Mobile Phone

Jai Ganesh · 2025-12-08 21:59:23

Mobile Phone

Gist

A cell phone (or mobile phone) is a portable, wireless device that uses cellular networks (radio waves connecting to cell towers) for voice calls and data, evolving from simple phones to powerful smartphones with internet, apps, cameras, and more, replacing traditional phones for communication.

A cellphone, also known as a mobile phone, allows users to make and receive calls over a radio frequency network while on the move. Modern cellphones support additional services beyond calls such as texting, multimedia messaging, email, internet access, Bluetooth, apps, and photos.

Summary

A mobile phone or cell phone is a portable wireless telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones (landline phones). This radio frequency link connects to the switching systems of a mobile phone operator, providing access to the public switched telephone network (PSTN). Modern mobile telephony relies on a cellular network architecture, which is why mobile phones are often referred to as 'cell phones' in North America.

Beyond traditional voice communication, digital mobile phones have evolved to support a wide range of additional services. These include text messaging, multimedia messaging, email, and internet access (via LTE, 5G NR or Wi-Fi), as well as short-range wireless technologies like Bluetooth, infrared, and ultra-wideband (UWB).

Mobile phones also support a variety of multimedia capabilities, such as digital photography, video recording, and gaming. In addition, they enable multimedia playback and streaming, including video content, as well as radio and television streaming. Furthermore, mobile phones offer satellite-based services, such as navigation and messaging, as well as business applications and payment solutions (via scanning QR codes or near-field communication (NFC)). Mobile phones offering only basic features are often referred to as feature phones (slang: dumbphones), while those with advanced computing power are known as smartphones.

The first handheld mobile phone was demonstrated by Martin Cooper of Motorola in New York City on 3 April 1973, using a handset weighing c. 2 kilograms (4.4 lbs). In 1979, Nippon Telegraph and Telephone (NTT) launched the world's first cellular network in Japan. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1993 to 2024, worldwide mobile phone subscriptions grew to over 9.1 billion; enough to provide one for every person on Earth. In 2024, the top smartphone manufacturers worldwide were Samsung, Apple and Xiaomi; smartphone sales represented about 50 percent of total mobile phone sales. For feature phones as of 2016, the top-selling brands were Samsung, Nokia and Alcatel.

Mobile phones are considered an important human invention as they have been one of the most widely used and sold pieces of consumer technology. The growth in popularity has been rapid in some places; for example, in the UK, the total number of mobile phones overtook the number of houses in 1999. Today, mobile phones are globally ubiquitous, and in almost half the world's countries, over 90% of the population owns at least one.

Details

A cell phone is a wireless telephone that permits telecommunication within a defined area that may include hundreds of square miles, using radio waves in the 800–900 megahertz (MHz) band. To implement a cell-phone system, a geographic area is broken into smaller areas, or cells, usually mapped as uniform hexagrams but in fact overlapping and irregularly shaped. Each cell is equipped with a low-powered radio transmitter and receiver that permit propagation of signals between cell-phone users.

Cellular telephones, or simply cell phones, are portable devices that may be used in motor vehicles or by pedestrians. Communicating by radio waves, they permit a significant degree of mobility within a defined serving region that may range in area from a few city blocks to hundreds of square kilometres. The first mobile and portable subscriber units for cellular systems were large and heavy. With significant advances in component technology, though, the weight and size of portable transceivers have been significantly reduced. In this section, the concept of cell phones and the development of cellular systems are discussed.

Cellular communication

All cellular telephone systems exhibit several fundamental characteristics, as summarized in the following:

