US 7,321,643 B2 | ||
Soft decision decoder, and log likelihood ratio calculator and method thereof for enhanced performance in soft decision decoding | ||
Dae-Ig Chang, Daejeon (Korea, Republic of); Dong-Weon Yoon, Daejeon (Korea, Republic of); and Nae-Soo Kim, Daejeon (Korea, Republic of) | ||
Assigned to Electronics and Telecommunications Research Institute, (Korea, Republic of) | ||
Filed on Sep. 12, 2003, as Appl. No. 10/662,195. | ||
Claims priority of application No. 10-2002-0055302 (KR), filed on Sep. 12, 2002. | ||
Prior Publication US 2004/0125883 A1, Jul. 01, 2004 | ||
Int. Cl. H04L 27/06 (2006.01) |
U.S. Cl. 375—341 [375/340] | 6 Claims |
1. A soft decision decoder comprising:
a first log likelihood ratio calculator and a second log likelihood ratio calculator, for using a receive signal y with noise
input from a receiver so as to perform soft decision decoding on a QAM (quadrature amplitude modulation) signal, the first
log likelihood ratio calculator and the second log likelihood ratio calculator incorporating channel estimation errors in
calculating a log likelihood ratio of a positive signal (x+) and a negative signal (x−), respectively;
a subtractor for determining a difference between outputs of the log likelihood ratio calculators; and
a comparator for receiving a calculation result on the difference of the log likelihood ratios of the subtractor, and determining
the QAM signal to be positive or negative according to a positive/negative state of the calculation result,
wherein each of the log likelihood ratio calculators comprises M adders for respectively adding M square values of M reference
signals xi and a ratio ρ of a symbol noise bandwidth of a QAM signal and a channel estimation filter noise bandwidth.
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