Wireless

Wireless communication, or sometimes simply wireless, is the transfer of information or power between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound.

The term wireless has been used twice in communications history, with slightly different meaning. It was initially used from about 1890 for the first radio transmitting and receiving technology, as in wireless telegraphy, until the new word radio replaced it around 1920. The term was revived in the 1980s and 1990s mainly to distinguish digital devices that communicate without wires, such as the examples listed in the previous paragraph, from those that require wires or cables. This became its primary usage in the 2000s, due to the advent of technologies such as mobile broadband, Wi-Fi and Bluetooth.

Wireless operations permit services, such as long-range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls, etc.) which use some form of energy (e.g. radio waves, acoustic energy,) to transfer information without the use of wires.[1][2][3] Information is transferred in this manner over both short and long distances.

History

Photophone

Photophony1
Bell and Tainter's photophone, of 1880.

The world's first wireless telephone conversation occurred in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams (which are narrow projections of electromagnetic waves). In that distant era, when utilities did not yet exist to provide electricity and lasers had not even been imagined in science fiction, there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather. Similar to free-space optical communication, the photophone also required a clear line of sight between its transmitter and its receiver. It would be several decades before the photophone's principles found their first practical applications in military communications and later in fiber-optic communications.[4][5]

Electricity based wireless

Early wireless

A number of wireless electrical signaling schemes including sending electric currents through water and the ground using electrostatic and electromagnetic induction were investigated for telegraphy in the late 19th century before practical radio systems became available. These included a patented induction system by Thomas Edison allowing a telegraph on a running train to connect with telegraph wires running parallel to the tracks, a William Preece induction telegraph system for sending messages across bodies of water, and several operational and proposed telegraphy and voice earth conduction systems.

The Edison system was used by stranded trains during the Great Blizzard of 1888 and earth conductive systems found limited use between trenches during World War I but these systems were never successful economically.

Radio waves

Guglielmo Marconi 1901 wireless signal
Marconi transmitting the first radio signal across the Atlantic.

In 1894, Guglielmo Marconi began developing a wireless telegraph system using radio waves, which had been known about since proof of their existence in 1888 by Heinrich Hertz, but discounted as communication format since they seemed, at the time, to be a short range phenomenon.[6] Marconi soon developed a system that was transmitting signals way beyond distances anyone could have predicted (due in part to the signals bouncing off the then unknown ionosphere). Guglielmo Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to this form of wireless telegraphy.

Modes

Wireless communications can be via:

Radio

Radio and microwave communication carry information by modulating properties of electromagnetic waves transmitted through space.

Free-space optical

FSO-gigabit-laser-link-0a
An 8-beam free space optics laser link, rated for 1 Gbit/s at a distance of approximately 2 km. The receptor is the large disc in the middle, the transmitters the smaller ones. To the top and right corner a monocular for assisting the alignment of the two heads.

Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to transmit wirelessly data for telecommunications or computer networking. "Free space" means the light beams travel through the open air or outer space. This contrasts with other communication technologies that use light beams traveling through transmission lines such as optical fiber or dielectric "light pipes".

The technology is useful where physical connections are impractical due to high costs or other considerations. For example, free space optical links are used in cities between office buildings which are not wired for networking, where the cost of running cable through the building and under the street would be prohibitive. Another widely used example is consumer IR devices such as remote controls and IrDA (Infrared Data Association) networking, which is used as an alternative to WiFi networking to allow laptops, PDAs, printers, and digital cameras to exchange data.

Sonic

Sonic, especially ultrasonic short range communication involves the transmission and reception of sound.

Electromagnetic induction

Electromagnetic induction has short range communication and power. This has been used in biomedical situations such as pacemakers, as well as for short-range Rfid tags.

Services

Common examples of wireless equipment include:[7][8]

Electromagnetic spectrum

Light, colors, AM and FM radio, and electronic devices make use of the electromagnetic spectrum. The frequencies of the radio spectrum that are available for use for communication are treated as a public resource and are regulated by national organizations such as the Federal Communications Commission in the USA, or Ofcom in the United Kingdom, or “international as ITU-R”, or European as ETSI. This determines which frequency ranges can be used for what purpose and by whom. In the absence of such control or alternative arrangements such as a privatized electromagnetic spectrum, chaos might result if, for example, airlines did not have specific frequencies to work under and an amateur radio operator were interfering with the pilot's ability to land an aircraft. Wireless communication spans the spectrum from 9 kHz to 300 GHz.

