Patent ID: 7103097

Claim:
In a digital subscriber line (DSL) system employing discrete multi-tone (DMT) technology, wherein a bandwidth is divided into a plurality of discrete symbols, a method for reducing peak-to-average ratio (PAR) values comprising: (a) dividing the plurality of discrete symbols into non-overlapping subsets of symbols, wherein an aggregation of the non-overlapping subsets of symbols produces the plurality of discrete symbols; (b) generating sub-sequences from the non-overlapping subsets of symbols by performing an inverse Fourier transform (IFT) on each of the non-overlapping subsets of symbols; (c) combining the generated sub-sequences using a binary vector to produce a combined sequence, wherein the binary vector has a number of elements equal to the number of sub-sequences, wherein the binary vector is an arrangement of elements, wherein the elements are either +1 or −1; (d) appending a pattern signal to the combined sequence to produce a patterned sequence, wherein the pattern signal corresponds to the arrangement of elements in the binary vector; (e) adding a cyclic prefix to the patterned sequence to produce a prefixed sequence; (f) adding a suffix to the prefixed sequence to produce a suffixed sequence; (g) upsampling the suffixed sequence to produce an interpolated sequence; (h) calculating a peak-to-average ratio (PAR) value of the interpolated sequence; (i) storing the calculated PAR value of the interpolated sequence; (j) iteratively repeating steps (c) through (i) to produce a plurality of binary vectors and a plurality of calculated PAR values, wherein each iteration uses a binary vector having a different arrangement of elements, wherein the iteration of steps (c) through (i) terminates when every different arrangement of elements has been used to combine the generated sub-sequences; (k) determining the lowest PAR value from the calculated PAR values; (l) selecting an optimal binary vector from the plurality of binary vectors, wherein the optimal binary vector is the binary vector corresponding to the lowest PAR value; (m) combining the generated sub-sequences using the optimal binary vector to produce an optimal combined sequence; (n) adding a cyclic prefix to the optimal combined sequence to produce an optimal prefixed sequence; (o) adding a suffix to the optimal prefixed sequence to produce an optimal PAR sequence; and (p) transmitting the optimal PAR sequence.