Patent ID: 8208571

Claim:
A method for detecting a periodic portion of a preamble of a data unit, the method comprising: generating angle information based on a complex signal corresponding to a received communication signal; generating an autocorrelation signal based on the angle information, wherein generating the autocorrelation signal includes generating a first multiplication signal by subtracting, from the angle information, a delayed-by-N version of the angle information, wherein N is an integer indicative of a period of the periodic portion, generating a second multiplication signal by subtracting, from the delayed-by-N version of the angle information, a delayed-by-2N version of the angle information; converting the first multiplication signal to a first complex multiplication signal having two components, converting the second multiplication signal to a second complex multiplication signal having two components, and generating the autocorrelation signal using the first complex multiplication signal and the second complex multiplication signal; and determining whether the periodic portion is present in the complex signal based on the autocorrelation signal.