出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/09/10 22:21:41」(JST)
A mobile phone is a portable telephone that can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Most modern mobile telephone services use a cellular network architecture, and therefore mobile telephones are often also called cellular telephones or cell phones. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming, and digital photography. Mobile phones which offer these and more general computing capabilities are referred to as smartphones.
The first handheld mobile phone was demonstrated by John F. Mitchell[1][2] and Martin Cooper of Motorola in 1973, using a handset weighing c. 4.4 lbs (2 kg).[3] In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion, penetrating 100% of the global population and reaching even the bottom of the economic pyramid.[4] In 2016, the top mobile phone manufacturers were Samsung, Apple and Huawei.[5]
A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a "pocket-size folding telephone with a very thin carbon microphone". Early predecessors of cellular phones included analog radio communications from ships and trains. The race to create truly portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive "generations", starting with the early "0G" (zeroth generation) services, such as Bell System's Mobile Telephone Service and its successor, the Improved Mobile Telephone Service. These "0G" systems were not cellular, supported few simultaneous calls, and were very expensive.
The first handheld mobile cell phone was demonstrated by Motorola in 1973. The first commercial automated cellular network was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway and Sweden.[6] Several other countries then followed in the early to mid-1980s. These first-generation (1G) systems could support far more simultaneous calls, but still used analog technology.
In 1991, the second-generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard. This 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.[7] 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, such as streaming media.[8] Consequently, the industry began looking to data-optimized fourth-generation technologies, with the promise of speed improvements up to ten-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard, offered in North America by Sprint, and the LTE standard, first offered in Scandinavia by TeliaSonera.
All mobile phones have a variety of features in common, but manufacturers seek product differentiation by adding functions to attract consumers. This competition has led to great innovation in mobile phone development over the past 20 years.
The common components found on all phones are:
Low-end mobile phones are often referred to as feature phones, and offer basic telephony. Handsets with more advanced computing ability through the use of native software applications became known as smartphones.
Several phone series have been introduced to address specific market segments, such as the RIM BlackBerry focusing on enterprise/corporate customer email needs, the Sony-Ericsson 'Walkman' series of music/phones and 'Cyber-shot' series of camera/phones, the Nokia Nseries of multimedia phones, the Palm Pre, the HTC Dream and the Apple iPhone.
In sound quality, smartphones and feature phones vary little. Some audio-quality enhancing features, such as Voice over LTE and HD Voice, have appeared and are often available on newer smartphones. Sound quality can remain a problem with both, as this depends not so much on the phone itself, as on the quality of the network and, in long distance calls, the bottlenecks/choke points met along the way.[9][10] As such, for long-distance calls even features such as Voice over LTE and HD Voice may not improve things. In some cases smartphones can improve audio quality even on long-distance calls, by using a VoIP phone service, with someone else's WiFi/internet connection.[11] Some cellphones have small speakers so that the user can use a speakerphone feature and talk to a person on the phone without holding it to their ear. The small speakers can also be used to listen to digital audio files of music or speech or watch videos with an audio component, without holding the phone close to the ear.
The most commonly used data application on mobile phones is Short Message Service (SMS) text messaging. The first SMS message was sent from a computer to a mobile phone in 1992 in the UK, while the first person-to-person SMS from phone to phone was sent in Finland in 1993. The first mobile news service, delivered via SMS, was launched in Finland in 2000,[citation needed] and subsequently many organizations provided "on-demand" and "instant" news services by SMS. Multimedia Messaging Service (MMS) was introduced in 2001.[citation needed]
GSM feature phones require a small microchip called a Subscriber Identity Module or SIM card, in order to function. The SIM card is approximately the size of a small postage stamp and is usually placed underneath the battery in the rear of the unit. The SIM securely stores the service-subscriber key (IMSI) and the Ki used to identify and authenticate the user of the mobile phone. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device, provided that this is not prevented by a SIM lock.
The first SIM card was made in 1991 by Munich smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja.[citation needed]
A hybrid mobile phone can hold up to four SIM cards. SIM and R-UIM cards may be mixed together to allow both GSM and CDMA networks to be accessed.
