Ce travail est consacré à la conception, l'analyse et l'optimisation des codes correcteurs d'effacements de niveau applicatif (AL-FEC). Nous nous intéressons à une famille des codes LDPC généralisés (GLDPC), nommés les codes GLDPC-Staircase, qui sont composé d'un code LDPC-Staircase code de base ainsi que des codes Reed-Solomon (RS) (codes externes). Dans la première partie de cette thèse, nous commençons par montrer que les codes RS ayant une construction basée sur la matrice "quasi" Hankel sont les codes MDS les plus appropriés pour obtenir la structure des codes GLDPC-Staircase. Ensuite, nous proposons un nouveau type de décodage à ces codes, baptisé décodage hybride (IT/RS/ML), pour atteindre les capacités de correction du décodage par maximum de vraisemblance (ML) avec de faible complexité. Afin d'étudier l'impact de la structure des codes GLDPC-Staircase sur le décodage, nous proposons une autre construction : ils diffèrent sur la nature des symboles de redondance LDPC générés. Puis, pour prédire le seuil de décodage et les écarts par rapport à la limite de Shannon des codes GLDPC-Staircase, nous élaborons une analyse asymptotique en fonction de la technique d'évolution de densité (DE), les technique EXIT (Extrinsic Information Transfer) et la théorème d'air. Finalement, en se basant sur l'analyse à taille finie et l'analyse asymptotique, nous réglons les importants paramètres internes de ces codes pour obtenir la configuration optimale sous le décodage hybride (IT/RS/ML). La deuxième partie de la thèse est consacrée à l'étude des codes GLDPC-Staircase dans diverses situations. Tout d'abord, nous montrons que ces codes ont des performances asymptotiquement très proches des limites théoriques de Shannon. En plus, à taille fini, ils permettent d'atteindre d'excellentes capacités de correction d'effacements (i.e., très proches de celle des codes MDS idéal) peu importe la taille des objets : très faible overhead de décodage, faible plancher d'erreur, et une zone ``waterfull'' raide. Nous montrons aussi que ces codes surpassent les codes Raptor, les codes LDPC-Staircase, et un autre code GLDPC avec une construction differente. Finallement, nous proposons une méthodologie générale pour régler le problème de l'impact de l'ordonnancement des paquets sur les performance des codes GLDPC-Staircase sur un grand nombre des canaux à effacements (avec perte en rafale ou pas). Cette étude montre le meilleur ordonnancement de paquets. Tous les résultats mentionnés ci-dessus montrent que les codes GLDPC-Staircase peuvent considérés comme des codes FEC de niveau applicatif (AL-FEC) universelle. / This work is dedicated to the design, analysis and optimization of Application-Level Forward Erasure Correction (AL-FEC) codes. In particular, we explore a class of Gen- eralized LDPC (GLDPC) codes, named GLDPC-Staircase codes, involving the LDPC- Staircase code (base code) as well as Reed-Solomon (RS) codes (outer codes). In the first part of this thesis, we start by showing that RS codes having “quasi” Han- kel matrix-based construction are the most suitable MDS codes to obtain the structure of GLDPC-Staircase codes. Then, we propose a new decoding type, so-called hybrid (IT/RS/ML) decoding, for these codes to achieve Maximum Likelihood (ML) correction capabilities with a lower complexity. To investigate the impact of the structure of GLDPC- Staircase codes on decoding, we propose another construction: they differ on the nature of generated LDPC repair symbols. Afterwards, to predict the capacity approaching GLDPC- Staircase codes, we derive an asymptotic analysis based on DE, EXIT functions, and area theorem. Eventually, based on finite length analysis and asymptotic analysis, we tune important internal parameters of GLDPC-Staircase codes to obtain the best configuration under hybrid (IT/RS/ML) decoding. The second part of the thesis benchmarks GLDPC-Staircase codes in various situations. First, we show that these codes are asymptotically quite close to Shannon limit performance and achieve finite length excellent erasure correction capabilities very close to that of ideal MDS codes no matter the objects size: very small decoding overhead, low error floor, and steep waterfall region. Second, we show that these codes outperform Raptor codes, LDPC- Staircase codes, other construction of GLDPC codes, and have correction capabilities close to that of RaptorQ codes. Last but not least, we propose a general-methodology to address the problem of the impact of packet scheduling on GLDPC-Staircase codes for a large set of loss channels (with burst loss or not). This study shows the best packet scheduling. All the aforementioned results make GLDPC-Staircase codes an ubiquitous Application-Level FEC (AL-FEC) solution.

