Implementation of A Novel M-QAM OFDM Timing Synchronization Method with FSO RoF System

In this paper, a novel symbol timing synchronization method is presented based on a training preamble design of CAZAC sequences. It's to provide good symbol frame detection accuracy in M-ary Quadrature Amplitude Modulation (QAM) for Orthogonal Frequency Division Multiplexing (OFDM). Compared with the conventional methods, the improved method effectively utilizes orthogonality of OFDM symbol and autocorrelation properties of CAZAC sequences. The method reduces the Inter Symbol Interference (ISI) and Inter Carriers Interference (ICI). In order to test and verify the scheme of symbol timing synchronization in reality, we built an experimental M-QAM OFDM Free Space Optical Communications (FSO) radio over fiber (RoF) system. Timing metric, Bit Error Rate (BER) and Mean Square Error (MSE) results confirmed that the proposed method outperforms conventional methods.