What is Li-Fi?
June 3, 2018 11:18 AM   Subscribe

 
Interesting, but I don't think it'll replace wifi for a while -- radio can travel through barriers that light can't. With one wifi hotpoint in my house, I can connect well enough from my front lawn to the machine shed out back, one of their lightbulbs might reach an entire room, if there's nothing in the way. And what happens if two lightbulbs are in the same room but for different networks?
posted by Blackanvil at 11:37 AM on June 3, 2018 [3 favorites]


> And what happens if two lightbulbs are in the same room but for different networks?

Same thing that happens for WiFi. You have to choose one.
posted by seanmpuckett at 11:46 AM on June 3, 2018 [3 favorites]


I hope this flickering that's too fast for the human eye is in fact actually too fast for the human eye, and not like all those other kinds of flickering that manufacturers claim you can't see (that you totally can see and give you eye strain and migraines).
posted by trackofalljades at 11:54 AM on June 3, 2018 [46 favorites]


You won't need a WiFi extender anymore, you just need a mirror.
posted by night_train at 11:58 AM on June 3, 2018 [3 favorites]


This tech seems more suited for big, open air infrastructure, like at a festival or a stadium. For home use, I live on the second floor on an apartment building, and able to connect at the entrance downstairs. That's about as good as it gets.
posted by lmfsilva at 12:00 PM on June 3, 2018


This sort of breathless reporting cracks me up. Start with the theoretical maximum bandwidth of light. Then get to the depressing reality of deployment; 30 Mbps, multiple users are a problem. They don't mention the issue of shadows. I mean by all means work on it, it's an exciting idea, but maybe I'll wait for generation 2 of consumer devices.
posted by Nelson at 12:02 PM on June 3, 2018 [19 favorites]


"Stop trying to make Li-Fi happen. It's not going to happen."

Yes, there are niche applications for it. But like many technologies, it's mostly as a solution in search of a problem.

(On the plus side: Firewalls are actual walls.)
posted by ArmandoAkimbo at 12:02 PM on June 3, 2018 [17 favorites]


It seems like line of sight would be an issue, and you could have literal person in the middle attacks.
posted by drezdn at 12:09 PM on June 3, 2018 [7 favorites]


Your IR remote was capable of 32tbps transfers all along, since the seventies, but You-Know-Who suppressed the technology! Wake up Sheeple!

But no, all I could think of while reading this dumbed-down marketing swill was - data from streetlamps? What for? More advertising to pay for those lamps? Yay!
posted by Laotic at 12:12 PM on June 3, 2018 [10 favorites]


For example, Li-Fi works better in buildings with thick walls that tend to block radio signals. Radio transmission is a problem in healthcare, especially. With Li-Fi, these old or very large buildings might be “wired” as simply as upgrading the light fixtures.

Jesus Christ this is sloppy writing. Sure, the light fixture can transmit the internet, but how do you get the internet to the light fixture in the first place? You know, I'll bet those old buildings with thick walls are not super amenable to running new ethernet cable. So that's going to be a problem. So we need some way to get the internet to the magic lightbulb. What about wifi? Oh wait, what were we talking about?
posted by slagheap at 12:14 PM on June 3, 2018 [22 favorites]


Isn't this dead yet?
posted by Devonian at 12:18 PM on June 3, 2018 [1 favorite]


I agree with folks who say that this seems pretty useless right now, but it does suggest a neat way to get around spectrum crunch. It certainly isn't one-size-fits-any yet as a solution, but it's an interesting and potentially necessary idea.

trackofalljades, can't you just imagine a distopian future where everything from your appliances to your furniture to your utilities are brimming with information rippling at the ragged edge of human perception? Your toaster and refrigerator hum at an infra-sound pitch that sometimes makes you see ghosts while making toast. The water coming out of your shower pulses imperceptibly, but always affects a crescendoing tinnitus in your left ear, so now you take baths. You can't sleep on the couch anymore, because you always wake up to a gasping orgasm.
posted by es_de_bah at 12:18 PM on June 3, 2018 [16 favorites]


The most sensible way to get the data to the light fixture would be to run power line communications (HomePlug) through the lighting wiring. How you'd route that in from the router would be a bit interesting.

That said, this does seem pretty breathless reporting.
posted by ambrosen at 12:21 PM on June 3, 2018 [2 favorites]


Spectrum isn't a problem, WiFi has got a 60 GHz band that'll support gigabits to lots of users, And it works in the dark.

The original 802,11 WiFi spec had an optical option. Nobody used it, because there was nothing it could do as well as wireless.