Applications

Mobile telephones

One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone, with more than 6.6 billion mobile cellular subscriptions worldwide as of the end of 2010.[10] These wireless phones use radio waves from signal-transmission towers to enable their users to make phone calls from many locations worldwide. They can be used within range of the mobile telephone site used to house the equipment required to transmit and receive the radio signals from these instruments.[11]

Data communications

Wireless data communications allows wireless networking between desktop computers, laptops, tablet computers, cell phones and other related devices. The various available technologies differ in local availability, coverage range and performance,[12][13] and in some circumstances users employ multiple connection types and switch between them using connection manager software[14][15] or a mobile VPN to handle the multiple connections as a secure, single virtual network.[16] Supporting technologies include:

Wi-Fi is a wireless local area network that enables portable computing devices to connect easily with other devices, peripheries, and the Internet.[17] Standardized as IEEE 802.11 a, b, g, n, ac, ax, Wi-Fi has link speeds similar to older standards of wired Ethernet. Wi-Fi has become the de facto standard for access in private homes, within offices, and at public hotspots.[18] Some businesses charge customers a monthly fee for service, while others have begun offering it free in an effort to increase the sales of their goods.[19]
Cellular data service offers coverage within a range of 10-15 miles from the nearest cell site.[12] Speeds have increased as technologies have evolved, from earlier technologies such as GSM, CDMA and GPRS, through 3G, to 4G networks such as W-CDMA, EDGE or CDMA2000.[20][21] As of 2018, the proposed next generation is 5G.
Low-power wide-area networks (LPWAN) bridge the gap between Wi-Fi and Cellular for low bitrate Internet of things (IoT) applications.
Mobile-satellite communications may be used where other wireless connections are unavailable, such as in largely rural areas[22] or remote locations.[12] Satellite communications are especially important for transportation, aviation, maritime and military use.[23]
Wireless sensor networks are responsible for sensing noise, interference, and activity in data collection networks. This allows us to detect relevant quantities, monitor and collect data, formulate clear user displays, and to perform decision-making functions[24]

Wireless data communications are used to span a distance beyond the capabilities of typical cabling in point-to-point communication and point-to-multipoint communication, to provide a backup communications link in case of normal network failure, to link portable or temporary workstations, to overcome situations where normal cabling is difficult or financially impractical, or to remotely connect mobile users or networks.

Peripheries

Periphery devices in computing can also be connected wirelessly as part of a Wi-Fi network or directly by optical infer-red, Bluetooth or Wireless USB. Originally these units used bulky, highly local transceivers to mediate between a computer and a keyboard and mouse; however, more recent generations have used small, higher-quality devices. A battery powers computer interface devices such as a keyboard or mouse and send signals to a receiver through a USB port by the way of an optical or radio frequency (RF) receiver. A RF design makes it possible to expand the range of efficient use, usually up to 10 feet but distance, physical obstacles, competing signals, and even human bodies can all degrade the signal quality.[25] Concerns about the security of wireless keyboards arose at the end of 2007, when it was revealed that Microsoft's implementation of encryption in some of its 27 MHz models was highly insecure.[26]

Energy transfer

Wireless energy transfer is a process whereby electrical energy is transmitted from a power source to an electrical load (Computer Load) that does not have a built-in power source, without the use of interconnecting wires. There are two different fundamental methods for wireless energy transfer. They can be transferred using either far-field methods that involve beaming power/lasers, radio or microwave transmissions or near-field using induction. Both methods utilize electromagnetism and magnetic fields.[27] Wireless energy transfer may be combined with wireless information transmission in what is known as Wireless Powered Communication. [28]

Medical technologies

New wireless technologies, such as mobile body area networks (MBAN), have the capability to monitor blood pressure, heart rate, oxygen level and body temperature. The MBAN works by sending low powered wireless signals to receivers that feed into nursing stations or monitoring sites. This technology helps with the intentional and unintentional risk of infection or disconnection that arise from wired connections.[29]

