About Your Mobile

The fourth-generation iPad (marketed as iPad with Retina display, colloquially referred to as the iPad 4) is a tablet computer produced and marketed by Apple Inc. The fourth-generation iPad features new and upgraded components such as the Apple A6X chip, and the Lightning connector, which was introduced on September 12, 2012. It shipped with iOS 6.0, which provides a platform for audio-visual media, including electronic books, periodicals, films, music, computer games, presentations and web content. It was announced at a media conference on October 23, 2012 as the fourth generation of the iPad line, succeeding the third-generation iPad, and was first released on November 2, 2012 in thirty-five countries. The device was released throughout December in ten other countries including China, India and Brazil. The third generation was discontinued following the fourth's announcement. The device is available with either a black or white front glass panel and can be purchased with various connectivity and storage options. Storage size options include 16 GB, 32 GB, 64 GB, and 128 GB; the available connectivity options are Wi-Fi only and Wi-Fi + Cellular with LTE capabilities. The fourth-generation iPad received primarily positive reviews and was praised for its hardware improvements as well as the Retina display, which was also featured in the device's predecessor. Furthermore, benchmarks reveal that the fourth-generation iPad is able to perform CPU-reliant tasks twice as fast as its predecessor. During the first weekend of sales, an aggregated amount of three million fourth-generation iPads and iPad minis were sold. Rumors regarding the next-generation iPad emerged shortly after the release of the third-generation iPad. At that point some speculated that the next iPad released would be of a smaller size.[18] Further speculations emerged in July 2012 when DigiTimes, with the help of unspecified sources, claimed that Apple made small revisions to the then upcoming iPad and scheduled its release for late 2012. On October 16, 2012, Apple announced a media event scheduled for October 23 at the California Theatre in San Jose, California. The company did not pre-disclose the subject of the event, but it was widely expected to be regarding the iPad Mini. Photographic images of the device's dock connector and front camera emerged shortly before the media event. At the media event, Apple CEO Tim Cook introduced a new version of iBooks and new generations of the MacBook Pro, Mac Mini, and the iMac before unveiling the fourth-generation iPad and the iPad Mini. During the unveiling, Apple stated that the fourth-generation iPad would be available to pre-order online in a selected number of countries starting October 26. On November 2, Apple released the Wi-Fi model of device in thirty-five countries across Europe, East Asia and North America. The cellular model was released in-store a few weeks after the initial release of the device. The release of the fourth-generation iPad led to the discontinuation of its predecessor, which angered many third-generation iPad users. In response, Apple extended its 14 day return policy to 30 days. ITProPortal noted that, since the price of both models is identical, consumers that purchased the third-generation iPad within this time frame were effectively allowed to exchange their discontinued device for the fourth-generation model.On January 29, 2013, Apple announced and scheduled the launch of the 128 GB variant of 4th generation iPad. It was released on February 5, 2013. Features [edit] Software [edit] See also: iOS and iOS 6 The fourth-generation iPad is shipped with iOS 6.0. It can act as a hotspot with some carriers, sharing its Internet connection over Wi-Fi, Bluetooth, or USB, and also access the Apple App Store, a digital application distribution platform for iOS. The service allows users to browse and download applications from the iTunes Store that were developed with Xcode and the iOS SDK and were published through Apple. From the App Store, GarageBand, iMovie, iPhoto, and the iWork apps (Pages, Keynote, and Numbers) are available. The iPad comes with several pre-installed applications, including Siri, Safari, Mail, Photos, Video, Music, iTunes, App Store, Maps, Notes, Calendar, Game Center, Photo Booth, and Contacts. Like all iOS devices, the iPad can sync content and other data with a Mac or PC using iTunes, although iOS 5 and later can be managed and backed up without a computer. Although the tablet is not designed to make phone calls over a cellular network, users can use a headset or the built-in speaker and microphone to place phone calls over Wi-Fi or cellular using a VoIP application, such as Skype. The device has a dictation application, using the same voice recognition technology as the iPhone 4S. The user speaks and the iPad types what they say on the screen, though the iPad must have an internet connection available (via Wi-Fi or cellular network) due to the feature's reliance on Apple servers to translate the speech. The fourth-generation iPad has an optional iBooks application, which displays books and other ePub-format content downloaded from the iBookstore. Several major book publishers including Penguin Books, HarperCollins, Simon & Schuster and Macmillan have committed to publishing books for the device. Despite being a direct competitor to both the Amazon Kindle and Barnes & Noble Nook, both Amazon.com and Barnes & Noble offer e-reader apps for the iPad. Hardware [edit] See also: iPad hardware There are four buttons and one switch on the fourth-generation iPad, including a "home" button near the display that returns the user to the home screen, and three plastic switches on the sides: wake/sleep and volume up/down, plus a software-controlled switch whose function varies with software updates. Externally, the fourth-generation iPad is identical to its predecessor apart from the differences between dock connectors used and change of manufacturers that produce the display. In addition, the WiFi only version weighs 652 grams while the cellular model weighs 662 grams – 2 grams heavier than their respective predecessors. The display responds to other sensors: an ambient light sensor to adjust screen brightness and a 3-axis accelerometer to sense orientation and switch between portrait and landscape modes. Unlike the iPhone and iPod Touch's built-in applications, which work in three orientations (portrait, landscape-left and landscape-right), the iPad's built-in applications support screen rotation in all four orientations, including upside-down. Consequently, the device has no intrinsic "native" orientation; only the relative position of the home button changes. The tablet is manufactured either with or without the capability to communicate over a cellular network. All models can connect to a wireless LAN via Wi-Fi. The fourth-generation iPad is available with 16, 32, 64 or 128 GB of internal flash memory, with no expansion option. Apple sells a "camera connection kit" with an SD card reader, but it can only be used to transfer photos and videos. The device has an Apple A6X SoC which comprises an Apple Swift dual-core CPU running at 1.4 GHz, a quad-core PowerVR SGX554MP4 GPU and 1 GB of RAM.[38] It also features a 5-megapixel, rear-facing camera capable of 1080p video recording; and a 720p HD front-facing videophone camera designed for FaceTime. The device features a 9.7" (diagonal) display with a resolution of 2,048 by 1,536 (QXGA) resulting in 3.1 million pixels, this gives the display a pixel density of 264 ppi. The total number of pixels used in the display of the fourth-generation iPad is four times that of the iPad 2 – providing even scaling from the prior model. The audio playback of the fourth-generation iPad has a frequency response of 20 Hz to 20,000 Hz. Without third-party software it can play the following audio formats: HE-AAC, AAC, Protected AAC, MP3, MP3 VBR, Audible formats (2, 3, 4, AEA, AAX, and AAX+), ALAC, AIFF, and WAV. This iPad uses an internal rechargeable lithium-ion polymer (LiPo) battery that can hold a charge of 11,560 mAh. The batteries are made in Taiwan by Simplo Technology (60%) and Dynapack International Technology (40%). The iPad is designed to be charged with a relatively high current of 2 amps using the included 12 W USB power adapter and Lightning connector. While it can be charged by an older USB port from a computer, these are limited to 500 milliamps (0.5 amps). As a result, if the iPad is in use while powered by a computer, it may charge very slowly, or not at all. High-power USB ports found in newer computers and accessories provide full charging capabilities. Apple claims that the battery can provide up to 10 hours of video, audio playback, or web surfing on Wi-Fi, 9 hours of web surfing over a cellular connection, or one month on standby. Like any rechargeable battery, the iPad's battery loses capacity over time. However, the iPad's battery is not user-replaceable. In a program similar to iPod and iPhone battery-replacement programs, Apple promised to replace an iPad that does not hold an electrical charge with a refurbished unit for a fee. During the battery replacement process, user data is not preserved/transferred, and repaired or refurbished units come with a new case. The warranty on the refurbished unit may vary between jurisdictions.

