Wireless Network and Communication

This document provides study material on wireless network and communication. It includes assignments on modulation techniques, frequency assignments, analog and frequency modulation waveforms, QAM constellation diagram, error detection process for CRC, frame check sequence, transmitted signal using Direct Sequence Spread Spectrum, infrastructure and ad hoc modes in WLAN, and a comparison of TCP and OSI protocols for wired and wireless LANs.

Running head: - WIRELESS NETWORK AND COMMUNICATION
WIRELESS NETWORK AND COMMUNICATION
Name of the Student
Name of the University
Author Note

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Assignment No-2
1. Convert the binary data “011010” into analog waveforms using following modulation
techniques:
a. Two level Amplitude Shift Keying
b. Two level Frequency Shift Keying
c. Two level Phase Shift Keying

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d. Differential Phase shift keying
e. Four level Amplitude Shift Keying
f. Four level Phase Shift Keying

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g. Eight level Amplitude Shift Keying
2. With fc = 500 kHz, fd = 25 kHz, and M = 16 (L = 4 bits), compute the frequency
assignments for each of the sixteen possible 4-bit data combinations.
Given: -
fc = 500 kHz, fd = 25 kHz, and M = 16, L = 4 bits
fi=fc + (2i – 1 – M) *fd
M=2^L =2^4 = 16, M=16
0000 where i=1, f1= 125KHz
0001 where i=2, f2= 175KHZ
0010 where i=3, f3= 225KHZ
0011 where i=4, f4= 275KHz
0100 where i=5, f5= 325KHz
0101 where i=6, f6= 375KHz
0110 where i=7, f7= 425KHz
0111 where i=8, f8=475KHz
1000 where i=9, f9=525KHz

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1001 where i=10, f10= 575KHz
1010 where i=11, f11= 625KHz
1011 where i=12, f12=675KHz
1100 where i=13, f13= 725KHz
1101 where i=14, f14=775KHz
1110 where i=15, f15=825KHz
1111 where i=16, f16=875KHz
This scheme can support data rate of
1/Tb = 2Lfd = 2*4*25 = 200Kbps
3. Draw the approximate Analog Modulation and Frequency Modulation waveforms in
complete steps for the following signal:

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4. Draw the 16 QAM Constellation Diagram having two different amplitude levels and
eight different phase levels.
5. Explain and draw the Error Detection Process for Cyclic Redundancy Check (CRC).
In the communication channel there are certain error which is detected easily by the
cyclic redundancy check. The check involves various steps in it. The CRC contains generator
both the receiver and the transmitter end (Wang 2013). The binary data division is done and
k-1 zeros is added. After the process the module-2 binary division is done by the process of
the key. The remainder of the division is stored and added at the end of the data. The added
data is made to form the encoded data and it is send at the receiver end. The receiver is added
by n-1 bits and send back to the sender side (Pi 2014).

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6. Compute the frame check sequence for the following information:
Message = 10111100, Pattern = 11011
7. Compute the transmitted signal using Direct Sequence Spread Spectrum for the
following information: Input: 1011, Locally Generated PN bit stream: 101011011010, T
= 3Tc

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8. What is the difference between Infrastructure and ad hoc modes in WLAN? Draw
their relative diagrams as well.
WLAN ad-hoc mode
WLAN infrastructure mode
The infrastructure mode network differs from that of the network of ad-hoc mode.
The infrastructure offers communication among the wireless node and the access node. the
communication process is indirect with the support of the wireless nodes. However, in case of
the ad-hoc node the each and every node is free to communicate as there is no requirement of
the access node (Sarkar, Basavaraju, and Puttamadappa 2016). The ad-hoc made entire set up
and the process involved is much easy. the entire set-up can be done at a much lesser cost. In
case of the infrastructure mode all the set-up is complex and difficult. The cost is high. The
ad-hoc mode is fast compare to the infrastructure mode (Sherlock et al., 2013).

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9. Compare the differences of TCP and OSI protocols for wired and wireless LANs
using
diagrams.
The OSI model can be said as a reference model. The TCP is more reliable compared
to the OSI model. The approach in both the model are different. The TCP and OSI model
comprises of horizontal and vertical approach respectively. The TCP model is protocol
dependent, however the OSI model is protocol independent (Ravali 2013.).
10. Explain why the square and circle shapes cells for cellular communications are not
appropriate as compared to hexagonal shape cells.
Every system comprises of certain advantages and disadvantages which need to be
overcome. For proper communication all the areas under the cell must have uniform
distribution of the signals and all the regions need to be covered by the cell (Rui, Jihong and
Hua 2014). In the square shape cell all the areas are not able to receive the signals and in the
circle shape cell there are certain areas where the signals cannot be transmitted. However, the
most preferred shape is the bee-hive or hexagon shape in which all the regions receive
uniform signal distribution and all the regions are covered within the cell. This is the reason
that it is the most preferred cell shape for cellular communication.

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References
Pi, Z., Samsung Electronics Co Ltd, 2014. Techniques for cyclic redundancy check encoding
in communication system. U.S. Patent 8,627,171.
Ravali, P., 2013. A comparative evaluation of OSI and TCP/IP models. International Journal
of Science and Research, 4(7), pp.514-521.
Rui, T., Jihong, Z. and Hua, Q., 2014. Distributed power control for energy conservation in
hybrid cellular network with device-to-device communication. China communications, 11(3),
pp.27-39.
Sarkar, S.K., Basavaraju, T.G. and Puttamadappa, C., 2016. Ad hoc mobile wireless
networks: principles, protocols, and applications. CRC Press.
Sherlock, K.G., Cooper, G.H., Guzik, J.R., Pearcy, D.P. and Valente, L.F.P., McAfee LLC,
2013. Identities correlation infrastructure for passive network monitoring. U.S. Patent
8,584,195.\
Wang, Z., Chen, C.J., Xiao, K., Jiang, H., Fife, J.R. and Bhoja, S., Broadcom Corp,
2013. Communication device employing binary product coding with selective additional
cyclic redundancy check (CRC) therein. U.S. Patent 8,572,460.