Multiple carrier frequency offsets tracking in co-operative space-frequency block-coded orthogonal frequency division multiplexing systems

This study addresses the problem of carrier frequency offset (CFO) tracking in co-operative space-frequency block-coded orthogonal frequency division multiplexing (OFDM) systems with multiple CFOs. Considering that the inserted pilot tones are decayed by data subcarriers in the presence of multiple CFOs, a novel recursive residual CFO tracking (R-RCFOTr) algorithm is proposed. This method first removes CFO-induced inter-carrier interference from data subcarriers, and then updates the residual CFO (RCFO) estimation of each OFDM block recursively. When used in conjunction with a multiple CFOs estimator, the proposed R-RCFOTr can effectively mitigate the impacts from the multiple RCFOs with affordable complexity. Finally, simulation results are provided to validate the effectiveness of our proposed R-RCFOTr algorithm, which has performance close to that of perfect CFO estimation at moderate and high signal-to-noise ratio, and significantly outperforms conventional CFO tracking algorithm for large CFOs.