On the CFO estimation for interleaved OFDMA uplinks

This study presents an eigen-filter-based carrier-frequency-offset (CFO) estimation algorithm for orthogonal-frequency-division-multiple-access (OFDMA) uplinks. The proposed approach takes the periodic time samples of the OFDMA signal as the input of the filter that intends to eliminate the CFO signatures of all users. The wieght vector of the filter is attained from the null space of the input vectors under the criterion of minimum output power. Based on the zeros of the filter response, the proposed approach estimates the CFOs in a polynomial rooting way. This study analytically derives the mean square error (MSE) of the CFO estimates as well.