When people began to use cell phones, there were few industry-wide standards for cell phone technology. Without standards, it was difficult and expensive to make calls to people that were on another network. Today, cell phone providers use industry standards, making it easier to use cell phones to make calls.
Cellular standards have not been adopted uniformly around the world. Some cell phones are capable of using multiple standards, whereas others can use only one standard. As a result, some cell phones can operate in many countries, and other cell phones can only be used locally.
The first generation (1G) of cell phones began service in the 1980s. First-generation phones primarily used analog standards. With analog, interference and noise cannot easily be separated from the voice in the signal. This factor limits the usefulness of analog systems. Few 1G devices are in use today.
In the 1990s, the second generation (2G) of mobile devices was marked by a switch from analog to digital standards. Digital standards provide higher call quality. These are some common 2G standards:
- Global System for Mobile (GSM)
- Integrated Digital Enhanced Network (iDEN)
- Code Division Multiple Access (CDMA)
- Personal Digital Cellular (PDC)
As 3G cell phone standards were being developed, extensions to the existing 2G standards were added. These transitional standards are known as 2.5G standards. These are some common 2.5G standards extensions:
- General Packet Radio Service (GPRS)
- Enhanced Data Rates for GSM Evolution (EDGE)
Third-generation (3G) standards enable mobile devices to go beyond simple voice and data communications. It is now common for mobile devices to send and receive text, photos, audio, and video. 3G even provides enough bandwidth for video conferencing. 3G mobile devices are also able to access the Internet to browse, play games, listen to music, and watch video. These are some common 3G standards:
- Universal Mobile Telecommunications System (UMTS)
- Evolution-Data Optimized (EV-DO)
- Freedom of Mobile Multimedia Access (FOMA)
- Time Division Synchronous Code Division Multiple Access (TD-SCDMA)
Fourth-generation (4G) standards provide ultra-broadband Internet access. Higher data rates allow users to download files much faster, perform video conferencing, or watch high-definition television. These are some common 4G standards:
- Mobile WiMAX
- Long Term Evolution (LTE)
The specification for 4G devices requires a maximum of 100 Mb/s communication for highly mobile devices like those in a car. The specification also requires a maximum of 1 Gb/s for devices being used by people moving slowly or standing still.
WiMAX and LTE
Even though Mobile WiMAX and LTE fall short of the data rate to be compliant with 4G (128 Mb/s and 100 Mb/s, respectively), they are still considered 4G standards, because they offer so much improvement over the performance of 3G. WiMAX and LTE are also forerunners to versions that will be compliant with the full specification of 4G.
Technologies that add multimedia and networking functionality can be bundled with cellular standards. The two most common are Short Message Service (SMS), used for text messaging, and Multimedia Message Service (MMS), used for sending and receiving photos and videos. Most cellular providers charge extra for adding these features.
To turn on or off cellular data on an Android device, as shown in Figure 1, use the following path:
Settings > Touch More under Wireless and Networks > Touch Mobile Networks > Touch Data enabled
To turn on or off cellular data on an iOS device, as shown in Figure 2, use the following path:
Settings > General > Cellular Data > turn cellular data on or off
As a mobile device moves from an area of 4G coverage to 3G coverage, the 4G radio shuts off and turns on the 3G radio. Connections are not lost during this transition.
Most mobile devices also have a setting called Airplane Mode that turns off all cellular, Wi-Fi, and Bluetooth radios. Airplane Mode is useful when traveling on an airplane or when located where accessing data is prohibited or expensive. Most mobile device functions are still usable, but communication is not possible.
To turn Airplane Mode on or off on an Android device, use the following path:
Settings > More > Airplane mode > OK
To turn Airplane Mode on or off on an iOS device, use the following path:
Settings and turn Airplane mode on or off