UnBounded/UnGuided Transmission Media

UnBounded/UnGuided Transmission Media

UnBounded/UnGuided Transmission Media

Unguided or wireless media sends the data through air (or water), which is available to anyone who has a device capable of receiving them. Types of unguided/ unbounded media are discussed below :

  • Radio Transmission
  • MicroWave Transmission

Radio Transmission

Its frequency is between 10 kHz to 1GHz. It is simple to install and has high attenuation. These waves are used for multicast communications.

Types of Propogation

Radio Transmission utilizes different types of propogation :

  • Troposphere : The lowest portion of earth’s atmosphere extending outward approximately 30 miles from the earth’s surface. Clouds, jet planes, wind is found here.
  • Ionosphere : The layer of the atmosphere above troposphere, but below space. Contains electrically charged particles.

Microwave Transmission

It travels at high frequency than the radio waves. It requires the sender to be inside of the receiver. It operates in a system with a low gigahertz range. It is mostly used for unicast communication.

There are 2 types of Microwave Transmission :

  1. Terrestrial Microwave
  2. Satellite Microwave

Advantages of Microwave Transmission

  • Used for long distance telephone communication
  • Carries 1000’s of voice channels at the same time

Disadvantages of Microwave Transmission

  • It is Very costly

Terrestrial Microwave

For increasing the distance served by terrestrial microwave, repeaters can be installed with each antenna .The signal received by an antenna can be converted into transmittable form and relayed to next antenna as shown in below figure. It is an example of telephone systems all over the world

Terrestrial Microwave

There are two types of antennas used for terrestrial microwave communication :

1. Parabolic Dish Antenna

In this every line parallel to the line of symmetry reflects off the curve at angles in a way that they intersect at a common point called focus. This antenna is based on geometry of parabola.

Parabolic Dish Antenna

2. Horn Antenna

It is a like gigantic scoop. The outgoing transmissions are broadcast up a stem and deflected outward in a series of narrow parallel beams by curved head.

Horn Antenna

Satellite Microwave

This is a microwave relay station which is placed in outer space. The satellites are launched either by rockets or space shuttles carry them.

These are positioned 36000KM above the equator with an orbit speed that exactly matches the rotation speed of the earth. As the satellite is positioned in a geo-synchronous orbit, it is stationery relative to earth and always stays over the same point on the ground. This is usually done to allow ground stations to aim antenna at a fixed point in the sky.

Satellite Microwave

Features of Satellite Microwave :

  • Bandwidth capacity depends on the frequency used.
  • Satellite microwave deployment for orbiting satellite is difficult.

Advantages of Satellite Microwave :

  • Transmitting station can receive back its own transmission and check whether the satellite has transmitted information correctly.
  • A single microwave relay station which is visible from any point.

Disadvantages of Satellite Microwave :

  • Satellite manufacturing cost is very high
  • Cost of launching satellite is very expensive
  • Transmission highly depends on whether conditions, it can go down in bad weather

 

Types of Communication Networks

types of communication networks

Local Area Network (LAN)

It is also called LAN and designed for small physical areas such as an office, group of buildings or a factory. LANs are used widely as it is easy to design and to troubleshoot. Personal computers and workstations are connected to each other through LANs. We can use different types of topologies through LAN, these are Star, Ring, Bus, Tree etc.

LAN can be a simple network like connecting two computers, to share files and network among each other while it can also be as complex as interconnecting an entire building.

LAN networks are also widely used to share resources like printers, shared hard-drive etc.

Local Area Network

Applications of LAN

  • One of the computer in a network can become a server serving all the remaining computers called clients. Software can be stored on the server and it can be used by the remaining clients.
  • Connecting Locally all the workstations in a building to let them communicate with each other locally without any internet access.
  • Sharing common resources like printers etc are some common applications of LAN.

Metropolitan Area Network (MAN)

It is basically a bigger version of LAN. It is also called MAN and uses the similar technology as LAN. It is designed to extend over the entire city. It can be means to connecting a number of LANs into a larger network or it can be a single cable. It is mainly hold and operated by single private company or a public company.

Metropolitan Area Network

Wide Area Network (WAN)

It is also called WAN. WAN can be private or it can be public leased network. It is used for the network that covers large distance such as cover states of a country. It is not easy to design and maintain. Communication medium used by WAN are PSTN or Satellite links. WAN operates on low data rates.

Wide Area Network

Wireless Network

It is the fastest growing segment of computer. They are becoming very important in our daily life because wind connections are not possible in cars or aeroplane. We can access Internet at any place avoiding wire related troubles.. These can be used also when the telephone systems gets destroyed due to some calamity/disaster. WANs are really important now-a-days.

Wireless Network

Inter Network

When we connect two or more networks then they are called internetwork or internet. We can join two or more individual networks to form an internetwork through devices like routers gateways or bridges.

Inter Network with LAN and WAN

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