The first mobile telephone calls were made from cars in 1946. Bell System's Mobile Telephone Service was made on 17 June in St. Louis, Missouri, followed by Illinois Bell Telephone Company's car radiotelephone service in Chicago on 2 October. The MTA phones were composed of vacuum tubes

and relays, and weighed over 80 pounds (36 kg). There were initially only 3 channels for all the users in the metropolitan area, increasing later to 32 channels across 3 bands. This service continued into the 1980s in large portions of North America. Due to the small number of radio frequencies available, the service quickly reached capacity. In 1956, the world’s first partly automatic car phone system, Mobile System A (MTA), was introduced in Sweden. John F. Mitchell, Motorola's chief of portable communication products in 1973, played a key role in advancing the development of handheld mobile telephone equipment. Mitchell successfully pushed Motorola to develop wireless communication products that would be small enough to use anywhere and participated in the design of the cellular phone. Martin Cooper, a Motorola researcher and executive, was the key researcher on Mitchell's team that developed the first hand-held mobile telephone for use on a cellular network. Using a somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on 3 April 1973 to his rival, Dr. Joel S. Engel of Bell Labs. As I walked down the street while talking on the phone, sophisticated New Yorkers gaped at the sight of someone actually moving around while making a phone call. Remember that in 1973, there weren't cordless telephones or cellular phones. I made numerous calls, including one where I crossed the street while talking to a New York radio reporter - probably one of the more dangerous things I have ever done in my life. —Martin Cooper, The new invention sold for $3,995 and weighed two pounds, leading to the nickname "the brick". The world's first commercial automated cellular network was launched in Japan by NTT in 1979, initially in the metropolitan area of Tokyo. In 1981, this was followed by the simultaneous launch of the Nordic Mobile Telephone (NMT) system in Denmark, Finland, Norway and Sweden. Several countries then followed in the early to mid-1980s including the UK, Mexico and Canada. On 6 March 1983, the DynaTAc mobile phone launched on the first US 1G network by Ameritech. It cost $100m to develop, and took over a decade to hit the market.[19] The phone had a talk time of just half an hour and took ten hours to charge. Consumer demand was strong despite the battery life, weight, and low talk time, and waiting lists were in the thousands. In 1991, the second generation (2G) cellular technology was launched in Finland by Radiolinja on the GSM standard, which 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. 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 like streaming media. Consequently, the industry began looking to data-optimized 4th-generation technologies, with the promise of speed improvements up to 10-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard (offered in the U.S. by Sprint) and the LTE standard, first offered in Scandinavia by TeliaSonera. Features

All mobile phones have a number of features in common, but manufacturers also try to differentiate their own products by implementing additional functions to make them more attractive to consumers. This 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 a given market segment, such as the RIM BlackBerry focusing on enterprise/corporate customer email needs; the SonyEricsson Walkman series of musicphones and Cybershot series of cameraphones; theNokia Nseries of multimedia phones, the Palm Pre the HTC Dream and the Apple iPhone.

The most commonly used data application on mobile phones isSMS text messaging. The first SMS text 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, and subsequently many organizations provided "on-demand" and "instant" news services by SMS.

Text messaging

The most commonly used data application on mobile phones is SMS text messaging. The first SMS text 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, and subsequently many organizations provided "on-demand" and "instant" news services by SMS.

SIM card

GSM feature phones require a small microchip called a Subscriber Identity Module or SIM Card, 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.

The first SIM card was made in 1991 by Munich smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja.

Multi-card hybrid phones

A hybrid mobile phone can hold up to four SIM cards. SIM and RUIM cards may be mixed together to allow both GSM and CDMA networks to be accessed.

From 2010 onwards they became popular in India and Indonesia and other emerging markets, 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 lost ground in the higher end smartphone market.

Kosher phones

There are Jewish orthodox religious restrictions which standard mobile telephones do not meet. To fulfill this demand, phones without Internet access, text messaging or cameras are required. These restricted phones are known as kosher phones and have rabbinical approval for use in Israel and elsewhere by observant Orthodox Jews. Some are even approved for use by essential workers (such as health, security and public services) on the sabbath, even though use of any electrical device is restricted.

Although these phones are intended to prevent immodesty, some vendors report good sales to adults who prefer the simplicity of the devices.

Bluetooth is a wireless technology standard for exchanging data over short distances (using short-

wavelength radio transmissions in the ISM band from 2400–2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Created by telecom vendor Ericsson in 1994, it was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization.

Bluetooth is managed by the Bluetooth Special Interest Group, which has more than 18,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. Bluetooth was standardized as IEEE 802.15.1, but the standard is no longer maintained. The SIG oversees the development of the specification, manages the qualification program, and protects the trademarks. To be marketed as a Bluetooth device, it must be qualified to standards defined by the SIG.[citation needed] A network of patents is required to implement the technology and are licensed only for those qualifying devices.

Bluetooth operates in the range of 2400–2483.5 MHz (including guard bands). This is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency band. Bluetooth uses a radio technology called frequency-hopping spread spectrum. The transmitted data is divided into packets and each packet is transmitted on one of the 79 designated Bluetooth channels. Each channel has a bandwidth of 1 MHz. The first channel starts at 2402 MHz and continues up to 2480 MHz in 1 MHz steps. It usually performs 1600 hops per second, with Adaptive Frequency-Hopping (AFH) enabled.

