Tuesday, November 08, 2005

Mobile Phone

A mobile phone is a device which behaves as a normal telephone whilst being able to move over a wide area (compare 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.

Some of the world's largest mobile phone manufacturers include Alcatel, Audiovox, Kyocera (formerly the handset division of Qualcomm), LG, Motorola, Nokia, Panasonic (Matsushita Electric), Philips, Samsung, Sagem, Sanyo, Siemens, SK Teletech, and Sony Ericsson.

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

Worldwide deployment

Mobile phones have a long and varied history that stretches back to the 1950s, with hand-held 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. 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, wealthier parts of Asia, and Australasia, mobile phones are now virtually universal, with the majority (in some countries and age groups up to 100 percent) of the adult, teenage, and even child population owning one. They are 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, a mixture of incompatible technical standards (many European nations and some Asian nations force the GSM standard by law on all phones, while in other Asian nations the CDMA standard is enforced; in the United States and Canada there is no such law and each provider chooses a standard), relatively high minimum monthly service charges (around $30), and the availability of relatively low-cost fixed-line networks (around $30 for unlimited local calling). Prepaid or pay as you go services, common elsewhere, are far less common in the U.S., and are much more expensive than comparable services in other countries. The shortage of telephone numbers in the North American Numbering Plan (NANP), and the lack of non-regional special telephone numbers for mobile services, means that the pricing system used elsewhere (calls cost more to make to a mobile, but are free to receive) cannot be used, and as a result users pay to receive calls, discouraging cellphone use. The same technical issues affect mobile telephony in Canada, as it uses the same mix of incompatible standards as does the U.S., and is also part of the NANP.

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. For phones on GSM networks, the operator will issue a SIM card which contains the unique subscription and authentication parameters for that customer; alternatively, the carrier will put the customer's handset identifier into its subscriber database so that the handset can make calls on the network. 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. Newer models sometimes include a noise meter, a thermometer, a compass and many other exotic features.

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.

Today, most models also allow for sending and receiving pictures and have a built-in digital camera. Sound and video recording is often also possible. 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 integrated or connected (i.e. using bluetooth) to cell phones, primarily to aid in dispatching emergency responders and road tow truck services.

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 (for example, 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 the DS-WCDMA and MC-CDMA 3G variants of the CDMA-2000 protocol. 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.

As can be deduced from the above, most mobile phone networks now use one of two standards, GSM or CDMA. A third standard, iDEN, is found exclusively in North America and is confined to use by the Nextel network. It's believed that this network will eventually disappear as Nextel merges with Sprint PCS, a CDMA carrier. Similarly, AT&T Wireless's TDMA network in North America is slowly being phased out as a result of its merger with Cingular, a GSM carrier.

Health controversy

Main article: 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). It is generally thought, however, that RF is incapable of producing any more than heating effects, as it is considered non-ionizing radiation, in other words that it lacks the energy to disrupt molecular bonds such as occurs in genetic mutations.

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, and other U.S. states and municipalities are following suit.

As technology progresses and data demands have increased on the mobile network, the latest in scares is the 3G higher bandwidth towers. The network has sparked many health concerns and community outrage. Examples of such can be seen from headlines around the world; locals in the UK pulling down 3G masts, authorities in Denmark lobbying against the Government's rollout of 3G Networks to stop until a dispute is made, Australia - Sydney Leichhardt protests banners were demonstrated outside housing and the local school to stop the 3G mast on the roof of a supermarket. The spurt of protest appears to be the common reason for human fear, the unknown. There have been very little communications between governments and communities providing information about the introduction of 3G upgrades. The ACA (Australian Communications Authority) and ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) recently announced that the 3G towers actually cause less radiation then the already present 2G network. An average radiation power output of 3watt. No governmental fact sheet is available and it is questionable that perhaps the current towers do release more radiation, however, the propagation of more towers inevitably adds to a more irradiated area.

Security concerns

Earlier mobile phones were fairly simple and the major security concern was "cloning", a variant of identity theft which is much more difficult with newer, digital systems. Many users fail to realize that a cell phone is literally a basic walkie-talkie style radio, with some computers helping along the way. Radio scanners dating to about 1996 or '97 typically can receive the old analog cell phones as easy as one can listen to an FM radio. However, over the years technology has made cell phones in the gigahertz range, well above most conventional scanners. In addition, many (most) cell phones on the market today are backed by many digital type encryption systems. There are also new means of digital communications, such as text messaging and e-mail. As of 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 widespread 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. However, the rise of cellular phone operating system programming platforms shared by many manufacturers such as Java, Microsoft operating systems, Linux or Symbian OS, may in the future change this status quo.

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. The Commwarrior.A virus was identified in March 2005, and it attempts to replicate itself through MMS to others on the phone's contact list. Like Cabir, Commwarrior.A also tries to communicate via Bluetooth wireless connections with other devices, which can eventually lead to draining the battery. The virus requires user intervention for propagation however. Bluetooth telephones are also subject to bluejacking, which is the generally benign transmission of messages from anonymous Bluetooth users. In 2004, rumors spread of using Bluetooth to arrange casual sex hookups; this activity, widely publicized in both print and online media as toothing, was revealed to be a hoax in 2005.

Mobile phone culture

In less than twenty years, mobile telephones have gone from being rare and expensive pieces of equipment used by businesses to a pervasive low-cost personal item. In many affluent countries, mobile phones now outnumber land-line telephones, with most adults and many children now owning mobile phones and is not uncommon for young adults to own simply a cell phone instead of a land-line for their residence, even in the U.S. where mobile phone use is less prevalent than other industrialized countries. Mobile phone penetration is increasing around the world; this is particularly true of developing countries, where there is little existing fixed-line infrastructure.

With high levels of mobile telephone penetration, a mobile phone culture has evolved, where the mobile phone becomes a key social tool, and people rely on their mobile phone addressbook 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 mobile phone itself has become a totemic and fashion object, with users decorating, customizing, and accessorizing their mobile phones to reflect their personality.

The capabilities of mobile phones are now being expanded further, to become smartphones which can adopt the roles of Internet browser, game console, personal music player and personal digital assistant.

Mobile etiquette has become an important issue with mobiles ringing at funerals, weddings, movies and plays. Users often speak at increased volume, with the effect of nearby people hearing personal conversations that they don't necessarily want to hear; it has become common practice for places like libraries and movie theatres to ban the use of cell phones, even to the point of installing jamming equipment to prevent them. (In areas where public safety radio networks use frequencies near the cellular range, such jammers have been known to disrupt emergency operations. Such equipment, though cheap and readily available, is therefore illegal under most countries' communications regulations.)


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