1) The geographic area served by a cellular system is broken up into smaller geographic areas, or cells. Uniform hexagons most frequently are employed to represent these cells on maps and diagrams; in practice, though, radio waves do not confine themselves to hexagonal areas, so the actual cells have irregular shapes.
2) All communication with a mobile or portable instrument within a given cell is made to a base station that serves the cell.
3) Because of the low transmitting power of battery-operated portable instruments, specific sending and receiving frequencies assigned to a cell may be reused in other cells within the larger geographic area. Thus, the spectral efficiency of a cellular system (that is, the uses to which it can put its portion of the radio spectrum) is increased by a factor equal to the number of times a frequency may be reused within its service area.
4) As a mobile instrument proceeds from one cell to another during the course of a call, a central controller automatically reroutes the call from the old cell to the new cell without a noticeable interruption in the signal reception. This process is known as handoff. The central controller, or mobile telephone switching office (MTSO), thus acts as an intelligent central office switch that keeps track of the movement of the mobile subscriber.
5) As demand for the radio channels within a given cell increases beyond the capacity of that cell (as measured by the number of calls that may be supported simultaneously), the overloaded cell is “split” into smaller cells, each with its own base station and central controller. The radio-frequency allocations of the original cellular system are then rearranged to account for the greater number of smaller cells.

Frequency reuse between discontiguous cells and the splitting of cells as demand increases are the concepts that distinguish cellular systems from other wireless telephone systems. They allow cellular providers to serve large metropolitan areas that may contain hundreds of thousands of customers.

Development of cellular systems

In the United States, interconnection of mobile transmitters and receivers with the public switched telephone network (PSTN) began in 1946, with the introduction of mobile telephone service (MTS) by the American Telephone & Telegraph Company (AT&T). In the U.S. MTS system, a user who wished to place a call from a mobile phone had to search manually for an unused channel before placing the call. The user then spoke with a mobile operator, who actually dialed the call over the PSTN. The radio connection was simplex—i.e., only one party could speak at a time, the call direction being controlled by a push-to-talk switch in the mobile handset. In 1964 AT&T introduced the improved mobile telephone service (IMTS). This provided full duplex operation, automatic dialing, and automatic channel searching. Initially 11 channels were provided, but in 1969 an additional 12 channels were made available. Since only 11 (or 12) channels were available for all users of the system within a given geographic area (such as the metropolitan area around a large city), the IMTS system faced a high demand for a very limited channel resource. Moreover, each base-station antenna had to be located on a tall structure and had to transmit at high power in order to provide coverage throughout the entire service area. Because of these high power requirements, all subscriber units in the IMTS system were motor-vehicle-based instruments that carried large storage batteries.

During this time a truly cellular system, known as the advanced mobile phone system, or AMPS, was developed primarily by AT&T and Motorola, Inc. AMPS was based on 666 paired voice channels, spaced every 30 kilohertz in the 800-megahertz region. The system employed an analog modulation approach—frequency modulation, or FM—and was designed from the outset to support subscriber units for use both in automobiles and by pedestrians. It was publicly introduced in Chicago in 1983 and was a success from the beginning. At the end of the first year of service, there were a total of 200,000 AMPS subscribers throughout the United States; five years later there were more than 2,000,000. In response to expected service shortages, the American cellular industry proposed several methods for increasing capacity without requiring additional spectrum allocations. One analog FM approach, proposed by Motorola in 1991, was known as narrowband AMPS, or NAMPS. In NAMPS systems each existing 30-kilohertz voice channel was split into three 10-kilohertz channels. Thus, in place of the 832 channels available in AMPS systems, the NAMPS system offered 2,496 channels. A second approach, developed by a committee of the Telecommunications Industry Association (TIA) in 1988, employed digital modulation and digital voice compression in conjunction with a time-division multiple access (TDMA) method; this also permitted three new voice channels in place of one AMPS channel. Finally, in 1994 there surfaced a third approach, developed originally by Qualcomm, Inc., but also adopted as a standard by the TIA. This third approach used a form of spread spectrum multiple access known as code-division multiple access (CDMA)—a technique that, like the original TIA approach, combined digital voice compression with digital modulation. (For more information on the techniques of information compression, signal modulation, and multiple access, see telecommunications.) The CDMA system offered 10 to 20 times the capacity of existing AMPS cellular techniques. All of these improved-capacity cellular systems were eventually deployed in the United States, but, since they were incompatible with one another, they supported rather than replaced the older AMPS standard.