Originally Gaussian frequency-shift keying (GFSK) modulation was the only modulation scheme available; subsequently, since the introduction of Bluetooth 2.0+EDR, π/4-DQPSK and 8DPSK modulation may also be used between compatible devices. Devices functioning with GFSK are said to be operating in basic rate (BR) mode where an instantaneous data rate of 1 Mbit/s is possible. The term Enhanced Data Rate (EDR) is used to describe π/4-DPSK and 8DPSK schemes, each giving 2 and 3 Mbit/s respectively. The combination of these (BR and EDR) modes in Bluetooth radio technology is classified as a "BR/EDR radio".

Bluetooth is a packet-based protocol with a master-slave structure. One master may communicate with up to 7 slaves in a piconet; all devices share the master's clock. Packet exchange is based on the basic clock, defined by the master, which ticks at 312.5 µs intervals. Two clock ticks make up a slot of 625 µs; two slots make up a slot pair of 1250 µs. In the simple case of single-slot packets the master transmits in even slots and receives in odd slots; the slave, conversely, receives in even slots and transmits in odd slots. Packets may be 1, 3 or 5 slots long but in all cases the master transmit will begin in even slots and the slave transmit in odd slots.

Bluetooth provides a secure way to connect and exchange information between devices such as faxes, mobile phones, telephones, laptops, personal computers, printers, Global Positioning System (GPS) receivers, digital cameras, and video game consoles. It was principally designed as a low-bandwidth technology.
Communication and connection.

A master Bluetooth device can communicate with a maximum of seven devices in a piconet (an ad-hoc computer network using Bluetooth technology), though not all devices reach this maximum. The devices can switch roles, by agreement, and the slave can become the master (for example, a headset initiating a connection to a phone will necessarily begin as master, as initiator of the connection; but may subsequently prefer to be slave).

The Bluetooth Core Specification provides for the connection of two or more piconets to form a scatternet, in which certain devices simultaneously play the master role in one piconet and the slave role in another.

At any given time, data can be transferred between the master and one other device (except for the little-used broadcast mode[citation needed]). The master chooses which slave device to address; typically, it switches rapidly from one device to another in a round-robin fashion. Since it is the master that chooses which slave to address, whereas a slave is (in theory) supposed to listen in each receive slot, being a master is a lighter burden than being a slave. Being a master of seven slaves is possible; being a slave of more than one master is difficult.[citation needed] The specification is vague as to required behavior in scatternets.

Many USB Bluetooth adapters or "dongles" are available, some of which also include an IrDA adapter. Older (pre-2003) Bluetooth dongles, however, have limited capabilities, offering only the Bluetooth Enumerator and a less-powerful Bluetooth Radio incarnation.[citation needed] Such devices can link computers with Bluetooth with a distance of 100 meters, but they do not offer as many services as modern adapters do.

Mobile banking and payments 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 may be deposited or withdrawn from M-PESA accounts at Safaricom retail outlets located throughout the country, and may be transferred electronically from person to person as well as used to pay bills to companies. Branchless banking has also been successful in South Africa and Philippines. A pilot project in Bali was launched in 2011 by the International Finance Corporation and an Indonesian bank Bank Mandiri. Another application of mobile banking technology is Zidisha, a US-based nonprofit microlending 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 the borrowers in rural Africa using the internet and mobile phones. 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 first commercial mobile payments systems, on the mobile operators Globe and Smart. Some mobile phone can make mobile payments via direct mobile billing schemes or through contactless payments if the phone and point of sale support near field communication (NFC).[ This requires the co-operation of manufacturers, network operators and retail merchants to enable contactless payments through NFC-equipped mobile phones.

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, of which the majority 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, classifying mobile phone radiation as "possibly carcinogenic to humans" after a team of scientists reviewed studies on cell phone safety. Mobile phones are in category 2B, which ranks it alongside Coffee and other possibly carcinogenic substances. At least some recent studies have found an association between cell 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.” One study of past cell 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)."This is a reversal from their 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. Certain countries, including France, have warned against the use of cell phones especially by minors due to health risk uncertainties. 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.

A cellular network or mobile network is a radio network distributed over land areas called cells, each served by at least one fixed-location transceiver, known as a cell site or base station. In a cellular network, each cell uses a different set of frequencies from neighboring cells, to avoid interference and provide guaranteed bandwidth within each cell. When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceivers (e.g., mobile phones, pagers, etc.) to communicate with each other and with fixed transceivers and telephones anywhere in the network, via base stations, even if some of the transceivers are moving through more than one cell during transmission. Cellular networks offer a number of advantages over alternative solutions: flexible enough to use the features and functions of almost all public and private networks increased capacity reduced power use larger coverage area reduced interference from other signals An example of a simple non-telephone cellular system is an old taxi drivers' radio system, in which a taxi company has several transmitters based around a city that can communicate directly with each other.

