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Wireless is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few metres for television remote control, or as far as thousands or even millions of kilometres for deep-space radio communications. It encompasses various types of fixed, mobile, and portable , , (PDAs), and . Other examples of wireless technology include units, or garage doors, wireless , and , , , , and cordless .


Introduction
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, computer networks, network terminals, etc.) which use some form of energy (e.g. (RF),acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances.


Wireless services
Common examples of wireless equipment include:


Wireless networks
(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:
  • To span a distance beyond the capabilities of typical cabling,
  • 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.


Modes
Wireless communications can be via: Applications may involve , , , and other .


Cordless
The term "wireless" should not be confused with the term "", 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 . This has caused some in the usage of the term "cordless", for example in .


History

Photophone
The world's first wireless telephone conversation occurred in 1880, when and invented and patented the , a telephone that conducted audio conversations wirelessly over modulated (which are narrow projections of ). In that distant era when utilities did not yet exist to provide , and had not even been conceived of in , there were no practical applications for their invention, which was highly limited by the availability of both sunlight and good weather. Similar to , 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 and later in .


Early wireless work
transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter in 1879. As this was before Maxwell's work was understood, Hughes' contemporaries dismissed his achievement as mere "Induction". In 1885, used a vibrator magnet for induction transmission. In 1888, Edison deployed a system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless patent for this method using inductance ().

In the history of wireless technology, the demonstration of the theory of by in 1888 was important. The theory of electromagnetic waves was predicted from the research of and . Hertz demonstrated that electromagnetic waves could be and caused to travel through space at straight lines and that they were able to be by an experimental apparatus. The experiments were not followed up by Hertz. around this time developed an early wireless detection device and helped increase the knowledge of millimeter length electromagnetic waves.J.C. Bose, Collected Physical Papers. New York, N.Y.: Longmans, Green and Co., 1927 Practical applications of wireless radio communication and radio remote control technology were implemented by later inventors, such as .


Radio
The term "wireless" came into public use to refer to a radio receiver or (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. , , ) used. and were awarded the 1909 for their contribution to wireless telegraphy.


Electromagnetic spectrum
Light, colors, AM and FM radio, and electronic devices make use of the . The frequencies of the that are available for use for communication are treated as a public resource and are regulated by national organizations such as the in the USA, or in the United Kingdom. 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 operator were interfering with the pilot's ability to land an . Wireless communication spans the spectrum from 9 kHz to 300 GHz. Henreich Hertz was the discoverer of the electromagnetic wave, it gave a platform for further inventions in wireless communication.


Applications of wireless technology

Mobile telephones
One of the best-known examples of wireless technology is the , also known as a cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide as of the end of 2010. Robust demand for mobile phone service will continue, UN agency predicts UN News Centre February 15, 2010 These wireless phones use radio waves to enable their users to make phone calls from many locations worldwide. They can be used within range of the used to house the equipment required to transmit and receive the from these instruments.


Wireless data communications
Wireless data communications are an essential component of mobile computing. Insights On Rugged Mobile Computers.pdf TCO Insights on Rugged Mobile Computers, VDC Research, 2007. The various available technologies differ in local availability, coverage range and performance,High Speed Internet on the Road, http://www.geeksontour.com/showme/wifi/wifi00_3ways.cfmMitchell, Bradley. Wireless Internet Service: An Introduction and in some circumstances, users must be able to employ multiple connection types and switch between them. To simplify the experience for the user, connection manager software can be used, What is Connection Manager? Microsoft Technet, March 28, 2003 Unwired Revolution or a deployed to handle the multiple connections as a secure, single .http://www.gd-itronix.com/index.cfm?page=Products:MobilityXE Supporting technologies include:

Wi-Fi is a wireless that enables portable computing devices to connect easily to the . About.com Standardized as a,b,g,n, approaches speeds of some types of wired . Wi-Fi has become the de facto standard for access in private homes, within offices, and at public hotspots. "Wi-Fi" 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.O'Brien, J. & Marakas, G.M.(2008) Management Information Systems (pp. 239). New York, NY: McGraw-Hill Irwin

Cellular data service offers coverage within a range of 10-15 miles from the nearest . Speeds have increased as technologies have evolved, from earlier technologies such as , and , to networks such as , or .Lachu Aravamudhan, Stefano Faccin, Risto Mononen, Basavaraj Patil, Yousuf Saifullah, Sarvesh Sharma, Srinivas Sreemanthula. "Getting to Know Wireless Networks and Technology", InformIT "What really is a Third Generation (3G) Mobile Technology", ITU

Mobile Satellite Communications may be used where other wireless connections are unavailable, such as in largely rural areasGeier, Jim. Wireless Network Industry Report 2007, Wireless-Nets, Ltd., 2008 or remote locations. are especially important for , , and use.Ilcev, Stojce Dimov, Global Mobile Satellite Communications for Maritime, Land and Aeronautical Applications, Springer, 2005


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.


Computer interface devices
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 . 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. 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.


Categories of wireless implementations, devices and standards


See also


Further reading


External links

References
    ^ (2018). 9780672320583, Sams.
    ^ (2018). 9780521837163, Cambridge University Press.
    ^ (2018). 047084888X, Wiley-IEEE Press. 047084888X
    ^ (2018). 9780130930033, Prentice Hall.
    ^ (2018). 9780130422323, Prentice Hall.
    ^ (2018). 9781555582579, Digital Press.
    ^ (2018). 9780521845274, Cambridge University Press.
    ^ (1995). 00471106070, John Wiley & Sons. 00471106070

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