Nirma University of Science and Technology 2008 B.Tech Information Technology data communication - Question Paper

Nirma University of Science & Technology
Institute of Technology
Supplementary Examination, July 2008
B. Tech. (All Programmes), Semester-IV(RR)
2CE223 DATA COMMUNICATION


Roll / examination No. Supervisor’s initial with date

Time: three Hours Max. Marks : 100
Instructions: 1. Attempt all ques..
2. Figures to right indicate full marks.
3. Sectionwise separate ans book to be used.
4. Draw figures wherever needed.

part – I

1. Do as directed: 20
(a) List and discuss different components of data communications. 05
(b) State the difference ranging from de facto standard and de jure standard. 02
( c) What do you mean by a protocol? 01
(d) State the difference ranging from LAN, MAN and WAN. 06
(e) What are the responsibilities of Presentation layer? 03
(f) Why do you require Analog-to-analog conversion of data? elaborate the different types? 03
[

2.
(a) List and discuss different modes of data transmission giving figures. 06
OR
(a) What is Topology? List and discuss different topologies giving illustrations. 06
(b) Why is the layered architecture desirable for Internet? 03
OR
(b) Why is the OSI Model called the OSI Reference Model? 03
( c) Write the full forms of subsequent abbreviations. 06
i) SMTP
ii) FTP
iii) DNS
iv) SNMP
v) TCP
vi) ICMP

3.
(a) Define the subsequent (Any three) with examples. 09
i) Period
ii) Phase
iii) Time Domain
iv) Frequency domain
(b) The bit stream 10000000000100 is provided. Convert it into subsequent encodings : 06
i) AMI
ii) B8ZS
iii) HDB3

part – II

4. Attempt any fourteen 14
(a) What is FTTC and who uses it?
(b) How does a DSU differ from a modem?
( c) What are the similarities and differences ranging from FDM and WDM?
(d) What are the disadvantages of optical fiber as a transmission medium?
(e) Define: (i) Noise (ii) Collision
(f) What are the conditions for the polynomial used by CRC generator?
(g) Define : (i) Transciever (ii) Shannon - Capacity
(h) What type of fault is undetectable by checksum?
(i) How is CRC superior to LRC?
(j) Define differential Manchester encoding
(k) What factors affect data rate of a link?
(l) Define Bandwidth of a line. What is the bandwidth of traditional telephone line?
(m) Define : (i) Attenuation (ii) Crosstalk
(n) What are the advantages of FDDI over a basic Token Ring?
(o) Why is there no AC field in 802.3 frame?
(p) Define : (i) Angle of refraction (ii) Distortion

5. Attempt any four 12
(a) Draw the time domain graph for bit trend 10110110 as it would appear on an RS -422 circuit. presume a one is five volts and a 0 is -5 volts. Draw the complement also.
(b) If a telephone line is passing the signal of 10 volts and noise is 0.005 percentage of the signal, what is the maximum data rate supported by the line?
( c) Three voice-grade lines, every using 4KHz, are frequency multiplexed together using AM and canceling the lower modulated band. Draw frequency domain representation of resulting signal if carrier frequency are at 4, 10 and 16 KHz respectively. What is the bandwidth of resulting signal?
(d) Construct the Hamming code for bit sequence 10011101
(e) For a 2500 meters long 10 Base five cable, speed of propagation is 60% of speed of light, obtain the maximum time it takes to sense a collision.

6. Write short-notes (Any Four) 24
(a) DTE – DCE interface
(b) Cellular Telephony
( c) Asynchronus TDM
(d) LRC with example
(e) Token Ring

Earning:   Approval pending.