Assignment of Networking

8/4/2019 Assignment of Networking

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ASSIGNMENT

SUBMITTED TO: SUBMITTEDBY:Mrs. Jasdeep Kaur Jyoti Bhanot

MCA 2ndSem

Roll no:2219/10


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Transmission medium:

Transmission medium provides physical entity for the conveyance of signals.

Transmission medium is the physical path between transmitter and receiver in adata transmission system.

Characterstics and quality of transmission medium:

The characteristics and quality of a data transmission are determined both by the

characteristics of the medium and the characteristics of the signal.

In the case of guided media, the medium itself is more important in

determining the limitations of transmission.For unguided media, the bandwidth of the signal produced by the transmitting

antenna is more important than the medium in determining transmission

characteristics.

Design of data transmission system:

A number of design factors relating to the transmission medium and to the

signal determine the data rate and distance:

Bandwidth. All other factors remaining constant, the greater the bandwidth of a

signal, the higher the data rate that can be achieved.

Transmission impairments. Impairments, such as attenuation, limit the

distance. For guided media, twisted pair generally suffer more impairment than

coaxial cable, which in turn suffers more than optical fiber.

Interference. Interference from competing signals in overlapping frequencybands can distort or wipe out a signal. Interference is of particular concern forunguided media, but it is also a problem with guided media. For guided media,

interference can be caused by emanations from nearby cables. For example,

twisted pair are often bundled together, and conduits often carry multiple

cables. Interference can also be experienced from unguided transmissions.

Proper shielding of a guided medium can minimize this problem.

Number of receivers. A guided medium can be used to construct a point-to-point link or a shared link with multiple attachments. In the latter case, each


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attachment introduces some attenuation and distortion on the line, limiting

distance and/or data rate.

Figure : Types of transmission media

Guided media:Guided media, which are those that provide a conduit from one device to

another, include twisted-pair cable, coaxial cable, and fiber-optic cable.

Guided Transmission Media uses a "cabling" system that guides the data signals

along a specific path. The data signals are bound by the "cabling" system.

Guided Media is also known as Bound Media.Cable is the medium through

which information usually moves from one network device to another.

Twisted pair cable and coaxial cable use metallic (copper) conductors that

accept and transport signals in the form of electric current. Optical fiber is a

glass or plastic cable that accepts and transports signals in the form of light.


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1)Twisted pair:

It is one types of copper cables, it consists of two insulated copper

wires that are twisted together in helical form. There are two types of twistedpairs, Unshielded Twisted Pair (UTP) cable and Shielded Twisted Pairs (STP).Both of types are used Ethernet LANs, they consists of four pairs of color-coded

wires that have been twisted together and then encased in a flexible plastic

sheath. STP cable differs then UTP as it supported with outer shield which give

it more noise immunity.

As seen in figure , the color codes identify the individual pairsand wires in the pairs and aid in cable termination.

The purpose of twisting the wire is to reduce electrical interference from

similar pairs closed by.


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Twisted pairs can run approximately 100 meter with out amplification, but for

longer distances, repeaters are needed. Twisted pairs can be used for eitheranalogue or digital transmission.

The bandwidth depends on the thickness of wire and the distance

traveled. Twisted pair can carry 10Mbps, 100Mbps or 1000MBps, this

variation depends on the category of cable.

Comparison of Unshielded and shielded twisted pairs:

Unshielded twisted pair (UTP).

Ordinary telephone wire.

Subject to external electromagnetic interference.

Shielded twisted pair (STP)

Shielded with a metallic braid or sheath.

Reduces interference.

Better performance at higher data rates.

More expensive and difficult to work compared to UTP.


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Twisted Pair advantages:

It is a thin, flexible cable that is easy to string between walls. More lines can be run through the same wiring ducts. UTP costs less per meter/foot than any other type of LAN cable.

