Efficient physical layer preamble format

A method for processing a preamble of a data unit received via a communication channel, wherein the preamble includes a first field and a second field associated with channel estimation information, wherein an ending portion of the first field includes a first sequence and a beginning portion of the second field includes a second sequence complementary to the first sequence, wherein a sum of out-of-phase aperiodic autocorrelation coefficients of the first sequence and the second sequence is zero, the method comprising:

• generating at least one correlation signal using a received signal corresponding to the preamble, wherein the at least one correlation signal includes at least one of 1) a cross-correlation between the received signal and the first sequence, 2) a cross-correlation between the received signal and the first sequence, and 3) an autocorrelation of the received signal;
• detecting a beginning of the second field based on the plurality of correlation signals;
• and
• using the detection of the beginning of the second field to decode the second field.