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Comment by bugsy | Hacker News Reader

I suppose at night someone could pick this up if there is a window in the room being used, but this is no different than normal wifi which can be picked up outside the house.

More of the problem is that it doesn't work room to room, only line of sight like with a remote control. Could be useful sending to wireless speakers from the media player, if the player is in a different location than the TV for some reason, but in the same room. I suppose it breaks down if you add a second device unless each one grabs its own specific light frequency and you have narrow optical filters able to distinguish between them.

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>More of the problem is that it doesn't work room to room, only line of sight like with a remote control.

If you could cheaply make the lights transmit and receive, and if the data were recoverable at very low illumination, you could employ mesh routing -- there's often quite a bit of overlap from lightbulb to lightbulb.

But you're correct -- answering the LoS problem is significant. This could be very useful in many applications, but it's no silver bullet.

While the LoS aspect is potentially desirable in specific applications, I agree that initially it can be perceived as a limiting factor. Researchers at Boston University,Rensselaer Polytechnic Institute, and Nakagawa Lab in Japan are working with software tools to characterize non LoS applications using reflective and refractive surfaces found indoors. A powerful system can be envisioned if someone managed to utilize these principles with a device that contains a receiver with a wide view.

Or you have a "networked" light socket in each room and a discovery protocol to figure out what room to route the data to. More work on the initial infrastructure side, but then you don't have to worry about mesh- your room is covered.

You'd network your light sockets to get around the room-to-room issue. Each room would have a light bulb "port". Some simple communication could then figure out which room your in (similar to access-point hopping used in large wifi distributions)

I can see this as a potential technology for sideband data: stream the video over the light, but the control data would still go through WiFi (and then you wouldn't bog down your wifi with torrent downloads)

Yeah, I think so. So now you have to wire your house with a wired network, and when you want to watch TV or use your computer you have to turn the lights in all the rooms on.

A simple CDMA or TDMA (code/time division multiple access) scheme allow multiple devices to receive/transmit at the same time. This is how cell phones work.

See: http://en.wikipedia.org/wiki/Code_division_multiple_access

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