The cellular cell phone technologies in general, depend on the network protocol used. There are two types of mobile network protocols widely prevalent, 2G and 3G.

Cell Phone Network Protocol: 2G.

There are two technologies commonly used by 2G cell-phone networks for transmitting information

1. Global System for Mobile Communication (GSM)

Global System for Mobile communications (GSM) uses Time Division Multiple Access [TDMA] technology. However, GSM implements TDMA using encryption to make phone calls more secure. GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 850-MHz and 1900-MHz (also referred to as 1.9-GHz) band in the United States. GSM is the international standard in Europe, Australia and much of Asia and Africa which also means that under most circumstances the calls that you make are on GSM.GSM system allows cell-phone users to use one phone anywhere where the standard is supported. To connect to the specific service providers in these different countries, GSM users simply switch subscriber identification module (SIM) cards. SIM cards are small removable disks that slip in and out of GSM cell phones. They store all the connection data and identification numbers you need to access a particular wireless service provider.

2. Code Division Multiple Access (CDMA)

CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. It started as a concept in World-war II and was brought to cell phones by telecom giant Qualcomm. CDMA is the most widely used cellphone technology in US and is a base for the 3G wireless carriers. The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHzbands. CDMA employs analog-to-digital conversion (ADC) in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern (code), so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. CDMA is compatible with other cellular technologies; thereby enabling nationwide roaming.

Cell Phone Network Protocol: 3G

3G technology is the latest in mobile communications. 3G stands for “third generation” and is the successor to 2G technology. 3G technology is intended for the true multimedia cell phone, smartphones with increased bandwidth and transfer rates to accommodate Web-based applications and phone-based audio and video files. 3G’s high data rates are ideal for downloading information from the Internet and sending and receiving large, multimedia files. 3G phones are like mini-laptops and can accommodate broadband applications like video conferencing, receiving streaming video from the Web, sending and receiving faxes and instantly downloading e-mail messages with attachments.

There are three technologies commonly used by 3G cell-phone networks for transmitting

1. CDMA2000 – based on 2G Code Division Multiple Access

2. Wideband Code Division Multiple Access (WCDMA)

Both of these technologies are similar to CDMA used in 2G network protocol but with higher speeds of transfer and download rates.

3. Time-division Synchronous Code-division Multiple Access (TD-SCDMA)

The standard combines time division multiple access (TDMA) with an adaptive, synchronous-mode code division multiple access (CDMA) component. TD-SCDMA supports data transfer like speech or video from the Internet at much faster rates than any of the technologies in 2G network.


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