Although AMPS was the first cellular system to be developed, a Japanese system was the first cellular system to be deployed, in 1979. Other systems that preceded AMPS in operation include the Nordic mobile telephone (NMT) system, deployed in 1981 in Denmark, Finland, Norway, and Sweden, and the total access communication system (TACS), deployed in the United Kingdom in 1983. A number of other cellular systems were developed and deployed in many more countries in the following years. All of them were incompatible with one another. In 1988 a group of government-owned public telephone bodies within the European Community announced the digital global system for mobile communications, referred to as GSM, the first such system that would permit any cellular user in one European country to operate in another European country with the same equipment. GSM soon became ubiquitous throughout Europe.

The analog cellular systems of the 1980s are now referred to as “first-generation” (or 1G) systems, and the digital systems that began to appear in the late 1980s and early ’90s are known as the “second generation” (2G). Since the introduction of 2G cell phones, various enhancements have been made in order to provide data services and applications such as Internet browsing, two-way text messaging, still-image transmission, and mobile access by personal computers. One of the most successful applications of this kind is iMode, launched in 1999 in Japan by NTT DoCoMo, the mobile service division of the Nippon Telegraph and Telephone Corporation. Supporting Internet access to selected Web sites, interactive games, information retrieval, and text messaging, iMode became extremely successful; within three years of its introduction, more than 35 million users in Japan had iMode-enabled cell phones.

Beginning in 1985, a study group of the Geneva-based International Telecommunication Union (ITU) began to consider specifications for Future Public Land Mobile Telephone Systems (FPLMTS). These specifications eventually became the basis for a set of “third-generation” (3G) cellular standards, known collectively as IMT-2000. The 3G standards are based loosely on several attributes: the use of CDMA technology; the ability eventually to support three classes of users (vehicle-based, pedestrian, and fixed); and the ability to support voice, data, and multimedia services. The world’s first 3G service began in Japan in October 2001 with a system offered by NTT DoCoMo. Soon 3G service was being offered by a number of different carriers in Japan, South Korea, the United States, and other countries. Several new types of service compatible with the higher data rates of 3G systems have become commercially available, including full-motion video transmission, image transmission, location-aware services (through the use of global positioning system [GPS] technology), and high-rate data transmission.

The increasing demands placed on mobile telephones to handle even more data than 3G could led to the development of 4G technology. In 2008 the ITU set forward a list of requirements for what it called IMT-Advanced, or 4G; these requirements included data rates of 1 gigabit per second for a stationary user and 100 megabits per second for a moving user. The ITU in 2010 decided that two technologies, LTE-Advanced (Long Term Evolution; LTE) and WirelessMan-Advanced (also called WiMAX), met the requirements. The Swedish telephone company TeliaSonera introduced the first 4G LTE network in Stockholm in 2009.

Airborne cellular systems

In addition to the terrestrial cellular phone systems described above, there also exist several systems that permit the placement of telephone calls to the PSTN by passengers on commercial aircraft. These in-flight telephones, known by the generic name aeronautical public correspondence (APC) systems, are of two types: terrestrial-based, in which telephone calls are placed directly from an aircraft to an en route ground station; and satellite-based, in which telephone calls are relayed via satellite to a ground station. In the United States the North American terrestrial system (NATS) was introduced by GTE Corporation in 1984. Within a decade the system was installed in more than 1,700 aircraft, with ground stations in the United States providing coverage over most of the United States and southern Canada. A second-generation system, GTE Airfone GenStar, employed digital modulation. In Europe the European Telecommunications Standards Institute (ETSI) adopted a terrestrial APC system known as the terrestrial flight telephone system (TFTS) in 1992. This system employs digital modulation methods and operates in the 1,670–1,675- and 1,800–1,805-megahertz bands. In order to cover most of Europe, the ground stations must be spaced every 50 to 700 km (30 to 435 miles).

