Guided Network Transmission Media
Network transmission media , in other words, the communication channel or the physical path through which data is sent from the transmitter to the receiver is a key element of the data transmission process. These communication channels are meant to transfer the information in the form of bits mainly through a Local Area Network. When it is a fibre based communication path the bits will be in the form of light phases whereas in a copper based communication path the bits will be in the form of electrical signals. Different types of transmission media can be identified under the characteristics that are unique to them in terms of bandwidth , delay, ease of installation and cost. When considering the OSI Model transmission media is considered to be belonging to the physical layer.
There are few types of transmission media that are used frequently and they can be divided into two types as guided and unguided media . Coaxial cables, fiber optics and twisted pair cables fall under the guided media category. Radio waves, microwaves and infrared fall under the category of unguided transmission media. This article aims to discuss guided transmission media in detail.
Guided media is also called wired media .They require a physical medium for the transmission of information. They are used for communication between relatively short distances when compared with unguided media. They are considered to be very secure and of high speed .
(i) Twisted wire pair
Twisted pair cable consists of two insulated copper wires that are twisted together spirally. They are the most used type of transmission media and also the cheapest among them all. There is a protective casing covering the wires . There are two types of twisted pair cables : shielded and unshielded .
Shielded Twisted wire pair
There is a mesh around the wire , thereby leading to a higher transmission rate
Advantages :
- Better performance at a higher data rate in comparison to UTP
- Eliminates crosstalk
- Comparatively faster
- Comparatively difficult to install and manufacture
- More expensive
- Bulky
Unshielded twisted wire pair
This can block interference and does not depend on a physical shield
Advantages :
- Least expensive
- Easy to install
- High-speed capacity
- Susceptible to external interference
- Lower capacity and performance in comparison to shielded twisted pair
(ii) Coaxial Cable –
It has an outer plastic covering containing 2 parallel conductors each having a separate insulated protection cover. The coaxial cable transmits information in two modes: Baseband mode(dedicated cable bandwidth) and Broadband mode(cable bandwidth is split into separate ranges). Cable TVs and analog television networks widely use Coaxial cables.
Advantages:
- High Bandwidth
- Better noise Immunity
- Easy to install and expand
- Inexpensive
Disadvantages:
- Single cable failure can disrupt the entire network
(iii) Optical Fibre Cable –
It uses the concept of reflection of light through a core made up of glass or plastic. The core is surrounded by a less dense glass or plastic covering called the cladding. It is used for the transmission of large volumes of data.
The cable can be unidirectional or bidirectional. The WDM (Wavelength Division Multiplexer) supports two modes, namely unidirectional and bidirectional mode.
Advantages:
- Increased capacity and bandwidth
- Lightweight
- Less signal attenuation
- Immunity to electromagnetic interference
- Resistance to corrosive materials
Disadvantages:
- Difficult to install and maintain
- High cost
- Fragile