Assessment 2: Wireless Communication Antennas and Multiplexing Methods

This report provides an analysis of antennas and multiplexing techniques, crucial components of wireless communication systems. The first part of the report categorizes antennas based on their propagation patterns, differentiating between directional antennas (Yagi and Horn antennas) and omni-directional antennas (cellular antennas), detailing their strengths, weaknesses, and future applications. The second part focuses on multiplexing techniques, which are essential for sharing communication channels in wireless systems. It explores two key techniques: Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA), comparing their characteristics and applications. The report utilizes various sources to support the analysis, providing a comprehensive overview of these critical wireless communication technologies.

Running head: ASSESSEMENT
Assessment item 2
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ASSESSEMENT 2
Task 1
Antennas are important components of wireless communication as they facilitate the
transmission and reception of electromagnetic signals through free space. These electronic
devices will integrate electronic circuits without the need for physical conductors. In terms of
application, antennas are designed with different properties based on their design structure or
their design material (MIT, 2004). In this analysis, we categorise antennas based on their
propagation patterns, for instance, some antennas will propagate waves in limit directions
while other will have no restrictions, the direction of transfer.
Types of antennas
1. Directional antennas – These types of antennas will propagate signals in one direction
only. This attribute facilitates their high gain ratios and directivity outcomes. Examples Yagi
and Horn antenna ().
a. Yagi antenna – a common antenna that is used to transfer RF signals in one direction.
They are commonly applied in television set receivers.
Strength
• Yagi antennas have high gains and directivity.
• They are simple to design and install.
• Favourable for long distance transmission (radio-electronics, 2017).
Weaknesses
• Yagi antennas have limited gains.
• Their length also determines the gain which increases their size to accommodate
high gain requirements.

ASSESSEMENT 3
b. Horn antenna – another common example of a directional antenna that is characterised
by a pyramid design structure. This antenna will have a flare-like aperture that will increase
towards its transmission end. Now, due to its design (aperture) it has high gains, a property
that facilitates its application in UHF signals (Rouse, 2017).
Strengths
• They are attributed with high gains, an outcome that is facilitated by their design.
• Moreover, they can operate with different frequencies and bandwidth ranges.
• High directivity.
Weaknesses
• For optimal operation, horn antennas require extended aperture lengths (Rouse,
2017).
2. Omni-directional antennas – unlike the antennas discussed above, Omni-directional
antennas are designed to transmit (or receive) RF signals in all directions. Therefore, when
analysed they project signal lobes in all directions. Example; cellular antennas.
a. Cellular antenna – this antenna has minimal protrusions as its designs are not subject to
direction. This property makes the antenna a suitable accessory for mobile devices that
require miniature components. However, the same design tends to limit its gain and
directivity functions, which necessitates the need for booster towers (Carr, 2012).
Strengths
• First, a cellular antenna can operate in all directions.
• Secondly, it also has optimal amplification capabilities when compared to its size.

ASSESSEMENT 4
Weaknesses
• Low gains which limits their coverage distance.
• Poor directivity (Carr, 2012).
Future application (medium and long distance wireless links)
Directional antennas are still used today to propagate long distance signals as they exhibit the
necessary attributes. These attributes as highlighted above are determined by the design of the
antenna and also by the materials used. Nevertheless, when considering the design structure
(common design material), Omni-directional antennas are only convenient in applications
that require short distance transmissions such as Wi-Fi connections (WLAN) and cellular
communication which is boosted by telecommunication towers. Therefore, in the future, the
transmission of long range signals will be supported by directional antennas as they hold the
necessary operational requirements i.e. gain and directivity.
Task 2
Multiplexing techniques (multiple access of communication channels)
Wireless communication facilitates the transfer of information through radio spectrums.
These spectrums tend to have many limitations, the first being the capacity an outcome that
necessitates the application of multiple access schemes. In essence, multiple access schemes
are techniques that are used in mobile communication to share the communication channels.
Now, these communication channels are usually established between the mobile stations and
the receiver base station (Sengunthar, 2012).
When in operation, the communication system will divide the transmission area into sections
that communicate with each base station. This form of segmentation increases the overall
capacity of the communication channel which facilitates the transmission of more

ASSESSEMENT 5
information. In all, there are various methods or ways of dividing the channels in question
which produces the techniques outlined below.
1. Code division multiple access (CDMA)
In this technique, several transmitters will use a single channel to transfer information
simultaneously. To successfully achieve the task, unique pseudo codes are assigned to the
transmitters as well as the signal (information) themselves. Now, these codes are then used as
identification tags for the transmitted information, an action that facilitates the separation
process of the signals at the destination.
Characteristics
 CDMA users use all the available spectrum for the communication process.
 Users having the same identification codes can communicate with one another.
 Hands off between the communicating stations is handled appropriately as compared
to the other techniques (corps, 2000)..
 Suitable for voice and data communication.
2. Frequency division multiple access (FDMA)
The basic technique that can facilitate communication as provided by mobile phone service
providers. In this technique, an array of sub-band frequencies are used to divide the
communication channel. These frequency bands are then allocated to the different users who
access the same network during their communication process.
Characteristics
 Channels are usually left idle when not in use i.e. they are never re-allocated.
 It’s implemented in narrowband systems thus is less complex.
 Filtering is done to eliminate interferences.

ASSESSEMENT 6
 Frequency bands are used for communication (Zahra, 2015)
.
CDMA FDMA
Multiplexing is done using a unique set of
codes (pseudo-codes).
Frequency bands are used to split the
communication channel.
The full spectrum of communication is used
by each user.
The available spectrum is divided among
the users.
A technique that is recommended for both
voice and data communication.
This technique is commonly used for voice
communication.
Signals use the entire spectrum, therefore,
it's never idle.
A frequency band remains idle when not in
use (no re-allocation).
The communicating parties will only
identify users having the similar codes.
Communication is based on the frequency
bands developed at the start of the
transmission process.
(Zahra, 2015)

ASSESSEMENT 7
References
Carr, J. (2012). Directional or Omnidirectional antenna? Joe Carr's Radio Tech-notes,
Retrieved 14 August, 2017, from: http://www.dxing.com/tnotes/tnote01.pdf.
corps, W. (2000). FDMA vs. TDMA vs. CDMA. Connecting Wireless, Retrieved 14 August,
2017, from: http://wirelessapplications.com/pdf/lf/FD_TD_CDMA.pdf.
MIT. (2004). Chapter 3: Antennas. MIT, Retrieved 17 August, 2017, from:
https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-661-
receivers-antennas-and-signals-spring-2003/readings/ch3new.pdf.
radio-electronics. (2017). Yagi Antenna / Yagi-Uda Antenna. Antennas and propagation,
Retrieved 14 August, 2017, from:
http://www.radio-electronics.com/info/antennas/yagi/yagi.php.
Rouse, M. (2017). Horn antenna. Research gate, Retrieved 17 August, 2017, from:
http://searchmobilecomputing.techtarget.com/definition/horn-antenna.
Sengunthar, E. (2012). Chapter 9: Multiple Access Techniques for Wireless
Communications. School of information science and Engineering, SDU, Retrieved 19
August, 2017, from: http://www.erode-sengunthar.ac.in/dept/lm/ECE/WC/Multiple
%20Access%20Technique.pdf.
Zahra. (2015). FDMA-TDMA-CDMA. Multiple access techniques in wireless
communication, Retrieved 16 August, 2017, from:
https://www.slideshare.net/SammarKhan2/fdmatdmacdma.