For most of us a mobile phone is a part of our lives,but I am sure you're curious mind have always been struck by such question as How a mobile phone makes a call and why there are different generation of mobile communication.

Let's explore the Technology behind mobile communication, when you speak on your phone,your voice is picked up by your phone's microphone. The microphone turns your voice into digital signal with the help of MEMS sensor and IC. The digital signal contain your voice in the form of zeros and ones. An antenna inside your phone's received zeros and ones and transmits them into the form of electromagnetic waves .these waves transmits the zero's and one's by Alterting the wave characteristics such as the amplitude, Frequency, phase or combination of these.

For example, in case of frequency zero's and one's are transmitted by using low and high frequency signal respectively.  so if you could find a way to transmits these electromagnetic waves to your friends phone.you would be able to establish call.

However, Electromagnetic waves are incapable of travelling long distance but they can be loose their strength due to the presence of physical objects, that may be electrical equipment and some environmental factors.

Necessity of cellular Technology

Electromagnetic wave couldn't carry on forever,due to earth' s curve structure. To overcome these issues, cell tower are introduce using the concept of cellular Technology. In cellular Technology a geographical area is divided into hexagonal cells with each cell having it's own tower and frequency slot. Generally these cell tower are connected through wire or more specifically, Optical fiber cables.These Optical fiber cable are laid under the ground or under oceans to provide national and international connectivity.

The Electromagnetic waves produced by your phone are picked up by the tower in your cell and convert them into high frequency light pulse.These light pulse is carried to the base transceiver box located at the base tower for further signal processing. After processing your your voice signal is routed toward the destination tower upon receiving pulses. The designation tower radiates it's outward in the form of electromagnetic waves and your friend's phone then received the signal.this signal undergoes a reverse process and your friend's hear your voice.

So,it's true that mobile communication are not entirely wireless .They do use a wired medium too.This is how Mobile communication are carried out.However, there was a big issue that we intentionally left answered.Mobile communication is only successful when your tower transfer the signal to your friends tower.

How To Located Your Friend Tower

How does your tower know in which cell tower area your area's your friend's located ?. Well, for this process the cell tower gets help from something called switching center. The MSC (Mobile switching center) is the central point of a group of cell towers before moving further let's explain more information about MSC.
When you purchase a SIM Card all the subscription information is registered in a specific MSC This MSC will be your Home MSC. The Home MSC store information such as service plan, your current location and your activity status. If you move outside the range of your Home MSC .The new MSC, which served your instead is known as your foreign MSC. It communicates with your Home MSC in short your Home MSC always know which MSC area you are in.
To understand in which cell location is the subscriber within MSC area. The MSC uses a few technique one way is to update the subscriber location after certain period.

Location Area Based

When the crosses a predefined number of towers,the location update is again done the last one of these is when the phone is turned on. Let's try to understand all of these procedures,with an example. Suppose A wants to call B. When A dials B' Number.The call request arrived at A's  home MSC upon the receiving B number. The request will be forwarded to B's home MSC. Now B's home MSC checks for his current MSC .if B is in his home MSC the call request will be immediately send to his current cell location and it check whether B is engaged on another call or his mobile is switch off. if everything is positive B's phone rings and call will be connected. However, if B's is not in his home MSC. B's home MSC simply forwarded call request to foreign MSC will follow the previous explain procedures to locate B's location and establish a call.

Why frequency spectrum is quite important in mobile communication?

To transfer zeros and ones in digital communication each subscriber is allotted a frequency range. however, the frequency spectrum available for cellular communication and there are billions of subscriber.This issue is solved with the help of two technique
1) Frequency Slot distribution
2) Multiple Access Technique
In the first technique, Different frequency slots are carefully allotted to different cell towers  and in multiple Access technique the frequency slot is efficiently distributed among all the active users in cell areas.

   

Why are the different generation of mobile Technology?

1) 1G originally allowed used for the first time to carry a phone without a cable attached to it but suffers from two major problem,

  • the first problem was wireless transmission was in analog format. analog signal are easily altered by external sources,so it provides poor voice quality and poor security.
  • The second problem was that it used frequency division multiple Access which uses the available spectrum in an efficient ways.These factors paved the way for second Generation.

2) 2G used digital multiple Access Technology namely TDMA and CDMA Technology. second generation also introduce a revolutionary data services, SMS, and internet browsing.

3) 3G Technology was focused on giving a higher data transfer speed . It used a WCD multiple Access technique. Along with an increase in bandwidth to achieve this the 3G speed of 2MBPS. Allowed the transfer of data for uses such as GPRS, Videos ,voice call etc.was a huge step in the transformation of the basic phone to smartphone.

4) 4G which achieve speed of 20 to 100 MBPS.This was suitable for the  high resolution movies and television.The Higher speed wad made possible due to the  OFD multiple Access Technology and MIMO Technology. MIMO Technology used multiple transmitter and receiver antennas inside both mobile phone and towers.

The next generation of mobile communication 5G,to be rolled out soon will used enhanced MIMO Technology and millimetre waves. it will provide seamless connectivity to support the internet of things. such as driverless car and smart homes.