1 What is Telecommunication Rajesh123

8/22/2019 1 What is Telecommunication Rajesh123

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TELECOMMUNICATION


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-: INDEX :-

SR.No. Content


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What is telecommunication?

Telecommunications is the exchange of information over significant

distances by electronic means. A complete, single telecommunications circuit

consists of two stations, each equipped with a transmitter and a receiver. The

transmitter and receiver at any station may be combined into a single device

called a transceiver. The medium of signal transmission can be electrical wire or

cable (also known as "copper"), optical fiber or electromagnetic fields. The free-

space transmission and reception of data by means of electromagnetic fields is

called wireless

He simplest form of telecommunications takes place between two stations.

However, it is common for multiple transmitting and receiving stations toexchange data among themselves. Such an arrangement is called a

telecommunications network. The Internet is the largest example. On a smaller

scale, examples include:

Corporate and academic wide-area networks (WANs) Telephone networks Police and fire communications systems Taxicab dispatch networks Groups of amateur radio operators

Data is conveyed in a telecommunications circuit by means of an electrical

signal called the carrier or carrier wave. In order for a carrier to convey

information, some form of modulation is required. The mode of modulation can

be broadly categorized as either analog or digital. In analog modulation, some

aspect of the carrier is varied in a continuous fashion.


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The Role of TelecommunicationTo delivery multimedia, especially video, the key issue of bandwidth must be

addressed first. Bandwidth is communication power - the capacity of an

information channel to transmit bits without error in the presence of noise. In fiberoptics, in wireless communications, in new dumb switches, and in digital signal

processors, bandwidth will expand from 5 to 100 times as fast as the rise of

microprocessor speeds. With the rapid spread of national network of fiber and

cable, the dribble of kilobits from twisted-pair telephone lines is about to become a

firehouse of gigabits.

Broadband bandwidth and video compression are the important technologies to

successfully transmit video information. Thus, the focus on this paper is digital

video compression and broadband technology such as ADSL, hybrid network,

ISDN, ATM, frame rely, and SMDS. In addition, according to Benton Foundation

working paper, telephone and cable companies are currently testing delivery

systems for video-on-demand and near-video-on demand services. Those

interactive testbeds for video-on-demand service will be addressed as well.

Digital Video Compression Broadband Technology Delivery System of Video on Demand Digital Video Compression

MEG (Moving Picture Experts Group) is currently to generate standards for digital

video (sequences of images in time) and audio compression. The MPEG format

can support full-screen (640*480) 30 frames per second video with audio on

computers equipped with hardware MPEG decoders.


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Broadband Technology

1. Asymmetric Digital Subscriber Loop (ADSL)2. Hybrid Network3. Asynchronous Transfer Mode (ATM)4. Integrated Services Digital Network (ISDN)5. Frame Relay6. Switched Multimegabit Data Service (SMDS)

Asymmetric Digital Subscriber Loop (ADSL)

ADSL is a multimedia modem which can transmit more than 6 Mbps over twisted

pair copper and permits transmission of a single compressed, high- quality video

signal, at a rate of 1.5 Megabits per second, in addition to an ordinary voice phone

conversation. It is quick enough to bring remote multimedia - video, audio,

graphics, and text - to millions of users. ADSL makes room for Plain Old

Telephone Service (POTS) , so the phone line operates as it always did, for voice,

facsimile, and computer services. Even if ADSL fails, the line still works for

POTS. With ADSL, the following activities can be at the same time:

Voice call (or send/ receive a fax).

A selected video on demand or interactive education program. PC access to an office LAN at LAN speeds in one window, an Internet

Video in a second window, and a video conference using a screen corner.

Since ADSL could convert copper lines to multimedia driveways based oncustomer request, some telephone companies already appreciate the truth of

ADSL. Others have backed off because ADSL seems expensive and does

not transmit analog video.


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Hybrid Network

Networks that reach into the home are hybrids of the fiber-optic cable, existing

copper wire and coaxial cable used by telephone and cable television companies.

