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WLT620S - WIRELESS TECHNOLOGIES - 1ST OPP - NOV 2025 |
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nAm I BIA un IVE RSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTY OF COMPUTING AND INFORMATICS
DEPARTMENT OF COMPUTER SCIENCES
QUALIFICATION: BACHELOR OF COMPUTER SCIENCE
QUALIFICATION CODE: 07BCCS & 07BACS
COURSE CODE: WLT620S
SESSION: NOVEMBER 2025
DURATION: 3 HOURS
LEVEL: 7
COURSE NAME: WIRELESS TECHNOLOGIES
PAPER: 1
MARKS: 100
EXAMINER(S)
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
PROF DHARM SINGH JAT
MODERATOR: MS LOINI IIYAMBO
INSTRUCTIONS
1. Answer ALL the questions in section A and any THREE questions 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 PAPER CONSISTS OF FOUR PAGES {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 questions:
[20 marks, 2 marks for each]
(i) . Which multiplexing method is generally more efficient in systems where
users transmit in bursts?
A. TOM
B. FDM
C. Frequency Hopping
D. None of the above
(ii). Which multiple access technique is used by IEEE 802.11 standard for
wireless LAN?
A. CDMA
B. CSMA/CA
C. ALOHA
D. None of the mentioned .
(iii). Which of the following is a common WiFi range extender device?
A. Firewall
B. Repeater
C. Router
D. Modem
(iv) . Which WiFi standard introduced MIMO {Multiple Input Multiple Output)
technology?
A. 802.lla
B. 802.lln
C. 802 .llb
D. 802 .llg
(v). Which of the following is a wireless personal area network {WPAN)
technology?
A. Wi-Fi
B. Bluetooth
C. LTE
D. Ethernet
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(vi) . 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
(vii). A group of Cells is called __ ?
A. BSC
B. BTS
C. Cluster
D. Atom
(viii). 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.
(ix). 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.
(x) . A wireless network uses_ waves to transmit signals.
A. Mechanical
B. Radio
C. Sound
D. Water
Q2 (i). Explain the hand-off mechan ism in mobile communications.
[4]
(ii). Explain Time Division Multiplexing.
[4]
(iii) . Describe Multi-path propagation.
[4]
(iv) . What is WPA2, and why is it important in Wi-Fi networks?
[4]
(v). If the frequency of a radio wave is 5.0 GHz, what is the wavelength of the [4]
wave (velocity of light=3x108m/s)?
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SECTION 8
[60Marks]
This section contains FOUR questions
Attempt any THREE questions.
Q3 a)
A particular cellular system has the following characteristics : cluster size
=7, uniform cell size, user density=100 users/sq km, allocated frequency
spectrum = 900-949 MHz, bit rate required per user= 10 kbps uplink and
10 kbps downlink, and modulat ion 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]
If the available spectrum per cell (uplink or downlink) is divided into 35
channels and TOMA is employed within each channel:
(iii) What is the bandwidth and data rate per channel?
[5]
(iv) How many time slots are needed in a TOMA frame to support the [5]
required number of users, if each user requires 10 kbps?
Q4 a)
Calculate the maximum distance between the cell site and mobile if the [10]
Guard time is 246 µs and the electromagnetic radio waves propagate at
the speed of light (c = 3 x 105 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)
Assume a spectrum of 1920 KHz is allocated over a base frequency for
communication between station A and B.
(i) Divide the entire bandwidth into 4 sub bands.
[4]
[3]
(ii) Why do we divide the entire bandwidth into sub-bands?
(iii) Should we allocate a guard band? Why?
[3]
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b) Using an appropriate diagram, explain the following types of inter-frame [10]
spacing:
• Short Inter-Frame Spacing (SIFS)
• PCF Inter-Frame Spacing (PIFS)
• DCF Inter-Frame Spacing (DIFS)
GOOD LUCK!
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