Decoder an decoding method

摘要

A decoder (3') inputs the probability information AMP/CRxyt obtained by dividing the channel value obtained by multiplication of received value yt and a predetermined coefficient AMP by the first additive coefficient CR for regulating the amplitude of the received value yt and the probability information 1/CAxAPPt obtained by multiplying the a priori probability information APPt by the reciprocal of the second additive coefficient CA for regulating the amplitude of the a priori probability information APPt to a soft-output decoding circuit 23 formed on a single semiconductor substrate as a large scale integrated circuit. The soft-output decoding circuit (23) generates log soft-output CIxIlambdt and/or external information 1/CAxEXt, using the first additive coefficient CR, the second additive coefficient CA and the third additive coefficient CI for regulating the amplitude of arithmetic operations in the inside of the soft-output decoding circuit (23). With this arrangement, it is possible to optimally select a dynamic range and a quantization slot as well as a quantization slot necessary for inner arithmetic operations if codes needs to be input with a fixed number of bits.