Transmission medium is the possible roadway through which data can travel from the sender to the receiver in a computer network. In this chapter, we will discuss transmission media, its types, and concept of bit and bandwidth.

Summary

  • Transmission media is a basic requirement to establish a computer network.
  • There are generally two types of transmission media: Guided Transmission Media and Unguided Transmission Media.
  • Bit and Bandwidth are the measures of data transmission in a network.

What is a transmission medium?

In a computer network, transmission medium (plural: media) play a crucial role for data communication. Without these transmission media, sharing of data and making communication would be next to impossible.

Transmission medium is the possible roadway through which data can travel from the sender to the receiver in a computer network.

Transmission medium can be understood as the path for transportation of vehicles. If it is a vehicle like bus, car, or bike, it needs a physical path such as a highway to travel from the starting point to the ending point. Similarly, an airplane that flies in the sky can take any of the many possible paths for reaching the destination.

Types of Transmission Media

As explained in the above example, transmission medium can be of two types: Guided transmission media and Unguided transmission media.

I. Guided Transmission Media

Guided transmission media are the physical pathways made for data to travel through a fixed path from the sender to the receiver. These are also known as bounded transmission media. Example: cables, etc.

Features

  1. Data can only travel through a fixed physical pathway.
  2. Data can travel at a higher speed.
  3. Risk of data loss is minimum.

Types of Guided Transmission Media

There are three types of guided transmission media. They are:

  1. Coaxial Cable (CC) is the most common guided transmission media which is inexpensive. They are easy to set up. Some coaxial cables are EMI resistance. Example: Television wire.
  2. Twisted Pair Cable (TPC) are of two types: Shielded Twisted Pair (STP) and Unshielded Twisted Pair (UTP) which are also inexpensive and easy to set up.
  3. Fiber Optics Cable is the modern and advanced type of guided transmission media which is expensive and sensitive as well. Data travels in the speed of light in this media. It also provides finest data security as it has no EMI interference.

II. Unguided Transmission Media

Unguided Transmission Media are the electronic pathway for in which data can take one of the several routes for reaching the destination from the source. These are also known as unbounded transmission media. Example: Wi-Fi, Bluetooth, etc.

Features

  1. There are many paths for data communication.
  2. It allows for the sharing of data across large geographical area.
  3. It doesn't use cables rather it uses radio signals for data communication.

Types of Unguided Transmission Media

  1. Microwave System: is an unguided transmission media in which data travels in the form of high-speed radio signals in a straight line between two points (antennae). Antennae are compulsory.
  2. Communication satellites: help to transmit information from one place to another using satellites. Radio signal is first transmitted by a ground station to a satellite. The satellite in the space receives it and transmits to another station located in the Earth.
  3. Infrared: is another unguided transmission media that uses infrared technology to transmit data only when the transmitter is pointed towards the receiver. Antennae are not compulsory.
  4. Bluetooth: allows data transmission between computing devices within a small geographic area of 10m using wireless connections. It uses a frequency band of 2.4 GHz.
  5. Wi-Fi: (Wireless Fidelity) is a popular unguided or wireless transmission media that allows transmission of data across a large geographical area by establishing connections between computing devices. It uses a frequency band of 2.4 GHz or 5 GHz.

Concept of Bit and Bandwidth

Bit

Bit stands for Binary Digit. It is the smallest storage unit of data in computer. It represent a single binary value, either 0 or 1.

Bit Rate

Bit rate is defined as the amount of bits transmitted from the source to the destination per unit time (here, time is usually seconds).

Bandwidth

Bandwidth refers to the amount of data expected to be transmitted per second. It is measured in bits per second (bps) or Bytes per second in digital devices Hertz (Hz) or cycles per second (CPS) in analog devices.

Difference between Bit and Bandwidth

The major difference is that Bandwidth refers to the potential of data transmission whereas Bit Rate refers to the actual speed of data transmission.

Potential denotes the maximum rate at which the data can be transferred whereas actual speed refers at which rate the data is being transmitted over the network.