This dissertation presents measures of efficiency and locality for Internet addressing schemes. Historically speaking, many issues, faced by the Internet, have been solved just in time, to make the Internet just work~\cite{justWork}. Consensus, however, has been reached that today's Internet routing and addressing system is facing serious scaling problems: multi-homing which causes finer granularity of routing policies and finer control to realize various traffic engineering requirements, an increased demand for provider-independent prefix allocations which injects unaggregatable prefixes into the Default Free Zone (DFZ) routing table, and ever-increasing Internet user population and mobile edge devices. As a result, the DFZ routing table is again growing at an exponential rate. Hierarchical, topology-based addressing has long been considered crucial to routing and forwarding scalability. Recently, however, a number of research efforts are considering alternatives to this traditional approach. With the goal of informing such research, we investigated the efficiency of address assignment in the existing (IPv4) Internet. In particular, we ask the question: ``how can we measure the locality of an address scheme given an input AS-level graph?'' To do so, we first define a notion of efficiency or locality based on the average number of bit-hops required to advertize all prefixes in the Internet. In order to quantify how far from ``optimal" the current Internet is, we assign prefixes to ASes ``from scratch" in a manner that preserves observed semantics, using three increasingly strict definitions of equivalence. Next we propose another metric that in some sense quantifies the ``efficiency" of the labeling and is independent of forwarding/routing mechanisms. We validate the effectiveness of the metric by applying it to a series of address schemes with increasing randomness given an input AS-level graph. After that we apply the metric to the current Internet address scheme across years and compare the results with those of compact routing schemes.

Homes are involved in a significant fraction of Internet traffic. However, meaningful and comprehensive information on the structure and use of home networks is still hard to obtain. The two main challenges in collecting such information are the lack of measurement infrastructure in the home network environment and individuals’ concerns about information privacy. To tackle these challenges, the dissertation introduces Home Network Flow Logger (HNFL) to bring lightweight privacy-preserving passive measurement to home networks. The core of HNFL is a Linux kernel module that runs on resource-constrained commodity home routers to collect network traffic data from raw packets. Unlike prior passive measurement tools, HNFL is shown to work without harming either data accuracy or router performance. This dissertation also includes a months-long field study to collect passive measurement data from home network gateways where network traffic is not mixed by NAT (Network Address Translation) in a non-intrusive way. The comprehensive data collected from over fifty households are analyzed to learn the characteristics of home networks such as number and distribution of connected devices, traffic distribution among internal devices, network availability, downlink/uplink bandwidth, data usage patterns, and application traffic distribution.

Este trabalho apresenta um novo algoritmo, denominado Intercalamento Temporal por Transformada de Fourier (FTI), desenvolvido para complementar sistemas de modulação digital. Com este processo, a informação é distribuida de forma difusa ao longo de um conjunto de símbolos, tanto no domínio do tempo como no da frequência. Constitui-se em um processo computacionalmente eficiente, especialmente adequado para operar em conjunto com a modulação OFDM, e que apresenta consideráveis ganhos de desempenho em algumas situações de degradação; por exemplo, é mais tolerante a ruídos impulsivos de longa duração do que a modulação OFDM convencional. Apresenta-se também um outro mecanismo, denominado de Realimentação de Erro, que melhora o desempenho do sistema em praticamente todas as situaçoes analisadas. Embora implique em aumento da carga computacional, este processo consiste de uma operação determinística, que dispensa etapas de iteração ou recursos computacionais distintos dos já disponíveis. Neste trabalho foi avaliada a utilização destas técnicas em um sistema OFDM com características similares ao sistema ISDB-T, adequado para radiodifusão de TV Digital . / This work introduces a new transform-based time interleaving algorithm: FTI-OFDM (Fourier Transform Interleaved OFDM), in which binary information is spread over several symbols, both in time and frequency domains. This process, designed to be included in digital modulation systems, is computationally efficient when used in conjunction with OFDM modulation. Simulations are used to show its superiority over the usual binary time interleaving used in ordinary OFDM under several impairment scenarios, that include long impulsive noise and deep fading. Also introduced in this work is the additional method of decision error feedback (ERF), that enhances the performance of FTI-OFDM in almost all situations. Furthermore, ERF is deterministic and non-iterative and employs the same computational resources found in OFDM systems. The performance of an FTI-OFDM system, similar to ISDB-T standard, is evaluated under several impairments, such as are found in Digital TV broadcasting environment.