Satellite-based telephone communication

In order to augment the terrestrial and aircraft-based mobile telephone systems, several satellite-based systems have been put into operation. The goal of these systems is to permit ready connection to the PSTN from anywhere on Earth’s surface, especially in areas not presently covered by cellular telephone service. A form of satellite-based mobile communication has been available for some time in airborne cellular systems that utilize Inmarsat satellites. However, the Inmarsat satellites are geostationary, remaining approximately 35,000 km (22,000 miles) above a single location on Earth’s surface. Because of this high-altitude orbit, Earth-based communication transceivers require high transmitting power, large communication antennas, or both in order to communicate with the satellite. In addition, such a long communication path introduces a noticeable delay, on the order of a quarter-second, in two-way voice conversations. One viable alternative to geostationary satellites would be a larger system of satellites in low Earth orbit (LEO). Orbiting less than 1,600 km (1,000 miles) above Earth, LEO satellites are not geostationary and therefore cannot provide constant coverage of specific areas on Earth. Nevertheless, by allowing radio communications with a mobile instrument to be handed off between satellites, an entire constellation of satellites can assure that no call will be dropped simply because a single satellite has moved out of range.

The first LEO system intended for commercial service was the Iridium system, designed by Motorola, Inc., and owned by Iridium LLC, a consortium made up of corporations and governments from around the world. The Iridium concept employed a constellation of 66 satellites orbiting in six planes around Earth. They were launched from May 1997 to May 1998, and commercial service began in November 1998. Each satellite, orbiting at an altitude of 778 kilometres (483 miles), had the capability to transmit 48 spot beams to Earth. Meanwhile, all the satellites were in communication with one another via 23-gigahertz radio “crosslinks,” thus permitting ready handoff between satellites when communicating with a fixed or mobile user on Earth. The crosslinks provided an uninterrupted communication path between the satellite serving a user at any particular instant and the satellite connecting the entire constellation with the gateway ground station to the PSTN. In this way, the 66 satellites provided continuous telephone communication service for subscriber units around the globe. However, the service failed to attract sufficient subscribers, and Iridium LLC went out of business in March 2000. Its assets were acquired by Iridium Satellite LLC, which continued to provide worldwide communication service to the U.S. Department of Defense as well as business and individual users.

Another LEO system, Globalstar, consisted of 48 satellites that were launched about the same time as the Iridium constellation. Globalstar began offering service in October 1999, though it too went into bankruptcy, in February 2002; a reorganized Globalstar LP continued to provide service thereafter.

Smartphone

Smartphone is a mobile telephone with a display screen (typically a liquid crystal display, or LCD), built-in personal information management programs (such as an electronic calendar and address book)), and an operating system (OS) that allows other computer software to be installed for Web browsing, email, music, video, and other applications. A smartphone may be thought of as a handheld computer integrated within a mobile telephone.

The first smartphone was designed by IBM and sold by BellSouth (formerly part of the AT&T Corporation) in 1993. It included a touchscreen interface for accessing its calendar, address book, calculator, and other functions. As the market matured and solid-state computer memory and integrated circuits became less expensive over the following decade, smartphones became more computer-like, and more advanced services, such as Internet access, became possible. Advanced services became ubiquitous with the introduction of the so-called third-generation (3G) mobile phone networks in 2001. Before 3G, most mobile phones could send and receive data at a rate sufficient for telephone calls and text messages. Using 3G, communication takes place at bit-rates high enough for sending and receiving photographs, video clips, music files, e-mails, and more. Most smartphone manufacturers license an operating system, such as Microsoft Corporation’s Windows Mobile OS, Symbian OS, Google’s Android OS, or Palm OS. Research in Motion’s BlackBerry and Apple Inc.’s iPhone have their own proprietary systems.

Smartphones contain either a keyboard integrated with the telephone number pad or a standard “QWERTY” keyboard for text messaging, e-mailing, and using Web browsers. “Virtual” keyboards can be integrated into a touch-screen design. Smartphones often have a built-in camera for recording and transmitting photographs and short videos. In addition, many smartphones can access Wi-Fi “hot spots” so that users can access VoIP (voice over Internet protocol) rather than pay cellular telephone transmission fees. The growing capabilities of handheld devices and transmission protocols have enabled a growing number of inventive and fanciful applications—for instance, “augmented reality,” in which a smartphone’s global positioning system (GPS) location chip can be used to overlay the phone’s camera view of a street scene with local tidbits of information, such as the identity of stores, points of interest, or real estate listings.

