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Homework Help: 3 Quick questions about information theory

  1. Jun 19, 2010 #1
    1. The problem statement, all variables and given/known data

    A) Select uniquely decodable codes and instantaneous codes from Code1 to 5 of the image below:
    2ut2fxe.png

    B) Personal question about second-order extension probabilites. If we have:
    probability of a symbol a P(a) = p1
    probability of a symbol b P(b) = q1
    Which is the probability of symbols aa, ab, bb of the second-order extension of the source?

    C) What is "rate"?

    3. The attempt at a solution

    A)

    Uniquely decodable codes: 1,3,4,5 (in code 2 the extension(AE)=00100=extension(BA) )
    Instantaneous codes: 1,4,5 (code 2 was not uniquely decodable, and in code 3 A is prefix of other codes)

    B)

    P(aa) = p1*p1
    P(ab) = p1*q1
    P(bb) = q1*q1

    c)

    It depends on what it refers to:
    " Information rate R " : avg bits/symbol, R< Channel Capacity implies theoretical error-free transmission (Shannon)

    " transmission rate " : bits/time(sec)

    Is everything ok?

    Thanks in advance.
     
  2. jcsd
  3. Jun 27, 2010 #2
    Noone ?
     
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