For most folks , a mobile may be a a part of our lives. But I’m sure you’re curious minds have always been struck by such questions as how a mobile makes a call, and why there are different generations of mobile communications?
Let’s explore the technology behind mobile communications. When you speak on your phone, your voice is picked up by your phone’s microphone. The microphone turns your voice into a digital signal with the assistance of MEMS sensor and IC. The digital signal contains your voice in the form of zeros and ones. An antenna inside the phone receives these zeros and ones and transmits them within the sort of electromagnetic waves.
Electromagnetic waves transmit the zeros and ones by altering the wave characteristics, such as the amplitude, frequency, phase, or combinations of these.
For example, in the case of frequency, zero and one are transmitted by using low and high
frequencies respectively.
So, if you could find a way to transmit these electromagnetic waves to your friend’s phone, you would be able to establish a call. However, electromagnetic waves are incapable of traveling long distances.
They lose their strength thanks to the presence of physical objects, electrical equipment, and a few environmental factors. In fact, if there have been no such issues, even then, electromagnetic waves wouldn’t keep it up forever, thanks to the Earth’s curved structure.
To overcome these issues,cell towers were introduced, using the concept of cellular technology. In cellular technology, a geographic area is split into hexagonal cells with each cell having its own tower and frequency slot.
Generally, these cell towers are connected through wires, or more specifically,optical fiber cables. These optical fiber cables are laid under the ground or the ocean, to provide national or 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 pulses.
These light pulses are carried to the bottom transceiver box, located at the bottom of the tower for further signal processing, After processing, yourvoice signal is routed towards the destination tower. Upon receiving the pulses, the destination tower radiates it outwards within the sort of electromagnetic waves, and your friend’s phone then receives the signal. This signal undergoes a reverse process, and your friend hears your voice.
So, it’s true that mobile communications are not entirely wireless, they do use a wired medium too. This is how mobile communications are carried out. However, there was a big issue that we intentionally left unanswered. Mobile communication is merely successful when your tower transfers the signal to your friends tower. But how does your tower know during which cell tower area your friend is located? Well, for this process,the cell tower gets help from something called a mobile switching center.
The MSC is the central point of a group of cell towers. Before moving further, let’s explain more information about the MSC. When you purchase a SIM card, all the subscription information is registered during a specified MSC. This MSC will be your home MSC.
The home MSC stores information like service plans, your current location,and your activity status. If you progress outside the range of your home MSC, the new MSC, which serves you instead, is understood as a far off MSC. As you enter a far off MSC region, it communicates together with your home MSC.
In short, your home MSC always knows which MSC area you’re in. To understand in which cell location the subscriber is within the MSE area, the MSC uses a few techniques. One way is to update the subscriber location after a particular period. When the phone crosses a predefined number of towers, the situation update is again done. The last one of these is when the phone is turned on.
Let’s try to understan dall of these procedures with an example.
Suppose, Emma wants to call John. When Emma dials John’s number, the decision request arrives at Emma’s home MSC. Upon receiving John’s number, the request are going to be forwarded to John’s home MSC. Now, John’s MSC checks for his current MSC.
If John is in his home MSC, the call requests will be immediately sent to his current cell location, and it checks whether Johnis engaged on another call, or if his mobile is switched off. If everything is positive,John’s phone rings, and therefore the call are going to be connected. However, if John isn’t in his home MSC, John’s home MSC simply forwards the decision request to the foreign MSC. The foreign MSC will follow the previously explained procedure to locate John’s phone, and can then establish the decision .
Now, let’s discuss why the frequency spectrum is quite important inmobile phone communications.?? To transfer zeros and ones in data communication , each subscriber is allocated a frequency range. However, the frequency spectrum available for cellular communications is sort of limited, and there are billions of subscribers.
This issue is solved with the assistance of two technologies, one frequency slot distribution, and two, multiple access technique. In the first technique, different frequency slots are carefully allocated to different cell towers. In the multiple access technique, this frequency slot is efficiently distributed amongst all the active users within the cell area.
Now, the big question. Why are there different generations of mobile phone technologies?
1G originally allowedusers, for the first time, to carry a phone without a cable attached to it.
But 1G suffered from two major problems. The first problem was that the wireless transmission was in an analog format. Analog signals that are easily altered by external sources. So, it provided poor voice quality and poor security.
The second problem was that it used the frequency division multiple access technique, which used the available spectrum in an inefficient way. These factors paved the way for the second generation of mobile communications, 2G used digital multiple access technologies, namely TDMA, or CDMA technology. , SMS, and internet browsing. 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 two Mbps allowed the transfer of data for uses such as GPS, videos,voice calls, et cetera. 3G was a huge step in the transformation of the basic phone to a smartphone. Next came 4G, which achieved speeds of 20 to 100 Mbps.
This was suitable for high resolution movies and television. This higher speed was made possible due to the OFD multiple access technology, and MIMO technology. MIMO uses multiple transmitter receiver antennas inside both the mobile phone and the towers. The next generation of mobile communication, 5G, to be rolled out soon, will use enhanced MIMOtechnology and millimeter waves.
It will provide seamless connectivity to support the internet of things, such as driverless cars and smart homes.