Patent ID: 8102930

Claim:
A method for demapping first and second data symbols, wherein the first data symbol corresponds to a mapping of a group of four bits using a first 16-QAM constellation and the second data symbol corresponds to a mapping of the group of four bits using a second 16-QAM constellation different from the first 16-QAM constellation, the first and second data symbols each having a real component and an imaginary component, the method comprising: (a) generating an estimate for a first bit in the group of four bits by applying the real components of the first and second data symbols to a first formula derived using a first hybrid-QPSK constellation generated from the first and second 16-QAM constellations; (b) generating an estimate for a second bit in the group of four bits by applying the real components of the first and second data symbols to a second formula derived using the first hybrid-QPSK constellation; (c) generating an estimate for a third bit in the group of four bits by applying the imaginary components of the first and second data symbols to a third formula derived using a second hybrid-QPSK constellation generated from the first and second 16-QAM constellations; and (d) generating an estimate for a fourth bit in the group of four bits by applying the imaginary components of the first and second data symbols to a fourth formula derived using the second hybrid-QPSK constellation, wherein: the first and second 16-QAM constellations each have real components and imaginary components; the first hybrid-QPSK constellation is generated by plotting the real components of the first 16-QAM constellation on a first axis of a first coordinate plane and the real components of the second 16-QAM constellation on a second axis of the first coordinate plane; the second hybrid-QPSK constellation is generated by plotting the imaginary components of the first 16-QAM constellation on a first axis of a second coordinate plane and the imaginary components of the second 16-QAM constellation on a second axis of the second coordinate plane; and at least one of (i) the first hybrid-QPSK constellation is further generated by rotating the first coordinate plane and (ii) the second hybrid-QPSK constellation is further generated by rotating the second coordinate plane.