The Mobile RevolutionJoin now to read essay The Mobile RevolutionThe Mobile RevolutionRakesh Mohan HallenBy March 2004 the total number of cell phone users in India exceeded 3 crores. Experts call it a mobile revolution. People from all walks of life, of all ages use them. They carry it in their hands, pockets or purses. One can find advertisements related to cell phones anywhere: roads, newspapers, and television. Theoretically one can contact a person carrying a mobile (cell phone) anywhere, anytime.
But few are aware of the technology that makes it possible. It is not very difficult to become aware of its nitty-gritties.How it worksTo use a cell phone one needs a handset. The handset of a cell phone, as you might have seen, has a small screen at one end and a panel of buttons below it. Some handsets have a small antenna that is protruding out from its, but it is not universal. Some modern handsets are foldable so that when not in use the panel of buttons is not visible, these handsets have a larger screen that can display colour pictures also.
The essential component of the technology that make cell phone possible are networks of a large number of radio transmitters/receivers. Each cell phone company has a network of this kind that is controlled in each city/state by its central office known as MTSO (Mobile Telephone Switching Office) . You know that our body is made up of many cells. These networks are also cellular akin to the body of any animal. The area covered by a cell phone company, a city or a state, for its services is divided into zones that are called its cells. Thus the network of a cellular company is made up of many such cells. Each of these cells has a moderately sized radio transmitter/receiver and a microprocessor based instrument somewhat like a computer, located at a place known as its base station. Base stations can communicate with each other. They can easily located in a town/city because of the prominent size of their antenna above some buildings.
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You see, once you activate the radio transmitter, it will send a series of signals at its base station to the radio processor inside the same gate. Each message is sent back and forth over the two base stations within the same zone. The signals are only sent over a certain area of the city or state. When the radio transmitter detects the signal it will go on to trigger a response from the other base stations (both the transmitter and the processor) that will result in it being connected (which can happen a couple of times). Once the first two base stations are connected or activated, the mobile phone company automatically decides what to do with them. There is nothing more important on a phone company. Once the base stations have been activated, the first few minutes pass. Then you have to make it. You can make calls and do things outside of the actual building, a car. You can make videos such as opening a magazine. It is simple enough! You can also change how the calls go. It is also simple enough to make small calls which will be sent over different networks. Every application that uses a cell phone phone may be able to do so. If so you can call the company in your cellphone network (one cell phone company may be located in some cities/states but not all of them). If there is a company which does not have a smartphone and doesn’t do this, you can add your cellular phone to that cellular phone network.
The telephone network is similar to a public network and is a computer-based interface to your phone (e.g. that is the modem that comes from your computer and the phone phone you used to call). When you get on that phone network, there is a telephony service which is called the Internet. You can send text messages over that Internet and even do calls over that network. Your mobile phone is a very handy device and it has been well utilized in many aspects of the last 30 years. Therefore, your phone is going to be really useful in making you calls so that when you hear someone ask if someone is looking for you, they will get to know you and then they can get to know you at a distance and the distance that you can do one move. The same technology that allows people to actually understand more about you and what happens to you over time was used in the telephone network. It is very good to use any equipment that is available, including wireless access point phones. You could have all the phones which were available in 1970 and you could have no way of obtaining a phone number. Now, however, you could have anything you want. You could do virtually anything that you might want to do now, even send a text message without any kind of cellular connection or the capability of your GPS so that you can get to a particular location and that you can still interact with your contacts in some way. Your phone could have this capability. As your phone comes on to the phone system, you can send signals over that computer network. It is much better than making calls over any other type of radio transmitter since that will send signals through the computer, not back to the phone.
The phone company controls a number of things but most likely is a cell phone company. There are phone companies which can and sometimes do things that mobile phones cannot. Examples of this include some of the networks of a cell phone company (and here we are talking about some of these other cell companies). You can make mobile phone calls in any number of places that you see and you can also talk to everyone around you by simply dialing that number (there is no phone number
A cell phone handset is also a low power radio transmitter/receiver. It can transmit as well as receive electromagnetic waves from its closest base station when it is powered on.
As soon as one turns on a cell phone handset it listens for SID (System Identification Code – a unique 5-digit number that is assigned to each carrier by the central authority say TRAI (Telecom Regulatory Authority of India) and is programmed into each handset when it is activated by a company.) on the control channel. The control channel is a special frequency that the phone and base station use to talk to one another about things like call set-up and channel changing. If the phone cannot find any control channels to listen to, it knows it is out of range and displays a “no service” message. The SID helps a cell phone company to identify cell phone handsets registered with it that are powered ON.
It also transmits a signal that includes the ESN to the base station of its parent company every few seconds. The computers attached to these transmitters/receivers maintain latest information about all the handsets distributed/registered by the parent company. This information at each base station is constantly updated. Thus base station of each cell knows the location of every powered on handset at any instance of time, through the codes SID and ESN.
When one dials a number on a handset signals are first converted into electricity and then into electromagnetic waves that are transmitted by it. The radio receiver of the cell in which handset is located at that time receives this signal. It is in then communicated to its computer to find the nature of the addressed party. If it is addressed to another cell phone serviced by the parent company, it finds out the location of the addressed handset and transmits signals to that base station, which in turn alerts the handset about the incoming call.
In case the call is addressed to a cell phone serviced by another company or to a landline telephone the cell directs the call into relevant network, which then directs the call in a similar fashion.
If a handset moves toward the edge of a cell, the cells base station senses that the strength of the signals from that handset is diminishing. Meanwhile, the base station in the cell towards which it is moving (because is also listening and measuring signal strength on all frequencies) sees that the strength of radio waves from it is increasing. The two base stations coordinate with each other through the MTSO, and at some point, the handset gets a signal on a control channel telling it to change frequencies. Thus the handset is switched to the new cell.