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Questions and Answers
Who is regarded as the father of digital communication?
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?
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?
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?
What problem does Shannon aim to address in his communication model?
In the communication model, what does the 'Encoder' do?
In the communication model, what does the 'Encoder' do?
What does the term 'Data Compression' refer to in Shannon’s theory?
What does the term 'Data Compression' refer to in Shannon’s theory?
In Shannon’s theory, what is the purpose of adding a CRC?
In Shannon’s theory, what is the purpose of adding a CRC?
What does 'CC' stand for in the context of cellular phone communication?
What does 'CC' stand for in the context of cellular phone communication?
Which part of Shannon's original theory deals with the transmission of information through various channels?
Which part of Shannon's original theory deals with the transmission of information through various channels?
What can be inferred about the measurement of information in Shannon’s theory?
What can be inferred about the measurement of information in Shannon’s theory?
What does 'Unzip' signify in the context of data processing?
What does 'Unzip' signify in the context of data processing?
What is one primary function of the MPEG encoder in the context of video distribution?
What is one primary function of the MPEG encoder in the context of video distribution?
Which coding method is associated with error protection in WLAN IEEE 802.11b?
Which coding method is associated with error protection in WLAN IEEE 802.11b?
What does the entropy function H(X) represent in probability theory?
What does the entropy function H(X) represent in probability theory?
What major impairment is discussed in relation to computer network communications?
What major impairment is discussed in relation to computer network communications?
What is the outcome regarding the number of bits needed to store information about a die toss according to Shannon's theorem?
What is the outcome regarding the number of bits needed to store information about a die toss according to Shannon's theorem?
How is the optimal compression ratio calculated based on Shannon's findings compared to the original file size?
How is the optimal compression ratio calculated based on Shannon's findings compared to the original file size?
In the Binary Erasure Channel example, what does 'p' represent?
In the Binary Erasure Channel example, what does 'p' represent?
What happens when symbols are erased during transmission?
What happens when symbols are erased during transmission?
What did David Huffman contribute to information theory in 1952?
What did David Huffman contribute to information theory in 1952?
What is the significance of the number 2.585 in the context of storing outcomes of a die toss?
What is the significance of the number 2.585 in the context of storing outcomes of a die toss?
What method does Alice use to reduce the effects of packet loss in her communication with Bob?
What method does Alice use to reduce the effects of packet loss in her communication with Bob?
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?
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?
What represents the difference between Shannon's compressed file size and traditional ASCII representation for storing die outcomes?
What represents the difference between Shannon's compressed file size and traditional ASCII representation for storing die outcomes?
What is the maximum data transmission rate Alice can achieve after using repetition?
What is the maximum data transmission rate Alice can achieve after using repetition?
What percentage corresponds to the optimal compression ratio reported by Shannon?
What percentage corresponds to the optimal compression ratio reported by Shannon?
In what applications are Huffman codes commonly used?
In what applications are Huffman codes commonly used?
According to Shannon’s Channel Coding Theorem, what can be computed for a given channel?
According to Shannon’s Channel Coding Theorem, what can be computed for a given channel?
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?
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?
What is the formula for channel capacity in terms of Signal to Noise Ratio?
What is the formula for channel capacity in terms of Signal to Noise Ratio?
Which of the following coding techniques is NOT mentioned as a known code developed over 50 years?
Which of the following coding techniques is NOT mentioned as a known code developed over 50 years?
In what year did the Mariner 4 mission communicate with a data rate of 8.33 bps?
In what year did the Mariner 4 mission communicate with a data rate of 8.33 bps?
Which compression technique was used by the Mars Reconnaissance Orbiter for lossless data?
Which compression technique was used by the Mars Reconnaissance Orbiter for lossless data?
How many bps was the data rate for the Mars Exploration Rovers in 2004?
How many bps was the data rate for the Mars Exploration Rovers in 2004?
Which application has NOT utilized Shannon Theory?
Which application has NOT utilized Shannon Theory?
Which of the following statements about the Source Coding Theorem is true?
Which of the following statements about the Source Coding Theorem is true?
What was the frequency used by Mars Exploration Rovers in 2004?
What was the frequency used by Mars Exploration Rovers in 2004?
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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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