Digital Communication Systems ECS 452
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Data Compression: Dictionary-Based Coding 2 / 37 Dictionary-Based Coding Dictionary-Based Coding
Dictionary-based Coding already coded not yet coded search buffer look-ahead buffer cursor (N symbols) (L symbols) We know the past but cannot control it. We control the future but... Last Lecture Last Lecture: Predictive Lossless Coding Predictive Lossless Coding Simple and effective way to exploit dependencies between neighboring symbols / samples Optimal predictor: Conditional mean (requires storage of large tables) Affine and Linear Prediction Simple structure, low-complex implementation possible Optimal prediction parameters are given by solution of Yule-Walker equations Works very well for real signals (e.g., audio, images, ...) Efficient Lossless Coding for Real-World Signals Affine/linear prediction (often: block-adaptive choice of prediction parameters) Entropy coding of prediction errors (e.g., arithmetic coding) Using marginal pmf often already yields good results Can be improved by using conditional pmfs (with simple conditions) Heiko Schwarz (Freie Universität Berlin) — Data Compression: Dictionary-based Coding 2 / 37 Dictionary-based Coding Dictionary-Based Coding Coding of Text Files Very high amount of dependencies Affine prediction does not work (requires linear dependencies) Higher-order conditional coding should work well, but is way to complex (memory) Alternative: Do not code single characters, but words or phrases Example: English Texts Oxford English Dictionary lists less than 230 000 words (including obsolete words) On average, a word contains about 6 characters Average codeword length per character would be limited by 1 -
Minimax Redundancy for Markov Chains with Large State Space
Minimax redundancy for Markov chains with large state space Kedar Shriram Tatwawadi, Jiantao Jiao, Tsachy Weissman May 8, 2018 Abstract For any Markov source, there exist universal codes whose normalized codelength approaches the Shannon limit asymptotically as the number of samples goes to infinity. This paper inves- tigates how fast the gap between the normalized codelength of the “best” universal compressor and the Shannon limit (i.e. the compression redundancy) vanishes non-asymptotically in terms of the alphabet size and mixing time of the Markov source. We show that, for Markov sources (2+c) whose relaxation time is at least 1 + √k , where k is the state space size (and c> 0 is a con- stant), the phase transition for the number of samples required to achieve vanishing compression redundancy is precisely Θ(k2). 1 Introduction For any data source that can be modeled as a stationary ergodic stochastic process, it is well known in the literature of universal compression that there exist compression algorithms without any knowledge of the source distribution, such that its performance can approach the fundamental limit of the source, also known as the Shannon entropy, as the number of observations tends to infinity. The existence of universal data compressors has spurred a huge wave of research around it. A large fraction of practical lossless compressors are based on the Lempel–Ziv algorithms [ZL77, ZL78] and their variants, and the normalized codelength of a universal source code is also widely used to measure the compressibility of the source, which is based on the idea that the normalized codelength is “close” to the true entropy rate given a moderate number of samples. -
Digital Communication Systems 2.2 Optimal Source Coding
