4. Wireless
Wireless communication is the transfer of info. between two or more points
that are not connected by an electrical conductor.
The most common wireless technologies use radio.With radio waves distances can
be short, such as a few meters for television or as thousands or even millions of
kilometers for deep-space radio communication. It encompasses various types of
fixed, mobile, and portable applications, including tow-way radio, cellular
telephones, personal digital assistants (PDAs), and wireless networking. Other
examples of applications of radio wireless technology include GPS units, garage
door openers, wireless computer mice, keyboards, and, headphones, radio
receivers, satellite television, broadcast television and cordless telephones.
5. Introduction
Wireless operations permit services, such as long-range communications, that are
impossible or impractical to implement with the use of wires.
. History
Photophone :
The world’s first wireless telephone conversation occurred in 1880, when Alexander
Graham Bell and Charles Sumner Tainterinvented and patented the photophone, a
telephone that conducted audio conversations wirelessly over modulated light beams
(which are narrow projections of electromagnetic waves).
Ear.ly wireless work :
David E. Hughes transmitted radio signals over a few hundred years by means of a
clockwork keyed transmitter in 1879. As this was before Maxwell’s work was understood,
Hughes’ contemporaries dismissed his achievement as mere “Induction”. In 1885, Thomas
Edison used a vibrator magnet for induction transmission. In 1888, Edison deployed a
system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless
patent for this method using inductance.
.
Radio :
The term “wireless” came into public use to refer to a radio receiver or transceiver
establishing its usage in the field of wireless telegraphy early on; now the term is used to
describe modern wireless connections such as in cellular network and wireless broadband
internet.
6. Modes
Radio :
Radio communication, microwave communication, for e.g. long-range line-of-sight via highly
directional antennas, or short range communication.
Free-space optical :
Free-space optical (FSO) communication is an optical communication technology that uses
light propagating in free space to wirelessly transmit data for telecommunication or
computer networking.
Sonic :
Sonic, especially ultrasonic short range communication involves the transmission and
reception of sound.
Electromagnetic induction :
Electromagnetic induction short range communication and power. This has been used in
biomedical situations such as pacemakers, as well as for short-range Rfid tags.
Wireless services
•Telemetry control and traffic control system.
•Infrared and ultrasonic remote control system.
•The amateur radio service (Ham radio).
•Consumer and professional Marine VHF radio.
•Air band and radio navigation equipment used by aviators and air traffic control.
7.
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11.
12. 1. Networks Models : Client server model and peer-to-peer
model.
1.Client Server Model : In client server networks, servers
are typically powerful computers running advanced
network operating system and user work station (clients)
access data or run applications located on the server.
2.Peer-to-Peer Model : In peer-to-peer our architecture,
there are no dedicated services. All computers are equal
and therefore termed as peer and each of these machines
functions both as a client and a server. Peer-to-Peer
networks are designed for small to medium LANs.
•Components of network :
1.Sender/Receiver : A host computer at both ends which sends
and receives the data.
2.Communication Interface Devices : Network interface cards,
switches and routers, hubs, bridges, repeaters, and gateway,
modems, multiplexer, front and communication processor,
13. protocol converters, remote access devices.
3.Communication Channel : Guided media and unguided media.
4.Communication Software Function : Access control, network
management, data and file transmission, error detection and
control, data security.
•Definition of Network structure of topology :
Geometrical arrangement of computer resources, remote devices
and communication facilities to share the info. The four type of
network topology are :-
1.Star Topology
17. •Definition of Local area Network : A data transmission system
intended to link computers and associated with in a restricted
geographical area. It is useful for sharing resources like files, printers
or other applications.
1.Benefits of using LAN : Security inexpensive work station,
distributed processing, Emailing, and message broad-casting,
organizational benefits, data management benefits, software cost
and up-gradation.
2.LAN Requirements : Compatibility, interworking, growth path
and modularity, system reliability and maintenance.
3.Components of LAN : File server network operating system,
work stations, network interface card (NIC), network cabling.
4.Wireless LAN : It is a flexible data communication systems that
uses radio waves, microwaves, and infrared waves to transmit
and receive data over the air with minimizing the need for wired
connections.
18.
19. public network to connect remote sides or uses together with
“virtual” connections routed through the internet from the
company’s private network to the remote site or employee. Two type
of VPNs are :-
1.Virtual Private Dial-up network
2.Site-to-site VPN
•Broad Band Network (ISDN) : System of the digital phone
connections to allow simultaneous voice and data transmission
across the world. Two type of ISDN service are :-
1.Basic Rate Interface (BRI) : BRI consists of two 64Kbps B
channels and one 16Kbps D channel suitable for individual
users.
20. 2Primary Rate Interface (PRI) : PRI consists of 23 B
channels and 64Kbps D channels for users with higher
capacity requirements.
This is no end….