Categories of implementations, devices and standards

See also

References

  1. ^ "ATIS Telecom Glossary 2007". atis.org. Retrieved 2008-03-16.
  2. ^ Franconi, Nicholas G.; Bunger, Andrew P.; Sejdić, Ervin; Mickle, Marlin H. (2014-10-24). "Wireless Communication in Oil and Gas Wells". Energy Technology. 2 (12): 996–1005. doi:10.1002/ente.201402067. ISSN 2194-4288.
  3. ^ Biswas, S.; Tatchikou, R.; Dion, F. (January 2006). "Vehicle-to-vehicle wireless communication protocols for enhancing highway traffic safety". IEEE Communications Magazine. 44 (1): 74–82. doi:10.1109/mcom.2006.1580935. ISSN 0163-6804.
  4. ^ "Photo- and Graphophone".
  5. ^ "Alexander Graham Bell's Photophone – Ahead of its Time".
  6. ^ Icons of Invention: The Makers of the Modern World from Gutenberg to Gates. ABC-CLIO. 2009. p. 162. ISBN 978-0-313-34743-6.
  7. ^ Tech Target – Definition of Wireless – Posted by Margaret Rouse (April 2 control and traffic control systems
  8. ^ "Wireless headphones". Retrieved 25 May 2015.
  9. ^ Tsai, Allen. "AT&T Releases Navigator GPS Service with Speech Recognition". Telecom Industry News. Retrieved 2 April 2008.
  10. ^ Robust demand for mobile phone service will continue; UN agency predicts UN News Centre February 15, 2010,
  11. ^ Vilorio, Dennis. "You're a what? Tower Climber" (PDF). Occupational Outlook Quarterly. Archived (PDF) from the original on February 3, 2013. Retrieved December 6, 2013.
  12. ^ a b c "High Speed Internet on the Road". Archived from the original on September 3, 2011. Retrieved September 6, 2011.
  13. ^ Mitchell, Bradley. Wireless Internet Service: An Introduction
  14. ^ What is Connection Manager? Microsoft Technet, March 28, 2003
  15. ^ Unwired Revolution
  16. ^ http://www.gd-itronix.com/index.cfm?page=Products:MobilityXE
  17. ^ About.com
  18. ^ "Wi-Fi"
  19. ^ O'Brien, J. & Marakas, G.M.(2008) Management Information Systems (pp. 239). New York, NY: McGraw-Hill Irwin
  20. ^ Lachu Aravamudhan, Stefano Faccin, Risto Mononen, Basavaraj Patil, Yousuf Saifullah, Sarvesh Sharma, Srinivas Sreemanthula. "Getting to Know Wireless Networks and Technology", InformIT
  21. ^ "What really is a Third Generation (3G) Mobile Technology", ITU
  22. ^ Geier, Jim. Wireless Network Industry Report 2007, Wireless-Nets, Ltd., 2008
  23. ^ Ilcev, Stojce Dimov, Global Mobile Satellite Communications for Maritime, Land and Aeronautical Applications, Springer, 2006
  24. ^ F.L. Lewis. "Wireless Sensor Networks." Smart Environments: Technologies, Protocols, and Applications, ed. D.J. Cook and S.K. Das, John Wiley, New York, 2004. Automation and robotics research institute. 26 Oct. 2013
  25. ^ Paventi, Jared. "How does a Wireless Keyboard Work." Ehow. Web. 26 Oct. 2013.
  26. ^ Moser, Max; Schrödel, Philipp (2007-12-05). "27Mhz Wireless Keyboard Analysis Report aka "We know what you typed last summer"" (PDF). Retrieved 6 February 2012.
  27. ^ Jones, George. "Future Proof. How Wireless Energy Transfer Will Kill the Power Cable." MaximumPC. 14 Sept. 2010. Web. 26 Oct. 2013.
  28. ^ Suzhi Bi, Yong Zeng, and Rui Zhang (May 2016) "Wireless powered communication networks: an overview"
  29. ^ Linebaugh, Kate. "Medical Devices in Hospitals go wireless." Online.wsj. The Wall Street Journal. 23 May 2010. Web. 27 Oct. 2013.

Further reading

  • Geier, Jim (2001). Wireless LANs. Sams. ISBN 0-672-32058-4.
  • Goldsmith, Andrea (2005). Wireless Communications. Cambridge University Press. ISBN 0-521-83716-2.
  • Larsson, Erik; Stoica, Petre (2003). Space-Time Block Coding For Wireless Communications. Cambridge University Press.
  • Molisch, Andreas (2005). Wireless Communications. Wiley-IEEE Press. ISBN 0-470-84888-X.
  • Pahlavan, Kaveh; Levesque, Allen H (1995). Wireless Information Networks. John Wiley & Sons. ISBN 0-471-10607-0.
  • Pahlavan, Kaveh; Krishnamurthy, Prashant (2002). Principles of Wireless Networks – a Unified Approach. Prentice Hall. ISBN 0-13-093003-2.
  • Rappaport, Theodore (2002). Wireless Communications: Principles and Practice. Prentice Hall. ISBN 0-13-042232-0.
  • Rhoton, John (2001). The Wireless Internet Explained. Digital Press. ISBN 1-55558-257-5.
  • Tse, David; Viswanath, Pramod (2005). Fundamentals of Wireless Communication. Cambridge University Press. ISBN 0-521-84527-0.

