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Multi-user CFOs Estimation for SC-FDMA System Over Frequency Selective Fading Channels

Authors: Sushant Kumar, Sudhan Majhi, and Chau Yuen

Abstract: Frequency synchronization in single-carrier frequency division multiple access (SC-FDMA) uplink system is a challenging task due to the presence of different carrier frequency offsets (CFOs) for different users. In this paper, we propose a blind CFOs estimation algorithm for SC-FDMA uplink system by oversampling method in the presence of frequency selective fading channel. A cost function is derived which minimizes power of the off-diagonal elements of signal covariance matrix while estimating the correct CFOs. The off-diagonal elements are nothing but inter-carrier interference and multiple access interference introduced in the presence of multiple CFOs. A complete mathematical model has been presented for multiple CFOs estimation under multiple access scenarios. The proposed CFOs estimation method does not require channel state information which results in lower computational complexity. The higher iteration complexity of grid search algorithm has been further reduced by a deterministic approach. We also derive the Cramer-Rao bound for CFO estimation. The simulation results show that the proposed CFOs estimation method outperforms the existing subspace theory based methods, specifically in the low signal-to-noise ratio region.

Published in: IEEE Access
DOI: 10.1109/ACCESS.2018.2856578
Link: https://ieeexplore.ieee.org/document/8430732/