Patent ID: 7957482
Filing Date: 2011-06-07
Classification: H04L

Abstract:
1. A method for modifying a quadruple of data bits in a data transmission system using Quadrature Amplitude Modulation with 16 different modulation states, 16-QAM, in which a quadruple of data bits is mapped to a modulation symbol according to logical values and positions of said bits within said quadruple and according to a pre-defined mapping, wherein in the pre-defined mapping of bit value combinations to complex modulation states four bits in a quadruple of data bits are mapped to a modulation symbol, such that i) a bit on a first one of the four bit positions selects one of two contiguous regions of the 16-QAM modulation states based on its logical value, each of the two contiguous regions being formed by two rows adjacent to each other; ii) a bit on a second one of the four bit positions selects one of two contiguous regions of the 16-QAM modulation states based on its logical value, each of the two contiguous regions being formed by two columns adjacent to each other; iii) a bit on a third one of the four bit positions selects one of two non-contiguous regions of the 16-QAM modulation states based on its logical value, each of the two non-contiguous regions being formed by two rows not adjacent to each other; and iv) a bit on a fourth one of the four bit positions selects one of two non-contiguous regions of the 16-QAM modulation states based on its logical value, each of the two non-contiguous regions being formed by two columns not adjacent to each other, the method comprising the steps of: a) receiving a first quadruple of data bits; b) performing a pre-defined permutation of data bits within the first quadruple of data bits to obtain a second quadruple of data bits, wherein bits from positions in said first quadruple selecting contiguous symbol regions are shifted to positions in said second quadruple selecting non-contiguous symbol regions, and bits from positions in said first quadruple selecting non-contiguous symbol regions are shifted to positions in said second quadruple selecting contiguous symbol regions; and c) mapping data bits from the second quadruple to a modulation symbol according to their position in the quadruple and according to the pre-defined mapping of bit value combinations to complex modulation states.