METHOD AND APPARATUS FOR METRIC NORMALIZATION FOR HIGH SPEED DELAYED DECISION OUTPUT VITERBI DECODER

摘要

PURPOSE: A method and an apparatus for metric normalization for a high speed delayed decision output viterbi decoder are provided, which controls an overflow of a register storing an accumulated metric in an internal module of the decoder to prevent a performance degradation according to the normalization. CONSTITUTION: According to the method for preventing an overflow of an accumulated metric in a delayed decision output viterbi decoder decoding systematic regressive convolutional codes, the whole bit stream of the accumulated metric are divided. Then, a lower bit stream and the other bit stream as much as the number of bit stream expressing a differential reliability value of the accumulated metric are separated into two. When there are 8 states, a normalization requirement condition is judged using a value of the most significant bit of the accumulated path metric and then the normalization is performed by an arithmetic calculation of dividing the upper bit part among the divided bits by 2.