Analytical modeling of losses in FDP protocol of HbbTV based push-VOD services over DVB networks

International audienceHybrid broadcast broadband TV (HbbTV) is a technique providing Push-VOD services over an interactive hybrid TV. These services are broadcast using File Delivery Protocol (FDP) characterized by three levels of data represen- tation and give rise to three loss distribution that may result in QoS degradation and poor Forward Error Correction (FEC) recovery capabilities (if FEC is used within FDP). In this paper, we address for the first time the issue of depth analysis of loss propagation within FDP system to understand and foretell the perceptual VOD quality and the FEC behavior at receiver side. We first propose analytical models based on Markov chains to accurately predict the losses and the burstiness along the FDP system levels allowing to avoid the analysis by experimental NP-hard method. Then, based on simulation, we validate the proposed models for all tested average loss rates and average burst loss lengths. Finally, we show that the proposed Markov models allow to guess ahead effectively VOD QoS and FEC behavior. © 2017 IEEE

Joint beamforming and PAPR reduction in massive MIMO: Analysis of gain in energy efficiency

International audienceThe main goal of this article is to accurately quantity the gain in energy efficiency that can be obtained by combining PAPR reduction techniques with beamforming in the context of massive MIMO communications. To this purpose, we first derive and analyze the expressions of sum capacity, power consumption, and energy efficiency for hybrid, digital and analog beamforming for massive MIMO systems in the millimeter wave frequency range. Then, we use these results to derive and quantity the gain in energy efficiency at system level that can be obtained by combining PAPR reduction for improved power amplifier efficiency with beamforming in massive MIMO systems. In addition, we derive the expressions allowing to determine the optimal amount of antennas M that should be connected to each RF chain in a partially connected hybrid beamforming scheme in order to maximize the systems energy efficiency. Evaluation of the derived expressions clearly show that a noticeable gain in the systems energy efficiency is obtained when PAPR reduction is added, and allows to analyze the advantages and disadvantages of each approach from an energy efficiency point of view. © 2020 IEEE

Expression analytique du spectre pour les signaux multiporteuses :Impact conjoint des non-linéarités de l’amplificateur de puissance etde la fonction de prédistorsion

International audienceDans cet article, nous proposons de calculer l’expression analytique de la densité spectrale de puissance du signal multiporteuse àla sortie d’un amplificateur de puissnance (AP) en considérant qu’une technique de prédistorsion est activée. En fait, cette expression analytiqueest très utile pour déterminer la configuration optimale de l’AP et la technique de prédistorsion qui permet d’obtenir l’efficacité énergétiquemaximale tout en satisfaisant les exigences de linéarité

Modulation et codage de canal pour la radiodiffusion sonore numerique vers les mobiles

La perspective de mettre en oeuvre un service de radiodiffusion sonore numérique de haute qualité destiné aux récepteurs domestiques et mobiles s'impose de plus en plus. On assiste aujourd'hui à la pénétration croissante des techniques numériques, tant au niveau de la production des programmes qu'à celui de l'enregistrement. Il devient donc souhaitable de rendre cohérent l'ensemble de la chaîne "production, diffusion, réception", et par conséquent de proposer à l'usager un service de radiodiffusion sonore numérique d'une qualité équivalente à celle du disque compact. Le système proposé par le CCETT pour la radiodiffusion proprement dite s'appelle COFDM (Coded Orthogonal Frequency Division Multiplex). Ce système est particulièrement adapté à la diffusion de signaux numériques de hauts débits dans des canaux affectés de trajets multiples dont les caractéristiques varient dans le temps (réception mobile en milieu urbain). Il permet actuellement de transmettre 16 programmes stéréophoniques et des voies de données, soit un débit global de 5,6 Mbit/s, dans un canal de 7 MHz

Démodulation coherente du systeme de transmission multiporteuses COFDM dans un canal de radio mobile