Digital Communication Systems EES 452 Asst. Prof. Dr. Prapun Suksompong [email protected] 2. Source Coding 2.2 Optimal Source Coding: Huffman Coding: Origin, Recipe, MATLAB Implementation 1 Examples of Prefix Codes Nonsingular Fixed-Length Code Shannon–Fano code Huffman Code 2 Prof. Robert Fano (1917-2016) Shannon Award (1976 ) Shannon–Fano Code Proposed in Shannon’s “A Mathematical Theory of Communication” in 1948 The method was attributed to Fano, who later published it as a technical report. Fano, R.M. (1949). “The transmission of information”. Technical Report No. 65. Cambridge (Mass.), USA: Research Laboratory of Electronics at MIT. Should not be confused with Shannon coding, the coding method used to prove Shannon's noiseless coding theorem, or with Shannon–Fano–Elias coding (also known as Elias coding), the precursor to arithmetic coding. 3 Claude E. Shannon Award Claude E. Shannon (1972) Elwyn R. Berlekamp (1993) Sergio Verdu (2007) David S. Slepian (1974) Aaron D. Wyner (1994) Robert M. Gray (2008) Robert M. Fano (1976) G. David Forney, Jr. (1995) Jorma Rissanen (2009) Peter Elias (1977) Imre Csiszár (1996) Te Sun Han (2010) Mark S. Pinsker (1978) Jacob Ziv (1997) Shlomo Shamai (Shitz) (2011) Jacob Wolfowitz (1979) Neil J. A. Sloane (1998) Abbas El Gamal (2012) W. Wesley Peterson (1981) Tadao Kasami (1999) Katalin Marton (2013) Irving S. Reed (1982) Thomas Kailath (2000) János Körner (2014) Robert G. Gallager (1983) Jack KeilWolf (2001) Arthur Robert Calderbank (2015) Solomon W. Golomb (1985) Toby Berger (2002) Alexander S. Holevo (2016) William L. Root (1986) Lloyd R. Welch (2003) David Tse (2017) James L. -
Practical Parallel Hypergraph Algorithms
Practical Parallel Hypergraph Algorithms Julian Shun [email protected] MIT CSAIL Abstract v0 While there has been significant work on parallel graph pro- e0 cessing, there has been very surprisingly little work on high- v0 v1 v1 performance hypergraph processing. This paper presents a e collection of efficient parallel algorithms for hypergraph pro- 1 v2 cessing, including algorithms for computing hypertrees, hy- v v 2 3 e perpaths, betweenness centrality, maximal independent sets, 2 v k-core decomposition, connected components, PageRank, 3 and single-source shortest paths. For these problems, we ei- (a) Hypergraph (b) Bipartite representation ther provide new parallel algorithms or more efficient imple- mentations than prior work. Furthermore, our algorithms are Figure 1. An example hypergraph representing the groups theoretically-efficient in terms of work and depth. To imple- fv0;v1;v2g, fv1;v2;v3g, and fv0;v3g, and its bipartite repre- ment our algorithms, we extend the Ligra graph processing sentation. framework to support hypergraphs, and our implementations benefit from graph optimizations including switching between improved compared to using a graph representation. Unfor- sparse and dense traversals based on the frontier size, edge- tunately, there is been little research on parallel hypergraph aware parallelization, using buckets to prioritize processing processing. of vertices, and compression. Our experiments on a 72-core The main contribution of this paper is a suite of efficient machine and show that our algorithms obtain excellent paral- parallel hypergraph algorithms, including algorithms for hy- lel speedups, and are significantly faster than algorithms in pertrees, hyperpaths, betweenness centrality, maximal inde- existing hypergraph processing frameworks. -
Randomized Lempel-Ziv Compression for Anti-Compression Side-Channel Attacks
Randomized Lempel-Ziv Compression for Anti-Compression Side-Channel Attacks by Meng Yang A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Applied Science in Electrical and Computer Engineering Waterloo, Ontario, Canada, 2018 c Meng Yang 2018 I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public. ii Abstract Security experts confront new attacks on TLS/SSL every year. Ever since the compres- sion side-channel attacks CRIME and BREACH were presented during security conferences in 2012 and 2013, online users connecting to HTTP servers that run TLS version 1.2 are susceptible of being impersonated. We set up three Randomized Lempel-Ziv Models, which are built on Lempel-Ziv77, to confront this attack. Our three models change the determin- istic characteristic of the compression algorithm: each compression with the same input gives output of different lengths. We implemented SSL/TLS protocol and the Lempel- Ziv77 compression algorithm, and used them as a base for our simulations of compression side-channel attack. After performing the simulations, all three models successfully pre- vented the attack. However, we demonstrate that our randomized models can still be broken by a stronger version of compression side-channel attack that we created. But this latter attack has a greater time complexity and is easily detectable. Finally, from the results, we conclude that our models couldn't compress as well as Lempel-Ziv77, but they can be used against compression side-channel attacks. -
