Patent ID: 6772389
Filing Date: 2004-08-03
Classification: H03M

Abstract:
A turbo decoder for decoding codes used as an error correction code in wireless communication systems, wherein a binary LogMAP algorithm is used, comprising:means for splitting the sum of two input state metrics into an integral and a decimal part; means for comparing the integral parts of the two state metrics with one another to extract a maximum and a minimum integer value therefrom; means for obtaining a difference between the original integral part and the maximum or minimum integer value; means for calculating the sum of exponential terms of base-2 function in the decimal parts of the two input state metrics split by the splitting means; means for shifting only a decimal part with a smaller integral part among the exponential sums by the difference; a first addition means for adding the decimal part shift by the shifting means and a decimal part with a larger integral part among the exponential sums; means for applying a base-2 logarithm on the decimal part added by the adding means to thereby obtain a final value for the decimal part; and a second addition means for adding the maximum integral value from the comparing means and the final value for the decimal part from the applying means to thereby obtain a final value of the base-2 function.