introduction to mobile computing

1. Introduction To Wireless Communication And Mobile
Computing
Oda Bisil College Ambo Campus
Chapter One
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2. What is wireless Communication
Definition of Wireless Communication
 In a communication system, information is transmitted from transmitter to
receiver that are placed over a limited distance.
 Wireless Communication is a method of transmitting information from one point
to other, without using any connection like wires, cables or any physical
medium.
 Transfer of data between 2+ points that aren’t connected by any electrical
conductor.
 With the help of Wireless Communication, the transmitter and receiver can be
placed anywhere between few meters (like a T.V. Remote Control) to few
thousand kilometers (Satellite Communication).
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3. Cont.
 Wireless Communication doesn’t require
any physical medium but propagates the
signal through space.
 Since, space only allows for signal
transmission without any guidance, the
medium used in Wireless Communication
is called Unguided Medium.
 Typically use electromagnetic waves
 Transmitting/receiving voice and data
using electromagnetic waves in open
space.
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4. What is Electromagnetic Wave?
 Electromagnetic waves or EM waves are waves that are created as a
result of vibrations between an electric field and a magnetic field.
 Electromagnetic Waves carry the electromagnetic energy of
electromagnetic field through space.
 Electromagnetic Waves (usually Radio Waves) are used in wireless
communication to carry the signals.
 Can travels not only through air and solid materials, but also through
vacuum space
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5. How Electromagnetic waves formed
Electromagnetic waves are formed when an electric
field comes in contact with a magnetic field.
The Electric field and magnetic field of an
electromagnetic wave are perpendicular (at right
angles) to each other.
Both these fields are oscillating perpendicular to each
other and the direction of propagation of the
Electromagnetic Wave is again perpendicular to both
these fields.
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6. Pictorial representation of an Electromagnetic Wave is shown
below, where the Electric Field is acting in the Y – axis,
magnetic field is acting in the Z – axis and the Electromagnetic
Wave propagates in X – axis.
Cont.
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7. How communication takes place?
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8. Why Wireless Communication?
 The primary and important benefit of wireless communication is mobility.
 Wireless communication also offers flexibility and ease of use, which makes it
increasingly popular day – by – day.
 Another important point is infrastructure.
 The infrastructure for wireless communication can be installed easily and low cost.
Freedom from wires
 No bunches of wires running
 “Auto magical” instantaneous communications without physical connection setup,
e.g., Bluetooth, Wi-Fi
Global Coverage
 Communications can reach where wiring is infeasible or costly, e.g., rural areas, old
buildings, battlefield, vehicles, outer space (through Communication Satellites).
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9. Stay Connected
 Roaming allows flexibility to stay connected anywhere and any time
 Rapidly growing market attests to public need for mobility and
uninterrupted access
Flexibility
 Services reach you wherever you go (Mobility). E. g, you don’t have
to go to your lab to check your mail
 Connect to multiple devices simultaneously (no physical connection
required
 Increasing dependence on telecommunication services for business
and personal reasons Consumers and businesses are willing to pay for
it.
Cont.
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10. Advantages of Wireless Communication
 Cost (low cost when compared to wired communication)
 Mobility(It offers the freedom to move around while still connected to network)
 Ease of Installation(The setup and installation is very easy)
 Reliability(No chance of communication failure)
 Disaster Recovery(loss of communication infrastructure in wireless communication
system can be minimal)
Disadvantages of Wireless Communication
 Interference(There is a huge chance that radio signals from one wireless communication
system or network might interfere with other signals)
 Security(Since the signals are transmitted in open space, it is possible that an intruder can
intercept the signals and copy sensitive information)
 Health Concerns(Continuous exposure to any type of radiation can be hazardous)
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11. Basic Elements of a Wireless Communication System
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12.  A typical Wireless Communication System can be divided into three
elements:
 The Transmission Path:
A typical transmission path of a Wireless Communication
System consists of Encoder, Encryption, Modulation and
Multiplexing.
The signal from the source is passed through a Source Encoder,
which converts the signal in to a suitable form for applying
signal processing techniques.
This signal is then encrypted using an Encryption Standard so
that the signal and the information is secured and doesn’t allow
any unauthorized access
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13. Channel Encoding is a technique that is applied to the signal to
reduce the impairments like noise, interference, etc
During this process, a small amount of redundancy is introduced
to the signal so that it becomes robust against noise.
The modulated signal is then multiplexed with other signals using
different Multiplexing
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14. The Channel
 The channel in Wireless Communication indicates the medium of
transmission of the signal i.e. open space.
 A channel maybe subject to interference, distortion, noise, scattering etc.
and the result is that the received signal may be filled with errors.
Cont.
The Reception Path
 The job of the Receiver is to collect the signal from the channel and
reproduce it as the source signal
 The reception path of a Wireless Communication System comprises of
Demultiplexing, Demodulation, Channel Decoding, Decryption and Source
Decoding.
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15. Types of Wireless Communication Systems
 Television and Radio Broadcasting
 Satellite Communication
 Radar
 Mobile Telephone System (Cellular Communication)
 Global Positioning System (GPS)
 Infrared Communication
 WLAN (Wi-Fi)
 Bluetooth
 ZigBee
 Paging
 Cordless Phones
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16. Television and Radio Broadcasting
 Radio is considered to be the first wireless service to be broadcast. It is an
example of a Simplex Communication System where the information is transmitted
only in one direction and all the users receiving the same data.
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17. Satellite Communication
 Satellite Communication System is an important type of Wireless Communication.
Satellite Communication Networks provide worldwide coverage independent to
population density.
 Satellite Communication Systems offer telecommunication (Satellite Phones),
positioning and navigation (GPS), broadcasting, internet, etc.
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Bluetooth
Bluetooth is another important low range wireless communication system. It provides data,
voice and audio transmission with a transmission range of 10 meters.
Cont.

