7 ms·
'Li-fi 100 times faster than wi-fi'
- schappim 11y agoGreat, but you can't use it in the dark! Perhaps they could fix this with infrared?
- AYBABTME 11y agoor UVs..!
- snerbles 11y ago...then wireless networking really will cause cancer.
- the8472 11y agomaybe a deep violet right at the edge of the visible spectrum? all you would see is a faint glow
- drdaeman 11y agoI'm not sure but I heard short wavelength (blue/violet) visible light has most impact on circadian rhythms. If it's indeed the case, insomnia or any other kind of sleep disorder is not worth it.
- TeMPOraL 11y agoOk, but you'll be the one to explain to people who don't want to accept the ionizing/non-ionizing radiation distinction that this sort-of-UV is not the cancer-causing UV.
- hanniabu 11y agoI forget where I saw this (think it may have actually been a video), but they said the latest versions could work with the lights off as it is still flickering the light, but just dinner than what we could perceive. Of course this could with the assumption that the source I hard it from was correct and if so, then it's probably only feasible with lab grade sensors to pick up signals that sensitive.
- djmdjm 11y agoThere was an IR physical layer defined for 802.11 last century, but it didn't go anywhere. http://dl.acm.org/citation.cfm?id=2289301 http://dl.acm.org/citation.cfm?id=2289301
- blazespin 11y agoAccording to the article IR is slow.
- Sanddancer 11y agoThat's more protocol than anything. The IR used day-to-day was designed for consumer products in the 70s and 80s, so by necessity was a very simple protocol. There's no physical limitation for higher bandwidth IR.
- analognoise 11y agoAs I understand https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem https://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampli... IR has a frequency of between 430THz and 300GHz, so Max bandwidth would be between 215Tsymbols and 150Gsymbols (I used symbols instead of bits because I forgot the right term...) So there is an information-theory limit, as I understand it. If I was ever wrong, this is the right crowd to find the person who will correct me!
- Sanddancer 11y agoYeah, there is the Shannon Limit which gives the theoretical max, I was more trying to get at there not being a reason why we'd be stuck at remote control/irda speeds.
- hamiltonkibbe 11y agoIR comma doesn't the frequwncy of the light as a carrier, it uses pulsed IR (on=1 off=0 usually in the KHz range) the limitation is usually the rise time of the LEDs
- p1mrx 11y ago1Gbps is not 100X faster than Wi-Fi, unless you're talking about 802.11g under marginal conditions.
- davb 11y agoI've come to take the BBC's tech reporting with a pinch of salt.
- dazc 11y agoYou can rely on the BBC to give you the right time and roughly what the weather was like yesterday. Otherwise forget it.
- TeMPOraL 11y agoGiven that everyone else's reporting is worth the same or even less, I wonder where do you still find salt for all of that? I've run out of mine long ago.
- coldtea 11y agoIf only the next line wasn't: "Laboratory tests have shown theoretical speeds of up to 224Gbps". Which is still not 100X from all wi-fi (more like 10x), but it indeed is 100x faster than the wifi speeds most see in practice.
- Quinner 11y agoSo you're comparing the theoretical speeds in lab tests to actual speeds in the real world of older wifi tech? That's not really a fair nitpick.
- coldtea 11y agoI'm not. The article is. I just explained their probable reasoning -- and that the 100x doesn't refer to the 1Gbps speed since they go on to talk about higher possible speeds.
- jepler 11y agoSince fiber optics work just dandy, clearly getting your source to switch on and off at the requisite rate is not the trick. But if you're not shining down a fiber optic cable, you have the problem that intensity decreases as the square(?) of distance from the emitter; and that your multipath problems become a lot more pronounced.
- mmmBacon 11y agoThese 2 things are created in different semiconductor technology (materials) that have quite different properties. Most communications are either in GaAs for NIR or in InGaAS/InP for mid IR. Visible stuff here is generally a large GaN die pumping a phosphor material. As the size of the die increases so does its capacitance which ultimately limits the rate at which the signal can be modulated or the brightness of the source. Additionally in the visible you use Si detectors which are slow due also to their large capacitance. So I think it's unlikely you could ever realize 224Gb/s unless you were using WDM (wavelength multiplexing).
- motosynthesis 11y agoHow do you request the data to be transferred? This magical system is starting to get an awful lot more complicated.
- Sanddancer 11y agoBeamforming. The other articles I've seen on using the visible spectrum for communications mostly discuss sending to a mostly stationary object. It's not great for general purpose, but as a wiring replacement, can be rather useful.
