Mobile phone

From Wikipedia, the free encyclopedia

“Cell Phone” redirects here. For the 2003 Chinese film, see Cell Phone (film).

Several mobile phones

A mobile or cellular telephone is a long-range, portable electronic device for mobile communication. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched telephone network (PSTN) (the exception are satellite phones).

Mobile phones are distinct from cordless telephones, which generally operate only within a limited range of a specific base station. Technically, the term mobile phone includes such devices as satellite phones and pre-cellular mobile phones such as those operating via MTS which do not have a cellular network, whereas the related term cell(ular) phone does not. In North America, the two terms are used nearly interchangeably, but the term cellular telephone is not used outside this region.

[edit] History

Main article: History of mobile phones

Mobile phones from various years, ranging from a large late 1980s-era phone to tiny 2000s phones

The Mobile phone is one of the most used pieces of equipment today. The concept of using hexagonal cells for mobile phone base stations was invented in 1947 by Bell Labs engineers at AT&T and was further developed by Bell Labs during the 1960s. Radiophones have a long and varied history that stretches back to the Second World War when the military started to use radio telephony links and civil services in the 1950s, with hand-held cellular radio devices being available since 1983. Due to their low establishment costs and rapid deployment, mobile phone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony

In 1945, the 0G generation of mobile telephones were introduced. 0G mobile telephones, such as Mobile Telephone Service, were not officially categorized as mobile phones, since they did not support the automatic change of channel frequency in the middle of a call, when the user moved from one cell (base station coverage area) to another cell, a feature called "handover".

In 1970 Amos Joel of Bell Labs invented the "call handoff" feature, which allowed a mobile-phone user to travel through several cells during the same conversation. Martin Cooper of Motorola is widely considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting. Using a modern, if somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on April 3, 1973. At the time he made his call, Cooper was working as Motorola's General Manager of its Communications Division.

Fully automatic cellular networks were first introduced in the early to mid-1980s (the 1G generation). The first fully automatic mobile phone system was the 1981 Nordic Mobile Telephone (NMT) system. Until the late 1980s, most mobile phones were too large to be carried in a jacket pocket, so they were usually permanently installed in vehicles as car phones. With the advance of miniaturization and smaller digital components, mobile phones got smaller and lighter.

[edit] Manufacturers

Nokia Corporation is currently the world's largest manufacturer of mobile telephones, with a global market share of approximately 36% in Q4 of 2006.^[1] Other mobile phone manufacturers include Apple Inc., Audiovox (now UT Starcom), Benefon, BenQ-Siemens, High Tech Computer Corporation (HTC), Fujitsu, Kyocera, 3G, LG, Motorola, NEC, Panasonic (Matsushita Electric), Pantech Curitel, Philips, Research in Motion, Sagem, Samsung, Sanyo, Sharp, Siemens, Sierra Wireless, SK Teletech, Sony Ericsson, T&A Alcatel, and Toshiba. There are also specialist communication systems related to, but distinct from mobile phones, such as for exampleProfessional Mobile Radio.

[edit] Subscriptions

See also: List of mobile network operators of Europe

Several countries, including the UK, now have more mobile phones than people.^[2] There will be over four hundred million cell phone users in China by 2008. Luxembourg has the highest mobile phone penetration rate in the world, at 164% in December 2005. In Hong Kong the penetration rate reached 117% of population in September 2004.^[3] The total number of mobile phone subscribers in the world was estimated at 2.14 billion in 2005.^[4] Around 80% of world's population have mobile phone coverage as of 2006. This figure is expected to increase to 90% by the year 2010.^[5]

At present, Africa has the largest growth rate of cellular subscribers in the world.^[6] African markets are expanding nearly twice as fast as Asian markets.^[7] The availability of Prepaid or pay as you go services, where the subscriber does not have to commit to a long term contract, has helped fuel this growth on a monumental scale, not only in Africa but on other continents as well.

On a numerical basis, India is the biggest growth market adding about 6 million cell phones every month.[1]PDF (73.6 KiB) With 156.31 million cell phones, teledensity in the country is still low at 17.45% and country expects to reach 500 million subscribers by end of 2010.

All European nations and most Asian and African nations have adopted GSM. In other countries, such as the United States, Australia, India, Japan, and South Korea, legislation does not require any particular standard, and GSM coexists with other standards, such as CDMA and iDEN.

Some cellular systems are pay as you go, where top-ups can be purchased and added to a phone unit, in a wide variety of shops and even ATMs now, so there is no monthly bill. Many are "pay monthly", where a bill is issued every month for the amount of calls and text messages made.

[edit] Culture and customs

In fewer than twenty years, mobile phones have gone from being rare and expensive pieces of equipment used primarily by the business elite, to a pervasive low-cost personal item. In many countries, mobile phones now outnumber land-line telephones, with most adults and many children now owning mobile phones. In the United States, 50% of children own mobile phones.^[8] It is not uncommon for young adults to simply own a mobile phone instead of a land-line for their residence. In some developing countries, where there is little existing fixed-line infrastructure, the mobile phone has become widespread.

