Researchers Beam 230Mb/sec Wireless Internet WIth LEDs 218
MikeChino writes "A group of scientists from Germany's Fraunhofer Institute have devised a way to encode a visible-frequency wireless signal in light emitted by plain old desklamps and other light fixtures. The team was able to achieve a record-setting data download rate of 230 megabits per second, and they expect to be able to double that speed in the near future. While the regular radio-frequency Wi-Fi most of us use currently is perfectly fine, it does have its flaws — it has a limited bandwidth that confines it to a certain spectrum and if you've ever had someone leech off of your connection, you know that it also leaks through walls. LED wireless signals would theoretically have none of these downsides."
An idea that's been around (Score:3, Interesting)
US patent 6,542,270 [uspto.gov] ("Interference-robust coded-modulation scheme for optical communications and method for modulating illumination for optical communications"), issued April 1, 2003, assigns direct sequence spread spectrum-type codes to each overhead fluorescent light, so that communication and location-determination can be performed. The chip frequency of the coding scheme is fast enough that there is no human-audible or -visual effect, and supportable by electronic ballasts.
I RTFA (Score:3, Interesting)
I RTFA. It says that they achieve the bandwidth by filtering out the blue light. This makes sense, as white LEDs are actually blue LEDs with phosphors added to get the other colors. Phosphors are similar to glow-in-the-dark stuff, so they retain light for a little while. Presumably, the blue filter is only needed over the receiver.
The one questions is: how does your laptop equipped with this technology talk back? Will your laptop have a multi-watt emitter on the top (read "bright white light") lighting up the room for the upstream traffic?
Re:No upsides either (Score:3, Interesting)
Leaking through walls is not always a feature. I can't get the maximum benefit of my Wifi setup because I live in an apartment building and all my neighbors have devices chattering on every channel. All their routers are probably defaulted to high power, and there's nothing I can realistically do to improve my situation except switch to 802.11n/5G, which I did, and now I'm seeing more routers on that frequency range too.
I don't want to lose my through-walls access, but if it could be heavily supplemented by light within my own home then I have an extra channel that my neighbors systems won't degrade. Even better if the lights can work as repeaters so if I leave some doors open I can get good signal around many corners, and better still if they also support several invisible frequencies so that my signal strength doesn't depend on bright lighting (or any lighting!) and devices like IR remotes don't interfere when you use them. I've also heard others complain their microwave kills their wifi, and I don't know if that's true or not, but if it is then there is another practical problem solved by this technology.
Tell people about the practical benefits. As far as any security related story, I don't care. I already use WPA2/AES. 99.99% of the population probably doesn't care beyond that, either.
Re:No upsides either (Score:5, Interesting)
what if you could use the lighting that already exists in your house to do this? kinda like internet over power lines?
Retailers already use this technology to change the display tags on shelves. After hours, they send a series of codes to modulate the fluorescent lighting in such a way that it sends new data to smart shelf tags. The shelf tags display a product name and a price. Changing the prices on those shelf tags are a major operational cost of grocery retailers.
Fujitsu is one of the firms offering this. Here's Fujitsu's system [fujitsu.com].
Re:No upsides either (Score:0, Interesting)
Why wire your house, just put mirrors everywhere.
Just make sure to use an even number of mirrors.
Using an odd number of mirrors will flip your bits and should only be used when pairing two computers together.
Eventually most ports will automatically handle both setups, but Dell will inexplicably ship systems that don't for decades to come.
Desk lamps, OK, that's one way (Score:3, Interesting)
Now how do we communicate the other way ? Like from the laptop back to the router ? How do I twiddle the house lights from there. Inquiring minds want to know.
BTW what kind of light sensor did they use ? Cheap hopefully.
Re:No upsides either (Score:5, Interesting)
Even if it doesn't have windows open, you can still go through a closed or even shuttered window. Telescopes replace direction antennas and have phenomenal gain and accuracy. Lasers beamed back in can return signals and don't have to be visible ( You can control transmit spectrum a lot easier than receive spectrum ). AlGaAs based photonic detectors can pick up single photons and are sensitive enough to spot light coming through a thin gap in shutters or curtains. ( think more sensitive than military NV devices ).
Now, instead of being worried about people parking in cars just up the street, you need to worry about anything you can see from your house... Thos e hills 10km away? Not far enough. The highrise across the river? Huge risk.
The good news is that tinfoil is sufficient to stop all photons, so a few rolls of tinfoil and tinfoil plated tape will be all you need to secure the wireless visible spectrum devices in your house.
Until someone burns a ten micron hole in your defenses with an infra-red laser....
GrpA
Re:I RTFA (Score:1, Interesting)
The one questions is: how does your laptop equipped with this technology talk back? Will your laptop have a multi-watt emitter on the top (read "bright white light") lighting up the room for the upstream traffic?
Maybe use the LED backlight in your laptop's screen?