Method for detecting signal and estimating symbol timing

A method of signal detection and timing estimation, applied to a receiver of an orthogonal frequency division multiplex (OFDM) system, said OFDM system using a communication code frame format, each input signal conforming to said format comprising a short preamble, a long preamble, and a plurality of OFDM symbols, said short preamble comprising a plurality of short preambles with N1 data points, and said long preamble comprising a plurality of long preamble codes with N2 data points, said method comprising the steps of:

• (a) computing autocorrelation of said first N1 points of an input signal;
• (b) using a signal detection method to determine whether said first N1 points of said input signal conforming to said short preamble of said frame format;
• if not, returning to step (a);
• otherwise, proceeding to step (c);
• (c) using a short preamble ending detection mechanism to determine whether said first N1 points of said input signal being completely received;
• if not, repeating step
• (c);
• otherwise, proceeding to step (d);
• (d) performing coarse frequency compensation on a plurality of specific data points;
• and
• (e) performing the cross correlation computation on said N1+1 to N1+N2 points of said input signal and said long preamble stored at said receiver to find an ending boundary of one of a plurality of known long preambles, to define a sliding window and to find out a symbol boundary of the input signal.