that the proposed CFO estimator renders excellent performance with lower computational complexity. The proposed CFO estimate also has an advantage of allowing for more flexible pilot patterns. Index Terms—Carrier synchronization, maximum likelihood estimate, OFDM, time-varying multipath fading channel. I.

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