Carrier frequency offset estimation and correction for OFDMA uplink

The paper develops a new method for estimating and correcting the carrier frequency offsets (CFO) of orthogonal frequency division multiple access (OFDMA) systems at the uplink receiver. Multiple CFO of the different users in the OFDMA system may violate the orthogonality among subcarriers and induce inter-carrier interference (ICI) and inter-user interference (IUI). The IUI provides some extra challenges to CFO estimation not addressed in OFDM systems with only a single CFO. By significantly reducing the IUI, the paper presents an improved CFO estimator which can provide a higher accuracy than the existing approaches. After having estimated the CFO, the author also proposes a new method for CFO correction or compensation at the uplink receiver. Through simulations, it is shown that the new CFO estimator and the correction method outperform the existing approaches.