1. Cell Phone Technology

2. Cell Phone Frequencies Cell phones use full-duplex radios, rather than half-duplex radios like those used in walkie-talkies, so that the people can talk and hear one another at the same time.

3. Cell phones use cells in order to work. As a person travels, the phone changes cells so that there is service pretty much no matter where the person is.

4. Network Technologies: 2G The three technologies used by 2G cell phone networks for transmitting information: Frequency division multiple access (FDMA) Time division multiple access (TDMA) Code division multiple access (CDMA)

5. FDMA FDMA basically means that each call is put on its own frequency. So there is a “band” available (see photo) where signals can be sent on certain frequencies. This is not usually used for cell phones because it isn’t really advanced enough.

6. TDMA TDMA gives a certain amount of time per frequency. This is used by Electronics Industry Alliance and the Telecommunications Industry Association for Interim Standard 54 and Interim Standard 136

7. TDMA continued… In this method, a “narrow band” (30kHz wide and 6.7 milliseconds long) is split into three time slots. This gives it more space so more conversations can take place. This is also used for Global System for Mobile communications (GSM). GSM makes it possible for people to use their cell phone pretty much anywhere, no matter what country they are in.

8. CDMA This method digitalizes data and spreads it over the whole band, unlike the other two methods. Calls are overlaid on each other in a channel and each has a “unique sequence code”. With this, 8-10 calls can be made in the same channel space as that of an analog call (what was used for the first cell phones in the 80s)

9. Network Technologies: 3G The 3G technology is basically just to keep up with the advancements in our phones such as with photo and video. With this the bandwidths are increased and transfer rates are faster.

10. All of the information and pictures from this slide show can be found at: Layton, Julia, Marshall Brain, and Jeff Tyson. "How Cell Phones Work." How Stuff Works.. And "I-Mode FAQ." I-Mode.. (This was just for the photo on the last slide)