Mobile technologies defined

What Is a GSM Wireless Network?

A Global System for Mobile Communications (GSM) network is a series of virtually interconnected tower and satellite relays that send and receive digital signals allowing people to communicate wirelessly across the globe. The signal begins with a cell phone that places a call, and travels to the nearest GSM tower. That tower communicates the signal to a satellite, which in turn relays that signal to the tower nearest the call's destination, where it is then received by the call recipient. The GSM wireless network is the most popular wireless communications system today.

Original cell phone technology operated on an analog system, similar to a short-distance radio wave. This meant that many people could use the same frequency, but the frequency would vary by location. During the 1990s, new wireless licenses were made available, and as carriers built their own networks, the switch was made to digital signals.

The digital communications networks were carriers for Second-Generation (2G) cell phone technology, which featured less call interference and increased call security, owing to the digitized signal. The phone's batteries lasted longer, and more calling features could be offered since the network was expanded. The biggest advantage, however, was that the efficiency of digital capacity lowered the startup cost of a new carrier, allowing smaller players to join the industry and offer real competition that leads to lower service prices.

As digital communications evolved and networks developed, standards were set that would allow towers to transmit the signal from any carrier, regardless of which carrier the tower belonged to. Thus began the GSM wireless network, which currently operates in 900 megahertz and 1.8 gigahertz bands in Europe, and 850 megahertz and 1.9 gigahertz bands in the United States, Canada, Australia, and South America. The adoption of uniform standards allows cell phones to operate abroad the same as they do at home.

The GSM wireless network system currently boasts coverage in 218 countries, serving over 3.8 billion customers. There are very few areas where GSM coverage is unavailable — usually very remote, rural areas — and specialized satellite roaming features are available to cover any gaps in coverage. The 89% market share of the GSM network means that new mobile technologies are usually created in accordance with GSM standards, and the GSM wireless network technology has evolved along with it.

What Is CDMA?

CDMA stands for Code Division Multiple Access. It is a technique used for digital communication, and wireless technology in particular, that involves multiplexing. Whereas conventional communication systems use constant frequencies, CDMA uses multiple access, or multiplexing. Accomplished through the specific type known as spread spectrum in this case, multiplexing uses varied frequencies to transmit audio signals. This, coupled with code division, which requires a certain code to send and receive the frequency, further protects CDMA communications from interference.

Radio systems, one of the earliest forms of telecommunication, required users to communicate on distinct frequencies. Frequency Division Multiple Access (FDMA), one form of early wireless communication, only allowed users to operate on a single frequency. When tuning in to a radio to get sound, for instance, the listener must select one frequency or another, and must tune the frequency to filter out noise in the spectrum. Another form of early radio communication was Time Division Multiple Access (TDMA). In this case, users could not share a frequency, and each user had to coordinate his or her turn on that frequency in order to communicate.

Both FDMA and TDMA posed restrictions for early users, particularly the military. As early as World War II, militaries recognized the high value in using wireless technology to communicate across vast distances. Military communication units did not always have the time to wait their turn to transmit sound, or to find the right frequency.

Some telecommunication systems allowed military communication units to transmit sound into the same spectrum their adversaries used. Military signals needed a unique identification through a distinct code to avoid interference from enemy communication. The receiver of that message on the other end could then retrieve the message based on its unique code in the spectrum.

What is EDGE?

EDGE is a wireless network technology generally considered the next step in the 2G network. The name is an acronym that stands for Enhanced Data GSM Environment. Enhanced Data Rates for GSM Evolution is an alternative name that is also used. As both names suggest, EDGE is an improvement on the GSM wireless technology, which is second generation, or 2G, cell phone technology. Since EDGE is an improvement on existing technology and not necessarily a third generation, it is often referred to as 2.75G.

EDGE is used for the purpose of wireless data transfer, such as sharing pictures and videos or browsing the Internet via a mobile phone connection. This is because the technology offers data transfer rates up to four times faster than ordinary GSM networks. As phones with Internet browser capabilities, such as the Blackberry® and the iPhone®, have become more popular, faster data transfer has become ever more important.