Au cours des années passées, les progrès des techniques de codage à compression de débit de l'image et du son ont ouvert la voie aux concepts de diffusion numérique des signaux audiovisuels. En associant ces techniques à des procédés de modulation et de codage de canal adaptés aux caractéristiques des milieux de transmission, on dispose des éléments constitutifs d'une chaîne de diffusion numérique complète. Les développements relatifs à la radio numérique de qualité laser, en tant que successeur de la FM, ont été menés dans le cadre du projet Eureka 147 DAB. Aux Etats-Unis un vaste programme d'étude a pour but de définir un système de télévision à haute définition pour la diffusion terrestre dans des canaux de 6 MHz ! Cet article présente des résultats d'études en codage de canal et modulation, qui s'inscrivent précisément dans ce contexte de développement technologique très intense

Analysis of the coverage probability of cellular multicast single frequency networks

International audienceVideo streaming and mobile TV services have recently gained great research interest with the advances in mobile hardware technologies and the development of single frequency networks (SFN). However, the analysis of the coverage probability of these services in SFN has been and remains a complicated task due to the specific behavior of the received SFN signal and its effect on the useful signal. In this framework, we propose a new approach to model and evaluate the coverage probability for such network configuration. More particularly, using stochastic geometry, we propose a suitable approximation of the problem based on the closest SFN base stations. The resulted expressions represent a lower bound for the probability of coverage of the SFN. The proposed approximation leads to a good trade-off between accuracy and tractability. Numerical simulation results prove the validity of the proposed approach and related theoretical results, especially in a high path loss environment. © 2019 IEEE

Increase of DSTM Spectral Efficiency by the Extension of the Mathematical Weyl Group with Application to Differential MIMO Systems

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Theoretical performance of the gradient-based tone reservation PAPR reduction algorithm

International audienceIn this paper, we provide a theoretical analysis on the performance of the famous Gradient-based Tone-Reservation PAPR reduction algorithm. To that end, we study the amplitude statistical distribution of the time domain OFDM signals to which PAPR reduction has been applied. Such distribution is then integrated into a generic EVM expression in order to provide a closed form expression of this latter, which is validated and analyzed through numerical simulations. Thanks to this work, we provide theoretical tools to analytically assess the performance of the Gradient method relatively to the optimal TR algorithm, and hence allow further analysis about the complexity-PAPR reduction efficiency trade-off of TR PAPR reduction algorithms, which could be useful for the optimization of the power efficiency of any multicarrier system. © 2020 IEEE

Performance of DSTM MIMO systems using a double extension of the Weyl group in time-varying Rayleigh channel

International audienceThis paper presents a double extension of the mathematical Weyl group with the purpose of increasing the spectral efficiency of the Differential Space-Time Modulation (DSTM) scheme using this group of matrices. The error performance of the system is improved through an optimal selection of the matrices selected for a given spectral efficiency and an optimal mapping between the binary data vectors and the information matrices. Finally, the performance of the obtained system is evaluated using a more realistic time-varying channel model

Improving Energy Efficiency in Massive MIMO: Joint Digital Beam-steering and Tone-reservation PAPR Reduction

In this study, the authors propose a novel architecture based on the combination of peak-to-average power ratio (PAPR) reduction with digital beamforming (BF) for mm-wave massive multiple-input multiple-output (MIMO) systems. In order to keep the power amplifiers (PAs) working at the same input back-off thus maximising the system power efficiency, they propose to perform time-domain transmit beam-steering by adding progressive time delays to the signals at each antenna element, while keeping the amplitude weights unitary. They show that these time delays can be obtained with a finite impulse response filter implementation of time-domain fractional delay filter structures such as Lagrange interpolation polynomials. They also introduce an analysis on the PAPR of the interpolated signals, where they derive an upper bound to it and show that its value is similar to that of the signal at the input of the interpolation filters, showing the feasibility of the proposed method. In addition, they present a detailed analysis where they show that a significant reduction in computational complexity is obtained when compared to frequency-domain BF. Simulation results validate that the novel proposed scheme combining PAPR reduction and digital BF offers high-precision beam-steering maintaining reduced PAPR in the delayed signals fed to the antennas