Mobile phone is a part of our life.
When you talk on your phone, your phone’s microphone hears your voice, then the microphone converts your voice into digital signal with the help of a mem sensor and IC. Digital signal saves your voice as zero and one.
An antenna located inside your phone receives these zero and one signals, and converts them into electromagnetic waves and transmits them.
And the electromagnetic waves change the properties of the wave like Amplitude, Frequency, Phase or their combination to transmit the signals of zero and one.
For example, in terms of frequency, zero and one are transmitted as low and high frequencies respectively. So if you figure out how to send this electromagnetic waves to your friend’s phone, then you will be able to make a call. But electromagnetic waves are not able to travel much distance. These waves get destroyed due to many things, electronic devices and some environmental factors.
In fact, even if there is no such problem, waves cannot always exist due to the curvature of the earth, to solve this problem, cell towers were built using cellular technology.
In cellular technology, a geographical area is divided into eight-sided cells, in which each cell has its own tower and frequency slot. Generally, these cell towers are connected by wires or, more specifically, they are connected by optical fiber cables, these optical fiber cables are laid under the ground or in the sea. So that national or international connectivity can be created.
The electromagnetic waves generated by your phone reach the tower located in your cell. And there they are converted into high-frequency light pulses. These light pulses are sent to the base transceiver box located at the base of the tower for signal processing. After processing, the voice signal receives pulses in the destination tower. Converts it to magnetic waves and propagates it outside. And your friend’s phone accepts those signals, this signal then goes through the exact reverse process and your friend is able to hear your voice, so it is true that mobile communication is not completely wireless, in which wired medium should also be used. This is how mobile communication is carried out.
Mobile communication can be successful only if the tower sends the signals to you on your friend’s phone but how does your tower know which cell area your friend is in, although for this process the mobile switching center helps the cell tower ( MSC) is the central point of a group of cell towers.
Let’s understand about MSC in a better way
When you buy a SIM card, all the subscription information is punched to the MSC. This MSC is your home MSC. The home MSC service plan stores information such as your current location and the status of your activities if you access your home MSC. When you go out of range, the new MSC provides services to you, which is called Foreign MSC, as soon as you come to the area of MSC, it contacts your home MSC in short, your home MSC always knows this. To understand which MSC area you are in, which cell is in the area of the subscriber MSC area, MSC uses some techniques, one way is to update the subscriber location after a certain period of time. When the phone crosses a predetermined number of towers, the location is updated again, with the last location being when the phone was turned on.
Now let’s talk about why frequency spectrum is so important in mobile communication, each subscriber is allotted a frequency range to send zero and one digital communication, but for cellular communication, this available frequency spectrum is limited, while there are trillions of subscribers in the world. is present.
To solve this problem, the help of two techniques is taken.
1. Frequency Slot Distribution
In this technique different frequency slots are carefully allocated to different cell towers.
2 . multiple access technology
In this technique the frequency slots are distributed among the active users present in the areas of the cell.
1G made it possible to have wireless phones for the first time but there were two big problems with 1G
1. Wireless broadcasting was in the unlock format. The unlock signal can be easily changed by external factors, so it may result in poor voice quality and security level or
2. Frequency division multiple access technique was used which used the available spectrum in a downstream manner.
Due to these reasons, the way for the second generation of mobile communication was paved.
Digital multiple access technology was used in 2G, which was called Time Division Multiple Access (TDMA) and (CDMA) code division multiple access technology.
In the second generation, revolutionary data services, SMS and Internet browsing were also brought.
3G technology is designed keeping in mind to provide high speed of data transfer.
In this, along with using WCD multiple access technology, the band width was increased to achieve this goal.
With 3G speed of 2 mbps, users could send data of GPS, video and voice calls etc. 3G was a big step in turning a basic phone into a smartphone.
Next came 4G, in which the speed of 20 maps was achieved, which was suitable for high resolution movies and television.
This was possible due to high speed OFD multiple access technology and MIMO technology.
In mimo, multiple transmitter receiver antenna is used inside both mobile and towers.
The next generation of mobile communication is 5G, which will soon hit the market and will use more advanced mimo technology and millimeter waves. It will have seamless connectivity to support Internet of Thinking like driverless car and smart home etc.