Introduction to Information Theory
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Questions and Answers

Who is regarded as the father of digital communication?

  • Alan Turing
  • Claude Elwood Shannon (correct)
  • John von Neumann
  • Norbert Wiener
  • What does Shannon's definition of communication emphasize?

  • The speed of data transmission
  • The emotional impact of messages
  • The meaning conveyed by the messages
  • The technical accuracy of reproduced messages (correct)
  • What year did Claude Elwood Shannon publish his groundbreaking paper on communication theory?

  • 1968
  • 1938
  • 1948 (correct)
  • 1958
  • What problem does Shannon aim to address in his communication model?

    <p>Reliable transmission of data at maximal rate</p> Signup and view all the answers

    In the communication model, what does the 'Encoder' do?

    <p>Changes English symbols into a binary sequence</p> Signup and view all the answers

    What does the term 'Data Compression' refer to in Shannon’s theory?

    <p>Data Encoding</p> Signup and view all the answers

    In Shannon’s theory, what is the purpose of adding a CRC?

    <p>Error Correction</p> Signup and view all the answers

    What does 'CC' stand for in the context of cellular phone communication?

    <p>Convolutional Code</p> Signup and view all the answers

    Which part of Shannon's original theory deals with the transmission of information through various channels?

    <p>Channel Coding Theory</p> Signup and view all the answers

    What can be inferred about the measurement of information in Shannon’s theory?

    <p>It involves determining expected bits based on probabilistic events.</p> Signup and view all the answers

    What does 'Unzip' signify in the context of data processing?

    <p>Data Decompression</p> Signup and view all the answers

    What is one primary function of the MPEG encoder in the context of video distribution?

    <p>Data Encoding</p> Signup and view all the answers

    Which coding method is associated with error protection in WLAN IEEE 802.11b?

    <p>Convolutional Code</p> Signup and view all the answers

    What does the entropy function H(X) represent in probability theory?

    <p>The measure of uncertainty or information content</p> Signup and view all the answers

    What major impairment is discussed in relation to computer network communications?

    <p>Packet Loss</p> Signup and view all the answers

    What is the outcome regarding the number of bits needed to store information about a die toss according to Shannon's theorem?

    <p>2.585 bits are needed for each outcome</p> Signup and view all the answers

    How is the optimal compression ratio calculated based on Shannon's findings compared to the original file size?

    <p>By dividing original file size by compressed file size</p> Signup and view all the answers

    In the Binary Erasure Channel example, what does 'p' represent?

    <p>The packet loss rate</p> Signup and view all the answers

    What happens when symbols are erased during transmission?

    <p>They are lost during transmission</p> Signup and view all the answers

    What did David Huffman contribute to information theory in 1952?

    <p>A coding technique that achieves the optimal compression ratio</p> Signup and view all the answers

    What is the significance of the number 2.585 in the context of storing outcomes of a die toss?

    <p>It represents the base 2 logarithm of 6 outcomes</p> Signup and view all the answers

    What method does Alice use to reduce the effects of packet loss in her communication with Bob?

    <p>Sending each symbol multiple times</p> Signup and view all the answers

    If Alice's original network has a packet loss rate of p=0.25 and she repeats each symbol four times, what is the new packet loss rate?

    <p>0.00390625</p> Signup and view all the answers

    What represents the difference between Shannon's compressed file size and traditional ASCII representation for storing die outcomes?

    <p>Shannon's size is significantly smaller than ASCII size</p> Signup and view all the answers

    What is the maximum data transmission rate Alice can achieve after using repetition?

    <p>2 Mbps</p> Signup and view all the answers

    What percentage corresponds to the optimal compression ratio reported by Shannon?

    <p>32.31%</p> Signup and view all the answers

    In what applications are Huffman codes commonly used?

    <p>In various digital data compression and transmission contexts</p> Signup and view all the answers

    According to Shannon’s Channel Coding Theorem, what can be computed for a given channel?

