Any material substance that carries
an electronic signal and serves as
an interface between a sending
device and a receiving device.
A set of rules that governs the
exchange of information over a communications
SYNCHRONOUS VS ASYNCHROMUS
instantaneously, when it is sent IS synchronous1.
the receiver gets the message after
some delay—sometimes hours or
days after the message is sent.
enables business people to
communicate with coworkers and
clients from remote location.
in both directions at the same time, so a
• The rate at which data is exchanged (bps).
• A telecommunications system in
which a very high rate of data
exchange is possible.
GUIDED TRANSMISSION MEDIA TYPES
• Twisted-pair wire contains two or more twisted pairs of wire,
• usually copper .
• Because the twisted-pair wires are insulated, they can be placed close
• together and.
• also shows a typical coaxial cable,
similar to that used in cable television Installations.
• When used for data transmission,
• coaxial cable falls in the middle of the guided
• transmission media in terms of cost and performance.
The cable itself is more expensive than
• twisted-pair wires.
• consisting of many extremely thin strands of glass or plastic bound together
• in a sheathing
transmits signals with light beams.
These high-intensity light beams are generated by lasers
• These fibers have a thin coating, called cladding, which effectively works
• like a mirror, preventing the light from leaking out of the fiber.
WIRELESS COMMUNICATIONS OPTIONS
Wireless communications coupled with the Internet is
revolutionizing how and where we
gather and share information, collaborate in teams, listen to
music or watch video, and stay
in touch with our families and coworkers while on the road
SHORT RANGE WIRELESS OPTIONS
Near Field Communication (NFC)
A very short-range wireless connectivity
technology designed for cell
phones and credit cards.
A wireless communications specification
that describes how cell
phones, computers, faxes, personal
digital assistants, printers, and
other electronic devices can be
interconnected over distances of
10–30 feet at a rate of about 2 Mbps
ultra wideband (UWB)
• A wireless communications technology
• that transmits large
• amounts of digital data over short
• distances of up to 30 feet using a
• A wireless communications technology
• that operates at a frequency
• of 300 GHz and above.
MEDIUM RANGE WIRELESS
• Wi-Fi is a wireless telecommunications technology brand owned by the Wi-Fi Alliance,
• which consists of about 300 technology companies including AT&T, Dell
. The alliance exists to improve the ability of wireless local area
• network products.
WIDE AREA WIRELESS NETWORK OPTIONS
• Microwave is a high-frequency (300 MHz–300 GHz) signal sent through the air.
• Communications satellites are relay
• stations that receive signals from
• one Earth station and rebroadcast
• them to another.
3G Wireless Communications
• The International Telecommunications Union (ITU) established
• .a single standard for cellular networks in 1999.
• speeds in the range of 2–4 Mbs.
4G Wireless Communications
• 4G stands for fourth-generation broadband mobile wireless
• enhanced multimedia, smooth streaming video,
• also provide increased data transmission rates in the 20–40 Mbps range.
DIGITAL VS ANALOG DATA
• A signal that represents bits.
• A variable signal continuous in both
• time and amplitude so that any
• small fluctuations in the signal are
NETWORKS AND DISTRIBUTED
• The communications media,
• devices, and software needed to
• connect two or more computer
• systems or devices.
personal area network (PAN)
• A network that supports the
• interconnection of information
• technology within a range of 33 feet
• or so.
local area network (LAN)
• A network that connects computer
• systems and devices within a small
• area, such as an office, home, or
• several floors in a building.
wide area network (WAN)
• A telecommunications network that
• ties together large geographic
• An architecture in which multiple
• computer platforms are dedicated
• to special functions such as
• database management, printing,
• communications, and program
• A telecommunications hardware
• device that converts (modulates
• and demodulates) communications
• signals ].
• A device that combines data from
• multiple data sources into a single
• output signal that carries multiple/
SECURING DATA TRANSMISSION
The process of converting an original
message into a form that can
only be understood by the intended
Wired equivalent privacy (WEP)
An early attempt at securing wireless
communications based on
encryption using a 64- or 128-bit key
that is not difficult for hackers to
VIRTUAL PRIVATE NETWORK (VPN)
• virtual private network (VPN)
• A private network that uses a public
• network (usually the Internet) to
• connect multiple remote locations.
DIGITAL SUBSCRIBER LINE (DSL)
• A telecommunications service that
• delivers high-speed Internet access
• to homes and small businesses over
• the existing phone lines of the local
• telephone network.
VOICE OVER INTERNET PROTOCOL
• A collection of technologies and
• communications protocols that
• enables your voice to be converted
• into packets of data that can be sent
• over a data network such as the
• Internet, a WAN or LAN.
• A work arrangement whereby
• employees work away from the
• office using personal computers
• and networks to communicate via
• e-mail with other workers and to
• pick up and deliver results
• A collection of interconnected
networks, all freely exchanging
USE AND FUNCTIONING OF THE INTERNET
• A project started by the U.S. Department
• of Defense (DoD) in 1969 as
• both an experiment in reliable networking
• and a means to link DoD
• and military research contractors,
• including many universities doing
• military-funded research.
INTERNET PROTOCOL (IP)
• A communication standard that
• enables traffic to be routed from one
• network to another as needed.
HOW THE INTERNET WORKS
Transmission Control Protocol (TCP)
• The widely used Transport-layer
• protocol that most Internet applications
• use with IP.
• One of the Internet’s high-speed,
• long-distance communications
Uniform Resource Locator (URL)
• An assigned address on the Internet
• for each computer.
• Internet service provider (ISP)
• Any company that provides Internet
• access to people or organizations
THE WORLD WIDE WEB
World Wide Web
• A collection of tens of millions of
• server computers that work together
• as one in an Internet service using
• Highlighted text or graphics in a Web
• document that,
• Web client software such as Internet
• Explorer, Firefox, and Safari used to
• view Web pages.
Hypertext Markup Language
• The standard page description
• language for Web pages.
• Codes that let the Web browser
• know how to format text—as a
• heading, as a list, or as body
• text—and whether images, sound,
• and other elements should be
Extensible Markup Language
• The markup language for Web
• documents containing structured
• information, including words,
• pictures, and other elements.
Cascading Style Sheet (CSS)
• A file or portion of an HTML file that
• defines the visual appearance of
• content in a Web page.
WEB PROGRAMMING LANGUAGES
• An object-oriented programming
• language from Sun Microsystems
• based on C++ that allows small programs
• (applets) to be embedded
• within an HTML document
• Web services
• Standards and tools that streamline
• and simplify communication among
• Web sites for business and personal
SEARCH ENGINES AND WEB RESEARCH
• search engine
• A valuable tool that enables you to
• find information on the Web by specifying
• words that are key to a topic of
• interest, known as keywords.
FILE TRANSFER PROTOCOL (FTP)
• A protocol that describes a file
• transfer process between a host and
• a remote computer and allows
• users to copy files from one computer
• to another.
WEB LOG (BLOG)
• A Web site that people can create
• and use to write about their observations,
• experiences, and feelings
• on a wide range of topics.
INTRANETS AND EXTRANETS
virtual private network (VPN)
• A secure connection between two
• points on the Internet.
• The process by which VPNs transfer
• information by encapsulating traffic
• in IP packets over the Internet