Patent ID: 8009724
Filing Date: 2011-08-30
Classification: H04L,H04W,Y02D

Abstract:
1. A method of clear channel assessment with respect to a communications medium expected to sometimes carry a specified communications signal, comprising: attempting reception of the specified communications signal to produce a received signal; deriving the envelope of the received signal from the received signal; cross-correlating the envelope of the received signal with a locally-generated signal to obtain a cross-correlation result; combining multiple cross-correlations results to obtain a combined cross-correlation result; comparing the combined cross-correlation result to a threshold; and based on said comparing, producing a clear channel assessment result, wherein cross-correlating the envelope of the received signal with the locally-generated signal to obtain the cross-correlation result comprises cross-correlating the envelope of the received signal with a rectangular wave or a sine wave, wherein the specified communications signal is a multi-band OFDM ultra-wideband signal, and wherein the rectangular wave or the sine wave has a frequency that is equal to a symbol rate of the multi-band OFDM ultra-wideband signal.