Wireless communication media

 Many users opt for wireless transmission

media because it is more convenient than
installing cables.
 Businesses use wireless transmission media in
locations where it is impossible to install
cables cables.
 Types of wireless transmission media used in
communications include infrared, broadcast
radio, cellular radio, microwave and satellites.
 Infrared
 Infrared is a wireless transmission medium
that sends signals using infrared light waves.
 Mobile computers and devices such as mouse,
printer, smart phone, TV remote controllers
have a port that enables the transfer of data
from one device to another using infrared light
waves.
 Infrared is typically a line-of-sight technology,
which means that the signal is lost if anything
blocks the pathway between the two devices.
With infrared, the two devices will need to be
within one meter of one another.
 Broadcast radio
 Is a wireless transmission medium that
distributes radio signals through the air over
long distances such as between cities, regions
and countries.
 Bluetooth, WI-FI, WIMAX communications
technologies use broadcast radio signals.
 Cellular radio
 Is a form of broadcast radio that is used widely
for mobile communications, specifically
wireless modems and cell phones.
 A cell phone is a telephone device that uses
high frequency radio waves to transmit voice
and digital data messages.
 Some mobile users connect their notebook
computer to cell phone to access the web, send
and receive email
 Microwave
 Are radio waves that provide a high speed
signal transmission.
 Micro wave transmission often called fixed
wireless, involves sending signals from one
microwave station to another
 A microwave station is an earth based
reflective dish that contains the antenna,
transceivers and other equipment necessary for
microwave communication.
 To avoid possible obstructions such as
buildings or mountains, microwave stations
often sit on the tops of buildings, towers or
mountains
 Microwave transmission is used in
environments where installing physical
transmission media is difficult and where line
line of sight transmission is available
 Current users of microwave transmission
include universities, hospitals, governments,
telephone companies, home and small
business users.
 Satellite
 Satellite is a space station that receives
microwave signals from an earth based station,
amplifies the signals and broadcasts the signals
back over a wide area network to any number
of earth based stations.
 The earth based stations often are microwave
stations.
 Other devices such as smart phones also can
function as earth based stations
 Transmission from an earth based station to a
satellite is an uplink.
 Transmission from a satellite to an earth based
station is a downlink.
 Applications such as air navigation, television
and radio broadcasts, weather forecasting,
video conferencing and internet connections
use satellites
 The Internet Technology
 Internet: An interconnected network of
thousands of networks and millions of
computers, linking businesses, educational
institutions, government agencies, and
individuals
 World Wide Web (Web): One of the Internet’s
most popular services, providing access to
over 8 billion Web pages
Web Browsers
 Primary purpose to display Web pages
 Internet Explorer (88%) and Firefox (9%)
dominate the market
 Other browsers include:
1. Netscape
2. Opera
3. Safari (for Apple Macintosh)
Hypertext
 A way of formatting web pages with embedded links that
connect documents to one another, and that also link
pages to other objects such as sound, video, or animation
files Uses
 A web page is a specific collection of information
provided by a website and displayed to a user in a web
browser
 A website is a collection of web pages and related content
that is identified by a common domain name and
published on at least one web server.
 What do you need to connect to the
internet
 A computer
 The modem: is necessary if you are using a
telephone line to access the internet. It
translates the language that computers talk into
a language that can travel across phone lines
 Internet browser(software) and software to
connect you to the internet service provider
 An account with the internet service provider
 Internet key technology concepts
 Federal Networking Council definition of
Internet highlights three important concepts that
are the basis for understanding the Internet:
1. Packet switching Messages sliced and
reassembled
2. TCP/IP communications protocol Sequencing ,
assembling , addressing
3. Client/server computing
 Packet switching
 A method of slicing digital messages into
packets, sending the packets along different
communication paths as they become
available, and then reassembling the packets
once they arrive at their destination
 Uses routers: special purpose computers that
interconnect the computer networks that make
up the Internet and route packets to their
ultimate destination
 Routers use computer programs called routing
algorithms to ensure packets take the best
available path toward their destination
 TCP/IP(Transmission Control
Protocol/Internet Protocol)
 Protocol: A set of rules for formatting,
ordering, compressing, and error-checking
messages
 TCP: Establishes the connections among
sending and receiving Web computers, handles
the assembly of packets at the point of
transmission, and their reassembly at the
receiving end
 IP: Provides the Internet’s addressing scheme
 TCP/IP is divided into 4 separate layers:
Network Interface Layer
 Internet Layer
 Transport Layer
 Application Layer
 IP Address
 Internet address (also called IP address): a 32-
bit number expressed as a series of four
separate numbers marked off by periods, such
as 201.61.186.227
 IPv4 the current version of IP. Can handle up
to 4 billion addresses
 IPv6 (next generation of IP) will use 128-bit
addresses and be able to handle up to 1
quadrillion addresses
 Client/server computing
 Model of computing in which very powerful
personal computers (clients) are connected in a
network with one or more server computers
that perform common functions for the clients,
such as storing files, software applications
 Backbone: Consists of high-bandwidth fiber-
optic cable owned by a variety of Network
Service Providers (NSPs)
 Other internet protocols
 HTTP: Used to transfer Web pages
 SMTP, POP, and IMAP: Used to send and
receive e-mail
 FTP: Permits users to transfer files from server
to client and vice versa
 Telnet: Program that enables a client to emulate
a mainframe computer terminal
 SSL: Protocol that provides secure
communications between client and server
 Limitations of the Current Internet

