Pages

dimanche 27 janvier 2013

Mobile phone




Mobile phone

A mobile phone (also known as a cellular phone, cell phone and a hand phone) is a device that can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile phone operator, allowing access to the public telephone network. By contrast, a cordless telephone is used only within the short range of a single, private base station.
In addition to telephony, modern mobile phones also support a wide variety of other services such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming and photography. Mobile phones that offer these and more general computing capabilities are referred to as smartphones.
The first hand-held mobile phone was demonstrated by John F. Mitchelland Dr Martin Cooper of Motorola in 1973, using a handset weighing around 2.2 pounds (1 kg). In 1983, the DynaTAC 8000x was the first to be commercially available. From 1990 to 2011, worldwide mobile phone subscriptions grew from 12.4 million to over 5.6 billion, penetrating about 70% of the global population  and reaching the bottom of the economic pyramid.

History

The first mobile telephone call was made on 17 June 1946 from a car in St. Louis, Missouri, USA, using the Bell System's Mobile Telephone Service. This was followed in 1956 by the world’s first partly automatic car phone system, Mobile System A (MTA) in Sweden. The MTA phones were composed of vacuum tubes and relays, and had a weight of 88.2 pounds (40 kg).
John F. Mitchell, Motorola's chief of portable communication products and Martin Cooper's boss in 1973, played a key role in advancing the development of handheld mobile telephone equipment. Mitchell successfully pushed Motorola to develop wireless communication products that would be small enough to use anywhere and participated in the design of the cellular phone. Martin Cooper, a Motorola researcher and executive, was the key researcher on Mitchell's team that developed the first hand-held mobile telephone for use on a cellular network.  Using a somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on April 3, 1973 to his rival, Dr. Joel S. Engel of Bell Labs.
As I walked down the street while talking on the phone, sophisticated New Yorkers gaped at the sight of someone actually moving around while making a phone call. Remember that in 1973, there weren't cordless telephones or cellular phones. I made numerous calls, including one where I crossed the street while talking to a New York radio reporter - probably one of the more dangerous things I have ever done in my life.
The new invention sold for $3,995 and weighed two pounds, leading to a nickname "the brick".
The world's first commercial automated cellular network was launched in Japan by NTT in 1979, initially in the metropolitan area of Tokyo. In 1981, this was followed by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway and Sweden. Several countries then followed in the early-to-mid 1980s including the UK, Mexico and Canada.
On 6 March 1983, the DynaTAc mobile phone launched on the first US 1G network by Ameritech. It cost $100m to develop, and took over a decade to hit the market. The phone had a talk time of just half an hour and took ten hours to charge. Consumer demand was strong despite the battery life, weight, and low talk time, and waiting lists were in the thousands.
In 1991, the second generation (2G) cellular technology was launched in Finland by Radiolinja on the GSM standard, which sparked competition in the sector as the new operators challenged the incumbent 1G network operators.
Ten years later, in 2001, the third generation (3G) was launched in Japan by NTT DoCoMo on the WCDMA standard. This was followed by 3.5G, 3G+ or turbo 3G enhancements based on the high-speed packet access (HSPA) family, allowing UMTS networks to have higher data transfer speeds and capacity.
By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications like streaming media.Consequently, the industry began looking to data-optimized 4th-generation technologies, with the promise of speed improvements up to 10-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard (offered in the U.S. by Sprint) and the LTE standard, first offered in Scandinavia by TeliaSonera.

Aucun commentaire:

Enregistrer un commentaire