Decoder device for decoding convolutionally encoded message

摘要

A decoder device (VD) used for decoding digital messages according to the Viterbi convolutional decoding algorithm. This Viterbi decoder (VD) may be integrated in a portion of a single electronic chip for inclusion in a receiver of a handportable mobile station of a digital cellular radio system. The decoder (VD) includes a first module (VITALFA) to calculate transition probabilities for the possible state transitions between two successive states of the decoder, and a second module (VIPROB) to calculate, as a function of the state transition probabilities, path probabilities for the possible paths constituted by successive state transitions and ending in each of these states, and to select the path having the highest path probability value. The first/second module (VITALFA/VIPROB) of the device (VD) further calculates a state transition/path bit error rate which is function of the difference between the bits (softbits) received in the first module (VITALFA) and the bits (coded bits) expected for a same state transition/path respectively.