Fiber-optic cables will be used in the major arteries and portions of the distributionsystem, while existing copper and coaxial cable will be used in the last hundred

yards.

Hybrid networks can delivery a full range of high-bandwidth interactive service at

a fraction of the cost of fiber to the home. Digital compression, storage, and

transmission will reduce the cost of rewiring a neighborhood to a manageable

burden. High-capacity video file servers capable of storing thousands of hours of

programming will be attached at the regional level. Existing cable systems will be

replaced by high-capacity, noiseless fiber-optic cable that will reach from thesystem's head into each neighborhood.

Asynchronous Transfer Mode (ATM)

ATM is the most important short-term contributor to the tides of bandwidth. It puts

everything into same-sized boxes called cells and each one is 53 byes long,

including a five-byte address. Small packets of a uniform 53 bytes can be switched

at enormous speeds through an ATM network and dispatched to the end users on a

fixed schedule that can accommodate voice, video and data, all at once. ATM alsoturns networks of small computers into scaleable supercomputers. It combines with

fiber-optic links to provide a far simpler, more modular and more scaleable

solution than the complex copper backplane buses that perform the same functions

in large computers.

The basic principles of ATM:

ATM is considered as a specific packet oriented transfer mode based onfixed length cells. Each cell consists of an information field and a head,which is mainly used to determine the virtual channel and to perform the

appropriate routing.

The information field of ATM cells is carried transparently through thenetwork. No processing like error control is performed on it inside the

network.


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All service (voice, video, data) can be transported via ATM, includingconnectionless services.

Integrated Services Digital Network (ISDN)

ISDN is a technology designed for the public switched telephone network that

allows low-cost communication in data, voice, graphics, and video. It is designed

to run over the existing copper local loop that connects the telephone company's

central office to the home. Some of the characteristics that distinguish ISDN are:

It builds on groups of standard transmission channels. Bearer channels (B

channels) transmit user information at relatively high speeds, while separate data

channels (D channels) carry call set-up, signaling and other information.

It handles all type of information. They are all digitized and transmitted athigh speeds in the same flow of data.

It handles many devices and many telephone numbers on the same line. It supports up to 3 calls at the same time.

It offers variable, responsive transmission speeds. Two or more channels can be

combined into a single larger transmission "pipe." Channels can be assembled as

needed for a specific application, and then broken down and reassembled into

different groups for different applications.Charge of ISDN

Usage is charged at standard business voice rates for voice or datatransmission.

Usage and distance sensitive pricing (same as business voice). Time of day and volume discounts available. Options and rates.


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Frame Relay

Frame Relay is a packet based on interface standard that has been optimized for the

transport of protocol-oriented data. A frame relay network consists of user devices

and network devices that implement the standard interface. The user device isresponsible for delivering frames to the network in the prescribed format. The

network in the prescribed format. The network is responsible for switching or

routing the frames to the proper destination user device.

Benefits of Frame Relay

Reduced internetworking costs. Increased performance with reduced network complexity. Increased interoperability via international standards.

Switched Multimegabit Data Service (SMDS)

SMDS is a connectionless, cell-switched data transport service that offers total

end-to-end application solutions. With SMDS, organizations have the flexibility

they need for distributed computing and bandwidth-intensive applications. At the

same time, because SMDS supports both existing and emerging technologies, it

provides the scalability organizations need to support the application in the future.

Because SMDS is able to coexist with dedicated facilities, it enables customers tocreate hybrid public/ private networks. SMDS also allows for the easy expansion

of existing networks, since new sites can be quickly added to a SMDS net without

totally reconfiguring the network. Flat rate tariffs for SMDS service range from

$350 to $750 per mouth, plus a one-time installation charge per subscriber network

interface of $700 to $1000.


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WHY IT IS REQUIRED?Businesses would be lost without the current technological

advancements and a lot of companies would cease to exist. But this is not

the only benefit that telecommunications can bring. With these

advancements also comes science, without telecommunications, we would

be unable to fly with planes and helicopters or effectively navigate in the

seas. Besides this space travel would be near to impossible to achieve.