Chei Kwok-hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 66-73). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Typical Digital Communication Systems --- p.2 / Chapter 1.1.1 --- Source coding --- p.3 / Chapter 1.1.2 --- Channel coding --- p.5 / Chapter 1.2 --- Joint Source-Channel Coding System --- p.5 / Chapter 1.3 --- Thesis Organization --- p.7 / Chapter Chapter 2 --- Trellis Coding --- p.9 / Chapter 2.1 --- Convolutional Codes --- p.9 / Chapter 2.2 --- Trellis-Coded Modulation --- p.12 / Chapter 2.2.1 --- Set Partitioning --- p.13 / Chapter 2.3 --- Trellis-Coded Quantization --- p.14 / Chapter 2.4 --- Joint TCQ/TCM System --- p.17 / Chapter 2.4.1 --- The Combined Receiver --- p.17 / Chapter 2.4.2 --- Viterbi Decoding --- p.19 / Chapter 2.4.3 --- Sequence MAP Decoding --- p.20 / Chapter 2.4.4 --- Sliding Window Decoding --- p.21 / Chapter 2.4.5 --- Block-Based Decoding --- p.23 / Chapter Chapter 3 --- Soft Decoding Joint TCQ/TCM over AWGN Channel --- p.25 / Chapter 3.1 --- System Model --- p.26 / Chapter 3.2 --- TCQ with Optimal Soft-Decoder --- p.27 / Chapter 3.3 --- Gaussian Memoryless Source --- p.30 / Chapter 3.3.1 --- Theorem Limit --- p.31 / Chapter 3.3.2 --- Performance on PAM Constellations --- p.32 / Chapter 3.3.3 --- Performance on PSK Constellations --- p.36 / Chapter 3.4 --- Uniform Memoryless Source --- p.38 / Chapter 3.4.1 --- Theorem Limit --- p.38 / Chapter 3.4.2 --- Performance on PAM Constellations --- p.39 / Chapter 3.4.3 --- Performance on PSK Constellations --- p.40 / Chapter Chapter 4 --- Soft Decoding Joint TCQ/TCM System over Rayleigh Fading Channel --- p.42 / Chapter 4.1 --- Wireless Channel --- p.43 / Chapter 4.2 --- Rayleigh Fading Channel --- p.44 / Chapter 4.3 --- Idea Interleaving --- p.45 / Chapter 4.4 --- Receiver Structure --- p.46 / Chapter 4.5 --- Numerical Results --- p.47 / Chapter 4.5.1 --- Performance on 4-PAM Constellations --- p.48 / Chapter 4.5.2 --- Performance on 8-PAM Constellations --- p.50 / Chapter 4.5.3 --- Performance on 16-PAM Constellations --- p.52 / Chapter Chapter 5 --- Joint TCVQ/TCM System --- p.54 / Chapter 5.1 --- Trellis-Coded Vector Quantization --- p.55 / Chapter 5.1.1 --- Set Partitioning in TCVQ --- p.56 / Chapter 5.2 --- Joint TCVQ/TCM --- p.59 / Chapter 5.2.1 --- Set Partitioning and Index Assignments --- p.60 / Chapter 5.2.2 --- Gaussian-Markov Sources --- p.61 / Chapter 5.3 --- Simulation Results and Discussion --- p.62 / Chapter Chapter 6 --- Conclusion and Future Work --- p.64 / Chapter 6.1 --- Conclusion --- p.64 / Chapter 6.2 --- Future Works --- p.65 / Bibliography --- p.66 / Appendix-Publications --- p.73