 Bandwidth limitations
 Quality of service limitations e.g. latency
 Network architecture limitations
 Language development limitations e.g. HTML
is fixed and generic
 Wired Internet limitations eg. Wired
connection -> mobility
 Internet 2
 The second era of the Internet that is being
built today by private corporations,
universities, and government agencies
 Internet 2 has high speed network
 To appreciate benefits of Internet II, you must
understand limitations of the Internet’s current
infrastructure
Primary goals:
 Create a leading edge very-high speed network
for national research community
 Enable revolutionary Internet applications
 Ensure the rapid transfer of new network
services and applications to the broader
Internet community
 Area of focus of internet2
 Advanced network infrastructure
 New networking capabilities
 Middleware
 Advanced applications
 Benefits of Internet II Technologies

 IP Multicasting: set of technologies that enables

efficient delivery of data to many locations on a network
 Latency solutions: differentiated quality of service will
be able to assign different levels of priority to packets
depending on type of data being transmitted
 Guaranteed service levels: ability to purchase right to
move data through network at guaranteed speed in
return for higher fee
 Lower error rates
 Declining costs
 Reasons for using the internet
 To find information
 To watch videos
 To share files using cloud storage
 To communicate
 To solve problems
 To be educated
 GOOGLE SEARCH

HOW GOOGLE SEARCH ENGINE WORKS

• Google is a fully-automated search engine that
uses software known as "web crawlers" that
explore the web on a regular basis to find sites
to add to our index.
• In fact, the vast majority of sites listed in our
results aren't manually submitted for inclusion,
but are found and added automatically when
our web crawlers crawl the web.
Google Search works in essentially three stages:

• Crawling: Google searches the web with

automated programs called crawlers, looking
for pages that are new or updated. Google
stores those page addresses (or page URLs) in
a big list to look at later. We find pages by
many different methods, but the main method
is following links from pages that we already
know about.
• Indexing: Google visits the pages that it has
learned about by crawling, and tries to analyze
what each page is about. Google analyzes the
content, images, and video files in the page,
trying to understand what the page is about.
This information is stored in the Google index,
a huge database that is stored on many
computers.
• Serving search results(Ranking): When a
user performs a Google search, Google tries to
determine the highest quality results. The
"best" results have many factors, including
things such as the user's location, language,
device (desktop or phone), and previous
queries.
• For example, searching for "bicycle repair
shops" would show different answers to a user
in Paris than it would to a user in Hong Kong.
Google doesn't accept payment to rank pages
higher, and ranking is done algorithmically.