Because EDGE is an upgrade of GSM, it is easy for wireless carriers to upgrade their networks to offer it. The increase in data speed is achieved via more sophisticated coding, not by equipment, so new hardware is not usually necessary. Instead, a software upgrade enables the wireless carrier’s base stations to support data transfer speeds up to 384 kilobits per second (kbps).

EDGE first became available in the early 2000s. In 2003, Cingular began offering it as an upgrade to their GSM network. The wireless company also offered a mobile wireless Internet service for laptop users, which used a PCMCIA card to tap into the network. WiFi was therefore available to laptop users from almost anywhere that offered a strong cell phone signal.

Eventually EDGE became the standard, replacing less efficient wireless technology such as GPRS. Now virtually every cell phone company offers this technology. Likewise, EDGE will eventually be replaced by 3G technology such as WCDMA, which stands for Wideband Code-Division Multiple Access. As opposed to the EDGE technology’s data transfer speeds of up to 384 kbps, WCDMA offers speeds as fast as 2 megabits per second (mbps).

What is 3G?

The term 3G refers to the third generation of mobile phone standards as set by the International Telecommunications Union (ITU). 3G technologies allow mobile operators to offer more options to their users, such options include mobile broadband.

Compare 3G packages today mobile broadband

3G offers greater flexibility and services by making more efficient use of mobile bandwidth than its predecessor 2G.

The relationship between 2G and 3G is similar to that between dial-up to broadband or terrestrial TV and digital TV. In all of the latter examples, greater spectral efficiency has enabled more consumer choice and a more effective service.

3G and mobile broadband

3G enables devices such as mobile phones and mobile dongles to deliver broadband speed internet. Most new, top-of-the- range mobile phones are 3G enabled, making it easy to check emails and browse the web on the go.

While internet use via mobile phones has been slow to take off, mobile broadband via dongles, has taken off extremely fast. Mobile broadband allows customers to browse the internet, email and download files, music and video clips from their laptops and PCs wherever there's mobile coverage.

3G technology is made possible by two complementary technologies HSDPA and HSUPA (high speed download and upload packet access, respectively).

These technologies enable mobile broadband users to access download speeds of up to 7.2Mb and upload speeds of up to 1.76Mb via a mobile dongle, USB modem or MiFi.

Predecessors of 3G such as 2G and GPRS offered limited internet connectivity that was often costly and slow. Conversely, because 3G uses the airwaves more efficiently, it can offer speeds of up to 7.2Mb with prices start at just £10 a month

What Is an EVDO Modem?

An EVDO, or Enhanced Data Only or Evolution Data Optimized, modem is a device that helps carry mobile broadband. An EVDO modem can be a mobile SimCard, a USB device, a modem built into a laptop, or an external modem. The EVDO modem provides the ability to pick up EVDO signals, allowing users to connect to EVDO service providers.

These modems are wireless devices. They are inactive and inoperable unless you subscribe to a service provider that offers an EVDO connection. When you subscribe to a service provider, the EVDO modem receives a signal from the service provider so your device can connect to the internet.

The major difference between an EVDO modem and an ordinary modem is the large difference in speed. A traditional modem can only achieve Internet speeds of 128 kbps. An EVDO modem achieves transfer speeds of at least 600 kbps, with bursts of speed up to 2 mbps.

The modem is only the mechanism that receives data at this speed. The speed offered by the technology or service provider dictates how fast data is actually transferred to an EVDO modem. These operators charge subscription fees for limited amounts of data.

Generally, the high speeds on the EVDO network are achieved through 3G technology. EVDO is faster because the network sends data by splitting data into packets to save on bandwidth. The modem, or ‘aircard’, is the receptacle that receives this data transfer.

EVDO modems are versatile devices. They are offered as ExpressCards, USB dongles, and PACMACIA cards. Each of these different types of modems can be used on a range of data devices from phones to laptops.

courtesy: http://www.wisegeek.com/