the present invention relates to methods and devices for receiving signals in a wireless local area network , particularly in the case that the signals are orthogonal frequency division multiplexed signals . a signal detection apparatus is disclosed for an ofdm receiver , having : means for determining the correlation of corresponding samples of two received preamble symbol samples , one said sample delayed a predetermined duration with respect to the other ; signal detection being indicated when the correlation is greater than or equal to a threshold ; wherein the threshold is dependent on the signal power of the received preamble symbols .