EE 5501 Prof. N. Jindal Digital Communication Nov. 19, 2009 Practice Problems for Midterm 2 1. Consider the R = 1 / 2 binary convolutional code with memory 2 that outputs the following two coded bits for each information bit: u [ k ] + u [ k-1] u [ k ] + u [ k-2] (a) Draw the trellis diagram (with outputs labeled for each branch) for this code. (b) Compute d free for this code. Find all error events at d free , and for each write down the corresponding input sequence, output sequence, and input weight. (c) Write down the expression for the nearest neighbor approximation. (d) On the following page you are given the Matlab code for the Viterbi decoder for the [7 , class. Modify the Matlab code so that it implements the Viterbi decoder for the convolutional code in this problem. The code is terminated in state 00 by setting two additional information bits to zero.
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