Faculty Of Computer Studies
Course Code: T324
Course Title: Keeping ahead in ICTs
Final Examination---SOLUTION
Semester – Academic Year: Fall 2013 2014
Date: ----, 2014
Number of exam Pages:
(including this cover sheet)
() Time Allowed:
(3) Hours
Instructions:
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This exam has 3 parts worth 100 marks.
Part 1 (10% of marks): you should attempt all sub-parts of the question.
Part 2 (40% of marks): you should attempt all questions of this part.
Part 3 (50% of marks): you should attempt all questions of this part.
You should spend proportional amount of time in solving each part.
Use of calculator is allowed but it must not contain inside it anything
related to the course.
 You must use a separate answer booklet, to be provided to you
separately, to solve the exam.
 You must not solve any part of the exam on this paper and you must
provide all your answers on the separate answer booklet.
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Part 1: This part carries 10 marks of the total exam marks. You should
attempt all subparts below. Each subpart carries 1 mark.
Question 1: (10 marks) select the most appropriate choice.
1. Radio waves are usually ….. in characteristics:
a.
b.
c.
d.
Electric
Magnetic
Static
Electromagnetic
2. The User Datagram Protocol (UDP) is a:
a.
b.
c.
d.
Connection-less network layer protocol
connection-oriented network layer protocol
Connection-less transport layer protocol
connection-oriented transport layer protocol
3. The physical length of a 𝜆/4 rod to be used for a 2.4 GHz WiFi link in a free
space is:
a.
b.
c.
d.
15.34cm
1.5m
13mm
31.25mm
4. The polarization is:
a.
b.
c.
d.
the orientation of the magnetic field of an electromagnetic wave
the direction (i.e. orientation) of the wave
the direction of a directional antenna
the orientation of the electric field of an electromagnetic wave
5. Spread spectrum technologies for short range and very high data rate
applications such as distributing high definition (HD) video signals within a home
are generally known as
a. Broadband (BB)
b. Wi-Fi
c. Ultra wideband (UWB)
d. Narrow wideband (NWB)
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6. Which of the following statements is not correct?
a. Ad-hoc networks are isolated groups of mobile stations that communicate with each
other, but cannot communicate with stations outside their radio range.
b. Infrastructure networks are isolated groups of mobile stations that communicate with
each other, but cannot communicate with stations outside their radio range.
c. Propagation by means of ionosphere refraction is called a sky wave.
d. The TCP/IP model has four layers.
7. The RIS is:
a.
b.
c.
d.
A standardization organization
Used to track online documents
A standard format used by reference management software packages
A database that holds articles
8. The sensors in WSNs are often remote from any permanent power supply, and
may be mobile, so the required power must be delivered
a.
b.
c.
d.
Locally
Remotely
Globally
Formally
9. What are the BRICS?
a. Bulgaria, Russia, Indonesia, China, Slovenia
b. Brazil, Russia, India, China, South Africa
c. Bolivia, Russia, Italia, China, Spain
d. none of the above
10. The purpose of any system is often expressed in terms of:
a.
b.
c.
d.
Parameters
Input
Output
Subsystem
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Part 2: This part carries 40 marks of the total exam marks. You should
attempt all questions.
Question 2: (10 marks: 5 marks for each aspect)
Explain briefly the concept of electromagnetic compatibility in its two aspects.
Electrical goods that comply with standards for electromagnetic compatibility (EMC) do
not affect and are not affected by other devices. There are two aspects to EMC:
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Emissions: there are limits to the amount of power a device is allowed to radiate at
different frequencies;
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Immunity: the device must function normally in the presence of radio waves up to a
certain power at different frequencies.
Question 3: (10 marks: 5 marks for each type)
What is the major difference between Ad-hoc network and infrastructure
network?
Ad hoc networks are isolated groups of mobile stations that communicate with each
other, but cannot communicate with stations outside their radio range.
Infrastructure networks allow a station to communicate with other stations outside its
radio range. In the case of Wi-Fi networks, devices known as access points allow a
station access to other stations both within its own radio range and in other networks.
Question 4: (10 marks: 2 marks for each one)
List five characteristics of wireless sensor nodes
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They have large numbers of nodes.
Nodes are close together.
Nodes can fail.
Nodes cooperate.
Nodes have limited power and computational resources.
Node positions do not have to be determined in advance, i.e. the topology changes
(here topology means the arrangement of the connections between nodes, and
since these connections is wireless there is no reason why the communication
between the individual nodes cannot be switched at will).
Nodes broadcast. (This implies that any messages can be picked up by any node.
Messages are not addressed to specific nodes.)
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Question 5: (10 marks: 5 marks for each part)
a. Define briefly the notion of digital divide
The digital divide refers to the gap between those with regular, effective
access to digital technologies and those without. It normally refers to
access to information and services via the internet, but can also be used
with reference to other technologies.
b. What do you understand from the expression “knowledge economy”?
The knowledge economy is normally a term expressing the belief that
‘knowledge’ is the key to economic benefits, particularly in high tech
businesses such as software, telecommunications and so on. The notion
of the ‘knowledge economy’ is closely linked to that of the ‘information
society’.
Part 3: This part carries 50 marks of the total exam marks. You should
attempt all questions.
Question 6: (20 marks: 5 marks for each part)
a. Present in a figure the modulated signal of binary data 0111000101 in case
OOK is applied.
b. Present in a figure the modulated signal of binary data 0111000101 in case of
applying ASK with two amplitudes.
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c. Present in a figure the modulated signal of binary data 1000110100 in case
BPSK is applied.
d. Present in a figure the modulated signal of binary data 1000110100 in case
CPFSK is applied with two frequencies f1 (3 cycles per symbol duration) and f2
(1.5 cycles per symbol duration).
Question 7: (15 marks: 5 marks for each part)
a. DSSS is classified as narrow-band or spread spectrum technique?
Spread spectrum technique
b. Explain briefly the basic idea of DSSS
The idea with DSSS is to use a sequence of chips to represent a 1 in the data to be
transmitted. Every 1 in the data would be represented by the same code. Every 0 would
be represented by another code, usually the inverse of the code used to represent 1
(i.e. all the 1 chips would become -1 chips, and vice versa). How the chips are
transmitted depends on the modulation method used. Reception of the data depends on
the receiver ‘knowing’ the codes that are in use by the transmitter and being able to
synchronize with the transmitter.
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c. Why the sequence of chips, used in DSSS, is called as pseudo-noise
sequence?
This is the essence of direct sequence spread spectrum, where patterns of chips are
defined in a way that give an energy distribution resembling that of noise or in another
term provide a noise-like spectrum.
Question 8: (15 marks: 5 marks for each part)
What the usefulness of the communication between wireless sensor nodes in:
a. power management?
To inform the neighbor nodes of low power and consequent inability to route data.
b. mobility management?
To make sure that, through an awareness of one another’s location, nodes do not move
out of range.
c. task management?
To help nodes cooperate and avoid unnecessary sensing, processing and transmission
in a region that is more than adequately covered by sensor nodes.
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