Linear predictive receivers for phase-uncertain channels

In this paper, we propose linear predictive receivers for phaseuncertain channels. These receivers are attractive from a conceptual viewpoint because they generalize previous solutions based on noncoherent sequence detection. On the practical side, the proposed algorithms lend themselves to the implementation of adaptive receivers capable of copying with possible time variations of the statistics of the underlying phase model. 1

Low-complexity Noncoherent Iterative CPM Demodulator for FH Communication

In this paper, we investigate the noncoherent iterative demodulation of coded continuous phase modulation (CPM) in frequency hopped (FH) systems. In this field, one important problem is that the complexity of the optimal demodulator is prohibitive unless the number of symbols per hop duration is very small. To solve this problem, we propose a novel demodulator, which reduces the complexity by applying phase quantization and exploiting the phase rotational invariance property of CPM signals. As shown by computational complexity analysis and numerical results, the proposed demodulator approaches the performance of the optimal demodulator, and provides considerable performance improvement over the existing solutions with the same computational complexity

Coherent and Non-coherent Techniques for Cooperative Communications

Future wireless network may consist of a cluster of low-complexity battery-powered nodes or mobile stations (MS). Information is propagated from one location in the network to another by cooperation and relaying. Due to the channel fading or node failure, one or more relaying links could become unreliable during multiple-hop relaying. Inspired by conventional multiple-input multiple-output (MIMO) techniques exploiting multiple co-located transmit antennas to introduce temporal and spatial diversity, the error performance and robustness against channel fading of a multiple-hop cooperative network could be significantly improved by creating a virtual antenna array (VAA) with various distributed MIMO techniques. In this thesis, we concentrate on the low-complexity distributed MIMO designed for both coherent and non-coherent diversity signal reception at the destination node. Further improvement on the network throughput as well as spectral efficiency could be achieved by extending the concept of unidirectional relaying to bidirectional cooperative communication. Physical-layer network coding (PLNC) assisted distributed space-time block coding (STBC) scheme as well as non-coherent PLNC aided distributed differential STBC system are proposed. It is confirmed by the theoretical analysis that both approaches have the potential for offering full spatial diversity gain. 　　 Furthermore, differential encoding and non-coherent detection techniques are generally associated with performance degradation due to the doubled noise variance. More importantly, conventional differential schemes suffer from the incapability of recovering the source information in time-varying channels owing to the assumption of static channel model used in the derivation of non-coherent detection algorithm. Several low-complexity solutions are proposed and studied in this thesis, which are able to compensate the performance loss caused by non-coherent detection and guarantee the reliable recovery of information in applications with high mobility. A substantial amount of iteration gain is achieved by combining the differential encoding with error-correction code and sufficient interleaving, which allows iterative possessing at the receiver

Optimisation de la transmission de phonie et vidéophonie sur les réseaux à larges bandes PMR

