Wireless Network and Communication Assignment 2 - Student Solution

This assignment solution covers a range of topics in wireless networks and communication. It begins by converting binary data into analog waveforms using modulation techniques like ASK, FSK, PSK, and QAM. It then computes frequency assignments for different data combinations, explores analog and frequency modulation waveforms, and analyzes a 16 QAM constellation diagram. The solution also details the error detection process using Cyclic Redundancy Check (CRC) and calculates the frame check sequence. Furthermore, it computes the transmitted signal using Direct Sequence Spread Spectrum (DSSS), differentiates between infrastructure and ad hoc modes in WLAN, and compares TCP and OSI protocols for wired and wireless LANs. Finally, it explains the advantages of hexagonal cells in cellular communications and provides a comprehensive understanding of the subject matter.

WIRELESS NETWORK AND COMMUNICATION
Assignment 2
Name of the Student: ramreddy ravula
Student id: 43290
Lecture: Amina saleem

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

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

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= 325 KHz
0101 where i=6, f6= 375 KHz
0110 where i=7, f7= 425 KHz
0111 where i=8, f8=475 KHz
1000 where i=9, f9=525 KHz
1001 where i=10, f10= 575 KHz

1010 where i=11, f11= 625 KHz
1011 where i=12, f12=675 KHz
1100 where i=13, f13= 725 KHz
1101 where i=14, f14=775 KHz
1110 where i=15, f15=825 KHz
1111 where i=16, f16=875 KHz
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:

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).

Cyclic redundancy check method is a process of detecting the accidentally occurred errors in
the channel used for communication. The method uses a generator which is present in both
the receiver and in the sender portion (Ito and Atsumi 2014). The generator is present to
generate a polynomial which represents the key. The data generated is binary where k-1 zeros
are added. The remainder which is generator is encoded and send. At the receiver side with
the module 2 division binary division is done (Pi 2014). If the result is zero or the remainder is
all zeros there is no error in the communication channel and if the remainder are non-zero
than there is error in the communication channel (Edmondson et al., 2014).
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

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
Most of the networks operating today are based upon the infrastructure mode. All the
devices are mostly based upon a single access point. The infrastructure mode uses only one
access point which is centralized (Chhabra 2013). In case of the ad-hoc mode the mode is
based on peer to peer communication. This mode is not based on the concept of centralized
access point. The main advantage of this mode is that the setup process is very easy (Zhang
2013). However, the disadvantage of this mode is that it requires more number of resources

for its connection. The initial set up of the infrastructure mode is difficult but it is more useful
and gives access to all the devices and the connection is much easy (Lai et al., 2015). The
infrastructure mode serves as an ideal choice if the network setup need to be permanent. The
infrastructure mode can be created in device which can support such networks.
9. Compare the differences of TCP and OSI protocols for wired and wireless LANs
using diagrams.
The protocol which is used by the TCP is more stable (Khetan et al., 2013). The model is
based upon the server of the client which is used for the transmission of the data. The OSI
model is more theoretical and is used for the computing system. The TCP model comprises of
4 layers and the OSI model comprises of 7 layers. The model of TCP was developed by the
department of the defence. However, the model of the OSI was developed by the
international standard organization. The mostly used model and protocol is the TCP and the
OSI model is rarely used.

10. Explain why the square and circle shapes cells for cellular communications are not
appropriate as compared to hexagonal shape cells.
While designing the cell for the cellular communication two important aspects need to
be taken care all the points in the cell should receive equal amount of the signal and there
must be no blackspots (Muhonen et al., 2015). Blackspots are the region where the signal will
be unavailable. When number of cells are combined a region is created were the signal is
unavailable (Ponnampalam 2013).
. In case of the circle blackspots region is created when number of cells are combined
together. Therefore, the circle shape of cells is not preferred (Khetan et al., 2013). In case of
the square the distance is greater. All the regions do not receive the equivalent amount of
signal. Both the shapes consist of certain drawbacks which is overcome by the hexagon shape
the hexagon shape also known as the bee hive shape provides signal to all the regions and no
blackspots regions are created. This is the reason that it is the most preferable shape (Zirwas
and Mennerich 2015
.

References
Alani, M.M., 2014. Tcp/ip model. In Guide to OSI and TCP/IP models (pp. 19-50). Springer,
Cham.
Bora, G., Bora, S., Singh, S. and Arsalan, S.M., 2014. OSI reference model: An
overview. International Journal of Computer Trends and Technology (IJCTT), 7(4), pp.214-
218.
Chhabra, K., Marvell World Trade Ltd, 2013. Ad-hoc simple configuration. U.S. Patent
8,619,623.
Edmondson, R., Broglie, J.J., Adcock, A.F. and Yang, L., 2014. Three-dimensional cell
culture systems and their applications in drug discovery and cell-based biosensors. Assay and
drug development technologies, 12(4), pp.207-218.
Ito, M. and Atsumi, T., Semiconductor Energy Laboratory Co Ltd, 2014. Cyclic redundancy
check circuit and semiconductor device having the cyclic redundancy check circuit. U.S.
Patent 8,627,170.
Khetan, S., Guvendiren, M., Legant, W.R., Cohen, D.M., Chen, C.S. and Burdick, J.A., 2013.
Degradation-mediated cellular traction directs stem cell fate in covalently crosslinked three-
dimensional hydrogels. Nature materials, 12(5), p.458.
Lai, X., Cao, J., Du, Z., Tie, M., Ge, L. and Huang, Z., China Iwncomm Co Ltd,
2015. Method for implementing a convergent wireless local area network (WLAN)
authentication and privacy infrastructure (WAPI) network architecture in a local MAC mode.
U.S. Patent 9,015,331.
Muhonen, A., Staack, J.P., Rantalainen, T. and Kåll, J., Nokia Technologies Oy,
2015. Service provision in a communication system. U.S. Patent 9,107,031.
Pi, Z., Samsung Electronics Co Ltd, 2014. Techniques for cyclic redundancy check encoding
in communication system. U.S. Patent 8,627,171.
Ponnampalam, V., MediaTek Singapore Pte Ltd, 2013. WLAN Device and Method Thereof.
U.S. Patent Application 13/512,508.

Zhang, J., Samsung Electronics Co Ltd, 2013. Apparatus and method for establishing ad-hoc
mode connection using cellular network in wireless communication system. U.S. Patent
8,363,609.
Zirwas, W. and Mennerich, W., Nokia Solutions and Networks Oy, 2015. Configuring power
distribution within cooperation areas of cellular communication networks. U.S. Patent
9,161,318.