1. A method for detecting a preamble in a multi-cell communication system, the method comprising: obtaining a first frequency domain vector representing a plurality of cells from a receiving signal through applying a Fast Fourier Transform analysis on a time-domain vector sampled from the receiving signal; identifying a first segment with the highest energy among the plurality of cells through analyzing the first frequency domain vector; generating a second frequency domain vector from the first frequency domain vector by applying vector operations to the first frequency domain vector; generating one or more third frequency domain vectors corresponding to the first segment from the second frequency domain vector by applying one or more bit masks to the second frequency domain vector; calculating a correlation vector of one or more predetermined codes with the one or more third frequency domain vectors; and comparing one or more elements in the correlation vector with a predetermined threshold, wherein a preamble is present in the receiving signal if at least one element in the correlation vector exceeds the predetermined threshold.