From 2010 onwards, such phones became popular in India and Indonesia and other emerging markets,[12] and this was attributed to the desire to obtain the lowest on-net calling rate. In Q3 2011, Nokia shipped 18 million of its low-cost dual SIM phone range in an attempt to make up for lost ground in the higher-end smartphone market.[13]
There are Jewish orthodox religious restrictions which, by some interpretations, standard mobile telephones overstep. To deal with this problem, some rabbinical organizations have recommended that phones with text-messaging capability not be used by children.[14] Phones with restricted features are known as kosher phones and have rabbinical approval for use in Israel and elsewhere by observant Orthodox Jews. Although these phones are intended to prevent immodesty, some vendors report good sales to adults who prefer the simplicity of the devices. Some phones are approved for use by essential workers (such as health, security and public service workers) on the sabbath, even though the use of any electrical device is generally prohibited during this time.[15]
The world's largest individual mobile operator by number of subscribers is China Mobile, which has over 500 million mobile phone subscribers.[16] Over 50 mobile operators have over ten million subscribers each, and over 150 mobile operators had at least one million subscribers by the end of 2009.[17] In 2014, there were more than seven billion mobile phone subscribers worldwide, a number that is expected to keep growing.
| Quantity Market Shares according to Gartner (New Sales) |
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|---|---|---|---|---|
| BRAND | Percent | |||
| Samsung 2012 |
|
22.0% | ||
| Samsung 2013 |
|
24.6% | ||
| Nokia 2012 |
|
19.1% | ||
| Nokia 2013 |
|
13.9% | ||
| Apple 2012 |
|
7.5% | ||
| Apple 2013 |
|
8.3% | ||
| LG Electronics 2012 |
|
3.3% | ||
| LG Electronics 2013 |
|
3.8% | ||
| ZTE 2012 |
|
3.9% | ||
| ZTE 2013 |
|
3.3% | ||
| Others 2012 |
|
34.9% | ||
| Others 2013 |
|
34.0% | ||
| Note: "Others 2012" consists of Sony Ericsson, Motorola, HTC and Huawei.(2009-2010) | ||||
Prior to 2010, Nokia was the market leader. However, since then competition has emerged in the Asia Pacific region, from brands such as Micromax, Nexian and i-Mobile, which have chipped away at Nokia's market share. Android-powered smartphones have also gained momentum across the region at the expense of Nokia. In India, Nokia's market share dropped significantly to around 31% from 56% in the same period. Its share was displaced by Chinese and Indian vendors of low-end mobile phones.[18]
In Q1 2012, according to Strategy Analytics, Samsung surpassed Nokia, selling 93.5 million units as against Nokia's 82.7 million units. In 2012 Standard & Poor's downgraded Nokia to "junk" status, at BB+/B, with negative outlook due to high loss and an expected further decline owing to insufficient growth in Lumia smartphone sales to offset a rapid decline in revenue from Symbian-based smartphones that was forecast for subsequent quarters.[19]
In Q3 2014, the top ten manufacturers were Samsung (20.6%), Nokia (9.5%), Apple Inc. (8.4%), LG (4.2%), Huawei (3.6%), TCL Communication (3.5), Xiaomi (3.5%), Lenovo (3.3%), ZTE (3.0%) and Micromax (2.2%).[20]
| Market share of top-five worldwide mobile phone vendors, Q2 2015 | |||
|---|---|---|---|
| Rank | Manufacturer | Strategy Analytics report[21] | |
| 1 | Samsung | 20.5% | |
| 2 | Apple Inc. | 10.9% | |
| 3 | Huawei | 7.0% | |
| 4 | Microsoft | 6.4% | |
| 5 | Xiaomi | 4.6% | |
| Others | 50.6% | ||
Other manufacturers outside the top five include TCL Communication, Lenovo, Sony Mobile Communications, Motorola and LG Electronics. Smaller current and past players include Audiovox (now UTStarcom), BenQ-Siemens, BlackBerry, Casio, CECT, Coolpad, Fujitsu, HTC, Just5, Intex, Karbonn Mobiles, Kyocera, Lumigon, LYF, Micromax Mobile, Mitsubishi Electric, Modu, NEC, Neonode, OnePlus, Openmoko, Panasonic, Palm, Pantech Wireless Inc., Philips, Sagem, Sanyo, Sharp, Sierra Wireless, SK Teletech, Trium and Toshiba.
