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30 JANUARY 2012

Will Li-Fi be the new Wi-Fi?

"FLICKERING lights are annoying but they may have an upside. Visible light communication (VLC) uses rapid pulses of light to transmit information wirelessly. Now it may be ready to compete with conventional Wi–Fi.

'At the heart of this technology is a new generation of high–brightness light–emitting diodes,' says Harald Haas from the University of Edinburgh, UK. 'Very simply, if the LED is on, you transmit a digital 1, if it's off you transmit a 0,' Haas says. 'They can be switched on and off very quickly, which gives nice opportunities for transmitting data.'

It is possible to encode data in the light by varying the rate at which the LEDs flicker on and off to give different strings of 1s and 0s. The LED intensity is modulated so rapidly that human eyes cannot notice, so the output appears constant. ...

But some sound a cautious note about VLC's prospects. It only works in direct line of sight, for example, although this also makes it harder to intercept than Wi–Fi. 'There has been a lot of early hype, and there are some very good applications,' says Mark Leeson from the University of Warwick, UK. 'But I'm doubtful it's a panacea. This isn't technology without a point, but I don't think it sweeps all before it, either.'"

(Jamie Condliffe, 28 July 2011)

Jamie Condliffe (2011). New Scientist magazine, 23 July 2011.

Fig.1 Harald Haas, July 2011, TED.com.

2). Steve Perlman "Distributed–Input–Distributed–Output (DIDO) Wireless Technology: A New Approach to Multiuser Wireless".

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TAGS

applied research • bandwidth • broadband over power lines • device • DIDO • DIDO technology • Distributed-Input-Distributed-Output • experimental knowledge • fiber optics • Harald Haas • inventionLEDLED lighting • Li-Fi • LIFI • light • light bulb • lightingphysicsproblem solving researchpulsesignalsolutiontechnology innovation • TED Global • TED Talks • transmitting data • Visible Light Communication • VLC • wireless data • wireless technologies • wireless technology • wireless through LED

CONTRIBUTOR

Simon Perkins
15 MARCH 2011

A simple abstract model of human communication

"One of the first designs of the information theory is the model of communication by Shannon and Weaver. Claude Shannon, an engineer at Bell Telephone Laboratories, worked with Warren Weaver on the classic book 'The mathematical theory of communication'. In this work Shannon and Weaver sought to identify the quickest and most efficient way to get a message from one point to another. Their goal was to discover how communication messages could be converted into electronic signals most efficiently, and how those signals could be transmitted with a minimum of error. In studying this, Shannon and Weaver developed a mechanical and mathematical model of communication, known as the 'Shannon and Weaver model of communication'. ...

Shannon and Weaver broadly defined communication as 'all of the procedures by which one mind may affect another'. Their communication model consisted of an information source: the source's message, a transmitter, a signal, and a receiver: the receiver's message, and a destination. Eventually, the standard communication model featured the source or encoder, who encodes a message by translating an idea into a code in terms of bits. A code is a language or other set of symbols or signs that can be used to transmit a thought through one or more channels to elicit a response in a receiver or decoder. Shannon and Weaver also included the factor noise into the model. The study conducted by Shannon and Weaver was motivated by the desire to increase the efficiency and accuracy or fidelity of transmission and reception. Efficiency refers to the bits of information per second that can be sent and received. Accuracy is the extent to which signals of information can be understood. In this sense, accuracy refers more to clear reception than to the meaning of message. This engineering model asks quite different questions than do other approaches to human communication research."

(Communication Studies, University of Twente)

Shannon, C.E., & Weaver, W. (1949). The mathematical theory of communication. Urbana: University of Illinois Press.

Hawes, L.C. (1975). Pragmatics of analoguing: Theory and model construction in communication. Reading, MA: Addison–Wesley.

Fig.1 Mathematical (information) model of communication.

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TAGS

abstract modelabstractionaccuracyBell LabsBell Telephone LaboratoriesClaude Shannon • communicating system • communicationcommunication processcommunication theorydisorderefficiencyentropyfidelity • human communication research • information technologyinformation theorymeaning makingmessagemodel of communicationnoise • output • pioneeringpredictabilityrandomness • receiver • reception • redundancysignalsymbolsystems approachsystems theorytheory of communication • transmission • transmission model of communicationtransmitter • University of Twente • Warren Weaver

CONTRIBUTOR

Simon Perkins
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