18. RADAR
 It is basically an electromagnetic system used to detect the location and distance of an
object from the point where the RADAR is placed. It works by radiating energy into space
and monitoring the echo or reflected signal from the objects.
 A radar is an electromagnetic sensor, used to notice, track, locate, and identify different
objects which are at certain distances.
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ZigBee
It is a technology of home networking. ZigBee is a technological standard created for
controlling and sensor the network.
ZigBee is a standard that addresses the need of very low-cost implementation of Low power
devices with Low data rate for short-range wireless communications.
Cont.

19. 2/20/2022
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A cordless telephone or portable telephone is a telephone which has a portable
handset but which one can use like landline phone communication;
such telephones operate using radio-frequency transmission rather than a
physical insulated wire or a direct connection to a telephone line.
A cordless telephone's base station connects with the telephone network
through a telephone line (like a corded telephone) and also includes a charger
to charge the handset's batteries
Cont.

20. Paging
 Although it is considered an obsolete technology, paging was a major
success before the wide spread use of mobile phones.
 Paging provides information in the form of messages and it is a simplex
system i.e the user can only receive the messages.
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21. Wireless Local Area Network (WLAN)
 Wireless Local Area Network or WLAN (Wi-Fi) is an internet related wireless
service.
 Using WLAN, different devices like laptops and mobile phones can connect to an
access point (like a Wi-Fi Router) and access internet.
Infrared Communication
 Infrared Communication is another commonly used wireless communication in our
daily lives.
 It uses the infrared waves of the Electromagnetic (EM) spectrum. Infrared (IR)
Communication is used in remote controls of Televisions, cars, audio equipment etc.
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22. Mobile Telephone Communication System
 The most commonly used wireless communication system is the Mobile Phone
Technology.
 Today’s mobile phones are not limited to just making calls but are integrated with
numerous other features like Bluetooth, Wi-Fi, GPS, and FM Radio.
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Global Positioning System (GPS)
 GPS is solely a subcategory of satellite communication.
 GPS provides different wireless services like navigation, positioning, location,
speed etc. with the help of dedicated GPS receivers and satellites.
Cont.

23. Wireless Vs Mobile Computing
 In many cases, the terms mobile and wireless are used
interchangeably, even though they are two different things.
 Mobile is the ability to be on the move.
 A mobile device is anything that can be used on the move, ranging
from laptops to mobile phones.
 As long as location is not fixed, it is considered mobile.
 Wireless refers to the transmission of voice and data over radio
waves. It allows workers to communicate with enterprise data
without requiring a physical connection to the network.
 Wireless devices include anything that uses a wireless network to
either send or receive data.
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24. Wireless communication can be
 Fixed (e.g., Metropolitan Area Network)
– Portable (e.g., wireless interaction between TV
and VCR)
– Mobile (e.g., mobile phone)
 NOTE : Wireless does not necessarily mean mobile.
Cont.
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25. Application of Wireless Communication
1. Making Calls
 On a global level, billions of people have subscriptions for cellular
communication.
 This system works through bouncing radio waves from one cell tower to
another. These towers form a network for directing the waves.
 Thus, the call receivers will have the waves triangulated to their phone
antennae.
2. Connecting Devices
 Bluetooth technology allows people to connect various devices.
 It does this through short-range low-energy radio waves. Enabled
devices use these waves to link up with and access other connected
devices.
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26. 3. Accessing the Internet
 Many people log in to Wi-Fi but they never question how those connections are
possible. The answer is through wireless networks.
 These networks use routers to send radio frequency (RF) signals to other devices.
The devices must have wireless adapters to be able to get the signals and access
the Internet. This allows companies to share the internet in the office.
4. Enhance Security
 The different types of wireless communication can enhance security. For
example, walkie-talkies transmit and receive radio signals.
 They don’t suffer the same connection issues as cellphones.
 As such, businesses can give them to their security guards. Employees can also
use them to communicate within the building. Bluetooth can play a role in
opening locked doors.
Cont.
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27. 5. For Locating and Tracking
 A satellite communication technology allows satellites to connect to
devices on earth.
 Thus, people can make phone calls and even connect to the internet.
 Its most well-known use is in the Global Positioning System (GPS).
 This allows businesses to locate and track their vehicles and their
employees.
 Local ad-hoc network for the fast exchange of information (information
such as distance between two vehicles, traffic information, road
conditions) in emergency situations or to help each other keep a safe
distance.
 Local ad-hoc network with vehicles close by to prevent guidance system,
accidents, redundancy.
Cont.
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28.  Vehicle data from buses, trucks, trains and high speed train can be
transmitted in advance for maintenance.
 In ad-hoc network, car can comprise personal digital assistants (PDA),
laptops, or mobile phones connected with each other using the Bluetooth
technology.
Cont.
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29. Thank You
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