Unbiased carrier frequency offset estimation algorithm for TDS-OFDM systems

Carrier frequency offset (CFO) estimation must have sufficient precision for orthogonal frequency division multiplexing (OFDM) systems due to its sensibility to orthogonality between sub-carriers, especially for high rate OFDM transmission with narrow sub-carrier spacing. In time domain synchronous OFDM (TDS-OFDM), time domain pseudo-noise (PN) sequences are inserted between adjacent data blocks as guard interval (GI), which can be used for synchronization and channel estimation. However, the estimated CFO obtained from the PN training sequences maybe biased especially under severe multipath channels with long delay spread and strong echoes. In this paper, we proposed an unbiased carrier synchronization algorithm for TDS-OFDM systems. The correlation property based on the PN training sequences is adopted and error elimination algorithm is subsequently operated. Performance of the proposed algorithm is improved evidently from the simulation compared with conventional algorithm over several typical multipath channels, especially the strong power and long echo channels.