A world without telecommunications would not be possible; society

has made itself so used to this type of technology that the world would end

up collapsing if it was taken away. The reason in the tremendous growth of

telecommunications is because, as people and cities throughout the planet

grew, we needed a better way to relay messages between one another.

The greatest technological advancement that we could have possibly

got from this is the creation of the phone and internet. The phone was a

major piece of communication, Almost every household now has at least

one phone, with most having several.


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ANALOG SIGNALAn Analog or analogue signal is any continuous signal for which the time varying

feature (variable) of the signal is a representation of some other time varyingquantity, i.e., analogous to another time varying signal.

The most common form of analog signal transmission occurs electrically. In

order for this to happen, a voltage must be sent at a specific frequency. The flow of

this electrical charge is known as current. By controlling the frequency of the

current, information can be transmitted to another medium and presented on that

medium. For example, magnetic tape on a cassette conveys information to the

stereo which transmits it into electrical signals of specific frequencies which in

turn tell the speakers what noise to make.

DIGITAL SIGNALIn a digital signal, the information is encoded as a set of discrete values (for

example, a set of ones and zeros). A digital system uses two-state, either on/off or

A digital display shows discrete values as numbers (as opposed to an analogue

signal, such as the continuous sweep of a pointer on a dial).Uses modem to

translate analog to digital, digital to analog

In electronics and computing, a term meaning 'coded as numbers' is know

as digital. Digital electronics is The technology that underlies digital techniques.

Low-power, miniature, integrated circuits (chips) provide the means for the

coding, storage, transmission, processing, and reconstruction of information of all

kinds


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COMMUNICATION MEDIA AND CHANNELSCABLE MEDIA

TWISTED WIRESTwisted pair cabling is a type of wiring in which two conductors (the

forward and return conductors of a single circuit) are twisted together for the

purposes of canceling out electromagnetic interference (EMI) from external

sources; for instance, electromagnetic radiation from unshielded twisted pair

(UTP) cables, and crosstalk between neighboring pairs. It was invented by

Alexander Graham Bell

COAXIAL CABLECoaxial cable, or coax, is an electrical cable with an inner conductor

surrounded by a flexible, tubular insulating layer, surrounded by a tubular

conducting shield. The term coaxial comes from the inner conductor and the

outer shield sharing the same geometric axis.

Coaxial cable is used as a transmission line for radio frequency

signals, in applications such as connecting radio transmitters and receiverswith their antennas, computer network (Internet) connections, and

distributing cable television signals

FIBER-OPTIC CABLEAn optical fiber is made up of the core, (carries the light pulses), the

cladding (reflects the light pulses back into the core) and the buffer coating

(protects the core and cladding from moisture, damage, etc.). Together, all of

this creates a fiber optic which can carry up to 10 million messages at anytime using light pulses. Fiber optics is the overlap of applied.


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Wireless Media

MICROWAVEMicrowaves are electromagnetic waves with wavelengths ranging from as

long as one meter to as short as one millimeter, or equivalently, with

frequencies between 300 MHz (0.3 GHz) and 300 GHz.

While the name may suggest a micrometer wavelength, it is better

understood as indicating wavelengths very much smaller than those used in

radio broadcasting. The boundaries between far infrared light, terahertz

radiation, microwaves, and ultra-high-frequency radio waves are fairly

arbitrary and are used variously between different fields of study.

ORBITING SATELLITESA satellite Internet connection is an arrangement in which the upstream

(outgoing) and the downstream (incoming) data are sent from, and arrive at,

a computer through a satellite. Each subscriber's hardware includes a

satellite dish antenna and a transceiver (transmitter/receiver) that operates in

the microwave portion of the radio spectrum.

In a two-way satellite Internet connection, the upstream data is usually sent

at a slower speed than the downstream data arrives. Thus, the connection is

asymmetric.


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NETWORKSWhat is Network?

