| 摘要 |
PROBLEM TO BE SOLVED: To design a lattice code that has a long free distance despite the small constraint length of a binary convolutional code by replacing a multi- valued delay processor with a conventional processor via encoding. SOLUTION: A processor P<(2)> decides the branch metric Mυ'(t) for each of 2<m> pieces of encoder outputsυ'(t) based on the received sequence, a transmission function matrix and a symbol that is previously recovered and sends a group TM(t) to a processor P<(1)> . The processor P<(1)> uses a metric sequence as its input and applies the Viterbi algorithm to a lattice C to recover the symbol to be transmitted by resetting the decoding round-down length of the lattice C. Then a lattice code T is obtained by changing the transmission function matrix. Thus, the free distance of the code T is increased via the proper transmission function matrix and the constraint length of the lattice C is reduced.
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