Le yg d Question 1 (35) 03/01/2022 Final Exam-Fall 2021 .editepe University, EE354 Communication Systems, Doç. Dr. Engin

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Le Yg D Question 1 35 03 01 2022 Final Exam Fall 2021 Editepe University Ee354 Communication Systems Doc Dr Engin 1 (178.34 KiB) Viewed 58 times

Le yg d Question 1 (35) 03/01/2022 Final Exam-Fall 2021 .editepe University, EE354 Communication Systems, Doç. Dr. Engin Maşazade Question 2 (35) Question 3 (30) Total Question 1-(35 pts) Let the Fourier transform of x(t) is given by X() = a, 8 (-400m) n = 0 n = ±1 A₁ = 3. n = 12 otherwise message signal m(t). Let x (t) in Eq.'s (1) is applied to the input of the filter h(t) = 800sinc² (400nt) cos(800nt) and the output of the filter defines the (a) (20 pts) Show X(), x(t), the filter response H(), and the output of the filter in both time m(t) and frequency M domains. Express the AM signal s(t) = (A + m(t)) cos(2000rt). Then, plot its spectrum S(). (b) (10 pts) Let m(t) is applied to the input of the conventional Amplitude modulator with the modulation index μ = 0.5. (c) (5 pts) Compute the power efficiency of the AM signal s(t). Question 2 - (35 pts) modulation scheme. (a) (10 pts) A 3 kHz bandpass channel is to be used for transmission of M-QAM modulated symbols at a rate of R₂ = 9600 bits/sec. (4 pts) Show that the minimum value of M suitable for this transmission is M-16. Use a Nyquist Criterion pulse with a suitable roll off factor, r. (3 pts) What is the value of r? (3 pts) Plot the constellation diagram of the above 16-QAM day that achieves a bit eros probat achieves a bit (b) (5 pts) Determine the E/No at the receiver (in dB) that error probability of 10-6. (c) (5 pts) What should be the E/No if 16-PAM were used instead of 16-QAM in part (b)? (in dB) that achieves a bit error probability of 10-6. (d) (10 pts) A 3 kHz bandpass channel is to be used for transmission of M-QAM modulated symbols at a rate of now R₂ = 16000 bits/sec. (5 pts) What is the minimum value of M suitable for this transmission? (5 pts) Determine the E/No at the receiver (e) (5 pts) Create a table and compare your results found in parts (a), (b) and (c), (d). Question 3-(30 pts) Let you want to transmit R=4800 bits/sec information stream from a transmission channel which has a bandwidth of 15 kHz. You are allowed to use Nyquist criterion pulses with roll-off factor r=0 with an orthogonal non-coherent MFSK modulation. Assume that =10*W/Hz. (5 pts) Determine the maximum value of M which minimizes the E/No at the receiver? (10 pts) What should be the value of received power P, (in dB) so that the BER at the receiver is P, = 10-5. (10 pts) Now, you can use a channel with transmission bandwidth 20 kHz. What is the maximum value of M? Determine the value of P. (in dB) so that the BER at the receiver is P = 105. pts) Create a table and interpret your results found in part (a), (b) and (c).