7 ms·
Li-Fi Gets Ready to Compete with Wi-Fi
- brianpgordon 12y agoSo the obvious question is... what happens when line-of-sight is lost between the endpoints? With near-visual wavelengths, someone walking past could interrupt the connection. I could see this being useful for very limited applications in settings where radio is completely unusable, but it's a stretch. > In 25 years, every lightbulb in your house will have the processing power of your cellphone today And in 50 years, every hammer and wrench in your toolbox will be able to beat Ken Jennings on Jeopardy!
- tjohns 12y agoTo be fair, I replaced every lightbulb in my house with a Philips Hue -- which does have some limited processing power (enough to manage a Zigbee mesh connection). So the "every lightbulb in your house" comment doesn't seem completely unreasonable to me.
- batiudrami 12y agoDo you like them? What benefit do you get from them compared to regular light bulbs. Other than that they're damn cool, of course.
- manicdee 12y agoDim able and colour controlled without having to walk over to the switch on the wall. Integrate the controllers win IR sensors, you have lights that turn off when nobody is in the room. Built in sunrise alarm in every room! Turn the lights red when playing submarine simulators for extra authenticity :)
- deleted 12y ago[deleted]
- nitin_flanker 12y agoThat sounds cool
- mcpherrinm 12y agoAnd get poorly timed light effects when watching Sharknado! http://www.syfy.com/sharknado/sync http://www.syfy.com/sharknado/sync I have Hue bulbs everywhere too, and I really like them. Being able to sunrise and sunset them automatically is really nice, and they're a great ambient information display: One of mine near the door is blue if there is rain forecasted for today!
- TheCoreh 12y agoI have another question, could be seriously stupid: Do you need to have a strong, glowing light on the top of your computer for this to work? Could it use the monitor backlight? Imagine if the Apple logo in a MacBook is actually a Li-Fi "antenna".
- vilhelm_s 12y agoHeh, that would also be a good way for them to force their customers to display the branding, instead of e.g. covering it with stickers...
- Sanddancer 12y agoThe article says they are using 5 milliwatt LEDs for this, so it doesn't seem like you need that much brightness at all.
- tlarkworthy 12y agoMultiple lights is multiple paths, and maybe a slower connection off reflections on wall? Even if the above is not true, there is usually a very useful niche for every communication, especially a faster one. Wifi doesn't work all that well throughout the house. Wifi + LiFi might be a much better experience.
- yuumei 12y agoMaybe it would be good for people suffering from wifi interference.
- walterbell 12y agoIf they can shield neighboring wifi.
- MrBra 12y agoMmm.. led me think..
- jfoutz 12y agoIt's actually a nice feature. everybody needs line of sight. You, the FBI, the NSA, the local PD. Being able to kill a connection by closing a door is a win.
- wheels 12y agoThat seems naive. Current connections are encrypted. Those with the desire and means to break crypto aren't going to be deterred by line-of-sight issues.
- walterbell 12y agoIt's another layer of isolation - decreases range and increases cost of surveillance. Encryption is orthogonal, can be applied to both transports.
- ohitsdom 12y agoMy hammer and wrench can already beat Ken Jennings.
- apk17 12y agoLine-of-sight isn't strictly needed. IR remote controls can get along without; a white ceiling might reflect enough light for this as well.
- electromagnetic 12y agoIf you've got a remote with a good quality IR LED you can point it just about anywhere.
- walterbell 12y agoWould this be less susceptible to local surveillance than wifi, e.g. within a few hundred feet? How would it deal with interference from overlapping beams?
- wbkang 12y agoMy uneducated guess is just like wifi, you can use different frequency to distinguish between different "channels" maybe
- wyc 12y agoLine-of-sight communications are definitely less susceptible to surveillance than WiFi that has omnidirectional broadcast. Even if the signal bleeds due to refraction, at such high frequencies, this loss of power is extremely detrimental to making sense of the waveforms. Multipath interference can be managed with existing communications techniques, as light isn't the only EM wave that bounces off of things.
