Compensation of multiple carrier frequency offsets in amplify-and-forward cooperative networks

In this paper, we propose a method to find an optimal correction value for multiple carrier frequency offsets (CFO) compensation, where two received signals have different path gains, in orthogonal frequency division multiplexing (OFDM) systems. Multiple CFOs are occurred when two spatially-separated transmitters are used to transmit the same signal simultaneously. In this case, the sidelobes of the subcarrier spectrums of the undesired signals have similar magnitude with opposite signs. Based on this fact, we propose a self-cancellation method of intercarrier interference caused by multiple CFOs. In the proposed scheme, we compensate the multiple CFOs for the signal to intercarrier interference power ratio of the received signal to be maximized, instead only the signal power is maximized in the ordinary methods.