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

FPGA-Based Channel Coding Architectures for 5G Wireless Using High-Level Synthesis

We propose strategies to achieve a high-throughput FPGA architecture for quasi-cyclic low-density parity-check codes based on circulant-1 identity matrix construction. By splitting the node processing operation in the min-sum approximation algorithm, we achieve pipelining in the layered decoding schedule without utilizing additional hardware resources. High-level synthesis compilation is used to design and develop the architecture on the FPGA hardware platform. To validate this architecture, an IEEE 802.11n compliant 608 Mb/s decoder is implemented on the Xilinx Kintex-7 FPGA using the LabVIEW FPGA Compiler in the LabVIEW Communication System Design Suite. Architecture scalability was leveraged to accomplish a 2.48 Gb/s decoder on a single Xilinx Kintex-7 FPGA. Further, we present rapidly prototyped experimentation of an IEEE 802.16 compliant hybrid automatic repeat request system based on the efficient decoder architecture developed. In spite of the mixed nature of data processing—digital signal processing and finite-state machines—LabVIEW FPGA Compiler significantly reduced time to explore the system parameter space and to optimize in terms of error performance and resource utilization. A 4x improvement in the system throughput, relative to a CPU-based implementation, was achieved to measure the error-rate performance of the system over large, realistic data sets using accelerated, in-hardware simulation

An Optimizing Java Translation Framework for Automated Checkpointing and Strong Mobility

Long-running programs, e.g., in high-performance computing, need to write periodic checkpoints of their execution state to disk to allow them to recover from node failure. Manually adding checkpointing code to an application, however, is very tedious. The mechanisms needed for writing the execution state of a program to disk and restoring it are similar to those needed for migrating a running thread or a mobile object. We have extended a source-to-source translation scheme that allows the migration of mobile Java objects with running threads to make it more general and allow it to be used for automated checkpointing. Our translation scheme allows serializable threads to be written to disk or migrated with a mobile agent to a remote machine. The translator generates code that maintains a serializable run-time stack for each thread as a Java data structure. While this results in significant run-time overhead, it allows the checkpointing code to be generated automatically. We improved the locking mechanism that is needed to protect the run-time stack as well as the translation scheme. Our experimental results demonstrate an speedup of the generated code over the original translator and show that the approach is feasible in practice

Deep Generative Adversarial Networks: Applications in Musculoskeletal Imaging

In recent years, deep learning techniques have been applied in musculoskeletal radiology to increase the diagnostic potential of acquired images. Generative adversarial networks (GANs), which are deep neural networks that can generate or transform images, have the potential to aid in faster imaging by generating images with a high level of realism across multiple contrast and modalities from existing imaging protocols. This review introduces the key architectures of GANs as well as their technical background and challenges. Key research trends are highlighted, including: (a) reconstruction of high-resolution MRI; (b) image synthesis with different modalities and contrasts; (c) image enhancement that efficiently preserves high-frequency information suitable for human interpretation; (d) pixel-level segmentation with annotation sharing between domains; and (e) applications to different musculoskeletal anatomies. In addition, an overview is provided of the key issues wherein clinical applicability is challenging to capture with conventional performance metrics and expert evaluation. When clinically validated, GANs have the potential to improve musculoskeletal imaging.ope

Initial synchronisation in the multiple-input multiple-output aided single- and multi-carrier DS-CDMA as well as DS-UWB downlink

In this thesis, we propose and investigate code acquisition schemes employing both colocated and cooperative Multiple Input/Multiple Output (MIMO) aided Single-Carrier (SC) and Multi-Carrier (MC) Code Division Multiple Access (CDMA) DownLink (DL) schemes. We study their characteristics and performance in terms of both Non-Coherent (NC) and Differentially Coherent (DC) MIMO scenarios. Furthermore, we also propose iterative code acquisition schemes for the Direct Sequence-Ultra WideBand (DS-UWB) DL. There is a paucity of code acquisition techniques designed for transmit diversity aided systems. Moreover, there are no in-depth studies representing the fundamental characteristics of code acquisition schemes employing both co-located and cooperative MIMOs. Hence we investigate both NC and DC code acquisition schemes in the co-located and cooperative MIMO aided SC and MC DS-CDMA DL, when communicating over spatially uncorrelated Rayleigh channels. The issues of NC initial and post-initial acquisition schemes as well as DC schemes are studied as a function of the number of co-located antennas by quantifying the attainable correct detection probability and mean acquisition time performances. The research of DS-UWB systems has recently attracted a significant interest in both the academic and industrial community. In the DS-UWB DL, initial acquisition is required for both coarse timing as well as code phase alignment. Both of these constitute a challenging problem owing to the extremely short chip-duration of UWB systems. This leads to a huge acquisition search space size, which is represented as the product of the number of legitimate code phases in the uncertainty region of the PN code and the number of legitimate signalling pulse positions. Therefore the benefits of the iterative code acquisition schemes are analysed in terms of the achievable correct detection probability and mean acquisition time performances. Hence we significantly reduce the search space size with the aid of a Tanner graph based Message Passing (MP) technique, which is combined with the employment of beneficially selected generator polynomials, multiple receive antennas and appropriately designed multiple-component decoders. Finally, we characterise a range of two-stage iterative acquisition schemes employing iterative MP designed for a multiple receive antenna assisted DS-UWB DL scenario.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Error-resilient multi-view video plus depth based 3-D video coding

