The Theory of Nothing

How does the cellular phone work?

How does the cellular phone work?

Everyone has a cellular phone these days, even children and senior citizens, and most of them are smart phones. I don't know about you, but I wouldn't want to use a dumb phone. That's a joke!

I doubt that most people even care about how a cellular (some call it mobile) phone works. Actually, it's something that would have been considered impossible only a few decades back. The cellular phone is essentially a radiophone, and the idea goes back to a 1948 science fiction novel 'Space Cadet' by Robert Heinlein. The concept was also used in Star Trek as a communicator, something that resembled a flip phone. This is so typical of science fiction; ideas that are fiction become true with time.

Martin Cooper working at Motorola invented the first practical cell phone in 1973 and it was huge compared to what we have available today. It looked like a military Walkie-Talkie and probably weighed as much. Keep in mind that there were radiotelephones in cars before this, but the car phone provided the designers a lot of room for batteries and electronics.

A cellphone depends upon cell towers to operate. Cell towers are where the antennae that make up a cellular network are located. The antennae attached to these towers act as repeaters that can relay the signal from your phone to other towers through the network of your carrier. Each tower has transmitters, receivers, digital signal processors, and a GPS receiver. The GPS is involved in the control of the system that sends and receives data over 1x, 3g and higher systems. This also has to do with the SIM (Subscriber Identity Module) card in your phone that allows the system to recognize your carrier and provides security so that others can't intercept you signal. Well, maybe the government can.

GMS stands for Global System for Mobile Communications Services. This is what the carriers use to make their networks function according to an agreed upon system of hardware and software for mobile communications. This is necessary because a mobile phone must be able to receive and make calls from anywhere that coverage is available. You can imagine how many calls and accesses for data are made every day. It's mind boggling how all of this can be routed to the proper channels to get where it's supposed to go and do it almost instantaneously.

The most important thing that helps make this work is the SIM card in your phone. This module contains a secret key that provides authentication and encryption services inherent to your carrier. Besides you phone number, your phone has a unique identifier IMEI or International Mobile Equipment Identity. This helps locate stolen phones.

Your phone also operates at a specific frequency associated with your carrier. This is probably to prevent undue interference. When you dial a number on your cellphone, many operations go into effect to make the connection: the call is routed to the Gateway MSC, which is the starting point of getting into the Public Switched Telephone Network. This is where the system has to search to find the location of the phone that you, the caller, is asking for. Once this is determined, the call is routed to that phone, and then, depending upon whether the call is answered or not, determines the next action, if needed. All of this depends on computer programming.

The other thing that must happen is the conversion of analog speech to digital data. This conversion is necessary in order to send data, such as Internet information, along with speech on the same system, but this is a very simple explanation for a very complicated technology. Gone are the simple days when one picked up a phone and heard "Number Please?"

The smartphone is a special type of cell phone that combines the cellular phone with lots of other goodies; internet browser, media player, GPS navigation, computer interface and a camera, to name a few. What makes a smartphone useful is the fact that it can run apps, essentially programs designed to run on a mobile device. The 2007 Apple iPhone was the first to use a multi-touch interface, and it wasn't long until Android based phones appeared. Of course, the BalckBerry phone was once the darling of cellular phone enthusiasts, but the new Samsung and Apple devices have eclipsed it. The truth is that that modern smartphone is made possible by the miniaturization of processors, memory chips and other electronic devices like a camera. There is one heck of a lot of tech in that device that you use everyday.

Thanks for reading.