Twisted Pair Disadvantages:

susceptibility to interference and noise attenuation problem

o For analog, repeaters needed every 5-6kmo For digital, repeaters needed every 2-3km

relatively low bandwidth (3000Hz)

Coaxial Cables:

It is one type of copper cables. It consists of a stiff copper conductor asa core surrounded by a layer of flexible insulation, the insulator is incased by

cylindrical conductor often as a closely woven braided mesh. The outer

conductor is covered in a protective plastic sheath. as shown in the figure

The bandwidth possible depends on the cable length. For 1-Km cables, a

data rate of 1 to 2 Gbps is feasible. Longer cables can also be used but at lower

data rate or with periodic amplifiers.At one time, coaxial cable was the most widely used network cabling.


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There were a couple of reasons for coaxial wide usage. Coaxial was relatively

inexpensive, and it was light, flexible, and easy to work with. It was so popular

that it became a safe, easily supported installation. Coaxial cables are widely

used in telephone system but have now largely replaced by fiber optics on long

land routers. However coaxial cables are still widely used for TV cables andsome LAN.

Coaxial cable is more resistant to interference and attenuation than

twisted-pair cabling. Attenuation is the loss of signal strength which begins to

occur as the signal travels further along a copper cable.

Advantages:

-sufficient frequency range to support multiple channel

-lower error rates

-greater spacing between amplifiers is allowed because coaxial cable has theability to reduce noise and crosstalk.

Disadvantage:

-more expensive to install compared to others.

-the thicker the cable, the more difficult to work with.

Fiber Optics:

Fiber-optic cabling uses either glass or plastic fibers to guide light

impulses from source to destination. The bits are encoded on the fiber as lightimpulses. Optical fiber cabling is capable of very large raw data

bandwidth rates. With current optical fiber technology, the achievable

bandwidth is certainly in excess of 50,000 Gbps (50 Tbps). The current

practical signaling limit of a bout 1 Gbps which due to our inability to convert

between electrical and optical signals any faster.


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Advantages of fiber-optic cable

1.Higher Bandwidth : Higher data rate than TP & coaxial cable.

2.Less signal attenuation: Fiber-optic transmission distance is significantly

greater than that of other guided media. A signal can run for 50 km without

requiring regeneration. We need repeaters after every 5km for coaxial or TP

cable.

3.Noise resistance : Because fiber-optic transmission uses light rather than

electricity, noise is not a factor. External light, the only possible interference, is

blocked from the channel by the outer jacket.4.Light weight : Fiber-optic cables are much lighter than copper cables.

5.More immune to tapping (or Security) : Fiber-optic cables are more

immune to tapping than copper cables. Copper cables create antennas that can

easily be tapped.

6.Optical fiber can carry thousands of times more information than copper wire.

For example, a single-strand fiber strand could carry all the telephone

conversations in the United States at peak hour. Fiber is more lightweight than

copper. Copper cable equals approximately 80 lbs/1000 feet while fiber weighsabout 9 lbs/1000 feet.

7.Reliability : Fiber is more reliable than copper and has a longer life span.

8.Fiber optic cable can carry signals for longer distance without repeater than co-axial cable.


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Disadvantages of fiber-optic cable:

1.Installation/maintenance expertise : Installation and maintenance needexpertise that is not yet available everywhere.

2.Unidirectional : Propagation of light is unidirectional.

3.Cost : Fiber-optic cable is more expensive.

4.Fragility : Glass fiber is more easily broken than wire, making it less useful

for applications where h/w portability is required.

5.Limited physical arc of cable of cable. Bend it too much and it will Break.

Unguided Media:

This is the wireless media that transport electromagnetic waves without using a

physical conductor. Signals are broadcast either through air. This is donethrough radio communication, satellite communication and cellular telephony.

