Mobile phone

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Cellular links here. For the 2004 movie, Cellular, see Cellular (movie).

A mobile phone, the Sony Ericsson T630

A mobile phone is a mobile device which acts as a normal telephone whilst being able to move over a wide area (cf. cordless phone). Mobile phones allow connections to be made to the telephone network, normally by directly dialling the other party's number on an inbuilt keypad. Most current mobile phones use a combination of radio wave transmission and conventional telephone circuit switching, though packet switching is already in use for some parts of the mobile phone network, especially for services such as push to talk.

Mobile phone manufacturers include Motorola, Nokia, Samsung, Siemens, Sony Ericsson, Alcatel, LG and Sagem.

There are also specialist communication systems related to, but distinct from mobile phones, such as satellite phones and Professional Mobile Radio.

Contents

1 Worldwide deployment

2 Mobile phone features

3 Multi-mode mobile phones

4 Using mobile phones on aircraft

8.1 Mobile phone terms
8.2 Related systems which are not mobile phones
8.3 Terms in other languages

9 See also

10 External links

Worldwide deployment

Mobile phones have a long and varied history that stretches back to the early 1970's. 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. Such networks can often be economic, even with a small customer base, as mobile network costs are mostly call volume related, while fixed-line telephony has a much higher subscriber related cost component.

In most of Europe, wealthy parts of Asia, and Australia, mobile phones are now virtually universal, with the majority of the adult, teenage, and even child population owning one. They are less common in the United States — while widely available, market penetration is lower than elsewhere in the developed world (around 66 percent of the U.S. population as of 2003). Reasons advanced for this include incomplete coverage, relatively high minimum monthly service charges (around $30), and the availability of relatively low-cost fixed-line networks (around $30 for unlimited local calling). One consequence of this disparity in market penetration is a lag in the changing perception of the social status attached to mobile phone ownership. During the 1980's and 90's possessing a mobile phone was generally seen as an indicator of upwardly mobility, which is still just barely the case in North America, whereas particularly in Britain the mobile has become so ubiqitous and heavily used by the teenage population that it is looked upon as declasse.

Mobile phone features

Mobile phones are designed to work on cellular networks. Before the phone can be used, a subscription to a mobile phone operator is required. The operator will issue a SIM card which contains the unique subscription and authentication parameters for that customer. Once the SIM card is inserted into the phone, services can be accessed. Mobile phones do not only support voice calls; they can also send and receive data and faxes (if a computer is attached), send short messages (or "text messages"; see SMS), access WAP services, and provide full Internet access using technologies such as GPRS. Mobile phones usually have a clock and a calculator and often one can play some games on them.

Many mobile phones support 'auto-roaming', which permits the same phone to be used in multiple countries. For this to work, the operators of both countries must have a roaming agreement.

Newer models also allow for sending pictures and have a built-in digital camera. This gives rise to some concern about privacy, in view of possible voyeurism, for example in swimming pools. For this reason, Saudi Arabia has banned cameraphones entirely; South Korea has ordered manufacturers to ensure that all new handsets emit a beep whenever a picture is taken. Some swimming pools have banned camera mobile phones in their pools and changing rooms. Some companies and military agencies prohibit camera phones in certain locations for security reasons. On the other hand, cameras can be used by crime victims or witnesses to help identify the criminals.

GPS receivers are starting to appear in cell phones, primarily to aid in dispatching emergency responders.

Newer models have included many features aimed toward personalisation, such as user defined and downloadable ring tones and logos, and interchangeable covers, which have helped in the uptake by the teenage market. Usually one can choose between a ring tone, a vibrating alert, or a combination of both.

Multi-mode mobile phones

A multi-mode mobile phone is a phone which is designed to work on more than one GSM radio frequency. The multi-mode case occurs mostly in GSM which originated in the 900 MHz band, but expanded to other bands. See the GSM article for more details on this.

Multi mode phones have been valuable to enable roaming but are now becoming most important in allowing the introduction of WCDMA without customers having to give up the wide coverage of GSM. Almost every single true 3G phone sold is actually a WCDMA/GSM dual-mode mobile. This is also true of 2.75G phones such as those based on CDMA-2000 or EDGE.