External links

Bluetooth

Bluetooth is a wireless technology standard for exchanging data between fixed and mobile devices over short distances using short-wavelength UHF radio waves in the industrial, scientific and medical radio bands, from 2.400 to 2.485 GHz, and building personal area networks (PANs). It was originally conceived as a wireless alternative to RS-232 data cables.

Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 30,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. The IEEE standardized Bluetooth as IEEE 802.15.1, but no longer maintains the standard. The Bluetooth SIG oversees development of the specification, manages the qualification program, and protects the trademarks. A manufacturer must meet Bluetooth SIG standards to market it as a Bluetooth device. A network of patents apply to the technology, which are licensed to individual qualifying devices.

Guglielmo Marconi

Guglielmo Marconi, 1st Marquis of Marconi (Italian: [ɡuʎˈʎɛlmo marˈkoːni]; 25 April 1874 – 20 July 1937) was an Italian inventor and electrical engineer, known for his pioneering work on long-distance radio transmission, development of Marconi's law, and a radio telegraph system. He is credited as the inventor of radio, and he shared the 1909 Nobel Prize in Physics with Karl Ferdinand Braun "in recognition of their contributions to the development of wireless telegraphy".Marconi was also an entrepreneur, businessman, and founder of The Wireless Telegraph & Signal Company in the United Kingdom in 1897 (which became the Marconi Company). He succeeded in making an engineering and commercial success of radio by innovating and building on the work of previous experimenters and physicists. In 1929, Marconi was ennobled as a Marchese (marquis) by King Victor Emmanuel III of Italy, and, in 1931, he set up the Vatican Radio for Pope Pius XI.

Hotspot (Wi-Fi)

A hotspot is a physical location where people may obtain Internet access, typically using Wi-Fi technology, via a wireless local area network (WLAN) using a router connected to an internet service provider.

Public hotspots may be created by a business for use by customers, such as coffee shops or hotels. Public hotspots are typically created from wireless access points configured to provide Internet access, controlled to some degree by the venue. In its simplest form, venues that have broadband Internet access can create public wireless access by configuring an access point (AP), in conjunction with a router and connecting the AP to the Internet connection. A single wireless router combining these functions may suffice.Private hotspots may be configured on a smartphone or tablet with a mobile network data plan to allow Internet access to other devices via Bluetooth pairing or if both the hotspot device and the device/s accessing it are connected to the same Wi-Fi network.

LTE (telecommunication)

In telecommunication, Long-Term Evolution (LTE) is a standard for wireless broadband communication for mobile devices and data terminals, based on the GSM/EDGE and UMTS/HSPA technologies. It increases the capacity and speed using a different radio interface together with core network improvements. The standard is developed by the 3GPP (3rd Generation Partnership Project) and is specified in its Release 8 document series, with minor enhancements described in Release 9. LTE is the upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. The different LTE frequencies and bands used in different countries mean that only multi-band phones are able to use LTE in all countries where it is supported.

LTE is commonly marketed as 4G LTE & Advance 4G, but it does not meet the technical criteria of a 4G wireless service, as specified in the 3GPP Release 8 and 9 document series for LTE Advanced. LTE is also commonly known as 3.95G. The requirements were originally set forth by the ITU-R organization in the IMT Advanced specification. However, due to marketing pressures and the significant advancements that WiMAX, Evolved High Speed Packet Access and LTE bring to the original 3G technologies, ITU later decided that LTE together with the aforementioned technologies can be called 4G technologies. The LTE Advanced standard formally satisfies the ITU-R requirements to be considered IMT-Advanced. To differentiate LTE Advanced and WiMAX-Advanced from current 4G technologies, ITU has defined them as "True 4G".

Mobile phone

A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). Modern mobile telephone services use a cellular network architecture, and, therefore, mobile telephones are called cellular telephones or cell phones, in North America. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, video games, and digital photography. Mobile phones offering only those capabilities are known as feature phones; mobile phones which offer greatly advanced computing capabilities are referred to as smartphones.

The first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 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 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion—enough to provide one for every person on Earth. In first quarter of 2016, the top smartphone developers worldwide were Samsung, Apple, and Huawei, and smartphone sales represented 78 percent of total mobile phone sales. For feature phones (or "dumbphones") as of 2016, the largest were Samsung, Nokia, and Alcatel.