Principles of Communications ECS 332
Principles of Communications ECS 332 Asst. Prof. Dr. Prapun Suksompong (ผศ.ดร.ประพันธ ์ สขสมปองุ ) [email protected] 1. Intro to Communication Systems Office Hours: Check Google Calendar on the course website. Dr.Prapun’s Office: 6th floor of Sirindhralai building, 1 BKD 2 Remark 1 If the downloaded file crashed your device/browser, try another one posted on the course website: 3 Remark 2 There is also three more sections from the Appendices of the lecture notes: 4 Shannon's insight 5 “The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point.” Shannon, Claude. A Mathematical Theory Of Communication. (1948) 6 Shannon: Father of the Info. Age Documentary Co-produced by the Jacobs School, UCSD- TV, and the California Institute for Telecommunic ations and Information Technology 7 [http://www.uctv.tv/shows/Claude-Shannon-Father-of-the-Information-Age-6090] [http://www.youtube.com/watch?v=z2Whj_nL-x8] C. E. Shannon (1916-2001) Hello. I'm Claude Shannon a mathematician here at the Bell Telephone laboratories He didn't create the compact disc, the fax machine, digital wireless telephones Or mp3 files, but in 1948 Claude Shannon paved the way for all of them with the Basic theory underlying digital communications and storage he called it 8 information theory. C. E. Shannon (1916-2001) 9 https://www.youtube.com/watch?v=47ag2sXRDeU C. E. Shannon (1916-2001) One of the most influential minds of the 20th century yet when he died on February 24, 2001, Shannon was virtually unknown to the public at large 10 C. -
Marconi Society - Wikipedia
9/23/2019 Marconi Society - Wikipedia Marconi Society The Guglielmo Marconi International Fellowship Foundation, briefly called Marconi Foundation and currently known as The Marconi Society, was established by Gioia Marconi Braga in 1974[1] to commemorate the centennial of the birth (April 24, 1874) of her father Guglielmo Marconi. The Marconi International Fellowship Council was established to honor significant contributions in science and technology, awarding the Marconi Prize and an annual $100,000 grant to a living scientist who has made advances in communication technology that benefits mankind. The Marconi Fellows are Sir Eric A. Ash (1984), Paul Baran (1991), Sir Tim Berners-Lee (2002), Claude Berrou (2005), Sergey Brin (2004), Francesco Carassa (1983), Vinton G. Cerf (1998), Andrew Chraplyvy (2009), Colin Cherry (1978), John Cioffi (2006), Arthur C. Clarke (1982), Martin Cooper (2013), Whitfield Diffie (2000), Federico Faggin (1988), James Flanagan (1992), David Forney, Jr. (1997), Robert G. Gallager (2003), Robert N. Hall (1989), Izuo Hayashi (1993), Martin Hellman (2000), Hiroshi Inose (1976), Irwin M. Jacobs (2011), Robert E. Kahn (1994) Sir Charles Kao (1985), James R. Killian (1975), Leonard Kleinrock (1986), Herwig Kogelnik (2001), Robert W. Lucky (1987), James L. Massey (1999), Robert Metcalfe (2003), Lawrence Page (2004), Yash Pal (1980), Seymour Papert (1981), Arogyaswami Paulraj (2014), David N. Payne (2008), John R. Pierce (1979), Ronald L. Rivest (2007), Arthur L. Schawlow (1977), Allan Snyder (2001), Robert Tkach (2009), Gottfried Ungerboeck (1996), Andrew Viterbi (1990), Jack Keil Wolf (2011), Jacob Ziv (1995). In 2015, the prize went to Peter T. Kirstein for bringing the internet to Europe. Since 2008, Marconi has also issued the Paul Baran Marconi Society Young Scholar Awards. -
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Arxiv:1306.1586V4 [Quant-Ph]