Concept * In a cellular radio system, a land area to be supplied with radio service is divided into regular shaped cells, which can be hexagonal, square, circular or some other regular shapes, although hexagonal cells are conventional. Each of these cells is assigned multiple frequencies (f1 – f6) which have corresponding radio base stations. The group of frequencies can be reused in other cells, provided that the same frequencies are not reused in adjacent neighboring cells as that would cause co-channel interference. The increased capacity in a cellular network, compared with a network with a single transmitter, comes from the fact that the same radio frequency can be reused in a different area for a completely different transmission. If there is a single plain transmitter, only one transmission can be used on any given frequency. Unfortunately, there is inevitably some level of interference from the signal from the other cells which use the same frequency. This means that, in a standard FDMA system, there must be at least a one cell gap between cells which reuse the same frequency. In the simple case of the taxi company, each radio had a manually operated channel selector knob to tune to different frequencies. As the drivers moved around, they would change from channel to channel. The drivers knew which frequency covered approximately what area. When they did not receive a signal from the transmitter, they would try other channels until they found one that worked. The taxi drivers would only speak one at a time, when invited by the base station operator (this is, in a sense, time division multiple access (TDMA)). Cell signal encoding [edit] To distinguish signals from several different transmitters, frequency division multiple access (FDMA) and code division multiple access (CDMA) were developed. With FDMA, the transmitting and receiving frequencies used in each cell are different from the frequencies used in each neighbouring cell. In a simple taxi system, the taxi driver manually tuned to a frequency of a chosen cell to obtain a strong signal and to avoid interference from signals from other cells. The principle of CDMA is more complex, but achieves the same result; the distributed transceivers can select one cell and listen to it. Other available methods of multiplexing such as polarization division multiple access (PDMA) and time division multiple access (TDMA) cannot be used to separate signals from one cell to the next since the effects of both vary with position and this would make signal separation practically impossible. Time division multiple access, however, is used in combination with either FDMA or CDMA in a number of systems to give multiple channels within the coverage area of a single cell. Frequency reuse [edit] The key characteristic of a cellular network is the ability to re-use frequencies to increase both coverage and capacity. As described above, adjacent cells must use different frequencies, however there is no problem with two cells sufficiently far apart operating on the same frequency. The elements that determine frequency reuse are the reuse distance and the reuse factor. The reuse distance, D is calculated as where R is the cell radius and N is the number of cells per cluster. Cells may vary in radius in the ranges (1 km to 30 km). The boundaries of the cells can also overlap between adjacent cells and large cells can be divided into smaller cells.[2] The frequency reuse factor is the rate at which the same frequency can be used in the network. It is 1/K (or K according to some books) where K is the number of cells which cannot use the same frequencies for transmission. Common values for the frequency reuse factor are 1/3, 1/4, 1/7, 1/9 and 1/12 (or 3, 4, 7, 9 and 12 depending on notation).[3] In case of N sector antennas on the same base station site, each with different direction, the base station site can serve N different sectors. N is typically 3. A reuse pattern of N/K denotes a further division in frequency among N sector antennas per site. Some current and historical reuse patterns are 3/7 (North American AMPS), 6/4 (Motorola NAMPS), and 3/4 (GSM). If the total available bandwidth is B, each cell can only use a number of frequency channels corresponding to a bandwidth of B/K, and each sector can use a bandwidth of B/NK. Code division multiple access-based systems use a wider frequency band to achieve the same rate of transmission as FDMA, but this is compensated for by the ability to use a frequency reuse factor of 1, for example using a reuse pattern of 1/1. In other words, adjacent base station sites use the same frequencies, and the different base stations and users are separated by codes rather than frequencies. While N is shown as 1 in this example, that does not mean the CDMA cell has only one sector, but rather that the entire cell bandwidth is also available to each sector individually. Depending on the size of the city, a taxi system may not have any frequency-reuse in its own city, but certainly in other nearby cities, the same frequency can be used. In a large city, on the other hand, frequency-reuse could certainly be in use. Recently also orthogonal frequency-division multiple access based systems such as LTE are being deployed with a frequency reuse of 1. Since such systems do not spread the signal across the frequency band, inter-cell radio resource management is important to coordinate resource allocation between different cell sites and to limit the inter-cell interference. There are various means of Inter-cell Interference Coordination (ICIC) already defined in the standard. Coordinated scheduling, multi-site MIMO or multi-site beam forming are other examples for inter-cell radio resource management that might be standardized in the future.

