20072ee132A_1_ca2

20072ee132A_1_ca2 - Assume that all symbols are equally...

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EE132A, Spring 2007 Communication Systems Prof. John Villasenor Handout# 13 TA: Choo Chin (Jeffrey) Tan Computer Assignment 2 Assigned: Wednesday, May 9, 2007 Due: Wednesday, May 16, 2007 Consider the constellation shown below for a coherent QPSK system. In this system, the energy transmitted per symbol is E . As we have seen in class, the probability of bit error for this system is approximately = 0 erfc 2 1 N E P b E Use Matlab to plot this probability as a function of E b / N 0 in dB. In your plot, use a range from 0 to 10 dB. You can check the correctness of your plot by comparing it with the plot for binary antipodal signals (BPSK) appearing on page 408 of the textbook. Now consider the following one-dimensional constellation containing four possible symbols.
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Unformatted text preview: Assume that all symbols are equally likely to be transmitted. In this case, half of the time the symbol energy will be E /2, and half of the time the energy will be 3 E /2, so the average symbol energy will be E . Assume also that symbol errors, when they occur, involve only immediately adjacent symbols, and that Gray code labeling is used so that the bit error rate will be equal to half of the symbol error rate. Plot the bit error rate for this one-dimensional system on the same graph that you used for the QPSK error plot. Comment on your results. 2 E-2 E 2 3 E 2 3 E-A B C D -2 , 2 E E 2 , 2 E E -2 , 2 E E --2 , 2 E E...
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