Strong converse for the classical capacity of entanglement-breaking and Hadamard channels via a sandwiched R´enyi relative entropy Mark M. Wilde∗ Andreas Winter†‡ Dong Yang†§ May 23, 2014 Abstract A strong converse theorem for the classical capacity of a quantum channel states that the probability of correctly decoding a classical message converges exponentially fast to zero in the limit of many channel uses if the rate of communication exceeds the classical capacity of the channel. Along with a corresponding achievability statement for rates below the capacity, such a strong converse theorem enhances our understanding of the capacity as a very sharp dividing line between achievable and unachievable rates of communication. Here, we show that such a strong converse theorem holds for the classical capacity of all entanglement-breaking channels and all Hadamard channels (the complementary channels of the former). These results follow by bounding the success probability in terms of a “sandwiched” R´enyi relative entropy, by showing that this quantity is subadditive for all entanglement-breaking and Hadamard channels, and by relating this quantity to the Holevo capacity. Prior results regarding strong converse theorems for particular covariant channels emerge as a special case of our results. 1 Introduction One of the most fundamental tasks in quantum information theory is the transmission of classical data over many independent uses of a quantum channel, such that, for a fixed rate of communica- tion, the error probability of the transmission decreases to zero in the limit of many channel uses. The maximum rate at which this is possible for a given channel is known as the classical capacity of the channel. -
MÁSTER UNIVERSITARIO EN INGENIERÍA DE TELECOMUNICACIÓN TRABAJO FIN DE MASTER Analysis and Implementation of New Techniques Fo
MÁSTER UNIVERSITARIO EN INGENIERÍA DE TELECOMUNICACIÓN TRABAJO FIN DE MASTER Analysis and Implementation of New Techniques for the Enhancement of the Reliability and Delay of Haptic Communications LUIS AMADOR GONZÁLEZ 2017 MASTER UNIVERSITARIO EN INGENIERÍA DE TELECOMUNICACIÓN TRABAJO FIN DE MASTER Título: Analysis and Implementation of New Techniques for the Enhancement of the Reliability and Delay of Haptic Communications Autor: D. Luis Amador González Tutor: D. Hamid Aghvami Ponente: D. Santiago Zazo Bello Departamento: MIEMBROS DEL TRIBUNAL Presidente: D. Vocal: D. Secretario: D. Suplente: D. Los miembros del tribunal arriba nombrados acuerdan otorgar la calificación de: ……… Madrid, a de de 20… UNIVERSIDAD POLITÉCNICA DE MADRID ESCUELA TÉCNICA SUPERIOR DE INGENIEROS DE TELECOMUNICACIÓN MASTER UNIVERSITARIO EN INGENIERÍA DE TELECOMUNICACIÓN TRABAJO FIN DE MASTER Analysis and Implementation of New Techniques for the Enhancement of the Reliability and Delay of Haptic Communications LUIS AMADOR GONZÁLEZ 2017 CONTENTS LIST OF FIGURES .....................................................................................2 LIST OF TABLES ......................................................................................3 ABBREVIATIONS .....................................................................................4 SUMMARY ............................................................................................5 RESUMEN .............................................................................................6 ACKNOWLEDGEMENTS -
Channel Coding
1 Channel Coding: The Road to Channel Capacity Daniel J. Costello, Jr., Fellow, IEEE, and G. David Forney, Jr., Fellow, IEEE Submitted to the Proceedings of the IEEE First revision, November 2006 Abstract Starting from Shannon’s celebrated 1948 channel coding theorem, we trace the evolution of channel coding from Hamming codes to capacity-approaching codes. We focus on the contributions that have led to the most significant improvements in performance vs. complexity for practical applications, particularly on the additive white Gaussian noise (AWGN) channel. We discuss algebraic block codes, and why they did not prove to be the way to get to the Shannon limit. We trace the antecedents of today’s capacity-approaching codes: convolutional codes, concatenated codes, and other probabilistic coding schemes. Finally, we sketch some of the practical applications of these codes. Index Terms Channel coding, algebraic block codes, convolutional codes, concatenated codes, turbo codes, low-density parity- check codes, codes on graphs. I. INTRODUCTION The field of channel coding started with Claude