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones. It became the de facto global standard for mobile communications with over 80% market share. The GSM standard was developed as a replacement for first generation (1G) analog cellular networks, and originally described a digital, circuit switched network optimized for full duplex voice telephony. This was expanded over time to include data communications, first by circuit switched transport, then packet data transport via GPRS (General Packet Radio Services) and EDGE (Enhanced Data rates for GSM Evolution or EGPRS). Further improvements were made when the 3GPP developed third generation (3G) UMTS standards followed by fourth generation (4G) LTE Advanced standards. "GSM" is a trademark owned by the GSM Association. History [edit] Early European analog cellular networks consisted of a mix of technologies and protocols that varied from country to country, meaning that phones did not necessarily work on different networks. In addition, manufacturers had to produce different equipment to meet various standards across the markets. In 1982, work began to develop a European standard for digital cellular voice telephony when the European Conference of Postal and Telecommunications Administrations (CEPT) created the Groupe Spécial Mobile committee and later provided a permanent group of technical support personnel, based in Paris. Five years later in 1987, 15 representatives from 13 European countries signed a memorandum of understanding in Copenhagen to develop and deploy a common cellular telephone system across Europe, and European Union rules were passed to make GSM a mandatory standard. The decision to develop a continental standard eventually resulted in a unified, open, standard-based network which was larger than that in the United States. In 1989, the Groupe Spécial Mobile committee was transferred from CEPT to the European Telecommunications Standards Institute (ETSI). In 1987 Europe produced the very first agreed GSM Technical Specification (February). Ministers from the 4 big EU countries cemented their political support for GSM with the Bonn Minister’s Declaration (May) and the GSM MoU was tabled for signature (September). The MoU drew-in mobile operators from across Europe to pledge to invest in new GSM networks to an ambitious common date. It got GSM up and running fast. |quote=Before GSM, Europe had a disastrous mishmash of national analogue standards in phones and TV, designed to protect national industries but instead creating fragmented markets vulnerable to big guns from abroad.}}[3][4][5] In 1989, the Groupe Spécial Mobile committee was transferred from CEPT to the European Telecommunications Standards Institute (ETSI). In parallel, France and Germany signed a joint development agreement in 1984 and were joined by Italy and the UK in 1986. In 1986 the European Commission proposed reserving the 900 MHz spectrum band for GSM. Phase I of the GSM specifications were published in 1990. The world's first GSM call was made by the former Finnish prime minister Harri Holkeri to Kaarina Suonio (mayor in city of Tampere) on 1 July 1991 on a network built by Telenokia and Siemens and operated by Radiolinja. The following year in 1992, the first short messaging service (SMS or "text message") message was sent and Vodafone UK and Telecom Finland signed the first international roaming agreement. Work began in 1991 to expand the GSM standard to the 1800 MHz frequency band and the first 1800 MHz network became operational in the UK by 1993. Also that year, Telecom Australia became the first network operator to deploy a GSM network outside Europe and the first practical hand-held GSM mobile phone became available. In 1995, fax, data and SMS messaging services were launched commercially, the first 1900 MHz GSM network became operational in the United States and GSM subscribers worldwide exceeded 10 million. Also this year, the GSM Association was formed. Pre-paid GSM SIM cards were launched in 1996 and worldwide GSM subscribers passed 100 million in 1998. In 2000, the first commercial GPRS services were launched and the first GPRS compatible handsets became available for sale. In 2001 the first UMTS (W-CDMA) network was launched and worldwide GSM subscribers exceeded 500 million. In 2002 the first multimedia messaging services (MMS) were introduced and the first GSM network in the 800 MHz frequency band became operational. EDGE services first became operational in a network in 2003 and the number of worldwide GSM subscribers exceeded 1 billion in 2004. By 2005, GSM networks accounted for more than 75% of the worldwide cellular network market, serving 1.5 billion subscribers. In 2005, the first HSDPA capable network also became operational. The first HSUPA network was launched in 2007 and worldwide GSM subscribers exceeded two billion in 2008. The GSM Association estimates that technologies defined in the GSM standard serve 80% of the global mobile market, encompassing more than 5 billion people across more than 212 countries and territories, making GSM the most ubiquitous of the many standards for cellular networks.[7] Macau planned to phase out their GSM networks on June 4, 2015, making it the first region to decommission a GSM network.[8] GSM carrier frequencies [edit] Main article: GSM frequency bands GSM networks operate in a number of different carrier frequency ranges (separated into GSM frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networks operating in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the 850 MHz and 1900 MHz bands were used instead (for example in Canada and the United States). In rare cases the 400 and 450 MHz frequency bands are assigned in some countries because they were previously used for first-generation systems. Most 3G networks in Europe operate in the 2100 MHz frequency band. For more information on worldwide GSM frequency usage, see GSM frequency bands. Regardless of the frequency selected by an operator, it is divided into timeslots for individual phones to use. This allows eight full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame. Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8 channels is 270.833 kbit/s, and the frame duration is 4.615 ms. The transmission power in the handset is limited to a maximum of 2 watts in GSM 850/900 and 1 watt in GSM 1800/1900. Voice codecs [edit] GSM has used a variety of voice codecs to squeeze 3.1 kHz audio into between 6.5 and 13 kbit/s. Originally, two codecs, named after the types of data channel they were allocated, were used, called Half Rate (6.5 kbit/s) and Full Rate (13 kbit/s). These used a system based upon linear predictive coding (LPC). In addition to being efficient with bitrates, these codecs also made it easier to identify more important parts of the audio, allowing the air interface layer to prioritize and better protect these parts of the signal.as GSM was further enhanced in 1997 with the Enhanced Full Rate (EFR) codec, a 12.2 kbit/s codec that uses a full rate channel. Finally, with the development of UMTS, EFR was refactored into a variable-rate codec called AMR-Narrowband, which is high quality and robust against interference when used on full rate channels, or less robust but still relatively high quality when used in good radio conditions on half-rate channels. Subscriber Identity Module (SIM) [edit] Main article: Subscriber Identity Module One of the key features of GSM is the Subscriber Identity Module, commonly known as a SIM card. The SIM is a detachable smart card containing the user's subscription information and phone book. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this practice is known as SIM locking. Phone locking [edit] Main article: SIM lock Sometimes mobile network operators restrict handsets that they sell for use with their own network. This is called locking and is implemented by a software feature of the phone. A subscriber may usually contact the provider to remove the lock for a fee, utilize private services to remove the lock, or make use of free or fee-based software and websites to unlock the handset themselves. Unlocking a phone without an operator's consent is illegal in many countries and may carry severe penalties. In some countries (e.g., Bangladesh, Brazil, Chile, Hong Kong, India, Lebanon, Malaysia, Pakistan, Singapore) all phones are sold unlocked. In others (e.g., Singapore) it is unlawful for operators to offer any form of subsidy on a phone's price. GSM service security [edit] See also: UMTS security GSM was designed with a moderate level of service security. The system was designed to authenticate the subscriber using a pre-shared key and challenge-response. Communications between the subscriber and the base station can be encrypted. The development of UMTS introduces an optional Universal Subscriber Identity Module (USIM), that uses a longer authentication key to give greater security, as well as mutually authenticating the network and the user – whereas GSM only authenticates the user to the network (and not vice versa). The security model therefore offers confidentiality and authentication, but limited authorization capabilities, and no non-repudiation. GSM uses several cryptographic algorithms for security. The A5/1, A5/2 and A5/3 stream ciphers are used for ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within Europe and the United States; A5/2 is weaker and used in other countries. Serious weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time with a ciphertext-only attack, and in January 2007, The Hacker's Choice started the A5/1 cracking project with plans to use FPGAs that allow A5/1 to be broken with a rainbow table attack. The system supports multiple algorithms so operators may replace that cipher with a stronger one. On 28 December 2009 German computer engineer Karsten Nohl announced that he had cracked the A5/1 cipher. According to Nohl, he developed a number of rainbow tables (static values which reduce the time needed to carry out an attack) and have found new sources for known plaintext attacks. He also said that it is possible to build "a full GSM interceptor ... from open source components" but that they had not done so because of legal concerns. Nohl claimed that he was able to intercept voice and text conversations by impersonating another user to listen to their voice mails, make calls or send text messages using a seven-year-old Motorola cellphone and decryption software available free off the Internet. New attacks have been observed that take advantage of poor security implementations, architecture and development for smart phone applications. Some wiretapping and eavesdropping techniques hijack the audio input and output providing an opportunity for a 3rd party to listen in to the conversation. GSM uses General Packet Radio Service (GPRS) for data transmissions like browsing the web. The most commonly deployed GPRS ciphers were publicly broken in 2011. The researchers revealed flaws in the commonly used GEA/1 and GEA/2 ciphers and published the open source "gprsdecode" software for sniffing GPRS networks. They also noted that some carriers don't encrypt the data at all (i.e. using GEA/0) in order to detect the use of traffic or protocols they don't like, e.g. Skype, leaving their customers unprotected. GEA/3 seems to remain relatively hard to break and is said to be in use on some more modern networks. If used with USIM to prevent connections to fake base stations and downgrade attacks, users will be protected in the medium term, though migration to 128-bit GEA/4 is still recommended.

A mobile phone signal (or reception) is the signal strength (measured in dBm) of the connection to the
mobile phone with its network. Depending on various factors, such as proximity to a tower, obstructions such as buildings or trees, etc., the signal may vary. Most mobile devices use a set of bars of varying heights to display the strength of the signal where the device is located. Traditionally five bars are used; see five by five. Generally, a stronger mobile phone signal is easy to obtain in an urban area, though urban areas do have some "dead zones" where no reception can be obtained. On the contrary, many rural or minimally inhabited areas lack a signal or have a very weak reception; many mobile phone providers are attempting to set up towers in parts of these areas most likely to be occupied by users, such as along major highways. Even some national parks and other popular tourist destinations away from urban areas now have cell phone receptions. In an area where the signal would normally be strong, certain other factors may have an effect on the reception, thereby making it either stronger or weaker, or may cause complete interference. For example, a building with thick walls may prevent a mobile phone from being used. Many underground areas, such as tunnels and subway stations, lack a reception. Additionally, the weather and volume of network traffic may impact the strength.