LiFi is hugely over-promoted.
posted by Devonian at 12:29 PM on June 3, 2018 [4 favorites]


If FastCo Design suggests that something "may be," that thing just about by definition is not, and almost surely never will be. They're like Popular Mechanics with a thin, glossy overcoat of contemporaneity.
posted by adamgreenfield at 12:44 PM on June 3, 2018 [5 favorites]


On the plus side: Firewalls are actual walls.
On the down side, pentesting involves attempted penetration of actual walls
posted by mattamatic at 12:52 PM on June 3, 2018 [2 favorites]


The flickering, also known as “refresh rate” in the world of displays, occurs at 10 times the speed of the light

?
posted by qxntpqbbbqxl at 12:57 PM on June 3, 2018 [40 favorites]


, but how do you get the internet to the light fixture in the first place?

It is possible to inject a signal into power lines. But it's not much bandwidth and needs some kind of bridge between major circuits.

And a firewall is not even required for a denial of service attack, just a fire-towel.
posted by sammyo at 12:58 PM on June 3, 2018 [2 favorites]


Come to think of it, there is one possible application where routing of data to individual fixtures would not be necessary - autonomous/organized mobility.
If most streetlamps were replaced with LiFi lamps, those could form a sort of carrier signal network, connecting to each other and all vehicles underneath. Only a couple access points would be needed, because data streams from vehicles would automatically be routed from lamp to lamp around the network. The (future) bandwidth should allow for that, so each lamp would effectively work as a router/node of the general network.
Perhaps Philips is banking on this unlikely scenario, or perhaps it's all just a shot in the dark.
posted by Laotic at 1:22 PM on June 3, 2018 [4 favorites]


"A shot in the dark.." I see whst yoi did there.
posted by WalkerWestridge at 1:34 PM on June 3, 2018


It's Philips, so you know it's crap.
posted by MartinWisse at 1:44 PM on June 3, 2018 [2 favorites]


If most streetlamps were replaced with LiFi lamps

Not a derail I hope but I believe that one not too distant benefit of autonomous vehicles will be a reduction of infrastructure such as street lamps and the resultant lowering of light pollution. In any case SDC's are entirely disconnected from the internet, excepting for non-critical informational updates like traffic advisories.
posted by sammyo at 1:45 PM on June 3, 2018


qxntpqbbbqxl, I got caught on that, too. The rest of that sentence is pretty much "from video sources," so they're talking about the draw rate or pixels and pixel lines. As a few folks have pointed out: this is some sloppy, effusive writing.
posted by es_de_bah at 1:47 PM on June 3, 2018


Philips Lighting just unveiled...

When all you have is a bulb, everything looks like a socket.
posted by Thorzdad at 1:47 PM on June 3, 2018 [16 favorites]


I live in an area that is only served by Spectrum(Time-Warner-Comcast) and they are really terrible. I would love to have an alternative. This probably isn't it, but I encourage any alternatives
posted by theora55 at 1:50 PM on June 3, 2018 [1 favorite]


I am always stunned by metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother", when otherwise the site is pretty pro-science and progressive. I think it should be apparent, by this point in time in human history, that a significant amount of innovation comes by way of accidents/useless findings, and in order to create that innovation, it's really helpful to just have a culture of "fuck it, try anything and see what happens".
posted by FirstMateKate at 1:56 PM on June 3, 2018 [15 favorites]


> just imagine a distopian future where everything from your appliances to your furniture to your utilities are brimming with information rippling at the ragged edge of human perception? Your toaster and refrigerator hum at an infra-sound pitch that sometimes makes you see ghosts while making toast. The water coming out of your shower pulses imperceptibly, but always affects a crescendoing tinnitus in your left ear, so now you take baths. You can't sleep on the couch anymore, because you always wake up to a gasping orgasm.

This explains David Lynch movies perfectly.
posted by glonous keming at 2:03 PM on June 3, 2018 [13 favorites]


By the time this is able to go mainstream self-driving cars will be cruising around in complete darkness using lidar, and humans will be able to ugrade their eyes to perceive all the frequencies LiFi uses.
posted by blue_beetle at 2:13 PM on June 3, 2018 [2 favorites]


It seems to me that all the obvious problems with Li-Fi can be solved by simply connecting the two devices with fiber-optic cable and passing the Li-Fi signal through that.
posted by Faint of Butt at 2:35 PM on June 3, 2018 [6 favorites]


I am always stunned by metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother", when otherwise the site is pretty pro-science and progressive.

We're pro-science, progressive, and rabidly anti-marketing. Science is great unless there is the possibility that someone, somewhere, might have considered overhyping it, and then it's worse than Hitler.
posted by nebulawindphone at 2:43 PM on June 3, 2018 [12 favorites]


I am always stunned by metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother", when otherwise the site is pretty pro-science and progressive.