Lin Pui-Yu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 103-105). / Abstracts in English and Chinese. / Acknowledgement / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Nonlinear Phenomenon of Power Amplifier --- p.5 / Chapter 2.1. --- AM-AM and AM-PM Distortion --- p.5 / Chapter 2.2. --- Intermodulation Distortion --- p.7 / Chapter Chapter 3 --- Linearization Techniques --- p.10 / Chapter 3.1. --- Power Backoff --- p.11 / Chapter 3.2. --- Feedback --- p.12 / Chapter 3.3. --- Predistortion --- p.12 / Chapter 3.4. --- Feedforward --- p.14 / Chapter 3.5. --- Other Linearization Techniques --- p.15 / Chapter Chapter 4 --- Analysis of Feedforward Power Amplifier --- p.17 / Chapter 4.1. --- Feedforward Efficiency --- p.18 / Chapter 4.2. --- Design Criteria of the Auxiliary Amplifier --- p.20 / Chapter 4.3. --- Sensitivity Analysis --- p.21 / Chapter 4.3.1. --- Phase and Amplitude Mismatch --- p.22 / Chapter 4.3.2. --- Delay Mismatch --- p.23 / Chapter 4.3.3. --- Combined Effect --- p.25 / Chapter 4.3.4. --- Practical Consideration --- p.27 / Chapter 4.4. --- Other Design Criteria --- p.28 / Chapter Chapter 5 --- Adaptive Control Networks for FFPA --- p.29 / Chapter 5.1. --- Basic Principles of the Adaptive Control Network --- p.30 / Chapter 5.1.1. --- Lookup Table --- p.30 / Chapter 5.1.2. --- Power Minimization Vs. Correlation --- p.31 / Chapter 5.2. --- Analog Vs Digital Implementation of the Adaptive Control Network --- p.34 / Chapter 5.3. --- Techniques for Improving the Convergence Behaviour at the Distortion Cancellation Loop --- p.35 / Chapter 5.4. --- Important Notes on the Control Networks --- p.38 / Chapter Chapter 6 --- Novel Analysis of Adaptive FFPA --- p.40 / Chapter 6.1. --- Gradient algorithm --- p.40 / Chapter 6.2. --- Dual Loop Adaptive FFPA --- p.41 / Chapter 6.2.1. --- System Modeling --- p.42 / Chapter 6.2.2. --- Adaptation Behavior of the Distortion Extraction Loop --- p.44 / Chapter 6.2.3. --- Adaptation Behavior of the Distortion Cancellation Loop --- p.48 / Chapter 6.2.4. --- Accuracy Requirement of the Control Signals --- p.50 / Chapter 6.2.5. --- Effect of Delay Mismatch on the Convergence Accuracy --- p.51 / Chapter 6.2.6. --- Convergence Behaviors for Two Tone Input Signal --- p.52 / Chapter 6.2.6.1. --- Distortion Extraction Loop --- p.53 / Chapter 6.2.6.2. --- Distortion Cancellation Loop --- p.55 / Chapter 6.2.6.3. --- Simulation Results --- p.57 / Chapter 6.2.7. --- Convergence Behaviors for Digital Modulated Test signal --- p.60 / Chapter 6.2.7.1. --- Distortion Extraction Loop --- p.61 / Chapter 6.2.7.2. --- Distortion Cancellation Loop --- p.66 / Chapter 6.2.7.3. --- Simulation Results --- p.68 / Chapter 6.2.8. --- Comparison for the Adaptation Performance with Two Tone and Digital Modulated Test Signal --- p.70 / Chapter 6.3. --- Triple Loop Adaptive FFPA --- p.71 / Chapter 6.3.1. --- Adaptation Performance of the Additional Loop --- p.73 / Chapter 6.3.2. --- Adaptation Performance of the Distortion Cancellation Loop --- p.75 / Chapter 6.3.3. --- Improvement in Bias Error at the Distortion Cancellation Loop --- p.76 / Chapter 6.3.4. --- Effect of Delay Mismatch --- p.77 / Chapter 6.3.5. --- Simulation Results --- p.79 / Chapter Chapter 7 --- Implementation and Measured Performance of Triple Loop Adaptive FFPA --- p.85 / Chapter 7.1. --- Hardware Design --- p.85 / Chapter 7.1.1. --- Vector Modulator --- p.87 / Chapter 7.1.2 --- Complex Correlator --- p.88 / Chapter 7.2. --- Experimental Setup and Measured Results --- p.90 / Chapter Chapter 8 --- Conclusion --- p.95 / Appendix I Matlab Program for Simulation of Dual Loop Adaptive FFPA --- p.97 / Appendix II Matlab Program for Simulation of Triple Loop Adaptive FFPA --- p.100 / Reference --- p.103 / Author's Publication --- p.106

Ho Man-Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 65-66). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / List of Abbreviation --- p.iii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Digital Communication System --- p.3 / Chapter 1.2 --- Thesis Organization --- p.4 / Chapter 2. --- Error-Correcting Codes --- p.6 / Chapter 2.1 --- Convolutional Codes --- p.7 / Chapter 2.1.1 --- Generator Polynomials --- p.8 / Chapter 2.1.2 --- Generator Matrix --- p.9 / Chapter 2.1.3 --- Circuit Diagram --- p.10 / Chapter 2.1.4 --- State-transition Diagram --- p.11 / Chapter 2.1.4 --- Trellis Diagram --- p.12 / Chapter 2.1.5 --- Distance property --- p.13 / Chapter 2.2 --- Rate-Compatible Punctured Convolutional Codes --- p.14 / Chapter 2.3 --- Trellis-Coded Modulation --- p.17 / Chapter 2.3.1 --- General Model of TCM --- p.18 / Chapter 2.3.2 --- Trellis Representation --- p.20 / Chapter 2.3.3 --- Set Partitioning --- p.21 / Chapter 2.3.4 --- Code Modulation --- p.23 / Chapter 2.4 --- Decoding Algorithm --- p.25 / Chapter 2.4.1 --- Viterbi Algorithm --- p.27 / Chapter 2.4.2 --- List Viterbi Algorithm --- p.30 / Chapter 3. --- Unequal-Error-Protection for Embedded Image Coder --- p.33 / Chapter 3.1 --- SPIHT Coder --- p.35 / Chapter 3.1.1 --- Progressive Image Transmission --- p.36 / Chapter 3.1.2 --- Set Partitioning Sorting Algorithm --- p.37 / Chapter 3.1.3 --- Spatial Orientation Trees --- p.38 / Chapter 3.2 --- System Description --- p.39 / Chapter 3.3 --- Code Allocation --- p.41 / Chapter 3.4 --- System Complexity --- p.42 / Chapter 3.5 --- Simulation Result --- p.43 / Chapter 4. --- Unequal-Error-Protection Provided by Trellis-Coded Modulation --- p.51 / Chapter 4.1 --- System Description --- p.52 / Chapter 4.2 --- Unequal Constellation --- p.53 / Chapter 4.3 --- Free Distance --- p.55 / Chapter 4.4 --- Simulation Results --- p.59 / Chapter 5. --- Conclusion --- p.63 / Bibliography --- p.65

