### Data Communication, 2068 Chaitra - Old questions

TRIBHUVAN UNIVERSITY
INSTITUTE OF ENGINEERING
Examination Control Division
Full Marks:
80
Pass Marks
30
Time
3 hrs.

### Data Communication, 2068 Chaitra

Candidates are required to give their answers in their own words as far as practicable.
Attempt All questions.
The figures in the margin indicate Full Marks
Assume suitable data if necessary
[8]
• 1. Compare digital communication with analog communication system and explain digital communication system with the help of functional block diagram
• [2+6]
• 2. Distinguish between energy and power signals. Define invertibility of a system. Which properties (Linearity, Causality, Time invariance, Stability and Memory) processes by the following system (i) y[n] = 3x[n] - 4x[n-1] (ii) y(t) = $sin(2\pi x(t))$.
• [2+2+6]
• 3. Define unit impulse response. What is its significance in signal analysis?
• [4]
• 4. Describe the characteristics and performance of UTP cables over other guided transmission media.
• [4]
• 5. State and explain Shannon's channel capacity theorem.
• [4+6+6]
• 6. What is a modulation? Why is it required? Briefly explain the steps involved in encoding analog data as digital signal. Encode the following bit stream using unipolar (NRZ), polar (NRZ-L, NRZ-I, RZ, Manchester), bipolar (AMI) 10110001110.
• [4]
• 7. What is multiplexing? Explain its application.
• [4+2]
• 8. Compare FDM, WDM and TDM. What are the advantages and disadvantages of CDMA technique?
• [5]
• 9. What is switching? Differentiate between circuit and packet switching.
• [4+6]
• 10. Define Information and Entropy. The probability of five possible outcomes of an experiment are given as: $P(x_{1}) = 1/2, P(x_{2}) = 1/4, P(x_{3}) = 1/8, P(x_{4}) = P(x_{5}) = 1/16.$ Determine the entropy and information rate if there are 16 outcomes per second.
• [2+3]
• 11. Define Hamming Distance and minimum Hamming distance. Suppose a code has a Hamming distance $d_{min} = 4.$ What is the error detection and correction capability of this scheme?