Wireless Communications and

Mobile Computing
CHAPTER ONE: INTRODUCTION

 Wired Networks: term "wired" is used to differentiate

between wireless connections and those that involve
cables.
 A wired setup uses physical cables to transfer data
between different devices and computer systems.
 Most wired networks use Ethernet cables to transfer data
between connected PCs.
 In a small wired network, a single router may be used to
connect all the computers.
 Larger networks often involve multiple routers or
switches that connect to each other.
Wireless Network:
 Wireless technology is the method of delivering data
from one point to another without using physical wires,
and includes radio, cellular, infrared, and satellite.
 Many types of wireless devices are available today
 mobile terminals
 pocket size PCs
 handheld PCs
 Laptops
 cellular phone
 PDAs,
 Wireless sensors
 and satellite receivers,and others.
What is Wireless Communication ?
 Transmitting voice and data using electromagnetic
waves in open space (atmosphere)
 Electromagnetic waves
 Travel at speed of light (c = 3x108 m/s)
 Has a frequency (f) and wavelength (l)
c=fxl
 Higher frequency means higher energy photons
 The higher the energy photon the more penetrating
is the radiation
What is Wireless Communication ?
 Wireless communications is a type of data
communication that is performed and delivered
wirelessly.
 Wireless communication has various forms, technology
and delivery methods including:
 Satellite communication
 Mobile communication
 Wireless network communication
 Infrared communication
 Bluetooth communication
What is Wireless Communication ?
 Some of the devices used for wireless communication
are :
 cordless telephones,
 mobiles,
 GPS units,
 wireless computer parts, and
 satellite television
Types of Wireless Communication

Cellular Wireless Computer Network Radio Service

 History of Wireless Communications:
 Guglielmo Marconi invented the wireless telegraph in
1896
◦ Communication by encoding alphanumeric characters
in analog signal
◦ Sent telegraphic signals across the Atlantic Ocean
 1914 – first voice communication over radio waves
 Communications satellites launched in 1960s
 Advances in wireless technology
◦ Radio, television, mobile telephone, communication
satellites
 More recently
◦ Satellite communications, wireless networking,
cellular technology
 History wireless communications :
 1983 - Federal Communications Commission. (FCC)
allocates spectrum for analog cellular service (AMPS)
 1990 – Global System (or Standard) for Mobile(GSM)
digital cellular service introduced in Europe
 1995 - FCC auctions new Personal Communication
Service (PCS) licenses in U.S. for digital services

 Licensed and unlicensed frequency was allocated by

FCC.
Cont...


In 1970, the University of Hawaii developed the first
wireless network, called ALOHA net, to wirelessly
communicate data between the Hawaiian Islands.

The Institute of Electrical and Electronics Engineers (IEEE)
began to discuss standardizing WLAN technologies in 1991.

In 1997, the IEEE ratified the original 802.11 standard that
is the foundation of the WLAN technologies.

The name that many people recognize for the technology is
Wi-Fi.

Wi-Fi is a marketing term, recognized worldwide by
millions of people as referring to 802.11 wireless
networking.
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Installation
Wired Networks:
 Difficult to moderate (Because More no. of components
are used during installation
 require cables to be connected to each and every computer
in the network
Wireless Networks:
 Easy installation (neat and clean, no untidy cables are
used in this)
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Visibility Node to Node on same network

Wired Networks:
 All of the nodes on a wired network can hear all other
nodes
Wireless Networks:
 Many nodes on a wireless network cannot hear all of the
other wireless nodes on the same network
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Visibility Network to Network

Wired Networks:
 Networks are invisible to other wired networks.
 The presence of one wired network has no effect on the
performance of another wired network
Wireless Networks:
 Wireless networks are often visible to other wireless
networks.
 One wireless network can affect the performance of
other wireless networks.
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Time to installation
Wired Networks:
 More (due to connection of each and every computer in
the network)
Wireless Networks:
 Less (no untidy cable connections involves in this)

cost
Wired Networks:
 Less (such Ethernet, cables, switches are not expensive)

Wireless Networks:
 More (wireless adapters and access points are quite
expensive )
COMPARISONS OF WIRED AND WIRELESS NETWORKS

User connectivity
Wired Networks:
 Connectivity is possible only to or from those physical
locations where the network cabling extends
Wireless Networks:
 Connectivity is possible anywhere with out physical
cable attachment
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Mobility
Wired Networks:
 Limited (because it operates only on a connected
computers linked with the network)
Wireless Networks:
 Outstanding (enable wireless user to connect to network
and communicate with other users anytime, anywhere)
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Reliability
Wired Networks:
 High (Ethernet cables, switches are reliable because
manufactures have improving technology over several
decades)
Wireless Networks:
 Reasonably high( because if the major section like
router break down the whole network will be affected)
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Speed and Bandwidth

Wired Networks:
 High: Up to 100 mbps

Wireless Networks:
 Low: Up to 54 mbps( depends upon standards 802.11g)

Cables
Wired Networks:
 Ethernet, copper and optical fibers

Wireless Networks:
 Works on radio waves and microwaves
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Hubs and switches