    <p>The channel capacity, C</p> Signup and view all the answers

    What is the channel capacity calculated in the example where Alice sends data at a rate of 8 Mbps with a packet loss rate of p=0.25?

    <p>0.75 Mbps</p> Signup and view all the answers

    What is the formula for channel capacity in terms of Signal to Noise Ratio?

    <p>$C = B imes log_2 (S/N)$</p> Signup and view all the answers

    Which of the following coding techniques is NOT mentioned as a known code developed over 50 years?

    <p>Quantum Codes</p> Signup and view all the answers

    In what year did the Mariner 4 mission communicate with a data rate of 8.33 bps?

    <p>1965</p> Signup and view all the answers

    Which compression technique was used by the Mars Reconnaissance Orbiter for lossless data?

    <p>FELICS Compression</p> Signup and view all the answers

    How many bps was the data rate for the Mars Exploration Rovers in 2004?

    <p>168 bps</p> Signup and view all the answers

    Which application has NOT utilized Shannon Theory?

    <p>Nutrition Science</p> Signup and view all the answers

    Which of the following statements about the Source Coding Theorem is true?

    <p>It is used in MPEG compression.</p> Signup and view all the answers

    What was the frequency used by Mars Exploration Rovers in 2004?

    <p>8.4 GHz</p> Signup and view all the answers

    Study Notes

    Introduction to Information Theory

    • Claude Elwood Shannon published “A Mathematical Theory of Communication” in 1948, establishing the foundation for digital communication.
    • A digital communication system consists of integral components: Source, Encoder, Communication Channel, Decoder, and Destination.

    Shannon’s Definition of Communication

    • Communication’s fundamental problem is accurately reproducing a selected message at a different point, focusing on the engineering aspects rather than semantic meaning.

    Shannon's Objectives

    • Shannon aimed to develop methods for reliably transmitting data over communication channels at maximal rates, leading to the emergence of Information Theory.

    Information Theory Key Concepts

    • Information measurement is defined using bits; Shannon introduced the entropy function: H(X) = −Σ p(x) log₂ p(x).
    • Entropy quantifies the level of uncertainty or information content in a random variable.

    Source Coding and Compression

    • Shannon’s First Source Coding Theorem indicates that, on average, H(X) bits are required for storing each outcome from a random source.
    • For example, tossing a die results in an entropy of approximately 2.585 bits per outcome, enabling optimal compression strategies.

    Compression Techniques

    • Huffman coding, developed by David Huffman in 1952, provides systematic methods for achieving optimal compression ratios and is widely used in digital data transmission.

    Communication Challenges

    • Packet loss in network communications can be modeled as erasures, complicating data recovery.
    • The Binary Erasure Channel represents loss where symbols may become unreadable.

    Shannon’s Channel Coding Theorem

    • Reliable communication is possible only if the data rate is below a calculated channel capacity C, which considers factors like signal loss.

    Channel Capacity Formula

    • The channel capacity can be expressed as C = B log₂(S/N), where B is bandwidth and S/N is the signal-to-noise ratio.

    Advances in Coding Techniques

    • Over the decades, numerous coding methods have been developed, including Hamming codes, Convolutional codes, Reed-Solomon codes, Turbo codes, and others, enhancing communication reliability.

    Applications of Shannon Theory

    • Information Theory principles apply broadly across JPEG 2000, MPEG compression, wireless communications, and optical communication.
    • In space communication, advancements illustrate the application of Shannon's theories, with progressively increasing data transmission rates and compression methods.

    Broader Implications of Information Theory

    • The principles of Information Theory extend into various fields, including economics, game theory, cryptography, quantum physics, biology, and genetics, underscoring its interdisciplinary significance.

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    Description

    Explore the fundamentals of information theory as introduced by Claude Shannon's seminal work in 1948. This quiz delves into the models of digital communication systems, including encoding and message processing. Understand the significance of coding in digital communication.

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