- ars 12y agoYou can use a lens to focus the light to travel in a narrow beam, so each beam is separate and don't interfere. A lens for radio frequencies is not practical (it's a satellite dish basically), so they use antennas that have a much broader beam.
- amjaeger 12y agoWhen my brother and I were younger we would sneak up to the door of each other's room and flip the light switch. It was mildly annoying. The kids of the future are going to go ballistic when a younger sibling flicks off their internet.
- _RPM 12y agoI find that this frustrates me now. When I have to restart my router for some arbitrary reason, I get impatient.
- frozenport 12y agoOr leave the light on to download Torrents?
- undersuit 12y agoYeah, but parents will now be able to control the internet and bed time.
- deleted 12y ago[deleted]
- ArchD 12y agoThe article mentions industrial applications being the first to use this. What are some example industrial applications where you need a high-bandwidth, low-latency, link that has to be wireless, that WiFi is not good enough?
- jwilliams 12y agoA lot of industrial processes generate immense interference - electroplating and arc welding spring to mind. I guess those would be a logical starting point.
- mistercow 12y agoTrue, but arc welding will also create enormous interference in the visible spectrum.
- electromagnetic 12y agoThat's easily shielded against by use of an aperture, where as RF interference is not nearly as easily shielded against.
- jrapdx3 12y agoHow about medical instrumentation/telemetry? In the ER, ICU and other bedside locations ability to communicate high bandwidth data is very valuable. Wireless transmission allows greater flexibility choosing devices to measure various parameters and freedom to set them up optimally around the patient. Another idea is having a completely sealed Li-Fi transmitter in an isolation chamber send experimental data through a transparent port for analysis. (My guess is Wi-Fi would be harder to package for the purpose.) I'm sure there are many other situations where high-speed short-distance transmission would be advantageous...
- yazaddaruvala 12y agoHave you heard of/seen Kiva robots? If the floor could just blink to the robot, that would be pretty cool! Especially if Li-Fi is cheaper / higher throughput. https://www.youtube.com/watch?v=Fdd6sQ8Cbe0#t=13 https://www.youtube.com/watch?v=Fdd6sQ8Cbe0#t=13
- wyc 12y agoI know that even cheap LEDs have rise and fall times of easily under 5 ns with the right circuitry[0]. This means that a transmitter of 100 MHz can be easily built with COTS parts, so the speeds they mention make sense to me. However, when I built a cheap optical communications system with LEDs and $0.10 diodes, the tough part was always getting the photodiode capacitance low enough to receive high frequencies while still sensitive enough to detect the signal accurately[1]. This is why lasers are very popular for communications: a concentrated beam can deliver a very high signal-to-noise ratio. With LEDs, it's tougher because the beam is dispersed and you don't want to blind people with high power output, so the signal is a lot harder to receive. It looks like they went with nice avalanche diodes instead of cheap ones, and I'm sure that have a well-designed integrated circuit helps a lot too. I'm very excited to see how this plays out. [0]: http://arxiv.org/ftp/arxiv/papers/1011/1011.1954.pdf http://arxiv.org/ftp/arxiv/papers/1011/1011.1954.pdf [1]: http://www.thorlabs.us/tutorials.cfm?tabID=31760 http://www.thorlabs.us/tutorials.cfm?tabID=31760
- Sniffnoy 12y agoA note -- if you're linking to arXiv, it's better to link to the abstract (http://arxiv.org/abs/1011.1954 http://arxiv.org/abs/1011.1954) rather than directly to the PDF. From the abstract, one can easily click through to the PDF; not so the reverse. And the abstract allows one to do things like see different versions of the paper, search for other things by the same authors, etc.
- JadeNB 12y agoThank you for advocating this practice! This kind of 'deep linking' seems to be the norm even among scholars, and I've never understood why.
- Luc 12y ago> This is why lasers are very popular for communications: a concentrated beam can deliver a very high signal-to-noise ratio. With LEDs, it's tougher because the beam is dispersed and you don't want to blind people with high power output I suppose I am missing something obvious... but laser beams are shaped into a beam by way of a lens at the end of a tube, right? The laser diodes I've seen emit light in all directions. You could just as well stick an LED at the bottom of that tube.