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Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2017-08-30T12:55:55Z No. of bitstreams: 1 Gabriela Dischinger Miranda.pdf: 9361011 bytes, checksum: 6de1bfd60b91a107b8b069cc79027a3c (MD5) / Made available in DSpace on 2017-08-30T12:55:55Z (GMT). No. of bitstreams: 1 Gabriela Dischinger Miranda.pdf: 9361011 bytes, checksum: 6de1bfd60b91a107b8b069cc79027a3c (MD5) Previous issue date: 2017-08-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / From a brief overview of the main communication theories we can see that many that are still used today were thought between the decades of 1930 and 29160, based on mass communication; media that assumes asymmetric communication and one to many. Communication on digital media, on the other hand, is two way, in which the individual not only has the possibility to send their own messages, bus also respond to those they receive. Therefore, new digital media changed radically the communication environment, making it important to review the main communication theories seeking to identify those that can still explain multimedia and transmedia communication. In this dissertation, we mapped these main communication theories and detailed how digital and transmedia communication works. With four case studies we illustrated how communication happens today and looked for those communications theories that still fits in this scenario / A partir de um breve panorama das principais teorias da comunicação percebemos que a maioria das teorias que perduram até hoje foram pensadas entre 1930 e 1960 baseadas nos meios de comunicação de massa; meios esses que preveem uma comunicação assimétrica e de um para muitos. A comunicação nos meios digitais, por outro lado, é uma via de mão dupla, por meio da qual o indivíduo não apenas passou a ter a possibilidade de transmitir suas próprias mensagens, mas também responder àquelas que recebe. Dessa forma, as novas mídias digitais trouxeram uma grande mudança no ambiente comunicacional, o que torna importante a revisão das principais teorias da comunicação com o objetivo de identificar aquelas que ainda conseguem explicar a comunicação multimeios e transmidiática. Nessa dissertação mapeamos as principais teorias da comunicação e detalhamos a comunicação digital e transmidiática. Através quatro de estudos de caso ilustramos a comunicação hoje e buscamos as principais teorias da comunicação que ainda se encaixam nesse cenário

L’onde acoustique est utilisée par de nombreux systèmes et organismes marins pour communiquer, naviguer ou inférer de l’information sur l’environnement. Le développement des activités humaines liées au monde de la mer induit une augmentation du nombre de sources acoustiques en activité simultanée dans l’océan. L’environnement acoustique sous-marin (ASM) est donc partagé par de nombreuses sources hétérogènes (sonars, modems, mammifères marins, ...) entrant involontairement en compétition pour l’utilisation d’une ressource offerte par le canal de transmission. L’objectif de ce travail de thèse est de proposer des solutions permettant aux systèmes de communications ASM d’adapter leurs paramètres de transmission de manière intelligente, autonome et décentralisée selon l’environnement acoustique dans lequel ils évoluent. A plusieurs égards, les problématiques de ce sujet de thèse sont proches de celles ayant motivé le développement des recherches sur la radio cognitive. Cependant, les spécificités du milieu acoustique, les sources d’interférencesde diverses natures, et l’absence de standards de communications posent de nouvelles difficultés. / Underwater acoustic waves are used by many systems and biologic organisms to communicate, navigate or infer information about the environment. Future developments of human maritime activities imply an increase of the number of active acoustic sources in the oceans. The underwater environment is therefore shared by many heterogeneous sources (sonars, modems, marine mammals, ...) competing involuntarily for using the physical resources offered by the communication channel.The goal of this thesis is to provide solutions allowing autonomous and decentralized adaptation of the transmission strategies of underwater acoustic communication systems, according to the environment. To some extent, this work deals with topics that are closely related to what has motivated the first researches on cognitive radio systems. However, the specific properties of the underwater environment, the heterogeneity of interfering acoustic sources, and the absence of communication standards rise new difficulties.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Joseph Y. N. Hui. / M.S.