- frozenport 11y agoCan we use a waveguide for beamforming? Maybe some kind of tube relying on total-internal reflection to guide our light around sharp corners?
- motosynthesis 11y agoi'm no computer scientist, but don't i have to request information in order to receive it? What i mean is, do i have to attach a LED light to my laptop to request the data from the LED in my roof?
- Sanddancer 11y agoYes and no. One could just receive broadcasted data -- a monitor on the other side of the room really doesn't need to send much info back. For a laptop, one wouldn't necessarily need to request data via an LED, the requests could be made over some other medium, like traditional wifi, with the responses coming from the LED.
- delbel 11y agoEvery couple of years I hear about this. Then it gets forgotten, and re-invented. Each time it never manifests into a real product. That reminds me, I think we're about due for another rehash of the "Voyager leaves the solar system" article, anyone? Or another segment on the local news where they say "Scientist find [wine|beer|cheese|coffee|nuts|fat|red meat] [good|bad|healthy] for you" article.
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- Freestyler_3 11y agoI have seen this before too, and I ask myself what impact it has on the life of the lamps. Others have made me think about other issues with this, like how the lamps will get their connection? -Someone then mentioned through the power grid network. And then I think you are limited to the bandwidth of that. How much infrastructure needs to change to make this li-fi happen? edit: spelling error, also I am thinking only about the impact on for example an office installing this. At a home this is too expensive for what it gives.
- TeMPOraL 11y agoDon't forget that we're overdue for another miracle development in batteries, as well as the next iteration of sprayed-glass coating that turns everything waterproof and bacteria-free.
- superuser2 11y agoThat's nice, but my 5-year-old 802.11n WAP still has ~20x the bandwidth you can buy for any amount of money at my house. Faster WiFi is not particularly interesting for consumers unless they're also getting faster ISPs.
- nitrogen 11y agoHas the entire world forgotten what a hard drive is? What LANs are? Good grief! You can transfer data on a network without sending it to Dropbox first! Faster local networks have tons of uses beyond just slaving them to someone's walled garden.
- spdionis 11y agoExcept the UX of that is horrible. I'd have no idea how to set-up that and I'm sure it would take me at least a couple of hours...
- muddi900 11y agoSamba/CIF is infinitely more simple than setting up Dropbox. But people have been trained on proprietary solutions, thanks to the iPod, hence find that simpler.
- hemdawgz 11y agoUnfortunately when I tried to set up a local synchronization solution I could not find any simple guides without already knowing what the names of the protocols were. Call me a filthy plebian, but in contrast all of my friends already knew what Dropbox was.
- muddi900 11y agoWell no, there's way to sync files simply but accessing files is quite simple. Regardless, even Dropbox uses local network bandwidth when syncing on two computers on the same network.
- jaybna 11y agoImagine if someone used ultrasonic sound in conjunction? Ultra fast networking and witless charging. Oh wait, that won't work....
- Veedrac 11y agoTo all the "lab tech never actually arrives" skeptics, it's worth noting that 12 years ago this was a thing: http://news.nationalgeographic.com/news/2003/03/0318_030318_internet.html http://news.nationalgeographic.com/news/2003/03/0318_030318_... In my opinion, expect to see VR as the first consumer device to pick this up - it's too bandwidth limited for today's wireless and sorely wants not to be.
- onion2k 11y agoWhy does VR need more bandwidth? Surely it's just a video feed in and some telemetry data out. Isn't latency more of a problem?
- loxs 11y agoMy experience is with Occulus. Full HD is not enough as you clearly see the pixels. I was so distracted by the "low" resolution that I couldn't immerse myself at all. Probably 4K will be better, but I suspect it still won't be enough
- moogly 11y agoFirst of all, you need a lot higher refresh rates, because you tie in your ocular-vestibular system which is very sensitive, compared to the visual feedback required to be comfortable sitting in front of a monitor. It's still unclear where the upper limit is, but the lower is probably at least 120 Hz. The consumer devices being released soon are running at 90 Hz, and that's the bare minimum. I've heard "1000 Hz" coming out of Michael Abrash's mouth, but that was somewhat of a hypothetical number. Secondly, higher resolution. You'll want at least 4K in the near future, because with a lower resolution display that close to your eyes, you'll discern individual pixels and the actual space between them (causing the infamous "screen door effect").
- Veedrac 11y agoEven further, strict latency requirements on an already-busy system prevent you from doing any interesting compression.
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