A mobile phone is a device which behaves as a normal telephone whilst being able to move over a wide area (cf. cordless phone which acts as a telephone only within a limited range). 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 internet access and WAP.
Mobile phone manufacturers include Audiovox, Kyocera (formerly the handset division of Qualcomm), Motorola, Nokia, Panasonic (Matsushita Electric), Samsung, Sanyo, 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.
Tuesday
Worldwide deployment
Mobile phones have a long and varied history that stretches back to the early 1970s. 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 Australasia, mobile phones are now virtually universal, with the majority of the adult, teenage, and even child population owning one. They are somewhat less common in the United States — while widely used, 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).
In most of Europe, wealthy parts of Asia, and Australasia, mobile phones are now virtually universal, with the majority of the adult, teenage, and even child population owning one. They are somewhat less common in the United States — while widely used, 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).
Mobile phone features
Mobile phones are designed to work on cellular networks and contain a standard set of services that allow phones of different types and in different countries to communicate with each other.
Before the phone can be used, a subscription to a mobile phone operator (a.k.a. carrier) 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 and receiving 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 entirely banned the sale of camera phones (although the country allows pilgrims on the Hajj to bring in camera phones); South Korea has ordered manufacturers to ensure that all new handsets emit a beep whenever a picture is taken.
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.
Before the phone can be used, a subscription to a mobile phone operator (a.k.a. carrier) 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 and receiving 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 entirely banned the sale of camera phones (although the country allows pilgrims on the Hajj to bring in camera phones); South Korea has ordered manufacturers to ensure that all new handsets emit a beep whenever a picture is taken.
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 (a.k.a. dual, tri or quad band) 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 including 1800 and 1900Mhz bands. Some multi-mode phones can operate on analog networks as well (e.g. dual band, tri-mode: AMPS 800 / CDMA 800 / CDMA 1900).
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 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.
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 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.
Mobile phone radiation and health
As with many new technologies, concerns have arisen about the effects on health from using a mobile telephone. There is little scientific evidence for an increase in certain types of rare tumors in long-time, heavy users. More recently a pan-European study provided significant evidence of DNA damage under certain conditions. So far, however, the World Health Organization Task Force on EMF effects on health has no definitive conclusion on the veracity of these allegations. (see also Electromagnetic radiation hazard).
Another controversial but perhaps more lethal health concern is the correlation with automobile accidents. Some countries, provinces and states are considering banning hand mobile phone use whilst driving or require that a "hands-free" system be used. Many European countries and New York already require a "hands-free" device for mobile phone use in vehicles.
Another controversial but perhaps more lethal health concern is the correlation with automobile accidents. Some countries, provinces and states are considering banning hand mobile phone use whilst driving or require that a "hands-free" system be used. Many European countries and New York already require a "hands-free" device for mobile phone use in vehicles.
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