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110年 - 110 國立中央大學_碩士班招生考試_通訊工程學系：通訊系統#110494

科目：研究所、轉學考(插大)◆通訊系統 | 年份：110年 | 選擇題數：0 | 申論題數：17

試卷資訊

所屬科目：研究所、轉學考(插大)◆通訊系統

選擇題 (0)

申論題 (17)

(a) Please briefly describe what the scenario is in communications to have such a model. (5%)
(b) Please write the transfer function of the system. (5%)
(c) Please write the impulse response of the system. (5%)
(d) If y(t) is further processed to have the output z(t) for recovering x(t), please draw the processing structure. (5%) 

(a) Write the expression for y(t) in terms of m(t), cos(·), ωc, and t. (5%)
(b) Describe the filter that yields an AM signal for g(t). Give the necessary filter type and the frequencies of interest. (5%)
(c) What is the value of M to yield a modulation index of 0.2? (5%)
(a) Find a set of basis functions for this signaling scheme. What is the dimension of the signal space? Express si(t) by the form of the data vector, in terms of these basis functions and the mathematical symbols in the above expression. (5%)
(b) Please sketch the observation space and show the optimal partitioning of the observation
(c) Please sketch a block diagram of the optimal (minimum symbol error probability) receiver for M=8.(5%)

(a) Write the expression of the spectrum of y(t) in terms of6306dfefe54a6.jpg.(10%)
(b) Sketch the spectrum of y(t), labeling all important frequencies and amplitudes. (5%) 
(a) What is the z-transform expression h[z] of the impulse response of the multipath channel? (5%)

(b) By ignoring the propagation delay T at the receiver, draw the structure of a tapped-delay- line equalizer with weighting coefficients not less than 6306e066c5137.jpgand give the coefficient values in order to accommodate the channel. (10%)
(a) If the binary number of Xis transmitted with equal probability P(+1)=P(-1) = 0.5 , what is the error probability for detecting Xfrom Y when Z =0? (5%)
(b) If the binary number of Xis transmitted with unequal probabilities P(+1)=0.6 and P(-1) = 0.4. Find the optimum decision threshold Z such that the error probability for detecting X from Y is minimum? What is the minimum detection error probability? (10%)
(c) Whether the case in (b) has smaller error probability than that in (a)? Do you think it could be a good communication policy to send the binary number with unequal probabilities based on minimum transmission error probability? Explain your reason. (5%)