An apparatus comprises a downconverter for providing a signal that may be a received orthogonal frequency division multiplexed (OFDM) symbols from a selected channel, each OFDM symbol comprising N subcarriers at least some of which are pilot subcarriers; and a processor that (a) correlates the received OFDM symbols for providing at least one correlated value, (b) generates a metric value as a function of the at least one correlated value and (b) compares the metric value to a threshold value for detecting if an incumbent signal is present.