Patent ID: 7324428

Claim:
A method for determining a number of a frame in a sequence of two or more frames, the method comprising: receiving a sequence of at least M+1 consecutive OFDM frames, each frame having an index m, having a designated preamble wherein the designated preamble has a selected length N 1 and an associated pseudo-noise signal PN(t;m) (m=0, . . . , M; M≧1); providing an overlap function OF(m;k) of the designated preambles with each of a sequence of selected reference signals, indexed by k=1, 2, . . . , K where K is a selected integer, and determining a phase φ(m) corresponding to a location of a maximum amplitude of the overlap functions OF(m;k) for each of the M+1 designated preambles of the sequence of at least M+1 consecutive OFDM frames; forming a selected pth order phase difference of the phases φ(m); and comparing the pth order difference with a selected table of pth order phase differences to determine a frame number of at least one frame of M+1 consecutive OFDM frames, the frame number uniquely identifying the at least one frame in the M+1 consecutive OFDM frames.