Patent ID: 7920636
Filing Date: 2011-04-05
Classification: H04L

Abstract:
1. A method for transmitting a data bit stream in a communication system using a 16-QAM (Quadrature Amplitude Modulation) constellation having 16 modulation symbols representable in four rows and four columns in a complex coordinate plane, each modulation symbol of the 16-QAM constellation representable by a combination of four data bits, and the 16-QAM constellation obeying the following mapping rules: a first one of the four data bits representing a modulation symbol selects one of two contiguous symbol regions of the 16-QAM constellation based on its logical value, each of the two contiguous symbol regions being formed by two rows adjacent to each other, a second one of the four data bits representing the respective modulation symbol selects one of two contiguous symbol regions of the 16-QAM constellation based on its logical value, each of the two contiguous symbol regions being formed by two columns adjacent to each other, a third one of the four data bits representing the respective modulation symbol selects one of two non-contiguous symbol regions of the 16-QAM constellation based on its logical value, each of the two non-contiguous symbol regions being formed by two rows not adjacent to each other, a fourth one of the four data bits representing the respective modulation symbol selects one of two non-contiguous symbol regions of the 16-QAM constellation based on its logical value, each of the two non-contiguous symbol regions being formed by two columns not adjacent to each other, the method comprising: expanding the number of data bits of the data bit stream by repeating the data bits of the data bit stream thereby forming a repeated data bit stream comprising, for each data bit of the data bit stream, a repeated data bit associated to the respective data bit of the data bit stream, interleaving at least one of the data bit stream or the repeated data bit stream, forming a sequence of data words from the data bit stream and the repeated data bit stream and mapping each data word to a modulation symbol of the 16-QAM constellation, wherein each data word has four bits and two bits of the respective data word are formed by data bits of the data bit stream and two bits of the respective data word are formed by data bits of the repeated data bit stream, and wherein a data bit of the data bit stream selects a contiguous symbol region and its associated repeated data bit of the repeated data bit stream selects a non-contiguous symbol region, or vice versa, modulating the modulation symbols to a carrier frequency, and transmitting the modulated symbols.