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Wireless communication (or just wireless, when the context allows) is the transfer of information (telecommunication) between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended 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 mouse, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications involve other electromagnetic phenomena, such as light and magnetic or electric fields, or the use of sound.

The term wireless has been used twice in communications history, with slightly different meanings. 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. Radio sets in the UK and the English-speaking world that were not portable continued to be referred to as wireless sets into the 1960s.[1][2] The term wireless 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.

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The first wireless telephone conversation occurred in 1880 when Alexander Graham Bell and Charles Sumner Tainter invented the photophone, the telephone that sent audio over a beam of light. The photophone required sunlight to operate, and a clear line of sight between the transmitter and receiver, which greatly decreased the viability of the photophone in any practical use.[6] It would be several decades before the photophone's principles found their first practical applications in military communications and later in fiber-optic communications.

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.

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 a communication format since they seemed, at the time, to be a short-range phenomenon.[7] 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). Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to this form of wireless telegraphy.

The wireless revolution began in the 1990s,[12][13][14] with the advent of digital wireless networks leading to a social revolution, and a paradigm shift from wired to wireless technology,[15] including the proliferation of commercial wireless technologies such as cell phones, mobile telephony, pagers, wireless computer networks,[12] cellular networks, the wireless Internet, and laptop and handheld computers with wireless connections.[16] The wireless revolution has been driven by advances in radio frequency (RF) and microwave engineering,[12] and the transition from analog to digital RF technology,[15][16] which enabled a substantial increase in voice traffic along with the delivery of digital data such as text messaging, images and streaming media.[15]

Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to transmit wireless 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".

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.[19] 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 the range of the mobile telephone site used to house the equipment required to transmit and receive the radio signals from these instruments.[20]

Wireless data communications allow 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,[21] and in some circumstances, users employ multiple connection types and switch between them using connection manager software[22][23] or a mobile VPN to handle the multiple connections as a secure, single virtual network.[24] Supporting technologies include:

Peripheral devices in computing can also be connected wirelessly, as part of a Wi-Fi network or directly via an optical or radio-frequency (RF) peripheral interface. Originally these units used bulky, highly local transceivers to mediate between a computer and a keyboard and mouse; however, more recent generations have used smaller, higher-performance devices. Radio-frequency interfaces, such as Bluetooth or Wireless USB, provide greater ranges of efficient use, usually up to 10 feet, but distance, physical obstacles, competing signals, and even human bodies can all degrade the signal quality.[32] 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 were highly insecure.[33]

Wireless energy transfer is a process whereby electrical energy is transmitted from a power source to an electrical 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. Energy can be transferred using either far-field methods that involve beaming power/lasers, radio or microwave transmissions, or near-field using electromagnetic induction.[34] Wireless energy transfer may be combined with wireless information transmission in what is known as Wireless Powered Communication.[35] In 2015, researchers at the University of Washington demonstrated far-field energy transfer using Wi-Fi signals to power cameras.[36]

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.[37]

Wireless providers are selling devices with WEA capability included. To find out if your phone can receive WEA alerts, contact your wireless provider. All the major providers participate in WEA on a voluntary basis.

Older Devices

Alerting authorities must include 90-character versions of their alerts to ensure the alert is received by older WEA-capable mobile phones.. When you include a 90- and a 360-character message in the same alert, wireless providers that participate in WEA will send the 90-character version to older phones and the 360-character version to newer phones.

PBS WARN (Warning, Alert, Response Network) provides a backup dissemination method of Wireless Emergency Alerts (WEAs) should IPAWS connection to wireless providers ever be interrupted. All WEAs sent via IPAWS are received and displayed by the PBS WARN website. The map shows all active WEAs that WARN is broadcasting in real time. EAS is not displayed.

No. In the nationwide WEA test, FEMA will send a test National Alert. Under the WARN Act, participating wireless carriers may offer their subscribers the capability to block all WEAs except National Alerts. Although it is possible to opt out from other types of WEAs, such as those warning of imminent threats and missing children, the FCC strongly urges the public to stay opted in to receive all these life-saving messages.

Wireless companies volunteer to participate in WEA, which is the result of a unique public/private partnership between the Federal Emergency Management Agency, the FCC, and the United States wireless industry in order to enhance public safety.

Authorized public safety officials send WEA alerts through FEMA's Integrated Public Alert and Warning System (IPAWS) to participating wireless carriers, which then push the alerts to compatible mobile devices in the affected area.

Consumers do not need to sign up for this service. WEA allows government officials to send emergency alerts to all subscribers with WEA-capable devices if their wireless carrier participates in the program.

Consumers should check with their wireless carrier regarding the availability of WEA-capable handsets. In addition, CTIA, a wireless trade association, publishes lists of WEA-capable phones offered by the largest wireless providers. ff782bc1db