A simple solution for the carrier frequency offset estimation for tile-based OFDMA uplink

This paper examines the challenging carrier frequency offset (CFO) estimation problem in the tile-based orthogonal frequency division multiple access (OFDMA) uplink systems. The existing solutions to this problem are either restricted to less flexible subcarrier assignments or too complex to implement in practice. This paper proposes simple iterative solutions with extremely low computational load, based on the repetitive structure of a tile-based training sequence. The proposed algorithm iteratively estimates the multiple CFOs and compensates the inter-carrier interference (ICI) and multi-user interference (MUI). The CFO estimation is conducted without the need of exhaustive search and requires significantly lower complexity compared to any other existing algorithms. The algorithm is modified to achieve further complexity reduction by performing the compensation based on a banded matrix. The proposed algorithms can be used with any subcarrier assignment schemes. The simulation results show that the proposed algorithms provides remarkable computational saving with their performance closely approaching the Cramer-Rao Bound (CRB).