Mobile phones are used for a variety of purposes, such as keeping in touch with family members, for conducting business, and in order to have access to a telephone in the event of an emergency. Some people carry more than one mobile phone for different purposes, such as for business and personal use. Multiple SIM cards may be used to take advantage of the benefits of different calling plans. For example, a particular plan might provide for cheaper local calls, long-distance calls, international calls, or roaming.
The mobile phone has been used in a variety of diverse contexts in society. For example:
Smartphones have a number of distinguishing features. The International Telecommunication Union measures those with Internet connection, which it calls Active Mobile-Broadband subscriptions (which includes tablets, etc.). In the developed world, smartphones have now overtaken the usage of earlier mobile systems. However, in the developing world, they account for only 20% of mobile telephony.
In 1998, one of the first examples of distributing and selling media content through the mobile phone was the sale of ringtones by Radiolinja in Finland. Soon afterwards, other media content appeared, such as news, video games, jokes, horoscopes, TV content and advertising. Most early content for mobile phones tended to be copies of legacy media, such as banner advertisements or TV news highlight video clips. Recently, unique content for mobile phones has been emerging, from ringtones and ringback tones to mobisodes, video content that has been produced exclusively for mobile phones.
In 2006, the total value of mobile-phone-paid media content exceeded Internet-paid media content and was worth US$31 billion.[31] The value of music on mobile phones was worth US$9.3 billion in 2007, and gaming was worth over US$5 billion in 2007.[32]
Mobile phone use while driving, including talking on the phone, texting, or operating other phone features, is common but controversial. It is widely considered dangerous due to distracted driving. Being distracted while operating a motor vehicle has been shown to increase the risk of accidents. In September 2010, the US National Highway Traffic Safety Administration (NHTSA) reported that 995 people were killed by drivers distracted by cell phones. In March 2011 a US insurance company, State Farm Insurance, announced the results of a study which showed 19% of drivers surveyed accessed the Internet on a smart phone while driving.[33] Many jurisdictions prohibit the use of mobile phones while driving. In Egypt, Israel, Japan, Portugal and Singapore, both handheld and hands-free use of a mobile phone (which uses a speakerphone) is banned. In other countries including the UK and France and in many U.S. states, only handheld phone use is banned, while hands-free use is permitted.
A 2011 study reported that over 90% of college students surveyed text (initiate, reply or read) while driving.[34] The scientific literature on the dangers of driving while sending a text message from a mobile phone, or texting while driving, is limited. A simulation study at the University of Utah found a sixfold increase in distraction-related accidents when texting.[35]
Due to the increasing complexity of mobile phones, they are often more like mobile computers in their available uses. This has introduced additional difficulties for law enforcement officials when attempting to distinguish one usage from another in drivers using their devices. This is more apparent in countries which ban both handheld and hands-free usage, rather than those which ban handheld use only, as officials cannot easily tell which function of the mobile phone is being used simply by looking at the driver. This can lead to drivers being stopped for using their device illegally for a phone call when, in fact, they were using the device legally, for example, when using the phone's incorporated controls for car stereo, GPS or satnav.
