Patent ID: 8588339

Claim:
A method of detecting temporarily available channels in a frequency band, comprising: (a) selecting a channel among a plurality of channels in a frequency band; (b) measuring an energy received in the selected channel; (c) comparing the measured energy received in the selected channel to a threshold established for the selected channel; (d) when the measured energy received in the selected channel exceeds the threshold established for the selected channel, determining the selected channel is unavailable for transmission, otherwise determining that the selected channel is available for transmission; (e) repeating (a) through (d) for each of a plurality of channels in the frequency band; (f) selecting one of the channels that was determined in (d) to be unavailable; (g) correlating a signal received in the selected unavailable channel with a known feature of a signal conforming to a particular transmission format; (h) comparing the correlation result to a second threshold; (i) when the correlation result in the selected unavailable channel exceeds the second threshold, determining that the signal received in the selected unavailable channel conforms to the particular transmission format, otherwise determining that no signal conforming to the particular transmission format is present in the selected unavailable channel; and (j) repeating (f) through (i) for each channel that was determined in (d) to be unavailable.