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WLT620S - WIRELESS TECHNOLOGIES - 1ST OPP - NOV 2023 |
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nAmlBIA UnlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTY OF COMPUTING AND INFORMATICS
DEPARTMENTOF COMPUTERSCIENCES
QUALIFICATION:BACHELOROF COMPUTERSCIENCE
QUALIFICATIONCODE: 07BCCS& 07BACS
COURSECODE: WLT620S
SESSION:NOVEMBER2023
DURATION: 3 HOURS
LEVEL: 7
COURSENAME: WIRELESSTECHNOLOGIES
PAPER: 1
MARKS: 100
FIRSTOPPORTUNITYEXAMINATION QUESTION PAPER
EXAMINER(S) PROFDHARM SINGH JAT
MODERATOR: MS LOINI IIYAMBO
INSTRUCTIONS
1. Answer ALL the questions in section A and any THREEquestions in section B.
2. Read all the questions carefully before answering.
3. Number the answers clearly
4. NUST's examination rules and regulations apply.
THIS QUESTION PAPERCONSISTSOF FOURPAGES(Excluding this front page)
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SECT/ONA
{40Marks]
This section contains TWO questions.
Attempt All questions.
Ql Choose the correct answer for each of the following multiple-choice question
(20 marks, 2 marks for each]
(i). At what frequencies do Wi-Fi radios make transmissions?
A. 3.5 GHz or 7.2 GHz
B. 2.4 GHz or 5.5 GHz
C. 2.0 GHz or 6.5 GHz
D. 3.0 GHz or 8.2 GHz
(ii). A group of Cells is called __ ?
A. BSC
B. BTS
C. Cluster
D. Atom
(iii). Which of the following wireless standards has the highest maximum data
rate?
A. 802.lln
B. 802.llb
C. 802.lla
D. 802.llg.
(iv). In wireless distribution system
A. multiple access points are inter-connected with each other.
B. there is no access point.
C. only one access point exists.
D. none of the mentioned.
(v). What is an access point (AP) in a wireless LAN?
A. device that allows wireless devices to connect to a wired network
B. wireless devices itself
C. both (A) and (B)
D. none of the mentioned.
(vi). The shape of the cellular region for maximum radio coverage is
A. circular
B. square
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C. oval
D. hexagon.
(vii). A wireless network uses_ waves to transmit signals.
A. Mechanical
B. Radio
C. Sound
D. Water
(viii). The area covered by one Transmitter in a GSM network is called __ ?
A. Licensed area
B. Octagon
C. Cell
D. Yard
(ix). Which multiple accesstechnique is used by IEEE802.11 standard for
wireless LAN?
A. CDMA
B. CSMA/CA
C. ALOHA
D. None of the mentioned.
(x). What causes fading of the received radio signals in a mobile
communication environment?
A. Direct propagation
B. Multipath Propagation
C. Bi-path Propagation
D. None of the above
Q2 (i). Explain two functions of the Physical layer in a wireless and mobile [4)
environment.
(ii). Explain Time Division Multiplexing.
[4]
(iii). Describe Multi-path propagation.
[4]
(iv). What is Wi-Fi Protected Access 2 (WPA2)?
[4]
(v). If the frequency of a radio wave is 30 GHz, what is the wavelength of the [4]
wave (velocity of light=3x10 8m/s)?
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SECTIONB {60Marks]
This section contains FOUR questions
Attempt any THREEquestions.
Q3 a}
A particular cellular system has the following characteristics: cluster size
=7, uniform cell size, user density=l00 users/sq km, allocated frequency
spectrum = 900-949 MHz, bit rate required per user= 10 kbps uplink and
10 kbps downlink, and modulation code rate = 1 bps/Hz.
(i.) How much bandwidth is available per cell using FDD?
[5]
(ii.} How many users per cell can be supported using FDMA?
[5]
b) Assume a spectrum of 960 KHz is allocated over a base frequency for
communication between station A and B.
[4]
(i} Divide the entire bandwidth into 4 sub bands.
[3]
[3]
(ii} Why do we divide the entire bandwidth into sub-bands?
(iii} Should we allocate a guard band? Why?
Q4 a} Calculate the maximum distance between the cell site and mobile if the [10]
Guard time is 123 µsand the electromagnetic radio waves propagate at
the speed of light (c= 3x105 km/s}.
b) Draw and explain the following Mode in Wireless Networking:
[10]
(i} Infrastructure Mode and
(ii} Ad-Hoc mode
Q5 a}
b}
Why does wireless networking use CSMA/CA instead of CSMA/CD? (10]
Explain.
Describe how a man-in-the-middle attack may be performed on a Wi-Fi (10]
network and the consequences of such an attack.
Q6 a}
(i} Of the following, what values are possible for a cluster size in a
cellular topology?
Assume a hexagonal geometry: Assume a hexagonal geometry: 5, 8, [2]
11, 13, 20, 21.
(ii} Explain your answer in (i}.
[4]
(iii) What is the Normalised repeat distance for the possible values in (i)? [4]
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b) With the help of a suitable diagram explain the following inter-frame (10]
spacing:
• Short inter-frame spacing (SIFS)
• PCFinter-frame spacing (PIFS)
• DCF inter-frame spacing (DIFS)
GOOD LUCK!
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