Wireless communication is the transfer of information over a distance without the use of electrical conductors or "wires". The distances involved may be short (a few meters as in television remote control) or long (thousands or millions of kilometers for radio communications). When the context is clear, the term is often shortened to "wireless". Wireless communication is generally considered to be a branch of telecommunications.
It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, garage door openers and or garage doors, wireless computer mice, keyboards and headsets, satellite television and cordless telephones.
Wireless operations permits 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, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF), infrared light, laser light, visible light, acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.
The term "wireless" has become a generic and all-encompassing word used to describe communications in which electromagnetic waves or RF (rather than some form of wire) carry a signal over part or the entire communication path. Common examples of wireless equipment in use today include:
Wireless networking (i.e. the various types of unlicensed 2.4 GHz WiFi devices) is used to meet many needs. Perhaps the most common use is to connect laptop users who travel from location to location. Another common use is for mobile networks that connect via satellite. A wireless transmission method is a logical choice to network a LAN segment that must frequently change locations. The following situations justify the use of wireless technology:
Wireless communication can be via:
The term "wireless" should not be confused with the term "cordless", which is generally used to refer to powered electrical or electronic devices that are able to operate from a portable power source (e.g. a battery pack) without any cable or cord to limit the mobility of the cordless device through a connection to the mains power supply. Some cordless devices, such as cordless telephones, are also wireless in the sense that information is transferred from the cordless telephone to the telephone's base unit via some type of wireless communications link. This has caused some disparity in the usage of the term "cordless", for example in Digital Enhanced Cordless Telecommunications.
In the last fifty years, wireless communications industry experienced drastic changes driven by many technology innovations.
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 conceived of 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 principals found their first practical applications in military communications and later in fiber-optic communications.
The term "wireless" came into public use to refer to a radio receiver or transceiver (a dual purpose receiver and transmitter device), establishing its usage in the field of wireless telegraphy early on; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. It is also used in a general sense to refer to any type of operation that is implemented without the use of wires, such as "wireless remote control" or "wireless energy transfer", regardless of the specific technology (e.g. radio, infrared, ultrasonic) that is used to accomplish the operation. While Guglielmo Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to wireless telegraphy, it has only been of recent years that Nikola Tesla has been formally recognized as the true father and inventor of radio.
David E. Hughes, eight years before Hertz's experiments, transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter. As this was before Maxwell work was understood, Hughes' contemporaries dismissed his achievement as mere "Induction". In 1885, T. A. Edison used a vibrator magnet for induction transmission. In 1888, Edison deploys a system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless patent for this method using inductance (U.S. Patent 465,971).
In the history of wireless technology, the demonstration of the theory of electromagnetic waves by Heinrich Hertz in 1888 was important. The theory of electromagnetic waves were predicted from the research of James Clerk Maxwell and Michael Faraday. Hertz demonstrated that electromagnetic waves could be transmitted and caused to travel through space at straight lines and that they were able to be received by an experimental apparatus. The experiments were not followed up by Hertz. Jagadish Chandra Bose around this time developed an early wireless detection device and help increase the knowledge of millimeter length electromagnetic waves.. Practical applications of wireless radio communication and radio remote control technology were implemented by later inventors, such as Nikola Tesla.
Light, colors, AM and FM radio, and electronic devices make use of the electromagnetic spectrum. In the US, the frequencies that are available for use for communication are treated as a public resource and are regulated by the Federal Communications Commission. 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 didn't have specific frequencies to work under and an amateur radio operator was interfering with the pilot's ability to land an airplane. Wireless communication spans the spectrum from 9 kHz to 300 GHz. (Also see Spectrum management)
Wireless technology may supplement or replace hard wired implementations in security systems for homes or office buildings.
Modern televisions use wireless (generally infrared) remote control units. Now radio waves are also used.
Perhaps the best known example of wireless technology is the cellular telephone and modems. These instruments use radio waves to enable the operator to make phone calls from many locations worldwide. They can be used anywhere that there is a cellular telephone site to house the equipment that is required to transmit and receive the signal that is used to transfer both voice and data to and from these instruments.
Wi-Fi is a wireless LAN technology that enables laptop PCs, PDAs, and other devices to connect easily to the internet. Technically known as IEEE 802.11 a,b,g,n, Wi-Fi is less expensive and nearing the speeds of standard Ethernet and other common wire-based LAN technologies. Several Wi-Fi hot spots have been popular over the past few years. Some businesses charge customers a monthly fee for service, while others have begun offering it for free in an effort to increase the sales of their goods.
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.
Answering the call of customers frustrated with cord clutter, many manufactures of computer peripherals turned to wireless technology to satisfy their consumer base. Originally these units used bulky, highly limited transceivers to mediate between a computer and a keyboard and mouse, however more recent generations have used small, high quality devices, some even incorporating Bluetooth. These systems have become so ubiquitous that some users have begun complaining about a lack of wired peripherals. Wireless devices tend to have a slightly slower response time than their wired counterparts, however the gap is decreasing. Initial concerns about the security of wireless keyboards have also been addressed with the maturation of the technology.
Many scientists have complained that wireless technology interferes with their experiments, forcing them to use less optimal peripherals because the optimum one is not available in a wired version. This has become especially prevalent among scientists who use trackballs as the number of models in production steadily decreases.
A electronic device that communicates with a main device without wires. This could be through Bluetooth, RF, or Infrared.
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The word wireless is normally used to refer to any type of electrical or electronic operation which is done without a "hard wired" connection. Wireless communication is the transfer of information over a distance without the use of wires. The distances involved may be short (when using a television remote control) or very long (thousands or even millions of kilometers for radio communications).
The term wireless technology is generally used for mobile information technology (IT) equipment. Examples include mobile phones, personal digital assistants (PDAs), Global Positioning System (GPS) units, garage door openers, wireless computer mice and keyboards, satellite television and cordless telephones.