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  • LED "hot spots"

    With the advent of LED lighting the idea is to integrate LED optical networks in the fixtures to provide optical wireless service -



    Article....

    Researchers Want LED "Hot Spots" to Replace Wi-Fi

    Could the networks of the future run on light


    Solid-state lighting is one of the hottest topics in the tech industry, and with good reason. The Department of Energy is sponsoring a $20M USD "L Prize" for advances in LED lighting, a type of light which uses solid-state components (diodes). The research is a big deal as lighting currently consumes 22 percent of the electricity in the U.S. If the DOE accomplishes its goals of reducing lighting energy use by 50 percent, it would save billions of dollars and reduce environmental impact.

    New research from Boston University's College of Engineering, funded by a National Science Foundation grant, indicates that LEDs may be not only the integral lighting component of the future, but may also form the backbone of future wireless networks.

    BU Engineering Professor Thomas Little describes the new research, stating, "Imagine if your computer, iPhone, TV, radio and thermostat could all communicate with you when you walked in a room just by flipping the wall light switch and without the usual cluster of wires. This could be done with an LED-based communications network that also provides light - all over existing power lines with low power consumption, high reliability and no electromagnetic interference. Ultimately, the system is expected to be applicable from existing illumination devices, like swapping light bulbs for LEDs."

    The primary goal of the research is to develop LEDs that do exactly that -- transmit information wirelessly via controlled blinking.

    Little continues, "This is a unique opportunity to create a transcendent technology that not only enables energy efficient lighting, but also creates the next generation of secure wireless communications. As we switch from incandescent and compact florescent lighting to LEDs in the coming years, we can simultaneously build a faster and more secure communications infrastructure at a modest cost along with new and unexpected applications."

    Professor Little and his colleagues imagine LED lighting in the room being hooked up to computer circuitry, which uses existing lighting to implement a wireless network which provides data to computers, personal digital assistants, television and radio reception, telephone connections and thermostat temperature control. Prototypes of the new network design, according to Professor Little, should start at around 1 to 10 Mbps. Better yet, bandwidth would be greater than in existing radio frequency (RF)-driven networks.

    In the new network, each LED light bulb would act as an access point. Another perk of the new design is beefed up security. Unlike RF networks, the new signal would not pass through walls or other opaque objects. This would help prevent snooping and connection theft. The new system would also use much less power than RF, as solid state lighting is energetically cheaper to the strong radio signals needed for wireless internet.

    The flickering which drove the network would be performed so fast the human eye could not see it. The network would ideally be able to operate outdoors as well as indoors. The first test deployment may be outdoors, with a likely candidate being car interiors. Professor Little continues, "This technology has many implications for automobile safety. Brake lights already use LEDs, so it's not a stretch to outfit an automobile with a sensor that detects the brake lights of the car in front of it and either alerts an inattentive driver or actively slows the car."

    While the technology seems very promising, one quandary is how to make the communication bidirectional. Professor Little and his team have not elaborate on this tricky point yet in the initial press. In order to send data requests, you would need a means of receiving light from devices such as cell phones or laptops, however, you ideally would want to avoid having to have a bright blinking transmitter on your device walls covered in sensors.
    Dr. Mordrid
    ----------------------------
    An elephant is a mouse built to government specifications.

    I carry a gun because I can't throw a rock 1,250 fps

  • #2
    Um... sure, its fine for situations where you have unrestricted line of sight to the transmitter. So that rules out cell phones and most other portable/handheld devices where the person using the device would be in the way.

    Comment


    • #3
      Affirmative. It would be much like a TV remote in that respect. If ANYTHING blocked the IR emmitter/detector on your device the connection would be lost. Everything handheld would need an "antenna" with the sensor at the end.

      Combined with other networking methods it could provide a valuable extra high-speed downlink. But I suspect its applications would be somewhat limited.

      Kevin

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      • #4
        My take is that each device would have numerous detectors/led's so they could 'see' any light/interface in the room, making them essentially omnidirectional.
        Dr. Mordrid
        ----------------------------
        An elephant is a mouse built to government specifications.

        I carry a gun because I can't throw a rock 1,250 fps

        Comment


        • #5
          Hard to have enough detectors on a device that can fit inside the palm of your hand without making it larger or look silly

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          • #6
            Yes, but lens makers are improving their products omnidirectionality every day...example below which can act as both input and output optics

            Omnidirectional lens patent 7362516....

            Assignee: O.D.F. Optronics (supplier to the US military and the Israili IDF)

            Abstract:

            The invention presents a wide-angle imaging assembly which comprises a main lens produced from an aspheric optical block. The aspheric optical block comprises a vertical axis of symmetry; a transparent upper surface, at least part of which is capable of reflecting rays that impinge upon it from the interior of the optical block; a transparent perimeter surface; and a transparent lower surface. The optical block is fabricated from material selected to enable optical transmittance of a specific spectral range. Light rays in the specific spectral range originating in a first scene, having a 360 degrees panoramic perimeter, are refracted by the transparent perimeter surface, enter the optical block, are then reflected by the upper surface towards the transparent lower surface, where they are then refracted by the transparent lower surface, and exit through it.
            Dr. Mordrid
            ----------------------------
            An elephant is a mouse built to government specifications.

            I carry a gun because I can't throw a rock 1,250 fps

            Comment


            • #7
              It won't fly. The beauty of WiFi is that you don't have to install lots of stuff.

              Neat idea, though.
              There's an Opera in my macbook.

