HW7 - ECE 402 Communications Engineering Homework 7(Fall...

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ECE 402: Communications Engineering Homework 7 (Fall 2009) Due: Tuesday 11/24 1. Suppose 64QAM is used to transmit data over an AWGN channel with the Nyquist pulse g ( t ) = (1 / T )sinc( t/T ). (a) What is the spectral eﬃciency η of 64QAM? (b) Find the E b /N 0 in dB required to achieve an error probability of 10 - 8 . Use the approximate M -QAM BER formula P b 4 log 2 M ± 1 - 1 M Q ˆs 3 PT ( M - 1) N 0 ! . Hint: At some point, you’ll need to solve an equation of the form Q ( x ) = b for x . You can use the MATLAB function qfuncinv to solve this: x=qfuncinv(b) . (c) According to Shannon’s Formula, what is the minimum E b /N 0 in dB required by any reliable communication system with this spectral eﬃciency η ? 2. A microwave transmitter has an output power of 0.1 W at a frequency of 2 GHz. Assume that this transmitter is used in a microwave communication system where the transmitting and receiving antennas are parabolic dishes, each 1.22 m in diameter. (a)

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This note was uploaded on 01/28/2012 for the course ECE 402 taught by Professor Townsend during the Fall '08 term at N.C. State.

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HW7 - ECE 402 Communications Engineering Homework 7(Fall...

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