A 2010 study reviewed the incidence of mobile phone use while cycling and its effects on behaviour and safety.[36] In 2013 a national survey in the US reported the number of drivers who reported using their cellphones to access the Internet while driving had risen to nearly one of four.[37] A study conducted by the University of Illinois examined approaches for reducing inappropriate and problematic use of mobile phones, such as using mobile phones while driving.[38]
Accidents involving a driver being distracted by talking on a mobile phone have begun to be prosecuted as negligence similar to speeding. In the United Kingdom, from 27 February 2007, motorists who are caught using a hand-held mobile phone while driving will have three penalty points added to their license in addition to the fine of £60.[39] This increase was introduced to try to stem the increase in drivers ignoring the law.[40] Japan prohibits all mobile phone use while driving, including use of hands-free devices. New Zealand has banned hand held cellphone use since 1 November 2009. Many states in the United States have banned texting on cell phones while driving. Illinois became the 17th American state to enforce this law.[41] As of July 2010, 30 states had banned texting while driving, with Kentucky becoming the most recent addition on July 15.[42]
Public Health Law Research maintains a list of distracted driving laws in the United States. This database of laws provides a comprehensive view of the provisions of laws that restrict the use of mobile communication devices while driving for all 50 states and the District of Columbia between 1992, when first law was passed, through December 1, 2010. The dataset contains information on 22 dichotomous, continuous or categorical variables including, for example, activities regulated (e.g., texting versus talking, hands-free versus handheld), targeted populations, and exemptions.[43]
In many countries, mobile phones are used to provide mobile banking services, which may include the ability to transfer cash payments by secure SMS text message. Kenya's M-PESA mobile banking service, for example, allows customers of the mobile phone operator Safaricom to hold cash balances which are recorded on their SIM cards. Cash can be deposited or withdrawn from M-PESA accounts at Safaricom retail outlets located throughout the country, and can be transferred electronically from person to person and used to pay bills to companies.
Branchless banking has also been successful in South Africa and the Philippines. A pilot project in Bali was launched in 2011 by the International Finance Corporation and an Indonesian bank, Bank Mandiri.[44]
Another application of mobile banking technology is Zidisha, a US-based nonprofit micro-lending platform that allows residents of developing countries to raise small business loans from Web users worldwide. Zidisha uses mobile banking for loan disbursements and repayments, transferring funds from lenders in the United States to borrowers in rural Africa who have mobile phones and can use the Internet.[45]
Mobile payments were first trialled in Finland in 1998 when two Coca-Cola vending machines in Espoo were enabled to work with SMS payments. Eventually, the idea spread and in 1999, the Philippines launched the country's first commercial mobile payments systems with mobile operators Globe and Smart.
Some mobile phones can make mobile payments via direct mobile billing schemes, or through contactless payments, if the phone and the point of sale support near field communication (NFC).[46] Enabling contactless payments through NFC-equipped mobile phones requires the co-operation of manufacturers, network operators and retail merchants.[47][48][49]
Mobile phones are commonly used to collect location data. While the phone is turned on, the geographical location of a mobile phone can be determined easily (whether it is being used or not) using a technique known as multilateration to calculate the differences in time for a signal to travel from the mobile phone to each of several cell towers near the owner of the phone.[50][51]
The movements of a mobile phone user can be tracked by their service provider and, if desired, by law enforcement agencies and their governments. Both the SIM card and the handset can be tracked.[50]
China has proposed using this technology to track the commuting patterns of Beijing city residents.[52] In the UK and US, law enforcement and intelligence services use mobile phoness to perform surveillance operations. They possess technology that enables them to activate the microphones in mobile phones remotely in order to listen to conversations which take place near the phone.[53][54]
Hackers are able to track a phone's location, read messages, and record calls, just by knowing the phone number.[55]
According to the Federal Communications Commission, one out of three robberies involve the theft of a cellular phone.[citation needed] Police data in San Francisco show that half of all robberies in 2012 were thefts of cellular phones.[citation needed] An online petition on Change.org, called Secure our Smartphones, urged smartphone manufacturers to install kill switches in their devices to make them unusable if stolen. The petition is part of a joint effort by New York Attorney General Eric Schneiderman and San Francisco District Attorney George Gascón, and was directed to the CEOs of the major smartphone manufacturers and telecommunication carriers.[56]
On Monday, 10 June 2013, Apple announced that it would install a "kill switch" on its next iPhone operating system, due to debut in October 2013.[57]
A study by the London School of Economics found that banning mobile phones in schools could increase pupils' academic performance, providing benefits equal to one extra week of schooling per year.[58]
The effect of mobile phone radiation on human health is the subject of recent interest and study, as a result of the enormous increase in mobile phone usage throughout the world. Mobile phones use electromagnetic radiation in the microwave range, which some believe may be harmful to human health. A large body of research exists, both epidemiological and experimental, in non-human animals and in humans. The majority of this research shows no definite causative relationship between exposure to mobile phones and harmful biological effects in humans. This is often paraphrased simply as the balance of evidence showing no harm to humans from mobile phones, although a significant number of individual studies do suggest such a relationship, or are inconclusive. Other digital wireless systems, such as data communication networks, produce similar radiation.
