Patent ID: 7280605

Claim:
An orthogonal frequency division multiplexing (OFDM) receiver of a wireless Local Area Network (LAN) system, comprising: a radio frequency (RF) module, adapted to receive a radio signal, and to extract therefrom and output an OFDM analog signal; an analog-to-digital (A/D) converter, adapted to sample and convert the OFDM analog signal into an OFDM digital signal; a first differential cross-correlation unit, adapted to perform a first cross-correlation of the OFDM digital signal and an expected differential value of a short training symbol, and to output a first differential cross-correlation value; a second differential cross-correlation unit, adapted to perform a second cross-correlation of the first differential cross-correlation value and an auto correlation value of the expected differential value of the short training symbol, and to output a second differential cross-correlation value; a first peak value detection unit, adapted to compare a previous first peak value Z(d max *(i−1)), which is a peak value among a previous M sample values of the second differential cross-correlation value, with a present first peak value Z(d max *(i)), which is a peak value among a following M sample values of the second differential cross-correlation value, in response to a second boundary detection signal indicating that a second condition is satisfied, and to output a first boundary detection signal corresponding to a first condition; a second peak value detection unit, adapted to compare a previous second peak value Z(d max+1 *(i−1)), which is a next sample value after the previous first peak value among the previous M sample values of the second differential cross-correlation value, with a present second peak value Z(d max+1 *(i)), which is a next sample value after the present first peak value among the following M sample values of the second differential cross-correlation value, in response to the first boundary detection signal indicating that the first condition is satisfied, and to output the second boundary detection signal corresponding to the second condition; a symbol clock generator, adapted to determine a location d max *(i−1) of the previous first peak value as a boundary between a long training symbol interval and a short training symbol interval, and to generate a symbol clock synchronized to the location d max *(i−1), when at least one of the first boundary value detection signal indicating that the first condition is not satisfied, and the second boundary value detection signal indicating that the second condition is not satisfied, is active; and an inverse fast Fourier transform (IFFT) unit, adapted to synchronize the OFDM digital signal to the symbol clock, to perform an IFFT for the synchronized digital signal, and to output a digital symbol.