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 LTE, LTE-Advanced,
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. Information is transferred in this manner
over both short and long distances.
Electricity based wireless
1.2.1 Early wireless
2.2 Free-space optical
2.4 Electromagnetic induction
4 Electromagnetic spectrum
5.1 Mobile telephones
5.2 Data communications
5.3 Energy transfer
5.4 Medical technologies
6 Categories of implementations, devices and standards
7 See also
9 Further reading
10 External links
See also: History of telecommunication
Main article: Photophone
Bell and Tainter's photophone, of 1880.
The world's first wireless telephone conversation occurred in 1880,
Alexander Graham Bell
Alexander Graham Bell and
Charles Sumner Tainter
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
Electricity based 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
World War I but these systems were never
Main article: History of radio
Marconi transmitting the first radio signal across the Atlantic.
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. 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
Karl Ferdinand Braun
Karl Ferdinand Braun were awarded the 1909 Nobel Prize for
Physics for their contribution to this form of wireless telegraphy.
Wireless communications can be via:
Radio and microwave communication carry information by modulating
properties of electromagnetic waves transmitted through space.
Main article: Free-space optical communication
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
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
WiFi networking to allow laptops, PDAs, printers, and
digital cameras to exchange data.
Sonic, especially ultrasonic short range communication involves the
transmission and reception of sound.
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.
Common examples of wireless equipment include:
Infrared and ultrasonic remote control devices
Professional LMR (Land Mobile Radio) and SMR (Specialized Mobile
Radio) typically used by business, industrial and Public Safety
Two-way radio including FRS Family
Radio Service, GMRS
Radio Service) and Citizens band ("CB") radios.
Radio Service (Ham radio).
Consumer and professional Marine VHF radios.
Airband and radio navigation equipment used by aviators and air
Cellular telephones and pagers: provide connectivity for portable and
mobile applications, both personal and business.
Global Positioning System
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.
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
Cordless telephone sets: these are limited-range devices, not to be
confused with cell phones.
Satellite television: Is broadcast from satellites in geostationary
orbit. Typical services use direct broadcast satellite to provide
multiple television channels to viewers.
See also: Spectrum management
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
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.
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.
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.
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, and in some
circumstances users employ multiple connection types and switch
between them using connection manager software or a mobile
VPN to handle the multiple connections as a secure, single virtual
network. 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. Standardized as
IEEE 802.11 a,b,g,n,
speeds of some types of wired Ethernet.
Wi-Fi has become the de facto
standard for access in private homes, within offices, and at public
hotspots. 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.
Cellular data service offers coverage within a range of 10-15 miles
from the nearest cell site. Speeds have increased as technologies
have evolved, from earlier technologies such as GSM, CDMA and GPRS, to
4G networks such as W-CDMA, EDGE or CDMA2000.
Low Power Wide Area Networks (LPWAN) bridge the gap between
Cellular for low bitrate IoT applications.
Mobile Satellite Communications may be used where other wireless
connections are unavailable, such as in largely rural areas or
remote locations. Satellite communications are especially
important for transportation, aviation, maritime and military use.
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
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
Periphery devices in computing can also be connected wirelessly as
part of a
Wi-Fi network or directly by optical infer-red,
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. 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.
Wireless energy transfer
Wireless 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.
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
Categories of implementations, devices and standards
Radio station in accordance with ITU RR (article 1.61)
Radiocommunication service in accordance with ITU RR (article 1.19)
Radio communication system
Radio or Professional Mobile Radio: TETRA, P25, OpenSky,
EDACS, DMR, dPMR
Cordless telephony:DECT (Digital Enhanced Cordless Telecommunications)
Cellular networks: 0G, 1G, 2G, 3G, Beyond 3G (4G), Future wireless
List of emerging technologies
Short-range point-to-point communication :
Remote controls, IrDA, RFID (
Radio Frequency Identification),
Wireless USB, DSRC (Dedicated Short Range
Communications), EnOcean, Near Field Communication
Wireless sensor networks: ZigBee, EnOcean; Personal area networks,
Ultra-wideband (UWB from WiMedia Alliance).
Wireless LAN (WLAN), (
IEEE 802.11 branded as Wi-Fi
Wireless Metropolitan Area Networks (WMAN) and (LMDS,
WiMAX, and HiperMAN)
Comparison of wireless data standards
List of emerging technologies
Personal area network
Radio resource management (RRM)
Timeline of radio
Wireless access point
Wireless Wide Area Network (True wireless)
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Look up wireless in Wiktionary, the free dictionary.
Nets, Webs and the Information Infrastructure at Wikibooks
Wireless at Curlie (based on DMOZ)
Bibliography - History of wireless and radio broadcasting
Cable protection system
Prepay mobile phone
The Telephone Cases
Timeline of communication technology
Undersea telegraph line
Edwin Howard Armstrong
John Logie Baird
Alexander Graham Bell
Jagadish Chandra Bose
Lee de Forest
Erna Schneider Hoover
Charles K. Kao
Alexander Stepanovich Popov
Johann Philipp Reis
Vladimir K. Zworykin
Free-space optical communication
Network switching (circuit
Public Switched Telephone
World Wide Web