Patent ID: 6389040
Filing Date: 2002-05-14
Classification: H04L

Abstract:
Apparatus for use in a receiver to generate a frequency offset estimate in response to a received signal comprising:a plurality of oscillators for generating a plurality of frequency signals each having a its own respective frequency; a plurality of mixing units, each mixing unit being supplied with said received signal and on a one-to-one basis with a corresponding one of said plurality of frequency signals for generating a mixed signal which is a version of said received signal multiplied by said corresponding one of said plurality of frequency signals; a plurality of metric calculation units, each metric calculation unit being supplied with one of said mixed signals for generating a metric value at the frequency of said supplied mixed signal in accordance with prescribed criteria including obtaining a first sum &Sum;n=0,n:s&af;(n)=sN-1&it;r&af;(n)&it;&ee;-j2Ï€&it;â€ƒ&it;f0&it;nâ€ƒand obtaining a second sum &Sum;s=02L-1&it;&LeftBracketingBar;&Sum;n=0,n:s&af;(n)=sN-1&it;r&af;(n)&it;&ee;-j2Ï€&it;â€ƒ&it;f0&it;n&RightBracketingBar;,â€ƒwhere r(n) is said received signal, s(n)is a state, L is a number of fast data symbols, N is a number of discrete frequencies, n is a time, eâˆ’j2&pgr;f0n is a discrete frequency and f0 is one of f1 through fN, said plurality of metric calculation units thereby generating a metric calculation over each of said plurality of frequencies; and an apparatus supplied with said plurality of metric calculations for selecting a metric calculation having a maximum magnitude, wherein the frequency over which said metric calculation having the maximum magnitude was made is the frequency offset estimate.