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posted by Fnord666 on Friday October 13 2017, @05:21AM   Printer-friendly
from the dark-side-has-cookies dept.

Energy-saving Light Emitting Diodes (LEDs) could help meet demand for wireless communications without affecting the quality of light or environmental benefits they deliver, new research funded by the Engineering and Physical Sciences Research Council (EPSRC) has shown.

A University of Edinburgh team has found that transmitting digital data via LEDs at the same time as using them to generate light does not make the light dimmer or change its colour. Nor does it make the LED more energy-hungry. Dr Wasiu Popoola of the University of Edinburgh, who led the research, says these concerns have held back the more widespread adoption of Light Fidelity, or LiFi, which uses household LEDs to enable data transfer.

But these findings help eliminate key hurdles to using LEDs to help satisfy the increasing global thirst for wireless communications. Preserving the quality of lighting is, in particular, a vital consideration as it can have a major effect on the physical and mental wellbeing of people in both their homes and their workplaces. LEDs have secured a huge increase in their share of the worldwide lighting market in recent years, as well as being used extensively in TV and other displays.

Uh huh. That's the same technology they use to keep the rest of you from seeing what I see.


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  • (Score: 4, Informative) by takyon on Friday October 13 2017, @06:04AM (8 children)

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday October 13 2017, @06:04AM (#581597) Journal

    A University of Edinburgh team has found that transmitting digital data via LEDs at the same time as using them to generate light does not make the light dimmer or change its colour.

    Could have sworn that was already asserted in previous articles about Li-Fi.

    'Li-Fi 100 Times Faster Than Wi-Fi' [soylentnews.org]

    From the image in the 2015 BBC article [bbc.com]:

    Modern LEDs, however, could transmit enough data for a stable broadband connection - but still look like normal white light

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  • (Score: 1) by anubi on Friday October 13 2017, @06:14AM (5 children)

    by anubi (2828) on Friday October 13 2017, @06:14AM (#581600) Journal

    My concern is the LED lighting is not bidirectional... they can send only.

    Something else would have to serve as the return channel.

    I have been involved with ( several years ago ) a lighting scheme using manchester-coded LED drive to illuminate signage or products. Having a cellphone with the correct sensor would enable it to read the QR-type code it is transmitting.

    Basically, if the phone "saw" a product illuminated by such light, the cellphone would then preload into the browser the URL of the product.

    It was an internal thingie. Died. Phones do not come with the appropriate high-speed photodetector needed to make this practical.

    I know at least one company has marketed the standard science_fair "talk on a light beam" technique for underwater communication for skin divers using head_mounted flashlights. If you "illuminate" a companion, you can talk to them.

    --
    "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
    • (Score: 2) by GreatAuntAnesthesia on Friday October 13 2017, @08:49AM (1 child)

      by GreatAuntAnesthesia (3275) on Friday October 13 2017, @08:49AM (#581650) Journal

      It could be handy in the home, assuming your devices were equipped to read it: If this was paired with a special wifi router then you could have normal 802.whatever upload speed, but muchly increased download speed (only between device & router, obviously, your broadband connection would still be a bottleneck.) If you could divide packets between the wifi and lifi channels, then that would make eavesdropping a hell of a lot harder.

      Also, it would be a great sell to radiophobes who are convinced that their phone / wifi router / whatever is giving them cancer: It could be marketed as "50% radiation free". Yeah yeah, light is still radiation, but when did facts ever stop marketers?

      • (Score: 1) by anubi on Friday October 13 2017, @09:21AM

        by anubi (2828) on Friday October 13 2017, @09:21AM (#581659) Journal

        Interesting thoughts. I'll throw another.

        I wonder if such a thing would also be useful in venues catering to the hard-of-hearing to provide captioning info and clean audio stream for attendees hearing aids?

        With the info coded onto the main venue lighting, everywhere in the building illuminated by those LED's, all driven in tandem, would receive the info. Probably could not get the bandwidth too high due to multipath considerations. ( Speed of light being about 1 foot per nanosecond. Before long everything starts looking like what one would expect from a mess of transmission cables, all different lengths, in parallel. )

        --
        "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
    • (Score: 1) by anubi on Friday October 13 2017, @09:11AM (2 children)

      by anubi (2828) on Friday October 13 2017, @09:11AM (#581658) Journal

      Just thinking about what I just typed... should I try that today, I think I would be sending up entire HTML pages and loading them into the browser.

      But the main problem is the way our browsers are coded these days, this technique would be ripe for malware.

      TCP not involved. Just a streaming transfer of HTML and image files for a page to be displayed using high speed manchester or QAM. The links in page would be active, as the browser would be invoked pointing to a file:/// . If its not online, the links are dead, but you still get the page text and images. Just have a standard place this particular app stores the incoming stream of files, and when it gets 'em all, invokes the browser. That way no one has to have connection to the internet to make this thing work.

      At LED speeds in the MHz, I would imagine I should be able to transfer the whole page with images in less than a second.

      The filesets could be saved off for later viewing much like saving photos.

      I think this would be a boon for merchants' display windows and cases... interested passerby can get a lot more info on the featured item.

      --
      "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
      • (Score: 3, Interesting) by GreatAuntAnesthesia on Friday October 13 2017, @09:38AM

        by GreatAuntAnesthesia (3275) on Friday October 13 2017, @09:38AM (#581666) Journal

        The unidirectional nature of it makes me think of the old teletext systems we used to have on TV.

      • (Score: 0) by Anonymous Coward on Friday October 13 2017, @03:50PM

        by Anonymous Coward on Friday October 13 2017, @03:50PM (#581822)

        so like you mean ti display test via a udp stream or something like that using a broadcast?

        isn't that what that was designed for originally? it doesnt have to be tcp or html. it can be text in an icmp payload for all that it matters.

  • (Score: 2) by bob_super on Friday October 13 2017, @06:02PM (1 child)

    by bob_super (1357) on Friday October 13 2017, @06:02PM (#581909)

    A University of Edinburgh team has found that transmitting digital data via LEDs at the same time as using them to generate light does not make the light dimmer or change its colour. Nor does it make the LED more energy-hungry.

    And it was already a lie the first time, as worded.
    Proper wording, from TFA, emphasis mine: Neither technique was found to significantly reduce the lightbulbs' brightness or their life expectancy, or to cause any significant change in the colour of the light. Both techniques also produced only a negligible change in the heat generated by the LED

    If your LED is on 100% of the time, it emits 100 units of light and 100 units of power.
    If it's on 90% of the time, you have 90 units of light, which you may not notice. But still dimmer.

    As far as energy-hungry, admitting that charging parasitic caps somewhat offsets the power saved by the off or reduced intensity, there is still the extra power for the data processing circuitry.

    • (Score: 2) by takyon on Friday October 13 2017, @06:42PM

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday October 13 2017, @06:42PM (#581933) Journal

      Just increase the lumens output by 10% to account for the data transfer use.

      The data processing circuitry might only be an extra 1-2 Watts, about another +10%, but whatever it is you'll be fine with it if you see a benefit from "Li-Fi".

      --
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