Nikola Tesla

Nikola Tesla (; Serbo-Croatian: [nǐkola têsla]; Serbian Cyrillic: Никола Тесла; 10 July 1856 – 7 January 1943) was a Serbian-American inventor, electrical engineer, mechanical engineer, and futurist who is best known for his contributions to the design of the modern alternating current (AC) electricity supply system.Born and raised in the Austrian Empire, Tesla received an advanced education in engineering and physics in the 1870s and gained practical experience in the early 1880s working in telephony and at Continental Edison in the new electric power industry. He emigrated in 1884 to the United States, where he would become a naturalized citizen. He worked for a short time at the Edison Machine Works in New York City before he struck out on his own. With the help of partners to finance and market his ideas, Tesla set up laboratories and companies in New York to develop a range of electrical and mechanical devices. His alternating current (AC) induction motor and related polyphase AC patents, licensed by Westinghouse Electric in 1888, earned him a considerable amount of money and became the cornerstone of the polyphase system which that company would eventually market.

Attempting to develop inventions he could patent and market, Tesla conducted a range of experiments with mechanical oscillators/generators, electrical discharge tubes, and early X-ray imaging. He also built a wireless-controlled boat, one of the first ever exhibited. Tesla became well known as an inventor and would demonstrate his achievements to celebrities and wealthy patrons at his lab, and was noted for his showmanship at public lectures. Throughout the 1890s, Tesla pursued his ideas for wireless lighting and worldwide wireless electric power distribution in his high-voltage, high-frequency power experiments in New York and Colorado Springs. In 1893, he made pronouncements on the possibility of wireless communication with his devices. Tesla tried to put these ideas to practical use in his unfinished Wardenclyffe Tower project, an intercontinental wireless communication and power transmitter, but ran out of funding before he could complete it.After Wardenclyffe, Tesla experimented with a series of inventions in the 1910s and 1920s with varying degrees of success. Having spent most of his money, Tesla lived in a series of New York hotels, leaving behind unpaid bills. He died in New York City in January 1943. Tesla's work fell into relative obscurity following his death, until 1960, when the General Conference on Weights and Measures named the SI unit of magnetic flux density the tesla in his honor. There has been a resurgence in popular interest in Tesla since the 1990s.

Verizon Communications

Verizon Communications Inc. (listen ) ( və-RY-zən) is an American multinational telecommunications conglomerate and a corporate component of the Dow Jones Industrial Average. The company is based at 1095 Avenue of the Americas in Midtown Manhattan, New York City, but is incorporated in Delaware.

In 1984, the Justice Department of the United States mandated AT&T Corporation to break up the Bell System and split into seven companies, called "Baby Bells". One of the baby bells, Bell Atlantic, came into existence in 1984 consisting of the separate operating companies New Jersey Bell, Bell of Pennsylvania, Diamond State Telephone, and C&P Telephone, with a footprint from New Jersey to Virginia. This company would later become Verizon.

As part of a rebranding of the Baby Bells in the mid-1990s, all of Bell Atlantic's operating companies assumed the holding company's name. In 1997, Bell Atlantic expanded into New York and the New England states by merging with fellow Baby Bell NYNEX. Although Bell Atlantic was the surviving company name, the merged company moved its headquarters from Philadelphia to NYNEX's old headquarters in New York City. In 2000, Bell Atlantic acquired GTE, which operated telecommunications companies across most of the rest of the country that was not already in Bell Atlantic's footprint. Bell Atlantic, the surviving entity, changed its name to "Verizon", a portmanteau of veritas (Latin for "truth") and horizon.In 2015, Verizon expanded its business into content ownership by acquiring AOL, and two years later it acquired Yahoo!. AOL and Yahoo were amalgamated into a new division named Oath Inc. (currently known as Verizon Media).

As of 2016, Verizon is one of three remaining companies that had their roots in the former Baby Bells. The other two, like Verizon, exist as a result of mergers among fellow former Baby Bell members. SBC Communications, bought out the Bells' former parent AT&T Corporation, and assumed the AT&T name. CenturyLink was formed initially in 2011 by the acquisition of Qwest (formerly named US West).

Verizon's subsidiary Verizon Wireless is the largest U.S. wireless communications service provider as of September 2014, with 147 million mobile customers. And as of 2017, Verizon is the only publicly-traded telecommunications company to have two stock listings in its home country, both the NYSE (principal) and NASDAQ (secondary). As of 2017, it is also the second largest telecommunications company by revenue after AT&T.

