METHOD AND DEVICE FOR CALCULATING LOG LIKELIHOOD RATIO OF BITS IN QAM SIGNALS

摘要

PROBLEM TO BE SOLVED: To provide a method and device for effectively calculating log likeli hood ratio on each bit in M-aryQAM modulated signals transmitted in a commu nication system, in order to reduce the time for calculating log likelihood ratio. SOLUTION: This method and device uses characteristics of the square Carnot mapping in QAM code set in order to reduce the number of distance calculation needed in determining log likelihood ratio on each bit in M-aryQAM modulated signals. The reduction of number of the calculation reduces the much more time needed in determining the log likelihood ratio, especially in the case of higher order M-aryQAM system.