This dissertation presents the continued study of a non-iterative decision feedback (DF) receiver/decoder design and its application to cellular communications or wireless local loop systems based on the IS-95(-A) standard of the Telecommunications Industry Association and also Personal Communications Services systems based on the American National Standards Institute standard J-STD- 008-1996, which use code-division multiple access (CDMA) spread spectrum technology. Specifically, the DF decoder presented herein can be used in the uplink of these systems, which simultaneously uses a concatenation of convolutional coding, interleaving, and orthogonal Walsh modulation. The main contributions of this dissertation are the demonstration that the DF concept works well in multipath fading environments, the design of a new time-efficient decoding algorithm, and a new interleaver design. Initially, the performance of the DF decoder is assessed in unfaded as well as Rayleigh fading multipath propagation in additive white Gaussian noise interference. Simulation results using coherent and noncoherent detection are presented for both independent Rayleigh fading and Rayleigh fading with a commonly used Doppler spectrum. The results show improved performance compared to conventional non-DF receivers using the same decoding metric. This is a prerequisite for application of the DF decoder in an actual mobile communications environment. The effectiveness of the initial DF decoder design, as it is applied to IS-95 based systems, is studied. It is found that the effectiveness of the DF decoder is determined by the decoding delay of the convolutional decoder and the interleaver specification. Based on these findings, two methodologies to improve the effectiveness of the DF decoder are investigated. First, the average decoding delay is reduced using sub-optimal convolutional decoding. Second, the combination of a new block interleaver design and the DF decoder is considered. Simulation results of average decoding delay, bit error rate and frame error rate are presented for coherent and noncoherent detection of unfaded and Rayleigh fading multipath signals. It is shown that both approaches result in better system performance, which can further improve the quality of service and/or capacity of an IS-95 based system. Finally, a simplified analysis of the DF decoder performance is presented. / Graduation date: 1999

Des applications compilées en code-octet et encodées dans le format de fichier class sont normalement chargées et exécutées par une machine virtuelle. La vérification du code-octet est un processus utilisé par une machine virtuelle pour renforcer la sécurité des systèmes distribués en garantissant la conformité du code de classes avec les règles du langage. Les algorithmes actuels de vérification du code-octet utilisent des approches comme l'analyse de flot de données, le model checking ou le code-certifié (similaire au proof-carrying code). Mais l'on dénote certains problèmes, en particulier dus aux sous-routines, avec soit des spécifications informelles et incomplètes, soit des algorithmes ne supportant qu'un sous-ensemble du jeu d'instructions du code-octet, ou encore des performances exponentielles proportionnellement à la taille du code des méthodes à vérifier. Dans ce mémoire nous présentons une technique de vérification du code-octet avec sous-routines par code-certifié. Nous présentons en particulier la conception d'un format de certificat, d'un algorithme de calcul de certificat et d'un algorithme de vérification pour l'ensemble du jeu d'instructions du code-octet. Notre algorithme de vérification a une complexité linéaire en proportion de la taille du code des méthodes. Le développement d'un vérificateur et d'un compilateur de certificats a servi à conduire des expérimentations qui montrent que le format de certificat proposé est suffisamment riche pour effectuer la vérification du code-octet. De plus, nous présentons les résultats de l'évaluation du coût en espace mémoire de la certification de classes avec une telle technique. L'observation montre un accroissement relativement faible de la taille d'un échantillon de plus de 35 000 classes suite à leur certification. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Vérification, Code-octet, Code-certifié, Analyse de flot de données, Sous-routines, Java.

The unprecedented growth of computing power and communication bandwidth in the last few decades has driven an explosion in the size and complexity of application software. Specifically, it has spurred an almost universal adoption of modular and extensible software designs, from ordinary PC applications, to operating systems kernels, and even to embedded systems. In many cases, however, the ability to extend software systems has come hand in hand with the need to isolate them from untrusted or potentially faulty extensions. This dissertation will focus on the important problem of code isolation, where existing techniques vary in many and often interrelated dimensions such as granularity, code complexity, invocation latency, dynamism, isolation strategy, permissible extension functionality, and degree of integration with the operating system kernel. Specifically, the implementation of a particular technique imposes restrictions on the properties of extensions. Examples include proof-based techniques that are only applicable to simple extensions of small granularity, hardware-based isolation techniques that typically incur a measurable invocation latency due to hardware re-configuration overhead, and programming language techniques that impose implementation and compiler restrictions. The goal of this dissertation is to explore the design space of code isolation techniques, identify characteristics of individual approaches, and then argue for and design a hybrid approach that combines their advantages while avoiding their drawbacks. The contributions of this thesis will be threefold: (1) a taxonomy of metrics and properties relevant to software code isolation techniques, (2) the design and implementation of a novel hybrid architecture for safe kernel extension with pliable characteristics, and (3) an evaluation of the hybrid approach and comparison with homogeneous alternatives.

