초록 ▼

A decoding process suitable for space links decodes a sequence of symbols received from a disturbed channel resulting from the convolutional coding of a sequence of information symbols to be transmitted. The trellis of the states of the coder is defined and, as a function of the symbols received, th

A decoding process suitable for space links decodes a sequence of symbols received from a disturbed channel resulting from the convolutional coding of a sequence of information symbols to be transmitted. The trellis of the states of the coder is defined and, as a function of the symbols received, the most likely path in the trellis is determined and this defines the most probable sequence of symbols transmitted. At each node of the trellis, the most probable path or survivor is determined by a sequence of algebraic values indicating a sequence of transmitted symbols and the likelihood of each of these symbols and by measuring the cumulative likelihood of the sequence. In a characteristic manner, the sequence of algebraic values at a node is established by a weighted shifted transfer, each algebraic value of the sequence being a function of all the algebraic values of the same node level of the sequences of algebraic values of the antecedents of the node and being a function of the algebraic value corresponding to the transition between those antecedents and the node.

대표청구항 ▼

A process for decoding a sequence of binary symbols received from a disturbed channel resulting from the convolutional coding achieved by a coder of a sequence of binary information symbols to be transmitted, in which said binary information symbols are introduced one by one into said coder, said pr

A process for decoding a sequence of binary symbols received from a disturbed channel resulting from the convolutional coding achieved by a coder of a sequence of binary information symbols to be transmitted, in which said binary information symbols are introduced one by one into said coder, said process comprising the steps of: determining the trellis of the states of the coder, said trellis comprising a system of nodes and branches, the nodes being arranged by states of 2m nodes, in which m is the number of symbols delayed in the coder, each node of a given state being connected to two nodes of the preceding state, called antecedents, by two branches corresponding to two binary information symbols; determining as a function of the sequence of binary symbols received, the path of greatest likelihood in the trellis to know the most probable sequence of binary information symbols transmitted, said path being determined by recurrence on the states of successive nodes while retaining, for each node, the most probable path, called the survivor, from among the two paths leading to it and passing through the antecedents of said node; and determining the survivor in each node by a sequence of algebraic values x′1-xL; x″1-x″L indicating a sequence of binary symbols and the likelihood of each of these symbols, and by a measurement v′c, v″c of the cumulative likelihood of said sequence, said process comprising also the steps of calculating the sequence of algebraic values of a node x2-xL, in function of the algebraic values of the antecedents of said node x″1-x′L, z and x″1-x″L, z; x2 being a function of x′2, x″2, z . . . xL being a function of x′L, x″L, z; and determining the final algebraic value of the sequence of algebraic values of said node as the algebraic value z corresponding to the transition between said antecedents and said node.