Verizon Wireless

Verizon Wireless (officially named Cellco Partnership and commonly shortened to Verizon) is an American telecommunications company which offers wireless products and services. It is a wholly owned subsidiary of Verizon Communications. Verizon Wireless is the largest wireless telecommunications provider in the United States.The company is headquartered in Basking Ridge, New Jersey. It was founded in 2000 as a joint venture of American telecommunications firm Bell Atlantic, which would soon become Verizon Communications, and British multinational telecommunications company Vodafone. Verizon Communications became the sole owner in 2014 after buying Vodafone's 45-percent stake in the company.It operates a national 4G LTE network covering about 98 percent of the U.S. population, which in December 2015 won or tied for top honors in each category of the RootMetrics RootScore Reports. Verizon Wireless offers mobile phone services through a variety of devices. Its LTE in Rural America Program, with 21 rural wireless carriers participating, covers 2.7 million potential users in 169 rural counties. Verizon Wireless announced in 2015 that it was developing a 5G, or fifth generation, network.

Wi-Fi

Wi-Fi () is technology for radio wireless local area networking of devices based on the IEEE 802.11 standards. Wi‑Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing.Devices that can use Wi-Fi technologies include, among others, desktops and laptops, video game consoles, smartphones and tablets, smart TVs, printers, digital audio players, digital cameras, cars and drones. Wi-Fi compatible devices can connect to the Internet via a WLAN and a wireless access point. Such an access point (or hotspot) has a range of about 20 meters (66 feet) indoors and a greater range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points.

Different versions of Wi-Fi exist, with different ranges, radio bands and speeds. Wi-Fi most commonly uses the 2.4 gigahertz (12 cm) UHF and 5 gigahertz (6 cm) SHF ISM radio bands; these bands are subdivided into multiple channels. Each channel can be time-shared by multiple networks. These wavelengths work best for line-of-sight. Many common materials absorb or reflect them, which further restricts range, but can tend to help minimise interference between different networks in crowded environments. At close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s.

Anyone within range with a wireless network interface controller can attempt to access a network; because of this, Wi-Fi is more vulnerable to attack (called eavesdropping) than wired networks. Wi-Fi Protected Access (WPA) is a family of technologies created to protect information moving across Wi-Fi networks and includes solutions for personal and enterprise networks. Security features of WPA have included stronger protections and new security practices as the security landscape has changed over time.

Wireless LAN

A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, office building etc. This gives users the ability to move around within the area and yet still be connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.

Most modern WLANs are based on IEEE 802.11 standards and are marketed under the Wi-Fi brand name.

Wireless LANs have become popular for use in the home, due to their ease of installation and use. They are also popular in commercial properties that offer wireless access to their employees and customers.

Wireless network

A wireless network is a computer network that uses wireless data connections between network nodes.Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Wireless telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure.Examples of wireless networks include cell phone networks, wireless local area networks (WLANs), wireless sensor networks, satellite communication networks, and terrestrial microwave networks.

Wireless power transfer

Wireless power transfer (WPT), wireless power transmission, wireless energy transmission (WET), or electromagnetic power transfer is the transmission of electrical energy without wires as a physical link. In a wireless power transmission system, a transmitter device, driven by electric power from a power source, generates a time-varying electromagnetic field, which transmits power across space to a receiver device, which extracts power from the field and supplies it to an electrical load. The technology of the wireless power transmission can eliminate the use of the wires and batteries, thus increasing the mobility, convenience, and safety of an electronic device for all users. Wireless power transfer is useful to power electrical devices where interconnecting wires are inconvenient, hazardous, or are not possible.

Wireless power techniques mainly fall into two categories, near field and far-field. In near field or non-radiative techniques, power is transferred over short distances by magnetic fields using inductive coupling between coils of wire, or by electric fields using capacitive coupling between metal electrodes. Inductive coupling is the most widely used wireless technology; its applications include charging handheld devices like phones and electric toothbrushes, RFID tags, and wirelessly charging or continuous wireless power transfer in implantable medical devices like artificial cardiac pacemakers, or electric vehicles.

In far-field or radiative techniques, also called power beaming, power is transferred by beams of electromagnetic radiation, like microwaves or laser beams. These techniques can transport energy longer distances but must be aimed at the receiver. Proposed applications for this type are solar power satellites, and wireless powered drone aircraft.An important issue associated with all wireless power systems is limiting the exposure of people and other living things to potentially injurious electromagnetic fields.

History
Pioneers
Transmission
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