Dead zones Areas where mobile phones cannot transmit to a nearby mobile site, base station, or repeater are known as dead zones. In these areas, the mobile phone is said to be in a state of outage. Dead zones are usually areas where mobile phone service is not available because the signal between the handset and mobile site antennas is blocked, usually by hilly terrain, excessive foliage, or physical distance. A number of factors can create dead zones which may exist even in locations in which a wireless carrier offers coverage, due to limitations in cellular/Mobile network architecture (the locations of antennas), limited network density, interference with other mobile sites, and topography. Since cell phones rely on radio waves, and radio waves travel though the air and are easily attenuated, mobile phones may be unreliable at times. Like other radio transmissions, mobile phone calls can be interrupted by large buildings, terrain, trees, or other objects between the phone and the nearest base station antennas. Many wireless service providers work continually to improve and upgrade their networks in order to minimize dropped calls, access failures, and dead zones (which they call "coverage holes" or "no-service areas"). Dropped calls [edit] Dropped call is the common term for a wireless mobile phone call that is terminated unexpectedly as a result of technical reasons, including presence in a dead zone. One reason for a dropped call is when the mobile phone moves out of range of a wireless network. An active call cannot usually be maintained across a different company's network (as calls cannot be re-routed over the traditional phone network while in progress), resulting in the termination of the call once a signal cannot be maintained between the phone and the original network. Another common reason is when a phone is taken into an area where wireless communication is unavailable, interrupted, interfered with, or jammed. From the network's perspective, this is the same as the mobile moving out of the coverage area. Occasionally, calls are dropped upon handoff between cells within the same provider's network. This may be due to an imbalance of traffic between the two cell sites' areas of coverage. If the new cell site is at capacity, it cannot accept the additional traffic of the call trying to "hand in." It may also be due to the network configuration not being set up properly, such that one cell site is not "aware" of the cell to which the phone is trying to handoff. If the phone cannot find an alternative cell to which to move that can take over the call, the call is lost. Co-channel and Adjacent channel interference can also be responsible for dropped calls in a wireless network. Neighbour cells with the same frequencies interfere with each other, deteriorating the quality of service and producing dropped calls. Transmission problems are also a common cause of dropped calls. Another problem may be a faulty transceiver (XCVR) inside the base station. Calls can also be dropped if a mobile phone at the other end of the call loses battery power and stops transmitting abruptly. Sun spots and solar flares are rarely blamed for causing interference leading to dropped calls. Experiencing too many dropped calls is one of the most common customer complaints received by wireless service providers. They have attempted to address the complaint in various ways, including expansion of their home network coverage, increased cell capacity, and offering refunds for individual dropped calls. Various signal booster systems are manufactured to reduce problems due to dropped calls and dead zones. Many options, such as wireless units and antennas, are intended to aid in strengthening weak signals. ASU [edit] Arbitrary Strength Unit (ASU) is an integer value proportional to the received signal strength measured by the mobile phone. It is possible to calculate the real signal strength measured in dBm (and thereby power in Watts) by a formula. However, there are different formulas for 2G and 3G networks. In GSM networks, ASU is equal to the RSSI (received signal strength indicator, see TS 27.007 sub clause 8.5). dBm = 2 × ASU - 113, ASU in the range of 0..31 and 99 (for not known or not detectable) In UMTS networks, ASU is equal the RSCP level (received signal code power, see TS 27.007 sub clause 8.69 and TS 27.133 sub clause 9.1.1.3) dBm = ASU - 116, ASU in the range of -5..91 and 255 (for not known or not detectable) It is widely disbelieved[by whom?] that ASU = "Active Set update". The Active Set Update is a signalling message used in handover procedures of UMTS and CDMA mobile telephony standards. On Android phones, the acronym ASU has nothing to do with Active Set Update. It has not been declared precisely by Google developers.

Is a mobile phone which is able to capture still photographs (and usually video). Since early in the 21st century the majority of mobile phones in use are camera phones.

Most camera phones are simpler than separate digital cameras. Their usual fixed focus lenses and smaller sensors limit their performance in poor lighting. Lacking a physical shutter, most have a long shutter lag. Flash, where present, is usually weak. Optical zoom and tripod screws are rare. Some also lack a USB connection, removable memory card, or other way of transferring their pictures more quickly than by the phone's inherent communication feature.

Some of the more expensive camera phones have only a few of these technical disadvantages, which apply most acutely in low light conditions and in any case have not inhibited their widespread use. Most model lines improve in these regards every year or two. Some, such as the Droid Incredible only have a menu choice to start an application program to activate the camera. Others, such as the BlackBerry Storm 2, Droid X, Motorola V980 and Nokia 5800 also have a separate camera button for quickness and convenience. Windows Phones can be configured to operate as a camera even if the phone is asleep. Some camera phones are designed to resemble separate low-end digital compact cameras in appearance and to some extent in features and picture quality, and are branded as both mobile phones and cameras, including certain Sony phones.

The principal advantages of camera phones are cost and compactness; indeed for a user who carries a mobile phone anyway, the additional size and cost are negligible. Smartphones that are camera phones may run mobile applications to add capabilities such as geotagging and image stitching. A few high end phones can use their touch screen to direct their camera to focus on a particular object in the field of view, giving even an inexperienced user a degree of focus control exceeded only by seasoned photographers using manual focus.

The camera phone, like many complex systems, is the result of converging and enabling technologies. There are dozens of relevant patents dating back as far as 1956. Compared to digital cameras of the 1990s, a consumer-viable camera in a mobile phone would require far less power and a higher level of camera electronics integration to permit the miniaturization.

The CMOS active pixel sensor "camera-on-a-chip" developed by Dr. Eric Fossum and his team in the early 1990s achieved the first step of realizing the modern camera phone as described in a March 1995 Business Week article. While the first camera phones, as successfully marketed by J-Phone in Japan, used CCD sensors and not CMOS sensors, more than 90% of camera phones sold today use CMOS image sensor technology.

Over the years there have been many videophones and cameras that have included communication capability. Some devices experimented with integration of the device to communicate wirelessly with Internet, which would allow instant media sharing with anyone anywhere. For example, in 1995 Apple experimented with the Apple Videophone/PDA. There were several digital cameras with cellular phone transmission capability shown by companies such as Kodak, Olympus in the early 1990s. There was also a digital camera with cellular phone designed by Shosaku Kawashima of Canon in Japan in May 1997.

On June 11, 1997, Philippe Kahn shared instantly the first pictures from the maternity ward where his daughter Sophie was born. He wirelessly transmitted his cell phone pictures to more than 2,000 family, friends and associates around the world. Kahn's wireless sharing software and camera integrated into his cell phone augured the birth of instant visual communications. Kahn's cell phone transmission is the first known publicly shared picture via a cell phone.

