A new approach to optimise Non-Binary LDPC codes for Coded Modulations

International audienceThis paper is dedicated to the optimisation of Non-Binary LDPC codes when associated to high-order modulations. To be specific, we propose to specify the values of the non-zero NB-LDPC parity matrix coefficients depending on the corresponding check node equation and the Euclidean distance of the coded modulation. In other words, we explore the joint optimisation of the modulation mapping and the non-binary matrix. The performance gains announced by a theoretical analysis based on the Union Bound are confirmed by simulations results. We obtain an 0.2-dB gain in the high SNR regime compared to other state-of-the-art matrices

Non-binary LDPC codes associated to high order modulations

Cette thèse est consacrée à l'analyse de l'association de codes LDPC non-binaires (LDPC-NB) à des modulations d’ordre élevé. Cette association vise à améliorer l’efficacité spectrale pour les futurs systèmes de communication sans fil. Notre approche a consisté à tirer au maximum profit de l'association directe des symboles d’un code LDPC-NB sur un corps de Galois avec une constellation de même cardinalité. Notre première contribution concerne la diversité spatiale obtenue dans un canal de Rayleigh avec et sans effacement en faisant subir une rotation à la constellation. Nous proposons d’utiliser l'information mutuelle comme paramètre d’optimisation de l’angle de rotation, et ce pour les modulations de type « BICM » et les modulations codées. Cette étude permet de mettre en évidence les avantages de la modulation codée par rapport à la modulation BICM de l’état de l’art. Par simulation de Monte-Carlo, nous montrons que les gains de codage théoriques se retrouvent dans les systèmes pratiques. Notre deuxième contribution consiste à concevoir conjointement l'étiquetage des points de constellation et le choix des coefficients d'une équation de parité en fonction de la distance euclidienne, et non plus de la distance de Hamming. Une méthode d’optimisation est proposée. Les codes ainsi construits offrent des gains de performance de 0.2 dB et ce, sans ajout de complexité.This thesis is devoted to the analysis of the association of non-binary LDPC codes (NB-LDPC) with high-order modulations. This association aims to improve the spectral efficiency of future wireless communication systems. Our approach tries to take maximum advantage of the straight association between NB-LDPC codes over a Galois Field with modulation constellations of the same cardinality. We first investigate the optimization of the signal space diversity technique obtained with the Rayleigh channel (with and without erasure) thanks to the rotation of the constellation. To optimize the rotation angle, the mutual information analysis is performed for both coded modulation (CM) and bit-interleaved coded modulation (BICM) schemes. The study shows the advantages of coded modulations over the state-of-the-art BCIM modulations. Using Monte Carlo simulation, we show that the theoretical gains translate into actual gains in practical systems. In the second part of the thesis, we propose to perform a joint optimization of constellation labeling and parity-check coefficient choice, based on the Euclidian distance instead of the Hamming distance. An optimization method is proposed. Using the optimized matrices, a gain of 0.2 dB in performance is obtained with no additional complexity

Codes correcteurs d'erreurs NB-LDPC associés aux modulations d'ordre élevé

This thesis is devoted to the analysis of the association of non-binary LDPC codes (NB-LDPC) with high-order modulations. This association aims to improve the spectral efficiency of future wireless communication systems. Our approach tries to take maximum advantage of the straight association between NB-LDPC codes over a Galois Field with modulation constellations of the same cardinality. We first investigate the optimization of the signal space diversity technique obtained with the Rayleigh channel (with and without erasure) thanks to the rotation of the constellation. To optimize the rotation angle, the mutual information analysis is performed for both coded modulation (CM) and bit-interleaved coded modulation (BICM) schemes. The study shows the advantages of coded modulations over the state-of-the-art BCIM modulations. Using Monte Carlo simulation, we show that the theoretical gains translate into actual gains in practical systems. In the second part of the thesis, we propose to perform a joint optimization of constellation labeling and parity-check coefficient choice, based on the Euclidian distance instead of the Hamming distance. An optimization method is proposed. Using the optimized matrices, a gain of 0.2 dB in performance is obtained with no additional complexity.Cette thèse est consacrée à l'analyse de l'association de codes LDPC non-binaires (LDPC-NB) à des modulations d’ordre élevé. Cette association vise à améliorer l’efficacité spectrale pour les futurs systèmes de communication sans fil. Notre approche a consisté à tirer au maximum profit de l'association directe des symboles d’un code LDPC-NB sur un corps de Galois avec une constellation de même cardinalité. Notre première contribution concerne la diversité spatiale obtenue dans un canal de Rayleigh avec et sans effacement en faisant subir une rotation à la constellation. Nous proposons d’utiliser l'information mutuelle comme paramètre d’optimisation de l’angle de rotation, et ce pour les modulations de type « BICM » et les modulations codées. Cette étude permet de mettre en évidence les avantages de la modulation codée par rapport à la modulation BICM de l’état de l’art. Par simulation de Monte-Carlo, nous montrons que les gains de codage théoriques se retrouvent dans les systèmes pratiques. Notre deuxième contribution consiste à concevoir conjointement l'étiquetage des points de constellation et le choix des coefficients d'une équation de parité en fonction de la distance euclidienne, et non plus de la distance de Hamming. Une méthode d’optimisation est proposée. Les codes ainsi construits offrent des gains de performance de 0.2 dB et ce, sans ajout de complexité

On Signal Space Diversity for non binary coded modulation schemes

International audienceIn this paper, we study high-spectral efficiency and high-order diversity communications for the next generation broadcasting systems. In this context, rotating a Quadrature Amplitude Modulation constellation with a Signal Space Diversity (SSD) technique is known to improve the decoding performance of the communication system over the Rayleigh fading channel. In this work, we consider the SSD technique applied to coded modulation schemes with the novelty of selecting the rotation angle from the analysis of the mutual information variations. In this context, it is known that coding modulation outperforms bit-interleaved coded modulation, but we show that coded modulation has also an extra advantage: the optimal rotation angle is only marginally impacted by the signal to noise ratio and the erasure rate of the fast Rayleigh fading channel. This opens the door to a robust coded modulation scheme particularly suited for broadcasting applications. Simulation results confirm the theoretical study with a gain of up to 1.2 dB when comparing to the DVB-T2 standard

Review of optimization techniques applied for the integration of distributed generation from renewable energy sources

Several potential benefits to the quality and reliability of delivered power can be attained with the installation of distributed generation units. To take full advantage of these benefits, it is essential to place optimally sized distributed generation units at appropriate locations. Otherwise, their installation could provoke negative effects to power quality and system operation. Over the years, various powerful optimization tools were developed for optimal integration of distributed generation. Therefore, optimization techniques are continuously evolving and have been recently the focus of many new studies. This paper reviews recent optimization methods applied to solve the problem of placement and sizing of distributed generation units from renewable energy sources based on a classification of the most recent and highly cited papers. In addition, this paper analyses the environmental, economic, technological, technical, and regulatory drivers that have led to the growing interest on distributed generation integration in combination with an overview about the challenges to overcome. Finally, it examines all significant methods applying optimization techniques of the integration of distributed generation from renewable energy sources. A summary of common heuristic optimization algorithms with Pro-Con lists are discussed in order to raise new potential tracks of hybrid methods that haven't been explored yet. 2017This publication was made possible by the National Priorities Research Program (NPRP) award [NPRP6-244-2-103] from the Qatar National Research Fund (QNRF); a member of the Qatar Foundation. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of QNRF.Scopus2-s2.0-8502003130