01 - Introduction to Wireless Communication Systems

In 1897 Gugliemo Marconi was the first to demonstrate that it was possible to establish a continuous communication stream with the ships that were sailing in the English Channel, by means of radio waves. Since then, the wireless technologies that make “on-the-move” communication possible for us have evolved remarkably. Today, facilitated by RF circuit fabrication and digital switching techniques, affordable high speed telecommunication has been largely deployed across the world.

We know, communication means transfer of information from source to recipient. In traditional telephony, when source and recipient were located in long distance, this transfer used to happen by connecting source and recipient physically through conducting wires, which would carry information in the form of electrical signals.

Now, what is Wireless Communication?

Any transfer of information between points that do not have a physical connection, like wire or cable connection, would be WIRELESS COMMUNICATION. Therefore, when you talk to your friend sitting beside you, technically wouldn’t you be communicating wirelessly? But since we are Engineers, let us leave aside such naive cases and have some qualitative examples of wireless communication systems.

Examples of wireless communication:

  • Short Distance - TV controlled by remote
  • Long Distance - Space Radio Communication

Components of a Communication System


The source is the originating point of the information that is to be conveyed. This information could be voice, text, picture, packet data etc. Usually, this message is encoded upon a carrier or a medium called the Baseband signal. The baseband signal carries no information on its own, but before reaching the transmitter, the information to be sent is added to it. The transmitter then sends out the message into the communication channel.

The channel is a medium through which the transmitter output is sent to the recipient. This in the wired system could be a wire, a coaxial cable, or an optical fiber. In wireless systems these are generally waves like IR or radio. At the other end of the channel would be the receiver. It would extract the information from the incoming signal received, by subtracting the baseband signal from it. The receiver output is the information that had come from the source, and this can be directed to the recipient.


Cellular Communication

Cellular Mobile Communication systems are wireless systems that divide a given geographical area into cells and use a large number of transmitters to communicate wirelessly within those cells. They provide mobility to the user within the cell, and when he/she moves from one cell to another, a ‘hand-off’ mechanism takes care of continuous connectivity. Therefore cellular communication ensures connectivity with a single network over a large geographical area.

Evolution of Cellular Radio Communication

Over the years, we have seen remarkable growth of cellular communication over radio. With ever increasing subscriber base and limited radio resource, providing quality telecom services became difficult. These issues led mobile service providers to research into technologies and  improve the quality of service and be able to support more users in their systems. Therefore Cellular communication has been continuously evolving into newer forms. Here’s a brief look into its journey from 1G to LTE.

North American Cellular 

  • Developed in the 1970’s, deployed in the early 1980’s
  • Initially operated in 800 MHz frequency range, then in 1900 MHz range

GSM (2G)

  • Newer than North American Cellular
  • All Digital Standard recommended by ETSI for Europe. 
  • Adapted in other countries.
  • Operates in 900 MHz range 

GPRS (2.5G) 

  • Is a packet based data service for mobile phones
  • 56-114 kbps

UMTS (3G)                                                                                    

  • 3GPP standards
  • Data rates starts from 384 kbps and runs into Mbps based on the technology

LTE (4G)  

  • Based on an all-IP packet switched network.
  • Peak data rates of up to approximately 100 Mbps

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