- discardorama 12y agoWhatever happened to UWB? Ten years ago, there was so much talk about UWB, and how it would provide so much bandwidth, etc. And now it's nowhere to be found. One huge advantage of radio is that it can work through walls; "Li-Fi" won't.
- kristoffer 12y agoUWB is used in the 803.15 WPAN (wireless personal area network) standards.
- bornabox 12y ago802.15 WPAN - It's kinda stalled for some time. And UWB really did get good press with some very promising features / performance back in the day. If I remember they ended up using it in some system for firefighters that can 'see' through walls, and it might've been used for such a system in the army as well. But overall UWB didn't deliver on it's promise.
- amreact 12y agoUWB is making steady progress in active tracking systems and passive tracking systems. I work for a company that does active tracking: http://pluslocation.com/ http://pluslocation.com/. PLUS is an offshoot of Time Domain, http://www.timedomain.com/ http://www.timedomain.com/. Time Domain does radar; I don't think they do any active tracking (could be wrong though). IIRC Time Domain is the company that did the see-through-walls system.
- jodrellblank 12y agoTime for the Timex Datalink Watch to make a comeback? http://en.wikipedia.org/wiki/Timex_Datalink#Optical_sensor http://en.wikipedia.org/wiki/Timex_Datalink#Optical_sensor Upon closer inspection however a small lens at the position of 12 o' clock on the watch face indicated the mode of the wireless data transmission through visible light.[4][16] Data was transmitted from the CRT of the computer through a series of pulsating horizontal bars,[17][18] that were then focused by the tiny lens and inputted into the watch EEPROM memory through an optoelectronic transducer operating in the visible light spectrum and employing optical scanning technology.[19][20] The CRT synchronization was possible only for systems operating on Windows 95 and Windows 98. The watch was compatible with Schedule+ and for the Datalink 70 model the time needed to download seventy phone numbers was about twenty seconds.[14][17]
- WalterBright 12y agoI'd like Li-Fi even for desktops. It's one less wire in that rat's nest behind the computer.
- gima 12y agoLet the headaches begin.
- cpach 12y agoLook here if you want to build your own optical communication system: http://ronja.twibright.com/ http://ronja.twibright.com/
- efqdalton 12y agoIt's interesting how things go back and forth in science... A Brazilian priest studied about using light to transmit data and achieved that around 1 century ago, even before Marconi Unfortunately his government didn't supported him, because he "was a mad priest" that wanted to send messages to other worlds, he said: "Give me a vibratory movement as large as the distance that separates us from these other worlds that roll our heads, or below our feet, and I will make the sound of my voice reach there." http://www.landelldemoura.com.br/lm04.htm http://www.landelldemoura.com.br/lm04.htm
- fakeyfake 12y agoGoing to repost this talk they held at UoE about it: https://www.youtube.com/watch?v=WRG9iXZbuAc https://www.youtube.com/watch?v=WRG9iXZbuAc (2014-04-23)
- NatW 12y agoContrary to the article's title, LiFi doesn't _compete_ with the majority of WiFi use cases due to its limited propagation characteristics. The article confirms as much: "“We don’t want to replace Wi-Fi,” he says. “That’s not our goal.” But Deicke says Li-Fi could complement existing communications technologies including WiFi"
- Igglyboo 12y agoWon't this technology be very distracting with the lights constantly flickering/pulsating?
- teraflop 12y agoAt the signaling rates they're talking about, the flicker frequency will be orders of magnitude too fast to be perceptible.
- Dylan16807 12y agoThink about the packet rate. Little flickers whenever it has something to send.
- teraflop 12y agoHmm, true, but that could be remedied by transmitting the signal with something like Manchester encoding, so that the average intensity is constant whether or not data is being sent.
- bch 12y agosee also: Reasonable Optical Near Joint Access (RONJA) -- http://en.wikipedia.org/wiki/RONJA http://en.wikipedia.org/wiki/RONJA