Part of the problem here is that the article isn't pro-science; its pro-rewritting-marketing-fluff, except is it even marketing if there's no product? There's an actual real discussion of how it works (what do the receivers/transmitters look like? infrared vs visible? what frequencies are involved? what's an actual reasonable bandwidth estimate?) and the advantages/disadvantages of light vs radio for different applications, but this article provides none of that. Trying everything is great; hyping it up without an honest discussion of what the technology realistically can do and the practical concerns involved in deploying it is what leads to Theranos and Energous and company. Uncritical tech journalism is a big part of why these things last for so long.

And it's this kind of unabashed puffery that ends up setting science and technology back. Optical data transmission, microfluidics, and wireless charging are useful technologies worthy of more research. It does them no favors to hype them up beyond what is reasonably achievable in the foreseeable future; people are eventually going to notice you failed to deliver, and then the whole field of study becomes suspect.

Transmitting data through light is cool (remember when Palm Pilots and HP laser printer had IR ports and you could theoretically print from your PDA if you somehow had something on it worth printing?). We can celebrate that while still acknowledging that walls exist and light sockets aren't magically wired up with ethernet.
posted by zachlipton at 2:46 PM on June 3, 2018 [16 favorites]


Also, I don't have a ceiling light in the main room of my apartment.
posted by Samizdata at 2:47 PM on June 3, 2018 [1 favorite]


X-Fi. X-rays would have incredibly high bandwidth, and you wouldn't have to worry about pesky gypsum drywall blocking the signal.
posted by clawsoon at 2:59 PM on June 3, 2018 [15 favorites]


Reads like a 1960's pop-sci article, I'm going to put this on the list with flying cars and hover boards.
posted by disclaimer at 3:01 PM on June 3, 2018 [1 favorite]


(And, like, I don't even think it's bad that we're rabidly anti-marketing. We-as-a-community — and also a lot of us-as-individuals — were around for the death of the early internet, and the subsequent zombie-like undeath of the social media that replaced it. We watched as this engine for hope and progress and sharing that we all loved got turned into an ad targeting platform, and then somehow, horribly, implausibly, used to destroy democracy. So it's not unreasonable that we hate marketing with the fervor of the traumatized. We came by that honestly. But... yeah, boy howdy we sure do hate us some marketing.)
posted by nebulawindphone at 3:06 PM on June 3, 2018 [21 favorites]


...metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother"...

For myself, I find this annoying because the future of an egalitarian, affordable, efficient, open internet genuinely is under threat, yet this sort of thing serves only to distract from, and possibly dilute concern for, that problem. "Don't worry about net neutrality, I hear we're gonna get internet from the streetlights!" Ack.

Also, Sturgeon's law applies to tech hype in general. Maybe double. I bet if you offered the average IT department a way to get WiFi with 2x the range and penetration, even with a meaningful speed penalty, they'd just about kill for it. And LiFi is the opposite of that.
posted by Western Infidels at 3:12 PM on June 3, 2018 [2 favorites]


Western Infidels: I bet if you offered the average IT department a way to get WiFi with 2x the range and penetration, even with a meaningful speed penalty, they'd just about kill for it.

...you're obviously talking about my X-Fi idea. You wouldn't just kill for it, you'd kill with it!
posted by clawsoon at 3:16 PM on June 3, 2018 [14 favorites]


The only signal that can truly surpass all barriers is love. That's why I'm in the process of developing a new wireless technology known as love-fi. The main problem is that it's slow, because you can't hurry it, and also the connection randomly cuts off after five long years of hard work and devotion because apparently this marriage just isn't worth fighting for anymore, Cheryl, you heartless bitch.
posted by dephlogisticated at 3:26 PM on June 3, 2018 [40 favorites]


I'm working on bifi. It has similarities to gaydar technology, but it's finally starting to be properly accepted as an alternative.
posted by howfar at 3:29 PM on June 3, 2018 [16 favorites]


oooh oooh i got one

HI-FI

It's like wi-fi but you get it directly to your brain by ingesting psychedelics.
posted by flabdablet at 3:55 PM on June 3, 2018 [2 favorites]


For example, Li-Fi works better in buildings with thick walls that tend to block radio signals.

... as it takes advantage of the well known light passing properties of thick walls.

I am always stunned by metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother", when otherwise the site is pretty pro-science and progressive


There are some very experienced technical people on this site. For them a lot of what is presented as "new" ideas are recognizable as things that have been already tried or are so problematic that no one has bothered.

Part of being pro-science and progressive is knowing separating the wheat from the chaff and I’ve always felt Metafilter was pretty good at that.
posted by Tell Me No Lies at 3:55 PM on June 3, 2018 [2 favorites]


If most streetlamps were replaced with LiFi lamps, those could form a sort of carrier signal network, connecting to each other and all vehicles underneath. Only a couple access points would be needed, because data streams from vehicles would automatically be routed from lamp to lamp around the network. The (future) bandwidth should allow for that, so each lamp would effectively work as a router/node of the general network.

