Physical Media - papersocean

Computer Networks:

Physical Layers

Data link Layer(DLL)

Network Layer

Transport Layer:

Session and Presentation Layer:

Application Layer:

Transmission media / physical media:

Transmission media can be classified into guided (wired) or unguided (wireless).

Guided (wired) technology:

Wired transmission media are those physical media in which we use wired technology to transmit signal from source to destination using cables like: twisted pair, coaxial, optical fiber.

1) Twisted pair cable:

A twisted pair cable consist of two conductor each with its own plastic insulation, twisted together there are two kinds of twisted pair cable.

Unshielded twisted pear(UTP)
Shielded twisted pair (STP )

There are mostly connected by RJ45. Twisted cable are used in Telephone lines to provide voice and data channel. In LANs such a 10 base T and 100 base also use twisted pair cable.

The transmission speed range from 2 million beats per second to hundred million bits per second.

2) Coaxial cable:

Carry signals of high frequency range than twisted pair cable instead of having two wires coax has a Centre core conductor of solid or standard wire and closed in insulated.

Transmission speed range from 200 millions to more than 500 million bit per second.

3) Optical fiber cable:

Fiber optics is made up of glass and transmit signals in the form of light. Connected used in fiber optics cables are subscribe channel conductor and MT-RJ connector.

Advantages of guided:

Higher brand width
Less signal attenuation
Immunity to electromagnetic interference
Resistance to corrosive material
Light weight

Disadvantages of guided transmission media :

Installation /maintenance is difficult
Unidirectional
Costly.

Wireless transmission media:

Wireless transmission media are those physical media in which we use wireless technology to transmit signal from destination using radio wave, microwave infrared.

Radio waves are used for multi cast Communication such as radio and television, omni directional antenna

Microwaves are used for unicast communication such as cellular telephone satellite network and wireless LAN they are Uni directional antenna

Infrared communication in a closed area using line of sigh propagation.

1) Terrestrial microwave:

Terrestrial microwave use Earth based transmission, transmitter and receiver. The equipment look similar to satellite dish terrestrial microwave use low gigahertz range which limits all communication to line of Sight.

2) Communication satellite:

The satellite use microwave radio as there telecommunication medium which are not deflected by the earth atmosphere. The satellite are patient in space typically 22000 miles for Geosynchronous satellite.

3) Cellular and PCS system:

Cellular and PCS system use several radio Communication Technology, this system are divide to different Geography areas.

4) Wireless LAN:

Wireless Local area network use a high frequency Radio Technology similar to digital cellular and a low frequency Radio Technology.

5) Infrared communication

which you transmit signal between device within a small distance not more than 10m peer to peer without anybody in the line of transmission.