Reduced path Viterbi decoder with inverse circuit of the encoder

The proposed system consists of the predecoder and the reduced-path Viterbi decoder. The predecoder separates the mixed channel noise from the received sequence. The path reduction is implemented by the number of errors counted in the predecoded error sequence. as a function of channel condition because the errors in the predecoded error sequence can be considered as the channel error sequence. Due to the reduction of the path, the number of ACS (add compare select) operations can be reduced, which occupies the dominant part in Viterbi decoding. The ACS reduction ratio for the proposed system is up to 30% for the (2,1,2) Ungerboeck code without degradation of the error performance