University of Delhi 2010-2nd Sem M.C.A 1st yr advanced computer networks UNIVERSITY - Question Paper
This question paper contains 3 printed pages.
6261 Your Roll No ......................
M.Sc. COMPUTER SCIENCE f II Sera.
J
MCS - 204 - Advanced Computer Networks (Admissions of2009 and onwards)
Time 2 hours Maximum Marks 50
(Write vour Roll No on the top immediately on receipt oj this question paper)
Answer at! questions
1 a) In an QAM modulation scheme, the number of
amplitude levels are 16 and the number of phase levels are 32 The maximum data rate possible is 14 4kbps What is the bandwidth allocated to the Modem ? 05
b) In CDMA multiple access scheme, the total bandwidth allocated is 2MHz The data rate of each channel is 10kbps Show that the number of uphnk and downlink channels are same for -
(i) CDMA/FDD,
(ii) CDMA/TDD 05
2 a) In amplitude modulated voice transmission, the
maximum signal frequency is 20KHz and the earner frequency is 1 OOKHz. What would be its frequency spectrum ? How would the frequency spectrum change if the modulation scheme is frequency modulation 9 05
b) In a thickly populated city with lot of intrusions, which of the following WLAN technologies would you prefer -
(i) Direct sequence spread spectrum,
(n) Frequency Hopping spread spectrum 9
Justify your answer 05
3 a) Why are the following mechanisms not possible m
WLAN 9
(i) Collision detection,
(ii) Carner sensing 05
b) Which of the following modes of WLAN take care of hidden terminals 9
(i) basic mode,
(ii) RTS/CTS mode.
Justify your answer 05
4 a) What is hand-off m CSM cellular network ? How is it
done? 05
b) In the GSM mobile network, how does a mobile station know -
(i) That it has a call,
(h) What uplink and down link channels has been allocated to it9 05
5 a) How does Wireless Local Loop serve the following applications 9
fi) Constant bit rate voice application,
(ii) Variable bit rate real - time application ? 05
b) Given the same total bandwidth, same channel data * rate and the same modulation scheme, which of the
following technologies would support more number of
uplink and downlink channels
(i) TDMA / FDD,
(ii) CDMA/FDD.
Justify your answer
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