The special challenge involved in producing a multi-mode mobile is in finding ways to share the components between the different standards. Obviously, the phone keypad and display should be shared, otherwise it would be hard to treat as one phone. Beyond that, though, there are challenges at each level of integration. How difficult these challenges are depends on the differences between systems. The different variants of the GSM system have only different frequencies and so aren't even considered true multi-mode phones but rather are called multi-band phones. When talking about IS-95/GSM multi-mode phones, for example, or AMPS/IS-95 phones, the base band processing is very different from system to system. This leads to real difficulties in component integration and so to larger phones.

An interesting special case of multi-mode phones is the WCDMA/GSM phone. The radio interfaces are very different from each other, but mobile to core network messaging has some quite strong similarities, meaning that software sharing is quite easy. Probably more importantly, the WCDMA air interface has been designed with GSM compatibility in mind. It has a special mode of operation, known as punctured mode, in which, instead of transmitting continuously, the mobile is able to stop sending for a short period and try searching for GSM carriers in the area. This mode allows for safe inter-frequency handovers with channel measurements which can only be approximated using "pilot signals" in other CDMA based systems.

A final interesting case is that of mobiles covering DS-WCDMA and MC-CDMA the 3G variant of CDMA-2000. Initially, the chip rate of these phones was incompatible. As part of the negotiations related to patents, it was agreed to use compatible chip rates. This should mean that, despite the fact that the air and system interfaces are quite different, even on a philosophical level, much of the hardware for each system inside a phone should be common with differences being mostly confined to software.

Using mobile phones on aircraft

The use of mobile phones is generally forbidden on aircraft during flight. One reason given for this is that the mobile phone could interfere with the sensitive equipment on the aircraft. This could be restated as "during development these aircraft were not designed to accept signals from mobile phones and there has not been sufficient testing to be sure that they could" as can be seen from plans to improve certification [1]. It is clear, however, that there is some level of interference is possible from active radio transmitters such as mobile phones on aircraft. Exactly how much and in what way is dependent on the particular phone system in use and the plane component in question. Whether that level of interference should have any influence on electronic systems which should be designed to fly through lightning storms without falling out of the sky is an entirely different question.

One area in which interference is likely is in the radio based audio equipment used for communicating from the aeroplane to the ground. The mobile phone transmitter will be much nearer to the receiver on the aircraft; this means that any cross talk from the mobile phone will have a strong effect.

Some mobile phone systems such as GSM may cause an irritating buzz (explained in the TDMA article) which would certainly disrupt communications from the pilot to ground. Unfortunately, the conditions on an aeroplane are exactly those which might cause this. The maximum speed of travel in a mobile phone system is limited by several factors, frequency changes, rate of change of timing offset, etc. The speed of an aeroplane often exceeds these (typically phones are designed for use in a fast car) which means the mobile will fail to register to the network and retry registration repeatedly.

Older analogue systems simply broadcast at a high power of up to several watts. This will cause more general interference, and since the voice signal is not encoded there may be direct cross talk into the communication systems of the plane.

Another factor is that from an altitude, distant cells are visible to the mobile with no line-of-sight attenuation from intervening obstacles. This means that the phone could try to establish contact with a far away cell where the signal will not be recognised. This transmission will probably be at maximum power due to the lack of prior response. The U.S. Federal Communications Commission prohibits the use of mobile phones in the air for this reason. This repeated sending of maximum power messages increases the risk of interference with electronic equipment on the aircraft.

All of the above having been said, according to the BBC "most of the evidence is circumstantial and anecdotal. There is no absolute proof mobile phones are hazardous." [2] Some airlines do allow use of mobiles phones in flight, only restricting their use (and use of all other electronic devices) during take off and landing when communications with the ground are most critical. Meanwhile the passenger aircraft manufacturers, such as Boeing and Airbus, have begun to introduce wireless services on their planes (e.g. WLAN) and radio based satellite phones are a standard installation on aeroplanes. Clearly there is a direct airline industry advantage in having control over communication systems from within an aeroplane, with no clear way for potential competitors to certify their systems as safe for use on board. Some articles have even gone so far as to accuse the airline industry of pushing the ban on mobile phones in order to increase revenue from on board telephones [3]. A number of new phones have an "aeroplane mode" feature that presumably stops all incoming and outgoing communications while still allowing the user to play games, type notes etc. However, it is doubtful whether a steward on an aeroplane would allow one to use a phone even if this feature was explained