What can be learned about design through the process of building? The intent of this thesis is to learn about building; to gain a true understanding of the way design decisions are realized through built components. If by knowing what is to come in a project's future, does the designer change their way of working? A disconnect exists between imagined and realized design. As an idea moves closer to reality, much of its' initial spirit can be lost in translation. This thesis was conceived as a design-build project, in an attempt to answer these questions. The intent was to consider a small-scale, built addition to an existing structure with a program simply focused on providing a place to vew from. By limiting the scope of building to a simple structure, it inherently forces a complete understanding of the nature of its connection. Through this consideration, one also must consider the limitations of assembling the work; that is, what are one or two people capable of making? The limits of solidarity result in a design that requires modularity; something that is able to be broken down into small, manageable pieceswhich are assembled to produce a whole. Therein lies both the challenge and the value of this thesis, as well as the lessons learned in building architecture. / Master of Architecture / What can be learned about design through the process of building? The aim of this Thesis was to take fundamental theoretical knowledge about building, acquired through my architectural education, and apply it through building a small structure. A freestanding concrete staircase, located at a research facility on Virginia Tech's campus, was chosen for the structure's site. The intent was to add an additional set of stairs to it, allowing visitors to reach a higher viewing point to look out over the hills of Blacksburg. The project was conceived as something small enough to be built quickly and with few people. By using primarily wood and simple hardware store materials, the project would be easy to work on and relatively inexpensive.

No description available.

Electronic signal processing techniques have assumed a prominent role in the design of fibre-optic communication systems. However, state-of-the-art systems operate at per-channel data rates of 100 Gb/s, which constrains the class of communication algorithms that can be practically implemented. Relative to LDPC-like codes, product-like codes with syndrome-based decoding have decoder dataflow requirements that are smaller by more than two orders of magnitude, which strongly motivates the search for powerful product-like codes. This thesis presents a new class of high-rate binary error-correcting codes, staircase codes, whose construction combines ideas from convolutional and block coding. A G.709-compliant staircase code is proposed, and FPGA-based simulation results show that performance within 0.5 dB of the Shannon Limit is attained for bit-error-rates below 1E-15. An error-floor analysis technique is presented, and the G.709-compliant staircase code is shown to have an error floor below 1E-20. Using staircase codes, a pragmatic approach for coded modulation in fibre-optic communication systems is presented that provides reliable communications to within 1 bit/s/Hz of the capacity of a QAM-modulated system modeled via the generalized non-linear Schrodinger equation. A system model for a real-world DQPSK receiver with correlated bit-errors is presented, along with an analysis technique to estimate the resulting error floor for the G.709- compliant staircase code. By applying a time-varying pseudorandom interleaver of size 2040 to the output of the encoder, the error floor of the resulting system is shown to be less than 1E-20.

Electronic signal processing techniques have assumed a prominent role in the design of fibre-optic communication systems. However, state-of-the-art systems operate at per-channel data rates of 100 Gb/s, which constrains the class of communication algorithms that can be practically implemented. Relative to LDPC-like codes, product-like codes with syndrome-based decoding have decoder dataflow requirements that are smaller by more than two orders of magnitude, which strongly motivates the search for powerful product-like codes. This thesis presents a new class of high-rate binary error-correcting codes, staircase codes, whose construction combines ideas from convolutional and block coding. A G.709-compliant staircase code is proposed, and FPGA-based simulation results show that performance within 0.5 dB of the Shannon Limit is attained for bit-error-rates below 1E-15. An error-floor analysis technique is presented, and the G.709-compliant staircase code is shown to have an error floor below 1E-20. Using staircase codes, a pragmatic approach for coded modulation in fibre-optic communication systems is presented that provides reliable communications to within 1 bit/s/Hz of the capacity of a QAM-modulated system modeled via the generalized non-linear Schrodinger equation. A system model for a real-world DQPSK receiver with correlated bit-errors is presented, along with an analysis technique to estimate the resulting error floor for the G.709- compliant staircase code. By applying a time-varying pseudorandom interleaver of size 2040 to the output of the encoder, the error floor of the resulting system is shown to be less than 1E-20.

This thesis presents a new low complexity erasure decoder for staircase codes in optical interconnects between data centers. We developed a parallel software simulation environment to measure the performance of the erasure decoding techniques at output error rates relevant to an optical link. Low complexity erasure decoding demonstrated a 0.06dB increase in coding gain when compared to bounded distance decoding at an output error rate of 3 × 10⁻¹². Further, a log-linear extrapolation predicts a gain of 0.09dB at 10⁻¹⁵. This performance improvement is achieved without an increase in the maximum number of decoding iteration and keeping power constant. In addition, we found the optimal position within the decoding window to apply erasure decoding to minimize iteration count and output error rates, as well as the erasure threshold that minimizes the iteration count subject to the constrained erasure decoding structure.

No description available.

