Splitting heuristics for disjunctive numerical constraints

International audienceRatschan has recently proposed a general framework for first-order formulas whose atoms are numerical constraints. It extends the notion of consistency to logical terms, but little is done with respect to the splitting operation. In this paper, we explore the potential of splitting heuristics that exploit the logical structure of disjunctive numerical constraint problems in order to simplify the problem along the search. First experiments on CNF formulas show that interesting solving time gains can be achieved by choosing the right splitting points

The bit interleaved coded modulation module for DVB-NGH: enhanced features for mobile reception

International audienceThis paper describes the main features of the DVB-NGH Bit-Interleaved Coded Modulation (BICM) module. This latter is derived from a sub-set of DVB-T2 BICM components with additional features intended to first lower receiver complexity and power consumption and then to increase receiver robustness over mobile reception. Therefore, the long code block size was removed, a different range of coding rates was chosen, non-uniform constellations were adopted in order to provide shaping gain, and the principle of signal space diversity was extended to four-dimensional rotated constellations. Moreover the structure of the time interleaver offers the possibility to significantly increase the interleaving depth, a feature required for mobility over terrestrial and satellite links

High diversity multi-block space-time code for broadcasting applications

International audienceWe propose a STBC that calls for a 2 times 2x2 matrix seen as a two-block matrix. It enjoys a flexible transmission rate and a diversity order of 8 for a 2x2 MIMO system by exploiting additional time diversity. Its decoding complexity is only proportional to the power of four of the constellation size. The STBC parameters have been optimized to suit fading channels with and without erasure events. These events are typical of single frequency networks that are becoming a popular topology thanks to their low bandwidth requirements. Unlike state-of-the art quasi-orthogonal structures, the proposed multi-block STBC can be jointly optimized for shaping and coding gain

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Multi-non-binary turbo codes

International audienceThis paper presents a new family of turbo codes called multi-non-binary turbo codes (MNBTCs) that generalizes the concept of turbo codes to multi-non-binary (MNB) parallel concatenated convolutional codes (PCCC). An MNBTC incorporates, as component encoders, recursive and systematic multi-non-binary convolutional encoders. The more compact data structure for these encoders confers some advantages on MNBTCs over other types of turbo codes, such as better asymptotic behavior, better convergence, and reduced latency. This paper presents in detail the structure and operation of an MNBTC: MNB encoding, trellis termination, Max-Log-MAP decoding adapted to the MNB case. It also shows an example of MNBTC whose performance is compared with the state-of-the-art turbo code adopted in the DVB-RCS2 standard

Intelligent Splitting for Disjunctive Numerical CSPs

International audienceDisjunctions in numerical CSPs appear in applications such as Design, Biology or Control. Generalized solving techniques have been proposed to handle these disjunctions in a Branch&Prune fashion. However, they focus essentially on the pruning operation. In this paper, we present experimental evidences that significant performance gains can be expected by exploiting the disjunctions in the branching operation