| 摘要 |
An apparatus and a method for calculating a soft metric mapping inputted to a channel decoder in a communication system using a hierarchical modulation method are provided to implement three type modulation methods by adding only several calculations without an additional circuit. An apparatus for calculating a soft metric mapping inputted to a channel decoder in a communication system using a hierarchical modulation method includes an orthogonal frequency signal analyzer(301), a first soft metric value combiner(302), an equal phase signal analyzer(303), and a second soft metric value combiner(304). The orthogonal frequency signal analyzer(301) calculates a parameter(A) by using a value(a) related to a minimum distance between signals in an orthogonal phase component of a reception signal and a constellation. The first soft metric value combiner(302) determines soft metric values of fourth and third demodulating symbol by using the parameter(A), the orthogonal phase component, and the minimum distance. The equal phase signal analyzer(303) calculates a parameter(B) by using a rule represented at the value(a) related to the minimum distance between the signal points. And, the second soft metric value combiner(304) determines soft metric values of second and first demodulating symbols by using the parameter(B), the equal phase component, and the minimum distance.
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