This is the series of network fundamental course for IT learners.
The student should follow the course from the first lecture...............................
Why Teams call analytics are critical to your entire business
Csc339 – lecture 2a network fundamental
1. CSC339 – NETWORK
FUNDAMENTAL
Jahan University
Computer Science Department
Lecturer: Islahuddin Jalal
Master in Cyber Security
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2. Class Policy
A student must reach the class-room in time. Late comers may join the class
but are not entitled to be marked present.
Attendance shall be marked at the start of the class and students failing to
secure 75% attendance will not be allowed to sit in final exam.
The assignment submission deadline must be observed. In case of late
submission, ten percent may be deducted from each day.
Those who are absent on the announcement date of the assignment/test.
Must get the topic/chapter of test/assignment confirmed through their peers.
Mobile phones must be switched-off in the class-rooms.
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3. Grading Evaluation for Network fundamental
Internal Evaluation
Midterm Exam 20%
Attendance 5%
Assignment/Presentations 5%
Quizzes/Tests 10%
Total Internal Evaluation 40%
Final-term Examination
Final-term Exam 60%
Total Marks 100%
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4. Topics to be discussed
Baseband transmission
Broadband transmission
Modes of channel operation
Attenuation
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5. Digital signal vs Analog signal
Signals can be analog or digital
Analog signals can have an infinite number of values in a range.
Digital signals can have only a limited
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6. Baseband Transmission
Baseband transmission
Digital signals are used
Time Division Multiplexing is possible
Baseband is bi-directional transmission
Short distance signal travelling
Entire bandwidth of the cable is consumed by a single signal in a baseband
transmission.
Using dedicated medium
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7. Baseband transmission
In baseband transmission, the required bandwidth is proportional to the bit
rate; if we need to send bits faster, we need more bandwidth.
Baseband transmission of a digital signal that preserves the shape of the
digital signal is possible only if we have a low pass channel with an infinite or
very wide bandwidth.
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9. Example of Baseband transmission
LAN uses a dedicated channel for two stations communicating with each
other.
In a bus topology LAN with multipoint connections, only two stations can
communicate with each other at each moment in time, the other stations need to
avoid from sending data.
In a star topology LAN, the entire channel between each station and the hub is
used for communication between these two entities.
Etc.
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10. Broadband transmission
Broadband:
Analog signals are used
Transmission of data is unidirectional
Signal travelling distance is long
Frequency division multiplexing is possible
The signals are sent on multiple frequencies and allow all the multiple signals are
sent simultaneously in broadband transmission.
Modulator is used
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11. Modulation of a digital signal for transmission on a bandpass
channel
12. Example of Broadband Transmission
Sending computer data over a telephone line
Digital Cellular telephone.
The digital cellular phones convert the analog audio signal to digital and then
convert it again to analog for transmission over a bandpass channel.
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13. Attenuation
Loss of energy
When a signal travels through a medium, it loses some of its energy due to the
resistance of the medium.
Some wire or medium carrying electric signals get warm after some time it is
converted into heat
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15. Data Transmission Rates
How fast we can send data
Bit per second over a channel
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16. Data Transmission rate
Depends of three factors
The bandwidth available
The level of the signals
The quality of the channel (the level of noise)
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17. Theoretical formulas for data rate
There are two formulas for calculating data rate
Noiseless Channel formula by Nyquist
BitRate = 2 * bandwidth * log2L
Noisy Channel formula by Shannon
Capacity = bandwidth * log2 (1+SNR)
SNR = signal to noise ratio = average signal power
average noise power
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18. Example of Noiseless channel formula
Consider a noiseless channel with a bandwidth of 3000Hz transmitting a signal
with two signal levels. The maximum bit rate can be calculated as:
BitRate = 2 * 3000 * Log22
= 6000 * Log22
= 6000 * 1
= 6000 bps
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19. Example of noisy channel formula
We can calculate the theoretical highest bit rate of a regular telephone line.
A telephone line normally has a bandwidth of 3000 Hz (300 to 3300) assigned
for data communications. The signal-to-noise ration is usually 3162. for this
channel the capacity is calculated as:
C= B log2 (1+SNR)
= 3000 log2 (1+3162)
=3000 log2 (3163)
=3000 * 11.62
=34860bps
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20. Modes of Channel Operation
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Three types of modes of Channel Operation
Simplex
Half duplex
Full duplex
21. Simplex
Data in a simplex channel is always one way. Simplex channels are not often
used because it is not possible to send back error or control signals to the
transmit end.
E.g Television, radio transmission
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22. Half duplex
A half-duplex channel can send and receive, but not at the same time.
E.g one-lane bridge, walkie-talkie
In some aspects, you can think of Internet surfing as being half-duplex, as a
user issues a request for a web document, then that document is downloaded
and displayed before the user issues another request
In addition, it is possible to perform error detection and request the sender
to retransmit information that arrived corrupted.
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24. Full duplex
Data can travel in both directions simultaneously.
There is no need to switch from transmit to receive mode like in half duplex.
Its like a two lane bridge on a two-lane highway.
E.g Mobile
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