Wired Networks:
 Need hubs and switches for connections

Wireless Networks:
 No need of hubs and switches

Security
Wired Networks:
 Good (by using some software like free wall
software etc.)
Wireless Networks:
 Weak (because wireless communication signals
travel through the air and can easily be intercepted
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Types
Wired Networks:
 Local Area Network(LAN)
 Metropolitan Area network(MAN)
 Wide Area Network

Wireless Networks:
1. By Network Formation and Architecture:
• Infra structure based network
• Infra structure less (ad hoc) network
COMPARISONS OF WIRED AND WIRELESS NETWORKS

2. By communication coverage area

 Wireless Local Area Network(WLAN)
 Wireless metropolitan Area network(WMAN)
 Wireless Wide Area Network(WWAN)
 Wireless Personal Area Network(WPAN)

3. Access Technology
 GSM Network
 TDMA Networks
 CDMA Networks
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Standards
Wired Networks:
 802.3

Wireless Networks:
 802.11a
 802.11b
 802.11g
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Signal Loss And Fading

Wired Networks:
 Less( because in the wired connections interference will be
less)
Wireless Networks:
 Wireless networks are often visible to other wireless
networks.
Interference
Wired Networks:
 Less (Networks are invisible to other wired networks. The
presence of one wired network has no effect on the
performance of another wired network)
COMPARISONS OF WIRED AND WIRELESS NETWORKS

Interference
Wireless Networks:
 Higher (the potential for radio interference due to weather,
other wireless devices, or obstructions like walls)
Wireless Applications (Services)
Wireless Technologies and Devices


Infrared (IR) is relatively low energy and cannot
penetrate through walls or other obstacles.

However, it is commonly used to connect and move
data between devices such as Personal Digital
Assistants (PDAs) and PCs.

IR only allows a one-to-one type of connection.

It is generally used for short-range, line-of-sight,
communications.

IR is also used for remote control devices, wireless
mice, and wireless keyboards.

Radio Frequency (RF)


RF waves can penetrate through walls and
other obstacles, allowing a much greater
range than IR.

Certain areas of the RF bands have been
set aside for use by unlicensed devices
such as wireless LANs, cordless phones
and computer peripherals.

This includes the 900 MHz, 2.4 GHz and
the 5 GHz frequency ranges.

Communications Satellites


A communication satellite is an artificial satellite
used specifically as a communication
transmitter/receiver in orbit.

It behaves like a radio relay station above the earth
to receive, amplify, and redirect analog and digital
signals carried on a specific radio frequency.

Data is passed through a satellite using a transponder
which is a signal path.

Most satellites have between 24 to 72 transponders,
with a single transponder capable of transmitting and
receiving 155 million bits of information per second.
 Advantages and Disadvantages of Wireless
Communication
 Advantages:

◦ mobility
◦ a wireless communication network is a solution in areas
where cables are impossible to install (e.g. hazardous
areas, long distances etc.)
◦ easier to maintain
 Communication has enhanced to convey the information
quickly to the consumers.
 Working professionals can work and access Internet
anywhere and anytime without carrying cables or wires
wherever they go.
 Wireless networks are cheaper to install and maintain
 Advantages and Disadvantages of Wireless Communication

 Disadvantages:

◦ has security vulnerabilities

◦ high costs for setting the infrastructure
◦ unlike wired comm., wireless comm. is influenced by
physical obstructions, climatic conditions, interference from
other wireless devices
 Wireless network has led to many security threats to mankind.
 It is very easy for the hackers to grab the wireless signals that
are spread in the air.
 Strong security protocols must be created to secure the wireless
signals like (Wi Fi Protected Access)WPA and WPA2.
 Wireless and Mobile Communications

 Definition of mobility:
◦ user mobility: users communicate anytime, anywhere,
with anyone
◦ device portability: devices can be connected anytime,
anywhere to the network
 Definition of wireless:

◦ Un-tethered, no physical wire attachment

 Applications Wireless and Mobile Communications

 Vehicles

◦ transmission of news, road conditions, weather

◦ personal communication using cellular
◦ position identification via GPS
◦ inter vehicle communications for accident prevention
◦ vehicle and road inter communications for traffic control,
signaling, data gathering
◦ ambulances, police, etc.: early transmission of patient data
to the hospital, situation reporting
◦ entertainment: music, video
 Applications Wireless and Mobile Communications

 Mobile workers
◦ access to customer files and company documents stored in a central
location
◦ collaborative work environments
◦ access to email and voice messages
 Replacement of fixed networks
◦ remote sensors, e.g., weather, environment, road conditions
◦ flexible work spaces
◦ LANs in legacy buildings
 Entertainment, education, ...
◦ outdoor Internet access
◦ intelligent travel guide with up-to-date
location dependent information
◦ ad-hoc networks for
multi user games
 Applications Wireless and Mobile Communications

 Health Care Applications and Services

 Financial Information and Services
 Educational Opportunities
 Community Empowerment
 Connection any time, any where
 Television Remote Control
 Wireless mouse & keyboard
 Wi-Fi
 Security systems
 Cellular Telephone
 Wireless energy transfer
 Computer Interface Devices
Thank you!