4G

4G refers to the fourth generation of cellular network technology, first introduced in the late 2000s and early 2010s. Compared to preceding third-generation (3G) technologies, 4G has been designed to support all-IP communications and broadband services, and eliminates circuit switching in voice telephony. It also has considerably higher data bandwidth compared to 3G, enabling a variety of data-intensive applications such as high-definition media streaming and the expansion of Internet of Things (IoT) applications.

The earliest deployed technologies marketed as "4G" were Long Term Evolution (LTE), developed by the 3GPP group, and Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX), based on IEEE specifications. These provided significant enhancements over previous 3G and 2G.

5G

5G, fifth-generation telecommunications technology. Introduced in 2019 and now globally deployed, 5G delivers faster connectivity with higher bandwidth and “lower latency” (shorter delay times), improving the performance of phone calls, streaming, videoconferencing, gaming, and business applications as well as the responsiveness of connected systems and mobile apps. 5G can double the download speeds for smartphones and improve performance considerably more for devices tied to the Internet of Things (IoT).

5G technology improves the data processing of more-advanced digital operations such as those tied to machine learning (ML), artificial intelligence (AI), virtual reality (VR), and augmented reality (AR), improving performance and the user experience alike. It also better supports autonomous vehicles, drones, and other robotic systems.

How 5G works

5G signals rely on a different part of the radiofrequency spectrum than previous versions of cellular technology. As a result, mobile phones and other devices must be built with a specific 5G microchip.

Three primary types of 5G technology exist: low-band networks that support a wide coverage area but increase speeds only by about 20 percent over 4G; high-band networks that deliver ultrafast connectivity but which are limited by distance and access to 5G base stations (which transmit the signals for the technology); and mid-band networks that balance both speed and breadth of coverage. 5G also supports “OpenRoaming” capabilities that allow a user to switch seamlessly and automatically from a cellular to a Wi-Fi connection while traveling, eliminating any interruption of service and the need for entering passwords to access the latter.

Telecom providers use a different type of antenna, known as MIMO (multiple-input multiple-output), to transmit 5G signals. This does not require the traditional large cell tower (base station) but can be deployed through a multiplicity of “small cells” (which are the micro boxes commonly seen on poles and lamp posts). Many observers see this as an aesthetic improvement to the city landscape. Proximity to these cells remains an issue globally, however, especially for rural and remote regions, underscoring the current limitations of 5G.

Security concerns accompany changing technologies. Since 5G networks rely on cloud-based data storage, they are susceptible to the same possible dangers as other types of cellar and noncellular networks, including data damage, cyberattacks, and theft. Additionally, companies must be mindful of data-point vulnerabilities during a transition to 5G from networks with different security capabilities.

How 5G is used

Besides the use of 5G for voice communications, the technology supports advanced IoT functionality. For example, 5G enables more-sophisticated smart home technology, including locks, lights, and appliances; more-advanced smart medical devices, such as blood sugar and blood pressure monitors; and enhanced retail experiences, facilitating such novelties as virtual product demonstrations and “phygital” shopping (blending the ease of online buying with the in-store experience).

5G technology can potentially enhance every field of work. Urban planners creating smart cities, for example, can move from magnetic loops embedded in roads for detecting vehicles (and triggering traffic signals and opening gates) to more efficient and cost-effective wireless cameras equipped with AI. Municipal trash collection can operate on demand, concentrating on key trash areas and at optimal times, instead of operating according to a schedule divorced from real-time needs. Inexpensive connected sensors can allow farmers to monitor water and soil nutrients remotely (and more frequently), while architects and engineers can more efficiently view information about infrastructure systems and operations, all done remotely on their smartphones or tablets; they can even contribute to site construction and building maintenance in real time through augmented-reality software. 5G can enable and enhance remote worker training, especially in fields with crippling worker shortages that result from frequent employee turnover and long training periods, as is common in emergency fields and medicine. Virtual reality, for instance, is common in training firefighters today, and emergency medical technicians (EMTs) can not only stay in better contact with 911 call centres and emergency rooms but also receive more efficient and effective interactive training, delivered to their personal phones and tablets, through ultrarealistic emergency simulations, all enabled through high-speed low-latency 5G technology.

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#1 2025-12-08 21:59:23

Mobile Phone

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