Design of low power Turbo decoder is one of the key issues in many modern communication systems such as 3 GPP. For the Turbo decoder architecture, the memory for the storage of the branch metric and state metric represents a major part of the entire decoder no matter in silicon area or power dissipation. Therefore, instead of saving the computed branch memory, this thesis adopts an alternative approach by saving the input in order to generate the branch memory on line. Furthermore, a novel design of state metric unit is proposed such that the size of the total state metric can be effectively reduced by a half with slightly overhead of adders/subtractors. For non-recursive systematic encoding applications, the same design methodology can further reduce the number of arithmetic units required in the soft-output calculating module. Our preliminary experimental result shows that the proposed design methodology can achieve 40% and 13% reduction on the gate count and power dissipation respectively.

This is a research on Performance Analysis of Random Complementary Code Based MIMO-CDMA System. In the first instance we discuss the produce method of random complementary codes by the basic matrix and pole matrix. Pole matrix is the produce method of Walsh Hadamard matrix. We discuss the properties of random complementary codes by the pole matrix and realize its auto-correlation and cross-correlation are perfect. Apply random complementary codes on Distributed Users and Antennas. Random complementary codes have the ideal auto-correlation and cross-correlation by way of direct-sequence spreading system, so it can solve multi-path interference and multi-access interference effectively. Apply Space-Time Block Codes on Distributed time and Antennas in the same user. Systems combine RCC with STBC. I design STBC RCC-CDMA System and two receivers. We discuss Signal Synthesis Receiver and Distributed Antennas Receiver with Rayleigh fading channel. In Chapter 2, we start to introduce random complete complementary codes and its property to resist interferences in different transmission. Chapter 3 is the introduction Performance Analysis of Random Complementary Code Based MIMO-CDMA System with full correlated Rayleigh fading channel. Chapter 4 is the introduction Performance Analysis of Random Complementary Code Based MIMO-CDMA System with multi-path Rayleigh fading channel. Chapter 5 is the introduce conclusion and to research a goal in the future.

SAGE (Statement Analysis Grouping Evaluation) system is a statement-based parallelizing compiler designed for PIM (Processor-in-Memory) architectures. By extracting the potential parallelism and utilizing the capabilities of PIM architectures, this system can achieve better performance of the applications. It analyzes the source codes, transforms the codes, makes good executing schedule and generates the codes which can execute on PIM architectures. This thesis focuses on the implementation of the code generator in the SAGE system. The code generator can transforms the original source codes into subroutines according to the corresponding HBG (Hyper Block Graph) and execution schedule which is determined by the other modules of SAGE system. It generates subroutines, inserts necessary arguments, determines the positions of caller and callee and generates the interface program for executing on PIM simulator. The generated codes after our code generator are also discussed.

Abstract For reducing the interference of multi-path and multi-user access, we propose to design a spreading code with ideal auto-correlation and cross-correlation. In this paper, we will introduce a code with ideal auto-correlation and cross-correlation. Recently, there has been great interest in applying zero correlation spreading codes to reduce interference of different users or their multi-path. The set of sequences having zero auto-correlation and cross-correlation plays an important part in typical DS-CDMA systems. A periodic sequence with zero out-of-phase auto-correlation is called a perfect or an orthogonal sequence, it can mitigate the multi-path interference. Similarly, a set of periodic sequences with zero cross-correlation values is called a set of uncorrelated sequences. However, it is impossible to be found in single sequence spreading code. In this paper, we propose a new code for ideal auto-correlation and cross-correlation, and the code set size is equal to the number of flock size.

This thesis presents an analysis of energy efficient residential windows in hot and humid climates. To accomplish this analysis, the use of accurate simulation tools such as DOE-2.1e is required, which incorporates the results from the WINDOW-5.2 simulation program to assess accurate fenestration performance. The thesis also investigates the use of optimal glazing types, which, for future applications, could be specified in the code to reduce annual net energy consumption to zero. Results show that combinations of low-E and double pane, clear-glazed windows, which are optimally shaded according to orientation are the best solution for lowering both annual energy consumption and peak electricity loads. The study also concludes that the method used to model fenestration in the simulation program plays an important role in accurately determining the effectiveness of the glazing option used. In this particular study, the use of the WINDOW-5.2 program is highly recommended especially for high performance windows (i.e., low-E glazing). Finally, a discussion on the incorporation of super high performance windows (i.e., super low-E, ultra low-E and dynamic / switchable glazing) into the IECC code concludes that these types of glazing strategies can reduce annual net energy use of the window to zero. Future work identified by this thesis includes a more extensive examination of the passive solar potential of high performance fenestration, and an examination of the appropriate methods for specifying these properties in future versions of the IECC code. This implies that future specifications for fenestration in the IECC code could aim for zero net annual energy consumption levels from residential fenestration.

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