Blind Joint CFO and STO Estimation for FBMC/OQAM Systems

Filter Bank Multi-Carrier based Offset Quadrature Amplitude Modulation (FBMC/OQAM) is a potential technique to substitute the traditional Cyclic-Prefix-based Orthogonal Frequency Division Multiplexing (CP-OFDM) in future communication systems. However, as any multicarrier system, FBMC/OQAM systems are sensitive to Sampling Time Offset (STO) and Carrier Frequency Offset (CFO). In this letter, a blind joint estimation of STO and CFO in FBMC/OQAM systems is proposed. To do this, we exploit the time guard interval used in burst transmission mode to transmit two virtual FBMC/OQAM symbols, one at the beginning and the other at the end of the burst. The signal received at these positions in a channel without distortion and without STO and CFO consists only of pure imaginary interference induced by adjacent data symbols. Based on the real orthogonality of FBMC/OQAM analysis/synthesis filters and assuming a known Channel Frequency Response (CFR) at the receiver, we derive a cost function that allows joint estimation of STO and CFO. Numerical results show an improvement in performance in comparison to other existing methods.