Viterbi decoder
AssigneeFujitsu Limited
InventorsAkira ENDO, Yuzo Nagai, Takeshi Inoue, Toshihiko Nawa, Keitaro Otsuka, Hitoshi Ando
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Abstract
In the present invention, the most likely transition source state bits are selected according to the path metric of the state bits corresponding to the state bits that could be taken for the encoded bits to be input, and are stored in the survival path memory. Therefore in the trace back processing, the decoded bits can be output only by repeating the extraction of the most significant bit of the transition source state bits. As a consequence, trace back processing can be performed very simply, and decoding processing becomes possible in a short time even if a general purpose processor executes the software.
Claims11
A viterbi decoder for inputting encoded bits which are convolutional-encoded from state bits having input bit and a preceding (K−1) number of input bits, and decoding the input bit string by most likelihood encoding of the encoded bits, comprising:
- a path memory generation processing unit which, for the encoded bits to be input, selects transition source state bits corresponding to predetermined state bits according to a path metric, and stores the transition source state bits in a survival path memory for each of a plurality of predetermined state bits that could be taken;
- and
- a trace back processing unit which, after storing of the transition source state bits in the survival path memory for the encoded bits to be input ends for the length of the trace back, extracts the most significant bit of state bits to be a start point of trace back, repeats the extraction of the most significant bit of the transition source state bits in the survival path memory corresponding to the state bits of which the most significant bit has been extracted, and outputting the extracted most significant bits as a decoding result.
A viterbi decoding program for inputting encoded bits which are convolutional-encoded from state bits having input bit and a preceding (K−1) number of input bits, and decoding the input bit string by most likelihood encoding of the encoded bits, which causes a computer to construct:
- a path memory generation processing unit which, for the encoded bits to be input, selects transition source state bits corresponding to predetermined state bits according to a path metric, and storing the transition source state bits in a survival path memory for each of a plurality of predetermined state bits that could be taken;
- and
- a trace back processing unit which, after storing of the transition source state bits in the survival path memory for the encoded bits to be input ends for the length of the trace back,extracts the most significant bit of state bits to be a start point of trace back, repeats the extraction of the most significant bit of the transition source state bits in the survival path memory corresponding to the state bits of which the most significant bit has been extracted, and outputting the extracted most significant bits as a decoding result.
Dependencies are inferred from the claim text.