In Japan, two competing projects were run by Sharp and Kyocera in 1997. Both had cell phones with integrated cameras. However, the Kyocera system was designed as a peer-to-peer video-phone as opposed to the Sharp project which was initially focused on sharing instant pictures. That was made possible when the Sharp devices was coupled to the Sha-mail infrastructure designed in collaboration with American technologist, Kahn. The Kyocera team was led by Mr. Kazumi Saburi.

In 1995, work by James Greenwold of Bureau Of Technical Services, in Chippewa Falls, WI, was developing a pocket video camera for surveillance purposes. By 1999, the Tardis recorder was in prototype and being used by the government. Bureau Of Technical Services, advanced further by the patent # 6,845,215,B1 on Body-Carryable, digital Storage medium, Audio/Video recording Assembly.

Cameras on cell phones proved popular right from the start, as indicated that the J-Phone in Japan had more than half of its subscribers using cell phone cameras in two years. The world soon followed. By 2003, more camera phones were sold worldwide than stand-alone digital cameras. In 2005, Nokia became the world's most sold digital camera brand. In 2006, half of the world's mobile phones had a built-in camera.

In 2006, Thuraya released the first satellite phone with an integrated camera. The Thuraya SG-2520 was manufactured by a Korean company called APSI and ran Windows CE.

By 2007, the first cell phones and other consumer products appeared using the Tardis technology to make the move from still cameras to full motion video.

In 2008, Nokia sold more camera phones than Kodak sold film based simple cameras, thus becoming the biggest manufacturer of any kind of camera.

In 2010, the worldwide number of camera phones totaled more than a billion. Most mobile phones, even inexpensive ones, were being sold with a camera. High end camera phones usually had a relatively good lens and high resolution, but a small sensor.

Twelve-megapixel camera phones have been produced by at least two companies. To highlight the capabilities of the Nokia N8 (Big CMOS Sensor) camera, Nokia created a short film, The Commuter, in October 2010. The seven-minute film was shot entirely on the phone's 720p camera. A 14 megapixel smartphone with 3x optical zoom was announced in 2010.

In 2012, Nokia announced Nokia 808 PureView. It features a 41 megapixel 1/1.2" sensor and a high resolution f/2.4 Zeiss all-aspherical 1-group lens. It also features Nokia's PureView Pro technology, a pixel oversampling technique that reduces an image taken at full resolution into a lower resolution picture, thus achieving higher definition and light sensitivity, and enables lossless zoom.

Text messaging, or texting, is the act of typing and sending a brief, electronic message between two or more mobile phones or fixed or portable devices over a phone network. The term originally referred to messages sent using the Short Message Service (SMS); it has grown to include messages

containing image, video, and sound content (known as MMS messages. The sender of a text message is known as a texter, while the service itself has different colloquialisms depending on the region. It may simply be referred to as a text in North America, the United Kingdom, Australia and the Philippines, an SMS in most of mainland Europe, and a TMS or SMS in the Middle East and Asia. Text messages can be used to interact with automated systems to, for example, order products or services, or participate in contests. Advertisers and service providers use direct text marketing to message mobile phone users about promotions, payment due dates, etcetera instead of using mail, e-mail or voicemail. In a straight and concise definition for the purposes of this English Language article, text messaging by phones or mobile phones should include all 26 letters of the alphabet and 10 numerals, i.e., alpha-numeric messages, or text, to be sent by texter or received by the textee. History 1920 – RCA Communications, New York introduced the first "telex" service.[citation needed] The first messages over RCA transatlantic circuits were sent between New York and London. Seven million words or 300,000 radiograms transmitted the first year. RCA today is known as Verizon Wireless.[citation needed] Alphanumeric messages have long been sent by radio using via Radiotelegraphy. Digital information began being sent using radio as early as 1971 by the University of Hawaii using ALOHAnet.[citation needed] Matti Makkonen has been referred to in different contexts as the "father of text messaging" but he rejects this epithet. "The SMS function is the result of extensive and open international cooperation, and GSM documents prove that it is based on the Franco-German proposal," he says. This proposal was developed by Friedhelm Hillebrand and Bernard Ghillebaert. The first technical solution was developed in a GSM subgroup under the leadership of Finn Trosby. It was further developed under the leadership of Kevin Holley and Ian Harris (see Wikipedia: Short Message Service).[1] SMS messaging was used for the first time on 3 December 1992, when Neil Papworth, a 22-year-old test engineer for Sema Group in the UK[2] (now Airwide Solutions), used a personal computer to send the text message "Merry Christmas" via the Vodafone network to the phone of Richard Jarvis. Modern SMS text messaging is understood to be messaging from one mobile phone to another mobile phone. Radiolinja became the first network to offer commercial person-to-person SMS text messaging service in 1994. When Radiolinja's domestic competitor, Telecom Finland (now part of TeliaSonera) also launched SMS text messaging in 1995 and the two networks offered cross-network SMS functionality, Finland became the first nation where SMS text messaging was offered as a competitive as well as commercial basis.[citation needed] The first text messaging service in the United States was provided by Omnipoint Communications, the first GSM carrier in America.[citation needed] George Schmitt, a former Airtouch executive who launched commercial GSM in Germany, lead a team that introduced texting as a commercial service in New York CIty in 1996. Omnipoint soon offered the first texting between the U.S. and the rest of the world.[citation needed] Initial growth of text messaging was slow, with customers in 1995 sending on average only 0.4 message per GSM customer per month. One factor in the slow take-up of SMS was that operators were slow to set up charging systems, especially for prepaid subscribers, and eliminate billing fraud, which was possible by changing SMSC settings on individual handsets to use the SMSCs of other operators. Over time, this issue was eliminated by switch-billing instead of billing at the SMSC and by new features within SMSCs to allow blocking of foreign mobile users sending messages through it.[citation needed] SMS is available on a wide range of networks, including 3G networks. However, not all text messaging systems use SMS, and some notable alternate implementations of the concept include J-Phone's SkyMail and NTT Docomo's Short Mail, both in Japan. E-mail messaging from phones, as popularized by NTT Docomo's i-mode and the RIM BlackBerry, also typically use standard mail protocols such as SMTP over TCP/IP.[citation needed] Today, text messaging is the most widely used mobile data service, with 74% of all mobile phone users worldwide, or 2.4 billion out of 3.3 billion phone subscribers, at end of 2007 being active users of the Short Message Service. In countries such as Finland, Sweden and Norway, over 85% of the population use SMS. The European average is about 80%, and North America is rapidly catching up with over 60% active users of SMS by end of 2008. The largest average usage of the service by mobile phone subscribers is in the Philippines, with an average of 27 texts sent per day by subscriber. Message format Standard SMS messaging uses 140 bytes (octets) per message, which translates to 160 characters (7 bits bytes) of the English alphabet using 7-bit encoding or as few as 70 characters for languages using non-Latin alphabets using UTF-16 encoding. (The commonly cited limit of 140 characters is imposed by some services like Twitter that reserve 20 characters for non-message content, like addressing.)