Cet exposé analyse les perspectives large bande des réseaux PMR, à travers l'évaluation du candidat LTE, et la proposition d'une possible évolution du codage canal, la solution brevetée des codes turbo à protection non uniforme. Une première étude dans le chapitre 2 se concentre sur l'analyse multi-couche et l'identification des problèmes clé des communications de voix et de vidéo sur un réseau LTE professionnel. Les capacités voix et vidéo sont estimées pour les liens montant et descendant de la transmission LTE, et l'efficacité spectrale de la voix en lien descendant est comparée à celle de PMR et GSM. Ce chapitre souligne certains points clé de l'évolution de LTE. S'ils étaient pas résolus par la suite, LTE se verrait perdre de sa crédibilité en tant que candidat à l'évolution de la PMR. Une telle caractéristique clé des réseaux PMR est le codage canal à protection non uniforme, qui pourrait être adapté au système LTE pour une évolution aux contraintes de la sécurité publique. Le chapitre 3 introduit cette proposition d'évolution, qui a été brevetée: les turbo codes à protection non uniforme intégrée. Nous proposons une nouvelle approche pour le codage canal à protection non uniforme à travers les codes turbo progressives hiérarchiques. Les configurations parallèles et séries sont analysées. Les mécanismes de protection non uniformes sont intégrés dans la structure de l'encodeur même à travers l'insertion progressif et hiérarchique de nouvelles données de l'utilisateur. Le turbo décodage est modifié pour exploiter de façon optimale l'insertion progressive de données dans le processus d'encodage et estimer hiérarchiquement ces données. Les propriétés des structures parallèles et séries sont analysées à l'aide d'une analogie aux codes pilotes, ainsi qu'en regardant de plus près leurs caractéristiques de poids de codage. Le taux de transmission virtuel et les représentations des graphs factor fournissent une meilleure compréhension de ces propriétés. Les gains de codage sont évalués à l'aide de simulations numériques, en supposant des canaux de transmission radio statiques et dynamiques, et en utilisant des codes de référence. Enfin, dans le chapitre 4, l'idée breveté du code turbo parallal progressif et hiérarchique (PPHTC) est évaluée sur la plateforme LTE. Une description détaillée de l'architecture des bearers de LTE est donnée, et ses conséquences sont discutées. Le nouveau codage canal est inséré et évalué sur cette plateforme, et ses performances sont comparées avec des schémas de transmission typique à LTE. L'analyse de la qualité de la voix aide à conclure sur l'efficacité de la solution proposée dans un système de transmission réel. Pourtant, même si cette dernière donne les meilleurs résultats, d'avantage d'optimisations devraient être envisagées pour obtenir des gains améliorés et mieux exploiter le potentiel du codage proposé. L'exposé se conclut dans le chapitre 5 et une courte discussion présente les futures perspectives de rechercheThis dissertation analyzes the PMR broadband perspectives, through the evaluation of the preferred candidate, LTE, and the proposal of a possible channel coding evolution, the patented solution of unequal error protection embedded turbo codes. A first study in chapter 2 focuses on the multi-layer analysis and the identification of key issues for professional-like LTE for voice and video communications. The voice and video capacities are estimated for both downlink and uplink LTE transmissions, and the downlink LTE voice system efficiency is compared with that of the PMR and Global System for Mobile Communications (GSM). This chapter helps highlighting some of the key points. If not resolved, the latter could lead to the LTE downfall as a candidate for the PMR evolution. One such key characteristic of PMR systems is the unequal error protection channel coding technique, which might be adapted to the LTE technology for its evolution to public safety requirements. Chapter 3 further introduces the proposed evolution patented ideas: the unequal error protection embedded turbo codes. We propose a new approach for the unequal error protection channel coding through the progressive hierarchical turbo codes. Both parallel and serial turbo configurations are closely studied. The unequal error protection mechanisms are embedded in the encoder s structure itself through the progressive and hierarchical insertion of new data. The turbo decoding is modified as to optimally exploit the progressive insertion of information in the encoding process and hierarchically estimate the corresponding data. Both parallel and serial configurations properties are analyzed using an analogy with a pilot code behavior, as well as a zoom on the weight error functions coefficients. The virtual code rate and factor graph interpretations also provide a better insight on the code properties. The code possible gains are highlighted through computer simulations in both static and dynamic transmission environments, by using carefully chosen benchmarks. Finally, in chapter 4, the patented idea of parallel progressive hierarchical turbo codes (PPHTC) is evaluated over the LTE platform. A detailed description is given of the voice transmission bearer architecture over LTE, and its consequences are discussed. The new channel code is inserted and evaluated over this platform and its performances compared with the existent LTE transmission schemes. The voice quality results help concluding on the efficiency of the proposed solution in a real transmission scenario. However, even though the newly presented solution gives the best results, further system optimizations should be envisaged for obtaining better gains and exploit the parallel progressive hierarchical turbo codes potential. The dissertation concludes in chapter 5 and a short discussion is given on future research perspectivesEVRY-INT (912282302) / SudocSudocFranceF

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Particules déterministes généralisées en filtrage non-linéaire : applications défense et télécommunications