- In information technology, a network is a series of points or nodes interconnectedby communication paths. Networks can interconnect with other networks and

contain subnetworks.

A network consists of multiple computers connected using some type of

interface, each having one or more interface devices such as a Network Interface

Card (NIC) and/or a serial device for PPP networking. Each computer is supported

by network software that provides the server or client functionality. The hardware

used to transmit data across the network is called the media. It may include copper

cable, fiber optic, or wireless transmission. The standard cabling used for thepurposes of this document is 10Base-T category 5 ethernet cable. This is twisted

copper cabling which appears at the surface to look similar to TV coaxial cable. It

is terminated on each end by a connector that looks much like a phone connector.

Its maximum segment length is 100 meters.

Star Topology

Star Topology is the most common type of network topology that is used in homes

and offices. In the Star Topology there is a central connection point called the hubwhich is a computer hub or sometimes just a switch. In a Star Network the best

advantage is when there is a failure in cable then only one computer might get

affected and not the entire network.


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Advantages of Star Topology Due to its centralized nature, the topology offers simplicity of operation. It also achieves an isolation of each device in the network. Disadvantage of Star Topology The network operation depends on the functioning of the central hub. Hence,

the failure of the central hub leads to the failure of the entire network.

BUS TOPOLOGY

A bus network uses a multi-drop transmission medium, all node on the network

share a common bus and thus share communication. This allows only one device to

transmit at a time. A distributed access protocol determines which station is to

transmit.

Advantages:

Failure of one of the station does not affect others. Good compromise over the other two topologies as it allows relatively high

rate of data tansmittion.

well suited for temporary networks that must be set up in a hurry. Easy to implement and extend.

Disadvantage:

Require a network to detect when two nodes are transmitting at the sametime.

Does not cope well with heavy traffic rates Difficult to administer/troubleshoot. Limited cable length and number of stations. A cable brake can disable the entire network; no redundancy. Maintenance cost may be higher in the long run. Performance degrade as additional computers are added.


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Ring topology

Also known as a ring network, the ring topology is a type of computer network

configuration where each network computer and device are connected to each

other forming a large circle (or similar shape). Each packet is sent around the ringuntil it reaches its final destination. Below is a visual example of a simple

computer setup on a network using a ring topology.

Advantage of Ring Topology

The data being transmitted between two nodes passes through all theintermediate nodes. A central server is not required for the management of

this topology.

Disadvantages of Ring Topology

The failure of a single node of the network can cause the entire network tofail.

The movement or changes made to network nodes affects the performanceof the entire network.


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LOCAL AREA NETWORK (LAN)

A local area network (LAN) supplies networking capability to a group of

computers in close proximity to each other such as in an office building, a school,

or a home. A LAN is useful for sharing resources like files, printers, games orother applications. A LAN in turn often connects to other LANs, and to the

Internet or other WAN.

GATEWAY:

A gateway may contain devices such as protocol translators, impedance

matching devices, rate converters, fault isolators, or signal translators as necessary

to provide system interoperability.

ROUTER:

By definition, a router transfers packets between networks. The router

chooses the next best link to send packets on in order to reach closer to the

destination. Routers use Internet Protocol

PEER - TOPEER:

Small isolated PC setups consisting of a few PC's may be run as peer to peer LAN.

There is no central server, neither a domain controller.


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WIDE - AREA NETWORK (WAN):Definition: A WAN spans a large geographic area, such as a state, province

or country. WANs often connect multiple smaller networks, such as local area

networks (LANs) or metro area networks (MANs).

The world's most popular WAN is the Internet. Some segments of the Internet

WANs generally utilize different and much more expensive networking equipment

than do LANs.

SWITCHED LINES:

It selects which line is fastest & accordingly Route determined by

current traffic.

DEDICATED LINES:

It always selects the high- volume traffic Constantly by this line

Conclusion:

works are becoming a strategic cornerstone for organizations in every industry.

As companies explore new global marketplaces and virtual organizations, they

raely increasingly on electronic communication.

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1 What is Telecommunication Rajesh123