midterm-2-2009 - Assume that the goal is to transport K...

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ECE 556 Midterm II Fall 2009 Problem 1 Consider the subcode of the Golay code obtained by taking only those codewords that project onto the all-zero hexacodeword. Find the dimension and weight enumerator of this code. What is the covering radius of the code (if you cannot get the exact answer, find the best upper and lower boun)? Don’t use a computer to answer this question! Problem 2 Find bounds on the size of the largest single deletion correcting code with codewords of length n. Read the problem from the last homework, pertaining to the ISBN code. Can you think of a similar idea (i.e. a way to use weighted sums of symbol values as checks) for the construction of a single deletion correcting code? Problem 3 Consider a network with K reliable channels between a transmitting and receiving node.
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Unformatted text preview: Assume that the goal is to transport K packets using these channels, each of which introduces a random delay captured X(i), i=1,…,K. Here, X(i) are i.i.d, exponentially distributed variables with mean m. Find the message reconstruction time for this communication scheme. Next, assume that the packets are viewed as symbols over a sufficiently large alphabet size, and that the K-set of packets is encodes into N packets using a Reed-Solomon code. Assume also that there now exist N available i.i.d. channels, with delays Y(i), i=1,…,K. If the delays are assumed to be exponentially distributed, find the value of their mean that will lead to the same message reconstruction delay as obtained in the first case....
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This note was uploaded on 02/08/2012 for the course ECE 556 taught by Professor Milenkovic,o during the Fall '08 term at University of Illinois, Urbana Champaign.

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