Method and apparatus for performing soft demapping in rotated quadrature amplitude modulation (QAM) based communication system

摘要

A soft demapping apparatus and method thereof includes a pre-processing unit to pre-process a reception signal obtained from a symbol representing bits. A candidate selection unit selects two candidates from among constellation points included in a constellation for each of the bits. A distance calculation unit calculates a Euclidean distance between the reception signal and the two candidates. A log-likelihood ratio (LLR) calculation unit calculates an LLR with respect to the bits based on the Euclidean distance between the reception signal and the two candidates.

主权项

1. A method to perform a soft demapping, the method comprising:
receiving a reception signal from a symbol representing bits; selecting two candidates from among constellation points in a constellation for each of the bits; and calculating a log-likelihood ratio (LLR) for each of the bits based on an Euclidean distance between the reception signal and the two candidates, wherein the calculating of the LLR comprises: storing, in a lookup table (LUT), the Euclidean distance between the reception signal and the two candidates and each index of the two candidates of a bit; and calculating the LLR of an alternative bit using the Euclidean distance between the reception signal and the two candidates and each index of the two candidates of the bit stored in the LUT.