Android is a Linux-based operating system designed primarily for touchscreen mobile devices such as smartphones and tablet computers. Initially developed by Android, Inc., which Google backed financially and later bought in 2005, Android was unveiled in 2007 along with the founding of the Open Handset Alliance: a consortium of hardware, software, and telecommunication companies devoted to advancing open standards for mobile devices. The first Android-powered phone was sold in October 2008. Android is open source and Google releases the code under the Apache License. This open source code and permissive licensing allows the software to be freely modified and distributed by device manufacturers, wireless carriers and enthusiast developers. Additionally, Android has a large community of developers writing applications ("apps") that extend the functionality of devices, written primarily in a customized version of the Java programming language. In October 2012, there were approximately 700,000 apps available for Android, and the estimated number of applications downloaded from Google Play, Android's primary app store, was 25 billion. These factors have contributed towards making Android the world's most widely used smartphone platform, overtaking Symbian in the fourth quarter of 2010, and the software of choice for technology companies who require a low-cost, customizable, lightweight operating system for high tech devices without developing one from scratch. As a result, despite being primarily designed for phones and tablets, it has seen additional applications on televisions, games consoles, digital cameras and other electronics. Android's open nature has further encouraged a large community of developers and enthusiasts to use the open source code as a foundation for community-driven projects, which add new features for advanced users or bring Android to devices which were officially released running other operating systems. Android had a worldwide smartphone market share of 75% during the third quarter of 2012, with 750 million devices activated in total and 1.5 million activations per day. The operating system's success has made it a target for patent litigation as part of the so-called "smartphone wars" between technology companies. Contents [hide]

1 History

2 Description

2.1 Interface

2.2 Applications

3 Development

3.1 Linux

3.2 Memory management

3.3 Update schedule

3.4 Open source community

4 Security and privacy

5 Licensing

5.1 Non-free software

6 Reception

6.1 Tablets

6.2 Market share and rate of adoption

6.3 Usage share of Android versions

6.4 Application piracy

7 Copyrights and patents

8 Beyond smartphones and tablets

9 See also

10 References

11 External links History Android

Inc. was founded in Palo Alto, California in October 2003 by Andy Rubin (co-founder of Danger), Rich Miner (co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile),[30] and Chris White (headed design and interface development at WebTV) to develop, in Rubin's words "smarter mobile devices that are more aware of its owner's location and preferences". The early intentions of the company were to develop an advanced operating system for digital cameras, when it was realised that the market for the devices was not large enough, and diverted their efforts to producing a smartphone operating system to rival those of Symbian and Windows Mobile (Apple's iPhone had not been released at the time). Despite the past accomplishments of the founders and early employees, Android Inc. operated secretly, revealing only that it was working on software for mobile phones. That same year, Rubin ran out of money. Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope and refused a stake in the company. Google acquired Android Inc. on August 17, 2005, making it a wholly owned subsidiary. Key employees of Android Inc., including Rubin, Miner and White, stayed at the company after the acquisition. Not much was known about Android Inc. at the time, but many assumed that Google was planning to enter the mobile phone market with this move. At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel. marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradable system. had lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part. Speculation about Google's intention to enter the mobile communications market continued to build through December 2006. Reports from the BBC and the Wall Street Journal noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that was developing a Google-branded handset. Some speculated that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators. In September 2007, InformationWeek covered an Evalueserve study reporting that Google had filed several patent applications in the area of mobile telephony. On November 5, 2007, the Open Handset Alliance, a consortium of technology companies including Google, device manufacturers such as HTC and Samsung, wireless carriers such as Sprint Nextel and T-Mobile, and chipset makers such as Qualcomm and Texas Instruments, unveiled itself, with a goal to develop open standards for mobile devices. That day, Android was unveiled as its first product, a mobile device platform built on the Linux kernel version 2.6. The first commercially available phone to run Android was the HTC Dream, released on October 22, 2008. Since 2008, Android has seen numerous updates which have incrementally improved the operating system, adding new features and fixing bugs in previous releases. Each major release is named in alphabetical order after a dessert or sugary treat; for example, version 1.5 Cupcake was followed by 1.6 Donut. The latest release is 4.2 Jelly Bean. In 2010, Google launched its Nexus series of devices—a line of smartphones and tablets running the Android operating system, and built by a manufacturer partner. HTC collaborated with Google to release the first Nexus smartphone, the Nexus One. The series has since been updated with newer devices, such as the Nexus 4 phone and Nexus 10 tablet, made by LG and Samsung, respectively. Google releases the Nexus phones and tablets to act as their flagship Android devices, demonstrating Android's latest software and hardware features. On 13 March 2013, it was announced by Larry Page in a blog post that Andy Rubin had moved from the Android division to take on new projects at Google. He was replaced by Sundar Pichai, who also continues his role as the head of Google's Chrome division, which develops Chrome OS. Description See also: List of features in Android and Android version history Interface Android's user interface is based on direct manipulation, using touch inputs that loosely correspond to real-world actions, like swiping, tapping, pinching and reverse pinching to manipulate on-screen objects. The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel. Android devices boot to the homescreen, the primary navigation and information point on the device, which is similar to the desktop found on PCs. Android homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content such as the weather forecast, the user's email inbox, or a news ticker directly on the homescreen. A homescreen may be made up of several pages that the user can swipe back and forth between, though Android's homescreen interface is heavily customisable, allowing the user to adjust the look and feel of the device to their tastes. Third party apps available on Google Play and other app stores can extensively re-theme the homescreen, and even mimic the look of other operating systems, such as Windows Phone. Most manufacturers, and some wireless carriers, customise the look and feel of their Android devices to differentiate themselves from the competition. Present along the top of the screen is a status bar, showing information about the device and its connectivity. This status bar can be "pulled" down to reveal a notification screen where apps display important information or updates, such as a newly received email or SMS text, in a way that does not immediately interrupt or inconvenience the user. In early versions of Android these notifications could be tapped to open the relevant app, but recent updates have provided enhanced functionality, such as the ability to call a number back directly from the missed call notification without having to open the dialer app first. Notifications are persistent until read or dismissed by the user.