Three Dimensional (3-D) video, by definition, is a collection of signals that can provide depth perception of a 3-D scene. With the development of 3-D display technologies and interactive multimedia systems, 3-D video has attracted significant interest from both industries and academia with a variety of applications. In order to provide desired services in various 3-D video applications, the multiview video plus depth (MVD) representation, which can facilitate the generation of virtual views, has been determined to be the best format for 3-D video data. Similar to 2-D video, compressed 3-D video is highly sensitive to transmission errors due to errors propagated from the current frame to the future predicted frames. Moreover, since the virtual views required for auto-stereoscopic displays are rendered from the compressed texture videos and depth maps, transmission errors of the distorted texture videos and depth maps can be further propagated to the virtual views. Besides, the distortions in texture and depth show different effects on the rendering views. Therefore, compared to the reliability of the transmission of the 2-D video, error-resilient texture video and depth map coding are facing major new challenges. This research concentrates on improving the error resilience performance of MVD-based 3-D video in packet loss scenarios. Based on the analysis of the propagating behaviour of transmission errors, a Wyner-Ziv (WZ)-based error-resilient algorithm is first designed for coding of the multi-view video data or depth data. In this scheme, an auxiliary redundant stream encoded according to WZ principle is employed to protect a primary stream encoded with standard multi-view video coding codec. Then, considering the fact that different combinations of texture and depth coding mode will exhibit varying robustness to transmission errors, a rate-distortion optimized mode switching scheme is proposed to strike the optimal trade-off between robustness and compression effciency. In this approach, the texture and depth modes are jointly optimized by minimizing the overall distortion of both the coded and synthesized views subject to a given bit rate. Finally, this study extends the research on the reliable transmission of view synthesis prediction (VSP)-based 3-D video. In order to mitigate the prediction position error caused by packet losses in the depth map, a novel disparity vector correction algorithm is developed, where the corrected disparity vector is calculated from the depth error. To facilitate decoder error concealment, the depth error is recursively estimated at the decoder. The contributions of this dissertation are multifold. First, the proposed WZbased error-resilient algorithm can accurately characterize the effect of transmission error on multi-view distortion at the transform domain in consideration of both temporal and inter-view error propagation, and based on the estimated distortion, this algorithm can perform optimal WZ bit allocation at the encoder through explicitly developing a sophisticated rate allocation strategy. This proposed algorithm is able to provide a finer granularity in performing rate adaptivity and unequal error protection for multi-view data, not only at the frame level, but also at the bit-plane level. Secondly, in the proposed mode switching scheme, a new analytic model is formulated to optimally estimate the view synthesis distortion due to packet losses, in which the compound impact of the transmission distortions of both the texture video and the depth map on the quality of the synthesized view is mathematically analysed. The accuracy of this view synthesis distortion model is demonstrated via simulation results and, further, the estimated distortion is integrated into a rate-distortion framework for optimal mode switching to achieve substantial performance gains over state-of-the-art algorithms. Last, but not least, this dissertation provides a preliminary investigation of VSP-based 3-D video over unreliable channel. In the proposed disparity vector correction algorithm, the pixel-level depth map error can be precisely estimated at the decoder without the deterministic knowledge of the error-free reconstructed depth. The approximation of the innovation term involved in depth error estimation is proved theoretically. This algorithm is very useful to conceal the position-erroneous pixels whose disparity vectors are correctly received

Aeronautical Engineering: A continuing bibliography with indexes, supplement 97

This bibliography lists 420 reports, articles, and other documents introduced into the NASA scientific and technical information system in May 1978

Development of Carbon Nanotube Field-Effect Transistor Arrays for Detection of HER2 Overexpression in Breast Cancer

We developed a carbon nanotube biosensor platform that was deployed at the National Cancer Institute and successfully detected the HER2 oncogene in real cancer cells at clinically relevant levels. HER2 is a receptor protein that resides on the surface of certain cancer cells and is associated with higher aggressiveness in breast cancers. Overabundance of HER2 at the chromosomal, cell surface, and intermediate gene expression levels can all indicate a dangerous HER2 status. At the present, testing for HER2 status requires labor-intensive laboratory procedures using expensive reagents. Cost remains the major barrier to widespread screening. We propose an integrated electronic testing platform based on direct label-free gene detection. The system would integrate the various labor-intensive processes that are usually performed by skilled laboratory technicians. The heart of the system is an array of carbon nanotube field-effect transistors that can detect unlabelled nucleic acids via their intrinsic electric charges. We developed a scalable fabrication technique for carbon nanotube biosensor arrays, hardware and software for data acquisition and analysis, theoretical models for detection mechanism, and protocols for immobilization of peptide nucleic acid probes and hybridization of nucleic acids extracted from cells. We demonstrated detection of HER2 from real cell lines which express cancer genes, thereby lowering the technological barrier towards commercialization of a low-cost gene expression biosensor. The system is suitable for lab-on-a-chip integration, which could bring rapid, low-cost cancer diagnoses into the clinical setting