| 摘要 |
PURPOSE: To optimize a method for calculating the reliability information in a communication system improved in the performance of RS decoding by obtaining reliability information of each symbol through the use of a convolution code as an internal code and an RS(read Solomon) as an external code. CONSTITUTION: A symbol defined at the point of a time (k) by a maximum likelihood path 1SV is set to be Uk ,sv . An opposing path merging to the maximum likelihood path 1SV at the points of times k+1 to k+3 is set to be 1k+1 to 1k+3 and a logarithmic maximum likelihood rates at a merging place is set to beΔk+1 toΔk+3 . Then, the setΦk of lower subscripts (j) satisfying the condition of (Uk ,j≠Uk ,sv ) are obtained and a minimum is selected from among the logarithmic maximum likelihood ratesΔj (but (j) belongs to the setΦk ) as reliability information.
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