The Layers of a Smartphone

Everyone has a smartphone, or so it seems. In fact, there were an estimated 1.4 billion smartphones in the world as of December 2013 [source: Koetsier]. People are constantly talking on them, taking pictures, surfing the Internet and doing dozens of other things, including shopping for cars. Captain Kirk would be jealous.

At their core, smartphones, and all cell phones for that matter, are mini radios, sending and receiving radio signals. Cell phone networks are divided into specific areas called cells. Each cell has an antenna that receives cell phone signals. The antenna transmits signals just like a radio station, and your phone picks up those signals just as a radio does.

Smartphones use cell phone network technology to send and receive data (think phone calls, Web browsing, file transfers). Developers classify this technology into generations. Do you remember the first generation? It included analog cell phone technology. However, as cell phone technology progressed, the protocols became more advanced. In 2014, cell phones are in the world of the fourth generation, or 4G. Although most carriers are expanding their 4G technology, some companies, such as Samsung, are developing 5G technology, which if recent tests are any indication, will allow you to download an entire movie in less than a second. You can read more about network technologies and protocols in the article How Cell Phones Work.

Special Considerations

Although cell phones share similarities with laptop computers, pagers and other devices, they have some peculiarities that make their development needs unique.

When you're making a call on a cell phone, you want to have access to other features (like an address book and calendar) at the same time.
Cell phones need to be "always on" like a standard landline phone, but efficient enough to run on a battery charge for as long as possible.
They need to be as functional as possible whether or not they are connected to voice and data networks at a given moment.
While a computer has pretty standard input methods -- almost all of them start with a keyboard and mouse by default -- a phone may have a number pad, a modified keyboard, a touch screen or some combination thereof.