Topic: Mobile Technologies

Mobile Technologies

From the heavy cordless phones of the 1980's to the smart phones of today, cellular phone technology has undergone a tremendous change.

But have you ever wondered how you can call someone across the world using a tiny phone? You might have heard of features like WAP and GPRS from cell phone vendors and service providers. But are you aware of what they really mean?

Rediff Guide to the Net has compiled a guide to make you familiar with today's mobile technologies. So next time you go to buy a phone, you know exactly what they're talking about.

Generations of mobile communications

The first generation (1G) of mobile communications was introduced in the late 1970s; it was primarily used for voice transfer. In the early 1990s, second generation (2G) systems came into existence and was further developed to 2.5G, which includes GSM, TDMA and CDMA. These were used for voice and data.

The next generation of mobile communications is 3G and this delivers data speeds from 384 kbps to 2 Mbps and over wireless interfaces such as GSM, TDMA and CDMA.

Mobile phone access technologies

Frequency division multiple access (FDMA)
The first-generation analog mobile access method; FDMA uses separate frequencies for each call. For example if there are four stations, each will receive their own frequency. Thus there is no interference between them. This reduces interference, but limits the number of users.

Time division multiple access (TDMA)
TDMA allocates unique time slots to each user within each channel, thus allowing many users to access the radio frequency without anyone's interference. Each mobile conversation uses only a particular frequency slot of the time.

Code division multiple access (CDMA)
Commercially introduced in 1995 by Qualcomm, CDMA quickly became one of the world's fastest-growing wireless technologies. 3G CDMA networks provide more capacity for voice traffic, along with high-speed data capabilities, hence many cellular service providers are now building or upgrading to it.

CDMA is used in both 2G and 3G wireless technologies. Indian Cell operators like Reliance IndiaMobile, TATA Indicom, BSNL and MTNL's  Garuda all use CDMA2000 technology and its variant CDMA1x.

Global system for mobile communications (GSM)
Developed on TDMA protocol in Europe, GSM is now the worldwide standard technology for mobile communications. The advantage of GSM is that it provides a high level of security, globally accepted technology standards and superior sound quality.

For any GSM phone to work, it requires a Subscriber Identity Module (SIM), a card that contains your telephone account information. Thus, an Indian GSM phone can be used in USA and other countries too.

Wireless technology platforms: GPRS, EDGE and WAP

What is GPRS?
GPRS, short for General Packet Radio Services, is an enhancement to GSM technology that integrates GSM and IP technology. GPRS offers an always-on, high speed connectivity to the Net. Thus you can check your email on the move and surf the Web at high speeds. Currently BPL Mobile and Hutch offer GPRS services in India.

What is WAP?
In this hi-tech age, people on the move need any-time access to the Net. This is where WAP comes in. It provides Internet access to cell phones. It is an open standard for wireless protocols that is independent of the service providers. To display Web content, the cell phone must have a WAP browser. Nowadays, cell phones often come with WAP and GPRS technology.

WAP and GPRS also allows you to download games, send mail and even transfer your messages to your PC.

What is EDGE?
The new EDGE ((Enhanced Data GSM Environment) interface has been developed specifically to meet the bandwidth needs of 3G. Promoted by Ericsson, it offers high-speed data transfers over GSM networks with just a software upgrade to the handset. EDGE allows speeds up to 384 kbps.