Patent ID: 8229022

Claim:
A modulation method in which data of (2n+1) bits are transmitted (where “n” is an integer more than 1) and a multilevel value is set to 2 (2n+1) , the method comprising: dividing, by a processor, signal points arranged in each of four quadrants into 8 subgroups corresponding to 3 bits of the data of (2n+1) bits, the four quadrants divided by an in-phase axis and an orthogonal axis that are perpendicular to each other; encoding, by the processor, the 3 bits so that an average Hamming distance between adjacent signal points in the 8 subgroups becomes a minimum; subjecting, by the processor, 2 bits of the data of (2n+1) bits to a Gray coding as a signal for allowing the four quadrants to be identified; in the case where “n” exceeds 2, relating 2×(n−2) bits within the data of (2n+1) bits to signals points in the eight subgroups as the (n−2) bits of two streams; and applying the Gray coding to the (n−2) bits of two streams in the in-phase axis direction and orthogonal axis direction independently.