Health controversy

As with many new technologies, concerns have arisen about the effects on health from using a mobile telephone (see Electromagnetic radiation hazard). Part of the radio waves emitted by a mobile telephone are absorbed by the human head; the radio waves emitted by a GSM-900 handset can have a power of up to 2 watts. The rate at which radiation is absorbed by the human body is measured by the Specific Absorption Rate (SAR), and its maximum levels for modern handsets have been set by governmental regulating bodies in many countries. Since the microwave spectrum is non-ionizing electromagnetic fields (EMF), according to the scientific consensus, the only effect on the human body is that the temperature of the head may increase by a harmless fraction of a degree during prolonged calling, actually several orders of magnitude less than that obtained during the exposure of head to direct sunlight for a time. The thick skull bones are a respectable heat shield developed by evolution, and the brain's blood circulation easily disposes of excess heat by instantaneously increasing local blood flow. However, some controversial studies claim that there exist other undesired effects on health as a direct result of the radiation. It has been claimed, for example, that some parts of the human head are more sensitive to damage due to increases in temperature, particularly in anatomical structures with poor vasculature, such as nerve fibers. More recent results from a Swedish scientific team have revealed that continous use of a mobile phone for a decade or longer can lead to a small increase in the probability of getting a certain type of brain tumor (acoustic neurinoma).

Another area of worry about effects on the population's health have been the radiation emitted by radio-base stations, because, in contrast to mobile handsets, it is emitted continuosly. Many measurements and experiments have shown, however, that radiation levels are low (particularly in modern antennas, in the range of 20 to 100 watts) and decay sharply with distance from the tower (with the square of distance). Thus, if international norms of safety are respected (in relation to minimal distance to human habitations and direction and intensity of field), there is no cause for additional precautions. Governmental authorities usually pass legislation which regulates the application of these norms.

The World Health Organization has a special study program on the effects of electromagnetical fields on human health which periodically examines the scientific evidence on these aspects. So far (the next report is scheduled for 2006-2007) it has concluded that there are no demonstrable effects of EMF used in mobile phones and wireless telecommunication systems on human health, and the single great health risk is using mobile phones while driving (it is estimated that in the USA alone, more than 2,000 deaths and 30,000 injuries occur every year due to the improper -- and forbidden in many states -- use of phones by motorists).

Security concerns

Earlier mobile phones were fairly simple and security wasn't much of a concern, but in 2004, even basic phones can send and receive text messages which makes them vulnerable to attack by worms and viruses. Advanced phones capable of e-mail can be susceptible to viruses that can multiply by sending messages through a phone's address book. Of more important concern, a virus may allow unauthorized users to access a phone to find passwords or corporate data stored on the device. Moreover, they can be used to commandeer the phone to make calls or send messages at the owner's expense. Unlike computers that are restricted to only a few widepread operating systems, cellular phones use a variety of systems that require separate programs to be designed in order to disable each one. While reducing overall compatibilty from an application design standpoint, this has the beneficial effect of making it harder to design a mass attack.

Bluetooth is a wireless communication feature now found in many higher-end phones, and the virus Cabir hijacked this function, sending Bluetooth phones on a search-and-destroy mission to infect other Bluetooth phones. In early November 2004, several web sites began offering a specific piece of software promising ringtones and screensavers for certain phones. Those who downloaded the software found that it turned each icon on the phone's screen into a skull-and-crossbones and disabled their phones, so they could no longer send or receive text messages or access contact lists or calendars. The virus has since been dubbed "Skulls" by security experts.

Future prospects

There is a great deal of active research and development into mobile phone technology that is currently underway. Some of the improvements that are being worked on are:

phones will incorporate more features from other handheld devices, for example MP3 players, PDAs, GPS receivers, digital cameras, etc.

One difficulty in adapting mobile phones to new uses is form factor. For example, ebooks may well become a distinct device, because of conflicting form-factor requirements — ebooks require large screens, while phones need to be smaller. However, this may be solved using folding e-paper or built-in projectors.

One function that will be useful in phones is translation function. Currently it is only available in stand-alone devices, such as Ectaco translators.

mobile phones will include various speech technologies as they are being developed. Many phones already have rudimentary speech recognition in a form of voice dialling. Of particular interest will be real-time voice translation (that must include speech recognition, machine translation and speech synthesis). However, more natural speech recognition and translation in these devices requires a drastic improvement in the state of technology: the phone's processor must be faster by several orders of magnitude with the phone requiring far more internal memory, or new ways of processing speech data must be found. Natural language processing requires inordinately powerful hardware.

developments in miniaturised hard disk drives to solve the storage space issue, therefore opening a window for phones to become portable music libraries and players similar to the iPod.

further improvements in battery life wil be required. Colour screens and additional functions put increasing demands on the device's power source, and battery developments may not proceed sufficiently fast to compensate. However, different display technologies, such as OLED displays, e-paper or retinal displays, smarter communication hardware (directional antennae, multi-mode and peer-to-peer phones) may reduce power requirements, while new power technologies such as fuel cells may provide better energy capacity.