With high levels of mobile telephone penetration, a mobile culture has evolved, where the phone becomes a key social tool, and people rely on their mobile phone address book to keep in touch with their friends. Many people keep in touch using SMS, and a whole culture of "texting" has developed from this. The commercial market in SMSs is growing. Many phones even offer Instant Messenger services to increase the simplicity and ease of texting on phones. Mobile phones in Japan, offering Internet capabilities such as NTT DoCoMo's i-mode, offer text messaging via standard e-mail.

The mobile phone itself has also become a totemic and fashion object, with users decorating, customizing, and accessorizing their mobile phones to reflect their personality. This has emerged as its own industry. The sale of commercial ringtones exceeded $2.5 billion in 2004.^[9]

[edit] Etiquette

The use of a mobile phone is prohibited in some railroad company carriages

Mobile phone etiquette has become an important issue with mobiles ringing at funerals, weddings, cinemas, and plays. Users often speak at increased volume which has led to places like book shops, libraries, movie theatres, doctors' offices, and houses of worship posting signs prohibiting the use of mobile phones, and in some places installing signal-jamming equipment to prevent usage (although in many countries, e.g., the United States, such equipment is currently illegal). Some new buildings such as auditoriums have installed wire mesh in the walls (turning the building into a Faraday cage) which prevents any signal getting through, but does not contravene the jamming laws.

Transportation providers, particularly those involving long-distance services, often offer a "quiet car" where phone use is prohibited, much like the designated non-smoking cars in the past. However many users tend to ignore this as it is rarely enforced, especially if the other cars are crowded and they have no choice but to go in the "quiet car". Mobile phone use on aircraft is also prohibited, because of concerns of possible interference with aircraft radio communications,^[10] although the airline Emirates have announced plans to allow limited mobile phone usage on some flights. In April 2007 the Federal Communications Commission (FCC) officially grounded the idea of allowing passengers to use cell phones during a flight. ^[11] In a similar vein signs are put up in UK petrol stations prohibiting the use of mobile phones due to hypothetical safety issues. Most schools in the United States have prohibited mobile phones in the classroom due to the high amount of class disruptions that result from their use, and due to the possibility of photographing someone (without consent).

[edit] Use in disaster response

In Japan, mobile phone companies provide immediate notification of earthquakes and other natural disasters to their customers free of charge. In the event of an emergency, disaster response crews can locate trapped or injured people using the signals from their mobile phones; an interactive menu accessible through the phone's Internet browser notifies the company if the user is safe or in distress.

[edit] Use by drivers

One phone in each hand

Main article: Mobile phones and driving safety

Mobile-phone use while driving is common but controversial. While few jurisdictions have banned motorists from using mobile phones while driving outright, some have banned or restricted drivers from using hand-held mobile phones while exempting phones operated in a hands-free fashion. It is generally agreed that using a hand-held mobile phone while driving is a distraction that brings risk of road traffic accidents. However, some studies have found similarly elevated accident rates among drivers using hands-free phones, suggesting that the distraction of a telephone conversation itself is the main safety problem.

Use of handheld mobile phones by drivers is illegal in many European countries and a number of Asian and South American countries and Australia. Use of hands-free mobiles is permitted. However some countries like Japan ban mobile phone use while driving completely. Similar laws exist in six U.S. states with legislation proposed in 40 other states. The United States Department of Defense has outlawed the use of all mobile phones while driving on any DOD installation, unless a hands-free device is used.

[edit] Applications

Mobile news services are expanding with many organizations providing "on-demand" news services by SMS. Some also provide "instant" news pushed out by SMS. Mobile telephony also facilitates activism and public journalism being explored by Reuters and Yahoo[2] and small independent news companies such as Jasmine News in Sri Lanka.

[edit] Power

Mobile phones can obtain power generally from batteries. Batteries can be recharged from mains power, a USB port or a cigarette lighter port in a automobile.

This section is a stub. You can help by expanding it.

[edit] Features

Main article: Mobile phone features

There is significant questions as to who first invented the camera phone, as numerous other people received patents filed in the early 90s for the device, including David M. Britz of AT&T Research in March of 1994. However, Phillipe Kahn claims to have first invented it in 1997 and the camera phone is now 85% of the market. In a recent Weekend America interview on public radio, Philippe Kahn, who built a camera phone, discusses its social impact and how it connects people around the world.[3] Mobile phones also often have features beyond sending text messages and making voice calls—including Internet browsing, music (MP3) playback, memo recording, personal organizers, e-mail, built-in cameras and camcorders, ringtones, games, radio, Push-to-Talk (PTT), infrared and Bluetooth connectivity, call registers, ability to watch streaming video or download video for later viewing, video call and serve as a wireless modem for a PC.