              Comment


              • #8
                And actually IR remote works also when illuminating wall that detector can see...perhaps "seeing" ambient lightning would also suffice here?

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                • #9
                  "The flickering would be too fast for humans to see."

                  Except the ones that can. And get seizures from it. Oops!
                  The Internet - where men are men, women are men, and teenage girls are FBI agents!

                  I'm the least you could do
                  If only life were as easy as you
                  I'm the least you could do, oh yeah
                  If only life were as easy as you
                  I would still get screwed

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                  • #10
                    Originally posted by Gurm View Post
                    Except the ones that can. And get seizures from it. Oops!
                    That is ridiculous. The pulsing would be of the order of GHz. Seizures are caused by a few Hz. You have 9 orders of magnitude difference. What would worry me more would be if some joker sent series of millions of 1s or 0s at a time. The level of lighting would vary.

                    I don't believe the idea is over-practical though. No chance of moving desks very far, omnidirectional or not. The light level from omnidirectional LEDs diminishes according to the inverse square of their radiative angle, no matter their optics. I had a hand-held with an IR link to my printer. That was far too critical angularly, as well. Think how critical the remote of a TV or aircon is when used across a room.

                    What may be worth exploring is ultrasound, though. It would be limited by the physical dimensions of the transducer to a max between 100 and 200 MHz, though. It would have the advantage of resonance, so could be made secure very easily by using two transducers per device (same security level as remote car keys). Casual visitors could not tune in to the system. This would be very difficult with a light system.
                    Brian (the devil incarnate)

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                    • #11
                      Remind me what the frequency of a dog whistle is? That seems like a neat idea Brian but I'd hate to take the dog to work and have it get all twitchy.
                      Wikipedia and Google.... the needles to my tangent habit.
                      ________________________________________________

                      That special feeling we get in the cockles of our hearts, Or maybe below the cockles, Maybe in the sub-cockle area, Maybe in the liver, Maybe in the kidneys, Maybe even in the colon, We don't know.

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                      • #12
                        Originally posted by Brian Ellis View Post
                        That is ridiculous. The pulsing would be of the order of GHz. Seizures are caused by a few Hz. You have 9 orders of magnitude difference. What would worry me more would be if some joker sent series of millions of 1s or 0s at a time. The level of lighting would vary.
                        Y'know, they always say that, but nobody has yet built a fluorescent light that doesn't make my brain hurt. I know those are at a lower frequency, right? But honestly, these things ALWAYS end up wigging someone's nervous system out.

                        I'm just being pessimistic. I understand, rationally, that we're talking about apples and pianos.
                        The Internet - where men are men, women are men, and teenage girls are FBI agents!

                        I'm the least you could do
                        If only life were as easy as you
                        I'm the least you could do, oh yeah
                        If only life were as easy as you
                        I would still get screwed

                        Comment


                        • #13
                          Originally posted by Brian Ellis View Post
                          That is ridiculous. The pulsing would be of the order of GHz. Seizures are caused by a few Hz. You have 9 orders of magnitude difference. What would worry me more would be if some joker sent series of millions of 1s or 0s at a time. The level of lighting would vary.
                          There are many signaling schemes that keep the average output power near constant. Manchester coding or the 8b/10b scheme that DVI uses would work just fine.
                          I don't believe the idea is over-practical though. No chance of moving desks very far, omnidirectional or not. The light level from omnidirectional LEDs diminishes according to the inverse square of their radiative angle, no matter their optics. I had a hand-held with an IR link to my printer. That was far too critical angularly, as well. Think how critical the remote of a TV or aircon is when used across a room.
                          The dropoff is the exact same as for RF, which makes sense since RF and optical signals are the same thing, albeit at vastly different frequencies. Optical tends to be more directional, which is true of anything in the multi-GHz range anyway. Lenses are to optics what directional antennas are to RF, so there are ways of changing the radiation and detection patterns of optical devices just like you can do with RF devices.

                          There are practical problems with optical that don't exist for RF though. More things block optical radiation than RF radiation. Paper for instance. A users hand is very opaque to light, but only partially opaque to RF. You wouldn't be able to put your PDA in a pocket either - this system seems like it would only be useful for "pull" data - things you actively access, vs. something like email or a phone call where the system pulls for you and you get notified. (This is only because the typical usage of a phone/PDA/whatever is to stick it in a pocket or drawer when you're not actively using it)

                          - Steve

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                          • #14
                            Originally posted by Claymonkey View Post
                            Remind me what the frequency of a dog whistle is? That seems like a neat idea Brian but I'd hate to take the dog to work and have it get all twitchy.
                            Dog whistles are in the 20-30kHz range, well below the MHz range Brian mentioned.

                            They're basically just above the (normal, non-GURM ) human hearing range.

                            - Steve

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                            • #15
                              1. the LED's used to do the networking would be infrared diodes fit into an array of white LED's (mostly UV LED's with white-producing phosphors), hence invisible to humans.

                              2. I can bounce my IR remote off walls and control a TV on the other side of a ~20 foot room, total travel distance ~25-26 feet, and the wall isn't even white so I doubt signal strength would be much of an issue.

                              3. I would imagine that devices so equipped would have multiple IR transducers to provide enhanced coverage.
                              Last edited by Dr Mordrid; 8 October 2008, 09:06.
                              Dr. Mordrid
                              ----------------------------
                              An elephant is a mouse built to government specifications.

                              I carry a gun because I can't throw a rock 1,250 fps

                              Comment

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