Traditionally, all functions of the mobile phone (microphone, speaker, radio communications, display, computer) were integrated in one single device. These functions could be separated into parts that communicate using short-range wireless radio technologies such as Bluetooth. It is possible that this opportunity will be used to further reduce the weight and footprint of the phone. A wearable display may be used by the phone.

Speculative improvements in the future may be inspired by an English team led by James Auger and Jimmy Loizeau who in 2002, developed an implant designed to be inserted into a tooth during dental surgery. This device consists of a radio receiver and transducer, which transmits the sound via bone conduction through the jawbone into the ear. Sound is transmitted via radio waves from another device (ostensibly a mobile phone) and received by the implant. The implant is currently powered externally, given that no current power source is small enough to fit inside the tooth with it. In addition, the implant was only designed to receive signals, not transmit them. Directly tapping into the inner ear or the auditory nerve is already technologically feasible and will become practical as surgical methods advance.

Terminology

Mobile phone terms

Cell phone or cellular telephone: Term used currently in America and during the 80s to refer to most mobile phones. This term applies specifically to mobile phones which use a cellular network.
Handy: A pseudo-anglicism, derived from the term Handy Talkie for a handheld military radio, that is used in Germany for a mobile phone (rare alternative spelling: Händi). Similarly another pseudo-anglic term Hand phone is used in South Korea.
Mobile phone: A term covering cellular phones, satellite phones and any phones giving wide ranging mobility.
Mobile: Short form of the above, a term in everyday usage in some English speaking countries.
Satellite phone: A mobile phone which communicates with a satellite rather than a land-based network.
Wireless phone: This is a term which is generally used to refer to a mobile phone although it could legitimately cover almost any phone which does not use a wire.
3G phone: A mobile phone which uses a 3G network.

Related systems which are not mobile phones

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.
Radio Phone: This is an term which covers radios which could connect into the telephone network. These phones may not be mobile, e.g. they may require a mains power supply.
Professional Mobile Radio: Professional mobile radio systems are very similar to mobile phone systems and attempts have even been made to use TETRA, the international digital PMR standard, to implement public mobile networks, but normally PMR systems are sufficiently separate from the phone network to not really be considered phones but rather radios.

Terms in other languages

In the US the phones are called cell phones or even simply cells.
In the UK, Australia and New Zealand, mobile phones are often called simply mobiles.
In Germany, they are called Handys
In Switzerland Natel
In the Netherlands mobieltjes
In Italy Telefonino (meaning small phone).
In Japan Keitai
In Sweden, they are sometimes called nalle, or teddy bear translated to English, originally referring to the term yuppie nalle since in the beginning only rich yuppies could afford them and they showed them off in a way that looked as they where carrying a yuppie teddy bear, nowadays only nalle is used representing that people always carry them around and feel insecure if they misplace them, like a child missing his/her teddy bear.
In Russia, they are often called trubka, or tube in English, because the receiver part of the stationary phones was called telephone tube and the mobile phone consists of receiver alone, in some sense.
In many Asian countries they are called hand phones.
In Belgium, they are called GSMs (Global System for Mobile communications)
In France, they are called Portable (literally portable)
In Israel, they are called Pelephone (literally wonder-phone), as derived from the first such operator
In Denmark, they are called mobilos or mobil
In Brazil, they are called celulares (singular form celular)
In Spain, they are called móviles
In Portugal, they are called telemóveis (singular form telemóvel)
In Poland, they are called komórki (singular form komórka), meaning cells.
Users of Esperanto usually talk about poŝtelefonoj ("pocket phones", pronounced poshtelefonoy).

External links

ca:Telèfon_mòbil da:Mobiltelefon de:Mobiltelefon eo:Posxtelefono es:Telefonía_móvil fi:Matkapuhelin fr:Téléphone_mobile he:טלפון_סלולרי it:Telefono_cellulare ja:携帯電話 ko:핸드폰 nl:Mobiele_telefoon no:Mobiltelefon pl:Telefon_komórkowy pt:Telefone_celular ru:Сотовый_телефон sv:Mobiltelefon zh-cn:手机