La technique de filtrage particulaire s'applique à tous les problèmes d'estimation des systèmes dynamiques markoviens, sans restriction sur la nature des non-linéarités et/ou des distributions de bruits. L'objet de ce mémoire est de montrer la généralité de la technique déterministe en filtrage particulaire, par opposition à l'ancienne version aléatoire, qui permet d'éviter l'aléa inutilement introduit tant en prédiction qu'une redistribution des particules après pondération bayésienne. Le présent travail, s'articule autour de deux apports: Le premier, concerne le filtrage optimal à maximum de vraisemblance, et porte sur l'estimation trajectorielle globale des variables d'état. Le second portant sur le filtrage particulaire déterministe, concerne le filtrage optimal à minimum de variance, et porte sur l'estimation marginale à l'instant courant, par redistribution déterministe conforme en loi. Cette approche délivre simultanément tous les modes (maxima locaux) de la densité de probabilité marginale de l'état courant. Le mémoire met l'accent sur plusieurs réalisations dans des domaines différents, communications: Nous avons développé un outil à base de filtrage particulaire qui permet d'estimer conjointement des paramètres cinématiques relatifs au récepteur et la détection du message transmis par un satellite. Nous avons également proposé une série de schémas d'estimation/décodage itératifs du message turbo-codé conforme au standard DVB-RCS. Estimation de cible en sonar: On a construit un récepteur passif particulaire se contentant d'écouter sa cible, afin d'identifier ses paramètres cinématiques. La version déterministe permet de faire diminuer considérablement la masse de calculs. Traitement du signal radar: Le premier récepteur déterministe, à maximum de vraisemblance est utilisé pour la détection/poursuite de cibles furtives et manoeuvrantes, dans le cas où il y un nombre très limité de mesures disponibles pendant un tour d'antenne du radar de veille. Le second récepteur consiste à appliquer la technique à minimum de variance au radar ARMOR, ce qui a permis de confirmer des gains inhabituels en termes de rapport signal sur bruit. La nouvelle technique déterministe à minimum de variance s'étend également au multi-cible et au traitement en présence de fouillis, avec l'incomparable économie calculatoire du déterministe.Particle filters are presently among the most powerful tools to estimate Markovian dynamical systems, regardless of the nature of nonlinearities and/or noise probability distributions. The purpose of this dissertation is to show the generality of deterministic particle filtering, as opposed to the former random version, which avoids randomization in the prediction stage as well as in the resampling stage after Bayesian correction. This work relies on two kinds of results: the first concerns the particle filter-based maximum likelihood estimator for sequential estimation of the state variables. The second patent, introducing deterministic particle filtering in the minimum variance sense, focuses on the current state marginal estimation using a resampling scheme consistant with the a posteriori distribution. This approach simultaneously delivers all modes (local maxima) of the marginal probability density function of the current state. The thesis focuses on several achievements in various fields: communications: The proposed particle algorithm makes possible the joint estimation of the kinematic channel parameters at the receiver side and the detection of the message transmitted by a satellite. We have also proposed several techniques for the iterative estimation and decoding of the turbo-coded message compliant with the DVB-RCS standard. Target estimation for sonar: We built a passive particle receiver only listening to its target, in order to identify its kinematic parameters. The deterministic version allows to significantly reduce the computational complexity. Radar signal processing: The first receiver , with deterministic maximum likelihood filtering, is used for the detection / tracking of steady and manoeuvering targets , when there is a very limited number of available measurements during a circular period of antenna of the radar. The second receiver applies the minimum variance technique to the ARMOR radar, confirming unusually high signal-to-noise gains. The novel deterministic technique based on minimum variance criteria can easily be extended to multitarget processing and tracking in the presence of clutter, with the incomparable complexity savings due to the deterministic technique

Towards Computational Efficiency of Next Generation Multimedia Systems

To address throughput demands of complex applications (like Multimedia), a next-generation system designer needs to co-design and co-optimize the hardware and software layers. Hardware/software knobs must be tuned in synergy to increase the throughput efficiency. This thesis provides such algorithmic and architectural solutions, while considering the new technology challenges (power-cap and memory aging). The goal is to maximize the throughput efficiency, under timing- and hardware-constraints

Technology 2001: The Second National Technology Transfer Conference and Exposition, volume 2

Proceedings of the workshop are presented. The mission of the conference was to transfer advanced technologies developed by the Federal government, its contractors, and other high-tech organizations to U.S. industries for their use in developing new or improved products and processes. Volume two presents papers on the following topics: materials science, robotics, test and measurement, advanced manufacturing, artificial intelligence, biotechnology, electronics, and software engineering