Ce travail est consacré à la conception, l'analyse et l'optimisation des codes correcteurs d'effacements de niveau applicatif (AL-FEC). Nous nous intéressons à une famille des codes LDPC généralisés (GLDPC), nommés les codes GLDPC-Staircase, qui sont com- posés d'un code LDPC-Staircase (code de base) ainsi que des codes Reed-Solomon (RS) (codes externes). Dans la première partie de cette thèse, nous commençons par montrer que les codes RS ayant une construction basée sur la matrice "quasi" Hankel sont les codes MDS les plus appropriés pour obtenir la structure des codes GLDPC-Staircase. Ensuite, nous proposons un nouveau type de décodage à ces codes, baptisé le décodage hybride (IT/RS/ML), pour atteindre les caspacités de correction du décodage par maximum de vraisemblance (ML) avec de faible complexité. Afin d'étudier l'impact de la structure des codes GLDPC- Staircase sur le décodage, nous proposons une autre construction : ils se diffèrent sur la nature des symboles de redondance LDPC générés. Puis, pour prédire le seuil de décodage et les écarts par rapport à la limite de Shannon des codes GLDPC-Staircase, nous élaborons une analyse asymptotique en fonction de la technique d'évolution de densité (DE), la technique EXIT (Extrinsic Information Transfer) et le théorème d'air. Finalement, en se basant sur l'analyse à taille finie et l'analyse asymptotique, nous ajustons les différentes paramètres internes de ces codes pour obtenir la configuration optimale sous le décodage hybride (IT/RS/ML). La deuxième partie de la thèse est consacrée à l'étude des codes GLDPC-Staircase dans diverses situations. Tout d'abord, nous montrons que ces codes ont des performances asymptotiquement très proches de la limite de Shannon. En plus, à taille finie, ils permet- tent d'atteindre d'excellentes capacités de correction d'effacements (i.e., très proches de celles des codes MDS) peu importe la taille des objets : très faible overhead de décodage, faible plancher d'erreur, et une zone "waterfall" raide. Nous montrons aussi que les performances de ces codes sont trés proches des codes RaptorQ et surpassent celles des codes Raptor, les codes LDPC-Staircase, et un autre code GLDPC avec une construction différente. Finalement, nous proposons une méthodologie générale pour étudier l'impact de l'ordonnancement des paquets envoyés sur les performances des codes GLDPC-Staircase sur un grand nombre des canaux à effacements (avec des pertes en rafale ou pas). Cette étude montre le meilleur ordonnancement de paquets. Tous les résultats mentionnés ci-dessus montrent que les codes GLDPC-Staircase peuvent considérés comme des codes AL-FEC universels.

Skolan har ett stort inflytande på dagens ungdomar och enligt läroplanen har skolan ett tydligt jämlikhetsuppdrag att förmedla. Att hjälpa eleven att problematisera människors lika värde oavsett kön och etnicitet samt bemöta fördomar med kunskap ingår i de mål lärarna bör ha sett till läroplanens formuleringar. Dock besitter kanske inte alla lärare de kunskaper som behövs om bland annat jämlikhet, jämställdhet, genus och etnicitet, om ett genuint intresse inte finns hos den enskilda personen. Kan läroböcker då ge läraren stöd? I svenskämnet ska eleverna i svenska 1 bland annat arbeta med området sociolekter, ett avsnitt som i stor utsträckning ger utrymme till både diskussion och reflektion i nämnda frågor. Syftet med uppsatsen är att se hur ser det ut i 5 av de läromedlen som finns i skolan. Är de jämlika och uppfyller de ett jämlikhetssyfte?   Undersökningen bygger på sociolektavsnittet i fem olika läromedel som är framtagna för gymnasiets kurs i svenska 1 respektive A. Till hjälp har två analysmodeller använts, genustrappan och etnicitettrappan. Resultatet visar att inget av de granskade läromedlen kan användas som hjälp i arbetet med jämlikhetsfrågor men att texterna kan nå ett jämlikhetssyfte om den enskilda läraren själv problematiserar och diskuterar exemplen. Samtidigt är de inte diskriminerande utan snarare könsneutrala, ett omdöme som dock inte är att sträva efter utifrån den forskning som gjorts inom jämställdhet.

This report is a Southern Paiute ethnographic study of the Grand Staircase- Escalante NM. This is the first report of activities conducted by the University of Arizona regarding Kaibab Paiute ethnographic resources currently within the boundaries of the Grand Staircase-Escalante National Monument (GSENM). The GSENM is a very large area that has been carved out of some of the most topographically and ecologically diverse lands in North America and contain a range of important Southern Paiute cultural resources and places. The Kaibab Paiute people were one of a number of Southern Paiute districts of the Southern Paiute nation who traditionally and aboriginally occupied and used the biotic and abiotic resources of this area. This study details the physical, prehistoric, historic, and cultural ties between the Southern Paiutes and the GSENM. In addition, this report presents the current relations of Southern Paiutes to this cultural landscape and the ways in which resource appropriation from the past continues to impact expressions of power in the present.