MITS5003 - Wireless Networks: Encoding, Multiplexing & Error Control

This assignment solution covers various aspects of wireless networks and communication, including encoding techniques, error control methods, and multiplexing. It begins by calculating the data rate required for robot-to-remote controller communication and explains three suitable encoding techniques. The solution then converts sensor data into a binary status string and represents it using ASK, FSK, and PSK encoding techniques. Furthermore, it calculates the CRC for the status string and discusses other error control and flow control techniques. The assignment also delves into multiplexing techniques such as FDM, TDM, and CDMA, highlighting their functionalities and differences. It compares OFDM with 3G, 4G, and WiMAX, focusing on channel equalization and symbol rate. Finally, it addresses practical aspects of wireless network security, including encryption, password management, firmware updates, and guest network removal. The solution also calculates theoretical maximum throughput and briefly explains 802.11b standard. This document is available on Desklib, a platform offering a wealth of study resources, including past papers and solved assignments, for students.

Assignment
Name
Subject
Date of Submission

Part I
a)
Total bandwidth =sum of all frequencies
4+6+4+2=16 bits/2secs
= 8bits/s
b).
-Digital to digital encoding- is the representation of digital data using digital signals.
-Digital to analog encoding- this involve conversion of digital data into analog signals. it
involves the following amplitude shifting key and Frequency shifting key.
-Analog to analog encoding- This amplitude modulation techniques and frequency
modulation techniques are used in processing of analog data.
c).
status string = speed* battey%/(obstacle *motor functionality)
5∗75.
11∗0.48 =71.022=
71/2 = 35,r 1
35/2 = 17, r 1
17/2 = 8, r 1
8/2 = 4, r 0
4/2 = 2, r is 0
2/2 = 1, r is 0
1/2 = 0, r is 1
1000111
d)
=10001111001101
e).

-Checksum –This is a method of error detection this divides data into equal bits, which are
then combined and send to the required destination.
Redundancy- allows the user to see if the incoming packets were affected in the process of
transmission.
Parity checking-.It increases the number of bits by one to show if either the number of bits in the
previous data is even or odd this ensures surety of data transfer.


Part II
a. FDM -Frequency division multiplexing
This is techniques that utilizes many frequencies to bring together a lot of signals to be
send over mediums for the reason of communication. Meaning that it carry frequencies
to each information stream and later combines various frequencies for transmission. The
activity of Frequency division multiplexing (FDM) relays on distributing the reachable
transmission capacity of a similar station in the midst in which the frequencies are to be
communicated. This shows numerous signals are conveyed at the same time with
individually flag involving an another recurrence space inside a typical transfer speed .
Every flag to be transmitted tweaks an alternate bearer . The tweak can be AM,SSB, FM
or PM . The regulated signals are then involved in shaping a combined flag which is
transmitted over a private channel.
Frequencies
Combined for transmission
TDM -Time division multiplexer—is one of of multiplexers which combine data
packets by distributing each stream in a different periods of time. It from time to time
trades or sends diverse spaces in excess of one transmission channel. Time-division
multiplexing was first created for applications in telecommunication to course various
transmissions all the while over a solitary transmission line. In the 1870s, it was built up
a period multiplexing arrangement of numerous Hughes transmit machines.

CDMA – code division multiplexing- this techniques where multiple signals of
information are clinked together for transmission over same signal bandwidth. This allow
users to share the same communication media.
CDMA utilizes supper range, an innovation that was developed during the Second World
War to prevent enemies from blocking and having access to transmission.. In super
range, a data flag is transferred overs space frequencies n related occurring frequency
range.
A pseudo-arbitrary dispersal code is used in multiplexing the base flag. Multiplexing with
a dispersal code creates the data transmission required for the flag, distributing it out
completes the reachable ranges.
Diagram showing cdma transmission
b. ofdm is different from 3G ,4G and WiMAX in the following criteria.

It can adapt to extreme channel association for insipite of weakening frequencies in
copper wire when contrasted with the rest.
Features.
 Channel equalization it uses many slow narrow band modulated frequencies
signals rather than narrow band signals.
 A low symbol rate, which eliminates inter-symbols transfer interference.
 It also facilitate the design of single frequency networks.
c.
I. It will be close 1 mhz
II. 802.11 a
III. By using a low symbol rate that makes utilization of monitor interims between
images that are moderate in it.
Part III
a)

b)
bss- is the basic service set-the maximum number of users that connect to a wireless access
point.
Meaning that is the mac address of the access point/connected users
= mac/8 for the rooms
While lounge = mac/25 number of connected users.
c)
Theoretical Maximum Throughput = (Packet Length ∗ 8 ∗ 1000000) / (Preamble + Header + ((Packet
Length + 28) ∗ 8 / Rate) + SIFS + Preamble + Header + (ACK ∗ 8 / Rate) + DIFS + ((Backoff / 2) ∗ Slot))
=(10*8*1000)/(5 +8(10+28)*8/100)+25+5+8+( 8/100) +10*8
8010/85.6
=93.57
d)
802.11b - The 802.11 high rate WiFi is an expansion to 802.11 that relates to remote LANs
and yields an association as quick as 11 Mbps transmission. It is more effective and has high
recurrence and channel data transfer capacity.
e)
 Encryption – encryption of the network using WPA2 network protocol to allow only
certain people to have access to the network.
 Passwords- setting of passwords to each access point so that the network is made
private to the employees and this will prevent un authorized access to the network.
 Updating of the firmware regularly to keep it up to date this prevents some attacks to
the network by hackers.
 Removing guest networking- turning off the guest network such that the network can
only be accessed by the employees who are registered in the system.

Bibliography
[1]Heinzelman, W.R., Chandrakasan, A. and Balakrishnan, H., January. Energy-efficient communication
protocol for wireless microsensor networks. In System sciences, 2000. Proceedings of the 33rd annual
Hawaii international conference on , 2010 (pp. 10-pp). IEEE.
[2] Lueng, K.T., Dao, S. and Shek, E., HRL Laboratories LLC. Apparatus and method for context-
sensitive dynamic information service composition via mobile and wireless network communication. U.S.
Patent 7,483,693, 2009
[3]. Gehring, S., Lynch, W., Rahardja, K., Rogerson, G. and Sparrell, C.J., Pulse-LINK Inc. Medium
access control protocol for centralized wireless network communication management. U.S. Patent
6,597,683. , 2012
[4] Wang, X., Gui, C., Wang, W. and Nova, M., Misonimo Chi Acquistion LLC. Multi-hop ultra wide band
wireless network communication. U.S. Patent , 2011.
[5] Wang, J.C., HTC Corp. Methods for establishing wireless network communication and device utilizing
same. U.S. Patent 7,672,291 , 2010