Maximum-likelihood carrier frequency offset estimation for OFDM systems in fading channels

Carrier frequency offset (CFO) is a major contributor to the inter-carrier interference in OFDM systems. This effect becomes more severe when compounded by the presence of Doppler fading in wireless channels. This paper presents two maximum-likelihood CFO estimation schemes, one in frequency domain and another in time-domain, both under Doppler fading. The properties of the estimators are analyzed and simulation results showing the performance gain of the proposed estimators over other estimation schemes are presented. Apart from improved accuracy, the time-domain maximum likelihood estimator features significantly reduced complexity