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.
Wireless operations permit services, such as mobile and interplanetary 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.) that use some form of energy (e.g.
radio waves and acoustic energy) to transfer information without the use of wires.[3][4][5]
Information is transferred in this manner over both short and long distances.
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
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.
electric currents to its antenna. The waves travel away from the antenna until they eventually reach the antenna of a receiver, which induces an electric current in the receiving antenna. This current can be detected and demodulated
to recreate the information sent by the transmitter.
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, and the transmitters are the smaller ones. To the top and right corner is 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 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".
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 that 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
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 only allows short-range communication and power transmission. It has been used in biomedical situations such as pacemakers, as well as for short-range RFID tags.
Services
Common examples of wireless equipment include:[17]
and pagers: provide connectivity for portable and mobile applications, both personal and business.
Global Positioning System (GPS): allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth.[18]
Cordless computer peripherals: the cordless mouse is a common example; wireless headphones, keyboards, and printers can also be linked to a computer via wireless using technology such as Wireless USB or Bluetooth.
Cordless telephone sets: these are limited-range devices, not to be confused with cell phones.
Satellite television: Is broadcast from satellites in
direct broadcast satellite
to provide multiple television channels to viewers.
AM and FM radios and other 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 organizations such as the American Federal Communications Commission, Ofcom in the United Kingdom, the international ITU-R or the European ETSI. Their regulations determine 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 was interfering with a pilot's ability to land an aircraft. Wireless communication spans the spectrum from 9 kHz to 300 GHz.[citation needed]
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.[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]
Data communications
"Wireless Internet" redirects here. For all wireless Internet access, see Wireless broadband. For mobile wireless Internet, see Mobile broadband.
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.[25] 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.[26]
Cellular data service offers coverage within a range of 10-15 miles from the nearest
EDGE or CDMA2000.[27][28] 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[29] or remote locations.[21]Satellite communications are especially important for transportation, aviation, maritime and military use.[30]
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[31]
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.
Peripherals
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]
Energy transfer
Main article:
Wireless energy transfer
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]
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.[37]
Categories of implementations, devices, and standards
^U.S. Army (1944). Technical Manual. US War Department. Retrieved 13 August 2022. In definitions given in the index, p. 162, the term "radio set" is listed as synonymous with the term "wireless set"
. Retrieved 13 August 2022. (p.396) In a public opinion poll in Sweden in 1942, 31.4 percent answered 'Yes' to the question "Do you usually listen to the foreign news on the wireless?'
^Vilorio, Dennis. "You're a what? Tower Climber"(PDF). Occupational Outlook Quarterly. Archived(PDF) from the original on 3 February 2013. Retrieved 6 December 2013.
