ABSTRACT
This paper deals with blind iterative Carrier Frequency Offsets (CFO) estimation based on modify Propagator Method (PM) for interleaved Orthogonal Frequency Division Multiple Access (OFDMA) uplink systems, without using specific training sequences. It has been shown that the PM based on the structural algebraic properties of the received data matrix has low computational load and is only efficient in nonnoisy environments. In conjunction with the usefulness of QR/LU factorizations, the presented searching-based CFO estimators can alleviate the finite sample and noise effects. Meanwhile, an approach is suggested which finds a new CFO vector based on Taylor series expansion of one initially given. The problem of finding the new CFO vector is formulated as the closed form of a generalized eigenvalue problem, which allows one to readily solve it. Since raising the accuracy of residual CFO estimation can provide more accurate residual CFO compensation, this paper also presents an iterative estimate approach with less computational load to improve CFO estimation performance. However, the proposed estimators are not only can estimate CFO, but also have less computational load. Finally, several computer simulation results are provided for illustrating the effectiveness of the blind estimate approaches under single OFDMA data block.
