Patent ID: 7551676

Claim:
A method for reducing peak-to-average power ratio in digital signal communications, the method comprising the steps of: modulating a frequency-domain input vector comprising a plurality of path vectors by applying a Gray code sequence of combinations of binary phase rotations to the plurality of path vectors, where, in each combination, the binary phase rotation of only one of the plurality of path vectors is changed from a previous combination in the Gray code sequence; and determining an optimal time-domain peak value based on the modulated frequency-domain input vector; wherein the frequency-domain input vector is X and the plurality of path vectors are V m , where m=0, 1, . . . , M−1 and M is an integer, such that X = ∑ m = 0 M - 1 ⁢ V m ; wherein the steps of modulating a frequency-domain input vector and determining an optimal time-domain peak value further comprise the steps of: calculating a time-domain equivalent x of the frequency-domain input vector X; calculating a time-domain equivalent v m of the plurality of path vectors V m ; establishing a sequence of time-domain vectors x u , where u=0, 1, . . . , U−1 and U represents distinct path numbers of the Gray code sequence such that U=2 M ; calculating a peak value for each of the sequence of time-domain vectors x u ; and determining an index number for a time-domain vector that has an optimal time-domain peak value among the sequence of time-domain vectors x u , and a corresponding path number.