US Patent 9398615 Carrier sensing and symbol timing in a WLAN system

A method for processing a preamble of a data unit received via a communication channel, wherein the preamble includes a first preamble field having a plurality of repetitions of a sequence, includes generating a cross-correlation output signal at least in part by correlating (i) a signal corresponding to the first preamble field of a received data unit with (ii) one or more repetitions of the sequence. The method also includes generating a correlation output signal at least in part by performing a correlation operation on the cross-correlation output signal, and, based at least in part on the correlation output signal, detecting the received data unit and/or determining timing associated with the received data unit.