On 31 May 2011, the World Health Organization stated that mobile phone use may possibly represent a long-term health risk,[59][60] classifying mobile phone radiation as "possibly carcinogenic to humans" after a team of scientists reviewed studies on mobile phone safety.[61] The mobile phone is in category 2B, which ranks it alongside coffee and other possibly carcinogenic substances.[62][63]
Some recent studies have found an association between mobile phone use and certain kinds of brain and salivary gland tumors. Lennart Hardell and other authors of a 2009 meta-analysis of 11 studies from peer-reviewed journals concluded that cell phone usage for at least ten years "approximately doubles the risk of being diagnosed with a brain tumor on the same ('ipsilateral') side of the head as that preferred for cell phone use".[64]
One study of past mobile phone use cited in the report showed a "40% increased risk for gliomas (brain cancer) in the highest category of heavy users (reported average: 30 minutes per day over a 10‐year period)".[65] This is a reversal of the study's prior position that cancer was unlikely to be caused by cellular phones or their base stations and that reviews had found no convincing evidence for other health effects.[60][66] However, a study published 24 March 2012 in the British Medical Journal questioned these estimates, because the increase in brain cancers has not paralleled the increase in mobile phone use.[67] Certain countries, including France, have warned against the use of mobile phones by minors in particular, due to health risk uncertainties.[68] Mobile pollution by transmitting electromagnetic waves can be decreased up to 90% by adopting the circuit as designed in mobile phone (MS) and mobile exchange (BTS, MSC etc.).[69]
In May 2016 preliminary findings of a long-term study by the U.S. government suggested that radio-frequency (RF) radiation, the type emitted by cellphones, can cause cancer.[70][71]
5G is a technology and term used in research papers and projects to denote the next major phase in mobile telecommunication standards beyond the 4G/IMT-Advanced standards. The term 5G is not officially used in any specification or official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum or ITU-R. New standards beyond 4G are currently being developed by standardization bodies, but they are at this time seen as under the 4G umbrella, not for a new mobile generation. Deloitte is predicting a collapse in wireless performance to come as soon as 2016, as more devices using more and more services compete for limited bandwidth for their operation.[72]
Studies have shown that around 40-50% of the environmental impact of mobile phones occurs during the manufacture of their printed wiring boards and integrated circuits.[73]
The average user replaces their mobile phone every 11 to 18 months,[74] and the discarded phones then contribute to electronic waste. Mobile phone manufacturers within Europe are subject to the WEEE directive, and Australia has introduced a mobile phone recycling scheme.[75]
Apple Inc. has realized how their products when not recycled impact the environment and waste valuable resources. Apple's Liam was introduced to the world, an advanced robotic disassembler and sorter designed by Apple Engineers in California specifically for recycling outdated or broken iPhones. Reuses and recycles parts from traded in products.[350]
Demand for metals used in mobile phones and other electronics fuelled the Second Congo War, which claimed almost 5.5 million lives.[76] In a 2012 news story, The Guardian reported: "In unsafe mines deep underground in eastern Congo, children are working to extract minerals essential for the electronics industry. The profits from the minerals finance the bloodiest conflict since the second world war; the war has lasted nearly 20 years and has recently flared up again. ... For the last 15 years, the Democratic Republic of the Congo has been a major source of natural resources for the mobile phone industry."[77]
The company Fairphone has attempted to develop a mobile phone that does not contain conflict minerals.
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| Look up mobile phone in Wiktionary, the free dictionary. |
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| リンク元 | 「携帯電話」「cellular phone」「portable phone」 |
| 関連記事 | 「cell」 |