Shannon’s 1948 landmark paper [1]. For the next half century, its central objective was to find practical coding schemes that could approach channel capacity (hereafter called “the Shannon limit”) on well-understood channels such as the additive white Gaussian noise (AWGN) channel. This goal proved to be challenging, but not impossible. In the past decade, with the advent of turbo codes and the rebirth of low-density parity-check codes, it has finally been achieved, at least in many cases of practical interest. As Bob McEliece observed in his 2004 Shannon Lecture [2], the extraordinary efforts that were required to achieve this objective may not be fully appreciated by future historians. -
Jacob Wolfowitz 1910–1981
NATIONAL ACADEMY OF SCIENCES JACOB WOLFOWITZ 1910–1981 A Biographical Memoir by SHELEMYAHU ZACKS Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences. Biographical Memoirs, VOLUME 82 PUBLISHED 2002 BY THE NATIONAL ACADEMY PRESS WASHINGTON, D.C. JACOB WOLFOWITZ March 19, 1910–July 16, 1981 BY SHELEMYAHU ZACKS ACOB WOLFOWITZ, A GIANT among the founders of modern Jstatistics, will always be remembered for his originality, deep thinking, clear mind, excellence in teaching, and vast contributions to statistical and information sciences. I met Wolfowitz for the first time in 1957, when he spent a sab- batical year at the Technion, Israel Institute of Technology. I was at the time a graduate student and a statistician at the building research station of the Technion. I had read papers of Wald and Wolfowitz before, and for me the meeting with Wolfowitz was a great opportunity to associate with a great scholar who was very kind to me and most helpful. I took his class at the Technion on statistical decision theory. Outside the classroom we used to spend time together over a cup of coffee or in his office discussing statistical problems. He gave me a lot of his time, as though I was his student. His advice on the correct approach to the theory of statistics accompanied my development as statistician for many years to come. Later we kept in touch, mostly by correspondence and in meetings of the Institute of Mathematical Statistics. I saw him the last time in his office at the University of Southern Florida in Tampa, where he spent the last years 3 4 BIOGRAPHICAL MEMOIRS of his life. -
Practical Forward Secure Signatures Using Minimal Security Assumptions
Practical Forward Secure Signatures using Minimal Security Assumptions Vom Fachbereich Informatik der Technischen Universit¨atDarmstadt genehmigte Dissertation zur Erlangung des Grades Doktor rerum naturalium (Dr. rer. nat.) von Dipl.-Inform. Andreas H¨ulsing geboren in Karlsruhe. Referenten: Prof. Dr. Johannes Buchmann Prof. Dr. Tanja Lange Tag der Einreichung: 07. August 2013 Tag der m¨undlichen Pr¨ufung: 23. September 2013 Hochschulkennziffer: D 17 Darmstadt 2013 List of Publications [1] Johannes Buchmann, Erik Dahmen, Sarah Ereth, Andreas H¨ulsing,and Markus R¨uckert. On the security of the Winternitz one-time signature scheme. In A. Ni- taj and D. Pointcheval, editors, Africacrypt 2011, volume 6737 of Lecture Notes in Computer Science, pages 363{378. Springer Berlin / Heidelberg, 2011. Cited on page 17. [2] Johannes Buchmann, Erik Dahmen, and Andreas H¨ulsing.XMSS - a practical forward secure signature scheme based on minimal security assumptions. In Bo- Yin Yang, editor, Post-Quantum Cryptography, volume 7071 of Lecture Notes in Computer Science, pages 117{129. Springer Berlin / Heidelberg, 2011. Cited on pages 41, 73, and 81. [3] Andreas H¨ulsing,Albrecht Petzoldt, Michael Schneider, and Sidi Mohamed El Yousfi Alaoui. Postquantum Signaturverfahren Heute. In Ulrich Waldmann, editor, 22. SIT-Smartcard Workshop 2012, IHK Darmstadt, Feb 2012. Fraun- hofer Verlag Stuttgart. [4] Andreas H¨ulsing,Christoph Busold, and Johannes Buchmann. Forward secure signatures on smart cards. In Lars R. Knudsen and Huapeng Wu, editors, Se- lected Areas in Cryptography, volume 7707 of Lecture Notes in Computer Science, pages 66{80. Springer Berlin Heidelberg, 2013. Cited on pages 63, 73, and 81. [5] Johannes Braun, Andreas H¨ulsing,Alex Wiesmaier, Martin A.G.