Koninklijke Philips Corporation N.V.

Thales

Catherine Lamy

Didier Nicholson

Olivier Pothier

Lisa Meilhac

In a method to protect and/or detect information in a data transmission system, the pieces of data exchanged have a format comprising one or more headers and a data zone. The method comprises at least one step for the insertion, into at least one header, of at least one EPB marker segment comprising redundancy data to detect and/or correct errors.

Method and system for the protection of data with a header in a transmission system

The invention relates to a variable-length error-correcting (VLEC) code construction method, in which the main steps are: defining all the needed parameters, generating a code having a fixed length L, storing in a set W thus obtained all the possible L-tuples dista22nt of the minimum diverging distance d 'min! from the codewords (one extra-bit being affixed at the end of all words if the new set W thus obtained is not empty), deleting all words of W that do not satisfy a distance criterion with all codewords, and verifying that all words of the final set W satisfy another distance criterion. Assuming that all distributions of number of codewords for the best VLEC codes have a similar curve allure of a bell shape type, it is then proposed, according to the invention, to define an optimal length value Lm until which the number of codewords increases with their length, whereas it decreases after said value Lm. According to this new construction method, called Lm optimization, it is possible to apply the so-called 'Ls optimization' method with avoiding the edges of the curve and to work locally, wherein Ls represents a length to which the thod skips back in the codeword deletion stage.

Method and device for building a variable length error-correcting code

The invention concerns a method for source decoding a variable-length soft-input codewords sequence (y [1:T]) into a soft-out-put bit sequence (Lv [1:T]), the variable-length soft-input input code-words sequence (y [1:T]) encoded in accordance with a VLC codewords table. It comprises&#x2014;a first stage () of implementing a stack decoding algorithm for a sequential estimation of an hard-output bit sequence of said variable length soft-input codewords sequence, including storage of intermediate data contained in the stack and generated by the stack decoding algorithm; and&#x2014;a second subsequent stage () of post-processing the stored intermediate data for generating the soft-output bit sequence (Lv [1:T]), a soft-output (L(x [t])) being provided for each bit.

Method end device for source decoding a variable-length soft-input codewords sequence

The invention relates to a variable-length error-correcting (VLEC) code technique, in which the main steps are: defining all the needed parameters, generating a code having a fixed length L1, storing in a set W thus obtained all the possible L1-tuples distant of the minimum diverging distance d[min] from the codewords (one extra-bit being affixed at the end of all words if the new set W thus obtained is not empty), deleting all words of W that do not satisfy a distance criterion with all codewords, and verifying that all words of the final set W satisfy another distance criterion. Assuming that most good codes do not have jump of length, the method according to the invention allows to reduce the set of examined VLEC codes. Following this hypothesis, a new construction method, called no hole optimization, is defined, in which it is avoided to add more than one bit at the end of each word of the set W. The new algorithm does not consider very unlikely code structures and thus allows to gain in complexity.

Method and device for building a variable-length error code

The invention relates to a variable-length error-correcting (VLEC) code technique, in which the main steps are: defining all the needed parameters, generating a code having a fixed length L, storing in a set W thus obtained all the possible L-tuples distant of the minimum diverging distance d[min] from the codewords (one extra-bit being affixed at the end of all words if the new set W thus obtained is not empty), deleting all words of W that do not satisfy a distance criterion with all codewords, and verifying that all words of the final set W satisfy another distance criterion. According to the invention, it is proposed to realize the codeword deletion not anymore only in the last obtained groupe of the code, but in the group of a given length value Ls to which the algorithm will skip back to in the codeword deletion operation, which allows to go back very quickly to smaller lengths and skip many steps of the previous methods.

The present invention relates to a method of source decoding of a variable-length codeword sequence, the decoding being based on an associated codeword table. It is characterized in that it comprises the steps of: creating a tree with tree-paths (T-PTH) and branches (B), decoding a received sequence (SQr), the step comprising the sub-steps of: extending the best tree-paths (BT_PTH) in the tree by computing first cumulative metrics (CM_LPTH) of the succeeding branches (B), selecting the codewords (CWDi) corresponding to the best tree-paths (BT_PTH), and saving corresponding data in paths (PTH), the corresponding data comprising second cumulative metrics (CM_STCK), reordering the saved paths (PTH) in accordance with their second cumulative metrics (CM_STCK), testing a priori conditions on top path (TOP_PTH), and if they are verified, outputting said top path, or otherwise returning to the extension sub-step.

Method of decoding a variable-length codeword sequence

The present invention relates to a method of source decoding variable-length codeword sequences, said decoding being based on an associated state diagram comprising a plurality of states (S) and on a code (C). It is characterized in that it comprises a step of reducing the states (S) in the state diagram in such a way that, at a bit time (Bj), only a number N of states in a group (G) of states is saved on the basis of a criterion derived from a partial metric computation and otherwise independently of an alphabet of said code (C), a group (G) being associated with a bit time (Bj). A group (G) corresponds to all the states (S) calculated at each bit time (Bj).

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Paris, France

Catherine Lamy