Synchronization is very important to orthogonal frequency division multiplexing (OFDM) systems. Taking aim at the problem that the timing inaccuracy of the S&C method and the indistinct peak of the timing metric produced by Park method under the low signal-to-noise ratio (SNR) and fading channel, a new symbol synchronization algorithm based on the training symbol is proposed in this paper. The new algorithm exploits the training symbol proposed by S&C to correlate the received signal with the known training symbol again at the receiving end to identify the start point of the OFDM symbol. The result of the simulation shows that the proposed method’s timing metric is of the impulse-shaped peak under the condition of the lower SNR and multipath fading channel, and has smaller timing errors compared with the conventional method in terms of mean-square error (MSE) of the timing estimator.
Real-time experimental demonstration of optical OFDM symbol synchronization in directly modulated DFB laser-based 25km SMF IMDD systems