Patent ID: 8160170
Filing Date: 2012-04-17
Classification: H04L

Abstract:
1. A method for receiving a data bit stream in a communication system, the data bit stream having been modulated by a transmitter using a 16-QAM 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. 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 contiguous symbol regions being formed by two rows adjacent to each other, b. 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, c. 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, d. 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: receiving a transmission signal comprising the data bit stream, demodulating the transmission signal by detecting modulation symbols represented by data words of four data bits using the 16-QAM constellation, thereby associating each data bit of a received modulation symbol with a metric indicating the probability of the logical value of the respective bit of the received modulation symbol or indicating the logical value of the respective bit of the received modulation symbol, associating each data bit of the received modulation symbols that has selected one of the contiguous symbol regions or one of the non-contiguous symbols regions of the 16-QAM constellation to a repeated data bit representing its repetition within the data bits of the modulation symbols, wherein the repeated data bit has selected one of the non-contiguous symbol regions or one of the contiguous symbol regions of the 16-QAM constellation, respectively, combining each data bit having selected one of the contiguous symbol regions of the 16-QAM constellation with its associated repeated data bit based on the metric of the respective data bit and the metric of the repeated data bit to reconstruct the data bit stream.