Patent ID: 8718205

Claim:
A method of hard bit level and soft bit level demapping in a receiver wherein a received signal was modulated in a transmitter by mapping a different 6 bit modulating data sequence to each of 64 constellation points to create a non-square, Gray coded, QAM signal point constellation, the method of hard bit level and soft bit level demapping comprising: equalizing said received signal to remove channel distortion from said received signal thereby creating an equalized signal; demodulating said equalized signal into an in-phase related symbol y I and a quadrature phase related symbol y Q ; and demapping said in-phase related symbol y I and said quadrature related symbol y Q into hard-bits or preliminary soft-bits by applying, for each of the 6 bits in the modulating sequence, a bit decision rule, the bit decision rule for a given bit determined by first partitioning the constellation plane into defined regions, where, in each region, the given bit value is either logical 1 or logical 0, then deducing the bit decision rule, where said bit decision rule is a function of the location of y I and or y Q in the given bit's partitioned constellation plane and declares a) whether the given bit is likely of value logical 1 or logical 0, and b) in the case of soft bit level demapping, the degree of confidence in the decision that the given bit is likely logical 1 or logical 0; and, optionally multiplying, in the case of soft bit level demapping, said preliminary soft-bits by a factor that is a function of said received signal's signal-to-noise ratio (SNR), thereby creating final soft-bits; and where the said non-square, Gray coded, QAM signal point constellation is the same as that created by modifying a square, Gray coded, QAM signal point parent constellation comprising 64 points, arranged with 16 points in each of four quadrants defined by I and Q axes intersecting at an origin of a phase-plane diagram, the signal points in each quadrant of the square array having I and Q relative component amplitudes of 1, 3, 5, and 7 units, the square, Gray coded, 64-QAM parent constellation being modified by eliminating an inner most 4 constellation points located at the complex positions 1 + 1 j, − 1 + 1 j, − 1 − 1 j and 1 − 1 j , replacing the inner most 4 constellation points with new constellation points, located at complex positions 1 + 9 j, − 1 + 9 j, − 1 − 9 j and 1 − 9 j, respectively, eliminating an outer most 4 constellation points, located at the complex positions 7 + 7 j, − 7 + 7 j, − 7 − 7 j and − 7 j, replacing the outer most 4 constellation points with new constellation points located at the complex positions 9 + 1 j, − 9 + 1 j, − 9 − 1 j and 9 − 1 j, respectively.