A frame synchronization method is disclosed. The method comprises correlating a stream with a pattern to generate a correlated result c(t). A first peak and a second peak are selected from the correlated result c(t), wherein the first peak is the peak with highest amplitude, and the second peak is the peak occurring later than the first peak with the second highest amplitude. The peak ratio of the two peaks is computed, and the position of the frame boundary is determined according to the ratio.