Unguided transmission media are methods that allow the transmission

ofdata without the use of physical means to define the path it takes. Examplesof this include microwave, radio or infrared.
http://en.wikipedia.org/wiki/Datahttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Data


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Communication satellites:

Satellite communication is based on ideas similar to those used for line-of-

sight. A communication satellite is essentially a big microwave repeater or relay

station in the sky. Microwave signals from a ground station is picked up by a

transponder, amplifies the signal and rebroadcasts it in another frequency,

which can be received by ground stations at long distances. To keep the satellite

stationary with respect to the ground based stations, the satellite is placed in a

geostationary orbit above the equator at an altitude of about 36,000 km. As the

spacing between two satellites on the equatorial plane should not be closer than4, there can be 360/4 = 90 communication satellites in the sky at a time. A

satellite can be used for point-to-point communication between two ground-

based stations or it can be used to broadcast a signal received from one station

to many ground-based stations Number of geo-synchronous satellites limited

(about 90 total, to minimize interference). International agreements regulatehow satellites are used, and how frequencies are allocated. Weather affects

certain frequencies. Satellite transmission differs from terrestrial

communication in another important way: One-way propagation delay is

roughly 270 ms. In interactive terms, propagation delay alone inserts a 1second delay between typing a character and receiving its echo.


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Use:

Now-a-days communication satellites are not only used to handle telephone,telex and television traffic over long distances, but are used to support various

internet based services such as e-mail, FTP, World Wide Web (WWW), etc.New types of services,based on communication satellites, are emerging.

Comparison/contrast with other technologies:

1. Propagation delay very high. On LANs, for example, propagation time is in

nanoseconds -- essentially negligible.

2. One of few alternatives to phone companies for long distances.

3. Uses broadcast technology over a wide area - everyone on earth could receivea

message at the same time!

4. Easy to place unauthorized taps into signal.

Microwave Transmission

Microwave transmission also requires line of sight in order to work properly. In

order to allow two way communications two frequencies are used. However,

this does not mean that there has to be two antennas because the frequencies can

be dealt with by one antenna at both ends.


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The distance covered by microwave signals is based upon the height of the

antenna. In order to increase this coverage each antenna has a built-in repeater

that regenerates the signal before passing it on to the next antenna in line. The

placement of the antenna to do this is approximately 25 miles.

The main drawback of microwave signals is that they can be affected by

weather, especially rain.

Properties

Suitable over line-of-sight transmission links without obstacles Provides good bandwidth[clarification needed] Affected by rain, vapor, dust, snow, cloud, mist and fog, heavy moisture,

depending on chosen frequency (see rain fade)

Uses:

Backbone or backhaul carriers in cellular networks. Used to linkBTS-BSC and BSC-MSC.

Communication with satellites Microwave radio relay links for television and telephone service providers

Advantages:

No cables needed Multiple channels available Wide bandwidth

Disadvantages:

Line-of-sight will be disrupted if any obstacle, such as new buildings, arein the way
http://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Wikipedia:Please_clarifyhttp://en.wikipedia.org/wiki/Wikipedia:Please_clarifyhttp://en.wikipedia.org/wiki/Wikipedia:Please_clarifyhttp://en.wikipedia.org/wiki/Rain_fadehttp://en.wikipedia.org/wiki/Backhaul_(telecommunications)http://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/Base_Transceiver_Stationhttp://en.wikipedia.org/wiki/Base_station_subsystem#Base_station_controllerhttp://en.wikipedia.org/wiki/Network_switching_subsystem#Mobile_switching_centerhttp://en.wikipedia.org/wiki/Communications_satellitehttp://en.wikipedia.org/wiki/Communications_satellitehttp://en.wikipedia.org/wiki/Network_switching_subsystem#Mobile_switching_centerhttp://en.wikipedia.org/wiki/Base_station_subsystem#Base_station_controllerhttp://en.wikipedia.org/wiki/Base_Transceiver_Stationhttp://en.wikipedia.org/wiki/Cellular_networkhttp://en.wikipedia.org/wiki/Backhaul_(telecommunications)http://en.wikipedia.org/wiki/Rain_fadehttp://en.wikipedia.org/wiki/Wikipedia:Please_clarifyhttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Line-of-sight_propagation


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Signal absorption by the atmosphere. Microwaves suffer from attenuationdue to atmospheric conditions.

Towers are expensive to build

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Assignment of Networking