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Abir BEN HADJ FREDJ
État académique
Thèse en cours...
Sujet: Computation for multiple access in wireless networks(from SISO to MIMO)
Direction de thèse:
Laboratoire:
Voisinage
Ellipse bleue: doctorant, ellipse jaune: docteur, rectangle vert: permanent, rectangle jaune: HDR. Trait vert: encadrant de thèse, trait bleu: directeur de thèse, pointillé: jury d'évaluation à mi-parcours ou jury de thèse.
Productions scientifiques
oai:hal.archives-ouvertes.fr:hal-01576140
Binary Subchannel Decomposition of Lattice-based Multiple Access Schemes
International audience
Lattice codes used under the Compute-and-Forward paradigm suggest an alternative strategy for the standard Gaussian multiple-access channel (MAC). It has been proven that decoding an integer linear combination of the transmitted codewords enables higher data rates compared to decoding the messages individually. Recent work of Gasptar et al. proposed a new multiple access channel technique that they called Compute-and-Forward Multiple Access Channel (CFMA). The authors proved that, in the case of a two-user MAC and without time sharing, the entire capacity region is achieved using CFMA and a single-user decoder for signal to noise ratios above 1 + √ 2. Throughout this paper, we will work within the Compute-and-Forward framework. The strategy relies on lattice codes, here we will construct lattices using a multi-level coding based construction called construction D. To decode the lattice points, a multi-stage decoder (MSD) should be implemented at the receiver part. In this paper, we propose a new decoding strategy that helps to perform the standard MSD algorithm in a less complex way. The new technique is called Binary Subchannel Decomposition (BSCD). Since, we make use of MSD, we need at each level of the decoder to compute soft-inputs: Log-Likelihood ratios. However the calculations are very complex since we must compute infinite sums of exponentials at each stage. Hereinafter we give efficient LLR approximation for multi-stage decoders. Simulation results about the performance of BSCD are included and compared to the performance of the standard multi-stage decoder.
Wimob 2017 The 13th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications. https://hal.archives-ouvertes.fr/hal-01576140 Wimob 2017 The 13th IEEE International Conference on Wireless and Mobile Computing, Networking and Communications., Oct 2017, Rome, ItalyARRAY(0x7f5470d4aee0) 2017-10-09
oai:hal.archives-ouvertes.fr:hal-01576137
LLR Computation for Multistage Decoding
International audience
Due to their linear and highly symmetrical structure , lattices are becoming of a great interest as potential transmission schemes. Lattice codes suggest a common view of channel and source coding and new tools for the analysis of information network problems. Several constructions have been proposed to build these lattices, some of which are based on multi-level coding and multistage decoding such as constructions D and πD. Soft-decision decoders corresponding to the different nested error-correcting codes used to construct such lattices need at each stage the computation of a soft input, namely Log-Likelihood Ratios. In this paper, we give an efficient computation of LLRs based on Jacobi theta functions for three different types of constructions; Binary construction D, Quaternary construction D and Binary construction πD.
European Conference on Networks and Communications (EuCNC 2016) https://hal.archives-ouvertes.fr/hal-01576137 European Conference on Networks and Communications (EuCNC 2016), Jun 2016, Athènes, Greece. <http://www.eucnc.eu/2016/www.eucnc.eu/index4678.html?q=node/173> http://www.eucnc.eu/2016/www.eucnc.eu/index4678.html?q=node/173ARRAY(0x7f5470d32348) 2016-06-27