Wireless Network & Communication

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Wireless Network & Communication 1
WIRELESS NETWORKS & COMMUNICATION
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Wireless Network & Communication 2
Assignment No 1
1. Using the layer models in Figure, describe the ordering and delivery of a pizza, indicating
the interactions at each level.
The guest effectively places a request with the host. The host communicates this order to the
counter clerk who requests the order with commis chef. The telephone coordination offers the
physical way for the order to be conveyed from host to counter clerk. The commis chef gives
the pizza to the counter clerk with the order. The counter clerk packages the pizza with the
carriage address and the carriage motorist enfolds all of the orders to be supplied. The road
offers the physical track for carriage Puppis, (2016).
2. The French and Chinese prime ministers need to come to an agreement by telephone, but
neither speaks the other’s language. Further, neither has on hand a translator that can translate
to the language of the other. However, both prime ministers have English translators on their
staffs. Draw a diagram similar to Figure 1 to depict the situation, and describe the interaction
and each level.
The French prime minister communicates with the French to English interpreter. The second
interpreter translates English to Chinese minister. The feedback then follows the loop but in
the reverse direction Smith, (2015).

Wireless Network & Communication 3
3. From the following figures, compute the maximum amplitude, frequency, time period and
phase for each of the wave. The x-axis represents the time in sec and y-axis represents the
amplitude.
Figure 1
Maximum amplitude: 15
Frequency: 0.3333 Hz
Time period: 3s
Phase: 0
Figure 2
Maximum amplitude: 4
Frequency: 0.15625 Hz
Time period: 6.4s
Phase: 0
Figure 3
Maximum amplitude:7.8
Frequency: 0.4545 Hz
Time period: 2.2s
Phase: 90

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4. Compute the amplitude, frequency, time period and phase for each of the following
equations and also draw their respective waveforms.
The general wave equation is given by:
v ( t ) = Amax sin(2 πft +θ ph)… … … … … .4
Where Amax the amplitude, f frequency is, T = 1
f is the time period and θph is the phase Li-Ke,
(2014). Using equation, the parameters of the equations a through d can be obtained as.
a. 10𝑆𝑖𝑛 (2𝜋 (100) 𝑡)
Amplitude: 10
Frequency: 100 Hz
Time period: 1/100=0.01s
Phase: 00
b. 20𝑆𝑖𝑛(2𝜋(30)𝑡 + 90)
Amplitude: 20
Frequency: 30 Hz
Time period: 1/30=0.033s
Phase: 900
c. 5𝑆𝑖𝑛(500𝜋𝑡 + 180)
Amplitude: 5
Frequency: 250 Hz
Time period: 1/250=0.004s
Phase: 1800

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d. 8𝑆𝑖𝑛 (400𝜋𝑡 + 270)
Amplitude: 8
Frequency: 200 Hz
Time period: 1/200=0.005s
Phase: 2700
5. Suppose that a digitized TV picture is to be transmitted from a source that uses a matrix of
480× 500 picture elements (pixels), where each pixel can take on one of 32 intensity values.
Assume that 30 pictures are sent per second. (This digital source is roughly equivalent to
broadcast TV standards that have been adopted.).
a. Find the source rate R (bps).
R=30∗450∗500∗5
¿ 7.2∗106 pixels
s
¿ 36 mbps
b. Assume that the TV picture is to be transmitted over a channel with 4.5-MHz
bandwidth and a 35-dB signal-to-noise ratio. Find the capacity of the channel
(bps). Hint: Use Shannon’s Criteria.
c=B log10 ( 1+ SNR )
¿ 4.5∗106 log10 ( 1+ 3162 )
¿ 52.335 mbps

Wireless Network & Communication 6
6. Determine the isotropic free space loss at 4 GHz for the shortest path to a synchronous
satellite from earth (35,863 km).
FSPL=10 log10 (( 4 πdf
c )2
)=20 log10 d +20 log10 f −147.55
¿ 20 log10 35863∗1000+20 log10 4∗109−147.55
¿ 195.58 dB
7. Given a signal as follows, compute the fundamental frequency, spectrum and
bandwidth. Also calculate the channel capacity using Nyquest criteria using M= 2, 4, 8,
where M is the number of levels. 𝑠(𝑡) = 5sin(200𝜋𝑡) + sin(600𝜋𝑡).
Fundamental frequency
ω1=200 π f 1=100 T1 =0.01 ω2=600 π f 2=200T 2=0.005
f 0=GCD ( 100,200 )=100 Hz
Spectrum
The frequency spectrum is between 100 Hz and 200 Hz Garg, (2017).
Bandwidth
Bandwidth=f 2−f 1=200−100=100 Hz
channel capacity
rb =2Wm

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M=2
rb =2∗100∗2=400 bits/ s
M=4
rb =2∗100∗4=800bits /s
M=8
rb =2∗100∗8=1600 bits/s
8. Explain how the data rate over a channel can be increased, without increasing the
bandwidth? What is the disadvantage of this approach? Hint: Nyquist Theorem.
According to Nyquist:
Bitrate=2∗Bandwidth∗log2 L
Where Bandwidth is a fixed parameter and L is the number of signal levels. Therefore, to
increase the bit rate we increase the signal levels L.
9. What is the main difference between Packet switching Virtual Circuit and Circuit
Switching? Also discuss the advantages of Packet switching Virtual Circuit over Circuit
Switching.
Packet switching virtual circuit is a means of transporting data over a packet switched
computer network in such a way that it appears as though there is a dedicated physical link
between source and destination end systems of this data. On the other hand, circuit switching
Advantages of Packet switching Virtual Circuit over Circuit Switching Fette, (2018).
i. It is easier and more affordable.

Wireless Network & Communication 8
ii. Requires less complicated infrastructure.
iii. Easier to add new nodes to the system.
10. In a LOS communication, consider d = 40km, the requirement is to make two antennas
(transmitter and receiver) such that the height of one antenna should be twice of the other.
Considering this, find the appropriate heights of these two antennas.
d=3.57( √ k h1 + √ k h2 )
h1=2h2
k =0.8
Therefore:
40=3.57 ( √0.8 h1 + √0.8 h1 )=3.57∗2 √0.8 h1
.h1=39.23m , h2=19.615 m
Reference
Fette, B. A. (2018). RF & wireless technologies. Amsterdam, Newnes/Elsevier.
http://www.dawsonera.com/depp/reader/protected/external/AbstractView/S9780080942582.
Garg, V. (2017). Wireless Communications & amp ; Networking: an introduction.
Burlington, Elsevier. http://public.eblib.com/choice/publicfullrecord.aspx?p=305685.
Li-Ke Huang. (2014). Challenges and design paradigm shifts in test and measurement
technologies to enable future wireless network R & D beyond 4G towards 5G. Stevenage,
IET.
Puppis, M. (2016). Trend in communication policy research. Bristol, Intellect.
http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&AN=1135698.

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Smith, J. R. (2015). Wirelessly powered sensor networks and computational RFID. New
York, Springer. http://public.eblib.com/choice/publicfullrecord.aspx?p=1081686.