DECODER UTILIZING SOFT INFORMATION OUTPUT TO MINIMIZE ERROR RATES

摘要

PURPOSE: A decoder utilizing soft information output to minimize error rates is provided to output hard information estimated of a received symbol, and soft information comprising the relative reliablity of the detection of that estimated output. CONSTITUTION: A coding system is disclosed wherein the receive side includes a decoder capable of producing, in addition to the hard information decoded output, either or both symbol and/or bit soft information values. For a certain information bit position, a value proportional to the joint probability that a received symbol and the set of all hypothesized transmitted code words that led to the estimated or detected hard information output is calculated. The calculated probabilities with respect to plural code words having a zero in that certain information bit position are compared to the calculated probabilities with respect to the plural code words having one in that certain information bit position. The result of the comparison provides an indication of whether the hard information output in that same information bit position is more likely one or zero.