In most countries, including European nations, Japan, Pakistan, Australia, Chile, Colombia, India,^[12] Maldives, Peru and Israel the person receiving a mobile phone call pays nothing. However, in Hong Kong, Canada, and the United States, one can be charged per minute. In the United States, a few carriers are beginning to offer unlimited received phone calls. For example as of December 2006, Sprint now has 4 plans under "Sprint Free Incoming Plans" section of their website, although the restriction is the receiving phone must be on the Sprint PCS network. For the Chinese mainland, it was reported that both of its two operators will adopt the caller-pays approach as early as January 2007.^[12]

[edit] Forensics and evidence

Law enforcement globally relies heavily upon mobile telephone evidence. The concerns over terrorism and terrorist use of technology promoted an enquiry by the UK House of Commons Home Affairs Select Committee into the use of evidence from mobile telephone devices, prompting leading mobile telephone forensic specialists to identify forensic techniques available in this area.^[13]

[edit] Health impacts

Main article: Mobile phone radiation and health

Since the introduction of mobile phones, concerns have been raised about the potential health impacts from cellular phone use.^[14] Studies from the National Cancer Institute and researchers at the Danish Institute of Cancer Epidemiology in Copenhagen do not show any link between cellular phone use and cancer.^[15] The Danish study only covered analog mobile phone usage up through 1995, and subjects who started mobile phone usage after 1995 were counted as non-users in the study.^[16] However, a study by the International Agency for Research on Cancer of 4,500 users found a statistically significant link between tumor frequency and mobile phone use.^[17]

[edit] Technology

Mobile phone tower

Cell Phone tower located in Lynnwood, WA

Mobile phones and the network they operate under vary significantly from provider to provider, and nation to nation. However, all of them communicate through electromagnetic microwaves with a cell site base station, the antennas of which are usually mounted on a tower, pole, or building.

The phones have a low-power transceiver that transmits voice and data to the nearest cell sites, usually not more than 5 to 8 miles (approximately 8 to 13 kilometres) away. When the mobile phone or data device is turned on, it registers with the mobile telephone exchange, or switch, with its unique identifiers, and will then be alerted by the mobile switch when there is an incoming telephone call. The handset constantly listens for the strongest signal being received from the surrounding base stations. As the user moves around the network, the mobile device will "handoff" to various cell sites during calls, or while waiting (idle) between calls it will reselect cell sites.

Cell sites have relatively low-power (often only one or two watts) radio transmitters which broadcast their presence and relay communications between the mobile handsets and the switch. The switch in turn connects the call to another subscriber of the same wireless service provider or to the public telephone network, which includes the networks of other wireless carriers. Many of these sites are camouflaged to blend with existing environments, particularly in high-scenery areas.

The dialogue between the handset and the cell site is a stream of digital data that includes digitized audio (except for the first generation analog networks). The technology that achieves this depends on the system which the mobile phone operator has adopted. Some technologies include AMPS for analog, and D-AMPS, CDMA2000, GSM, GPRS, EV-DO, and UMTS for digital communications. Each network operator has a unique radio frequency band.

[edit] Mobile communication studies

Since 2002, many books have been written on the social impact of mobile phones:

Agar, Jon, Constant Touch: A Global History of the Mobile Phone, 2004
Glotz, Peter & Bertsch, Stefan, eds. Thumb Culture: The Meaning of Mobile Phones for Society, 2005
Katz, James E. & Aakhus, Mark, eds. Perpetual Contact: Mobile Communication, Private Talk, Public Performance, 2002
Kavoori, Anandam & Arceneaux, Noah, eds. The Cell Phone Reader: Essays in Social Transformation, 2006
Ling, Rich, The mobile connection 2004 [4]
Ling, Rich and Pedersen, Per, eds. Mobile Communications: Renegotiation of the Social Sphere 2005
Nyíri, Kristóf, ed. Mobile Communication: Essays on Cognition and Community, 2003
Nyíri, Kristóf, ed. Mobile Learning: Essays on Philosophy, Psychology and Education, 2003
Nyíri, Kristóf, ed. Mobile Democracy: Essays on Society, Self and Politics, 2003
Nyíri, Kristóf, ed. A Sense of Place: The Global and the Local in Mobile Communication, 2005
Nyíri, Kristóf, ed. Mobile Understanding: The Epistemology of Ubiquitous Communication, 2006
Levinson, Paul, Cellphone: The Story of the World's Most Mobile Medium, and How It Has Transformed Everything! 2004
Rheingold, Howard, Smart Mobs: The Next Social Revolution, 2002

[edit] Terminology

[edit] Related non-mobile-phone systems

Cordless phone (portable phone): Cordless phones are standard telephones with radio handsets. Unlike mobile phones, cordless phones use private base stations that are not shared between subscribers. The base station is connected to a land-line. Increasingly, with wireless local loop technologies, namely DECT, the distinction is blurred.
Professional Mobile Radio: Advanced professional mobile radio systems can be very similar to mobile phone systems. Notably, the IDEN standard has been used as both a private trunked radio system as well as the technology for several large public providers. Similar attempts have even been made to use TETRA, the European digital PMR standard, to implement public mobile networks.
Radio phone: This is a term which covers radios which could connect into the telephone network. These phones may not be mobile; for example, they may require a mains power supply. Also, they may require the assistance of a human operator to set up a PSTN phone call.