On blind frequency-offset synchronization for OFDM communications

We address the problem of carrier frequency offset (CFO) synchronization in Orthogonal Frequency Division Multiplexing (OFDM) communications systems in the context of frequency-selective fading channels. We consider the case where the transmitted symbols are drawn from Phase-Shift-Keying (PSK) constellations. We propose and compare two algorithms to blindly estimate the CFO. The first method exploits the constant modulus of the PSK constellations. The second method exploits the finite alphabet property of these constellations. For both methods, using adequate parameterization, the estimation of the CFO is decoupled from the estimation of the other signal parameters. The first method is shown to outperform the second technique.