Patent ID: 7292650

Claim:
A metric generator comprising: a bit-distance calculator receiving a complex signal along with a constellation that is divided into a one group and a zero group for each bit location, in which the complex signal is modulated using the constellation, for calculating a first distance of the zero group and a second distance of the one group for each received bit, comprising: means for shifting the complex signal by a predetermined value depending on the constellation and extracting an integer part of the shifted complex signal; means for finding a first position and a second position respectively located in the zero and the one groups for each bit from a lookup table for the constellation, wherein the first position is nearest to the integer part of the shifted complex signal within the zero group of the constellation and the second position is nearest to the integer part of the shifted complex signal within the one group of the constellation; means for inversely shifting the first and the second positions by the predetermined value respectively; and means for respectively calculating the first distance of the zero group between the complex signal and the inversely shifted first position as well as the second distance of the one group between the complex signal and the inversely shifted second position; means for multiplying the first distance of the zero group by a weighting factor associated with the complex signal to yield a bit metric of zero for each received bit; and means for multiplying the second distance of the one group by the weighting factor associated with the complex signal to yield a bit metric of one for each received bit.