SOFT INPUT/SOFT OUTPUT DECODER USED FOR REPEATED ERROR CORRECTION DECODING DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce the capacity of a memory for temporarily storing external likelihood information.;SOLUTION: Adding circuits 400 to 430 add added values of metric calculation sections 240-1 to 240-8 with a state metric of a memory section 244. A maximum-value selection section 448 generates a likelihood 478, according to the added values of adding circuits 400 to 414, when a data bit is assumed to be one, and a maximum-value selection section 448 generates a likelihood 478 according to the added values of adding circuits 416 to 430 when a data bit is assumed to be zero. A subtracting circuit 450 subtracts the likelihood 478 from the likelihood 476 to generate a likelihood rate 480, and a subtracting circuit 452 subtracts a data 482 from the likelihood rate 480 to generate an external likelihood information 484. A renormalizing section 454 integrates the external likelihood information 484 with a renormalizing factor 504 for renormalization, and it stores the result temporarily stored in a memory 456. The external likelihood information stored in the memory 456 is used as a in-advance probability, for the following repetitive decoding.;COPYRIGHT: (C)2002,JPO