That would be fairly hellish to maintain.

There’s a reason why there are as few cell towers as possible in use.
posted by Tell Me No Lies at 3:58 PM on June 3, 2018 [2 favorites]


The Infra-red remote comment above kinda made me laugh, because...

We had an IBM PC jr. It was rad and fun for a kid like me.

What wasn't rad was the shitty IR remote that you always had to have the keyboard facing directly to the receiver built into the computer front panel. That's right, good bye any comfortable position for typing.

And yeah -this reminds me a bit of the whole home wiring as data transfer mentioned above as well (e.g. the comment that to get the data to the light you can use your electrical system).

That really took off, I see, too. Oh wait. no, it hasn't.
posted by symbioid at 3:58 PM on June 3, 2018 [3 favorites]


Is this unidirectional? The article just talks about receivers in PCs.
posted by snuffleupagus at 4:05 PM on June 3, 2018 [1 favorite]


It is possible to inject a signal into power lines. But it's not much bandwidth and needs some kind of bridge between major circuits.


I was at a start-up that pioneered Wireless LANs and we looked very carefully at power line data. After all if you could just install our box next to a lighting fixture to get data and power it meant no new cable runs, which would have been a serious competitive advantage.

It would require a major rework of power systems to pull off. It’s not just the multiple circuit problem, it’s that both the mains and the backup supply in an Enterprise often include scrubbers to smooth out the power (or so it was explained to me, I’m not an EE). Tweaking the scrubbers to not interfere with data was not a sure thing.
posted by Tell Me No Lies at 4:12 PM on June 3, 2018 [4 favorites]


I am always stunned by metafilter's tendency to leap at "this doesn't immediately solve any problems, why bother", when otherwise the site is pretty pro-science and progressive.

I'm with you on this one. I recall a big backlash against venmo on this site that took a "doesn't solve any problems for me, a person who can afford to just split the bill evenly when one of my friends orders steak and a bottle of wine and I don't at dinner, so why bother" that has stuck with me ever since.

Is this going to replace ethernet/wifi? Probably not. But alternative solutions are great - I'm posting right now on a computer connected to the router via powerline ethernet because my 60 year old condo's thick concrete walls are not exactly wifi friendly nor do they make running cat-6 throughout the place easy.

At first I didn't even think this was about using light refresh as a data carrier - I guessed this would be about turning those wifi enabled Philips Hue bulbs into a mesh network. Which leads me to ask, why don't they turn those hue bulbs into a mesh network?
posted by thecjm at 4:14 PM on June 3, 2018 [4 favorites]


Is this unidirectional? The article just talks about receivers in PCs.

There was a line in there about needing two dongles, one receiver and one transmitter.

Although why they would be separate dongles is beyond me.
posted by Tell Me No Lies at 4:14 PM on June 3, 2018


Yeah this seems like a solution in search of a problem. Maybe in very specific contexts it would be a better alternative to Wi-Fi, but as far as I understand it it's a step down from it.
posted by zardoz at 4:21 PM on June 3, 2018 [1 favorite]


Ah, I see.

A special dongle will do the trick to make today’s laptops and other devices capable of detecting Li-Fi. But down the road, your computer or smartphone could be equipped with two new Li-Fi-receiving components. One is a tiny light sensor. No big deal. Your devices already measure ambient light to manage auto brightness. The second is an infrared transmitter. That’s the exact same technology used in classic remote controls. Your computer would fire off requests to the internet much like we’ve been channel surfing for decades.

Maybe the IR detector needs some separation from the bulb to avoid interference.
posted by snuffleupagus at 4:22 PM on June 3, 2018 [1 favorite]


Leonard Cohen-Fi: Like a bird on a wire it has tried in its way to be free, but the venture capitalists keep asking when they're going to get their return on investment.
posted by clawsoon at 4:24 PM on June 3, 2018 [3 favorites]


But alternative solutions are great

In that case I present you with Internet Engineering Task Force RFC 1149 A Standard for the Transmission of IP Datagrams on Avian Carriers

It’s an early protocol but it has been updated over the years to handle quality of service and IPv6.

Unfortunately it has never moved beyond the Experimental state but as you say, alternatives. :-)
posted by Tell Me No Lies at 4:28 PM on June 3, 2018 [3 favorites]


Rotating disco ball hanging from the ceiling. Solves all the problems, and with a good beat you can dance away the night. I am assuming that this lie-fi thing only works at night. I mean, who turns on the lights during the day?
posted by njohnson23 at 4:29 PM on June 3, 2018


Yeah yeah carrier pigeons. Cute.

But seriously - "hey we've got wires already installed in every home, can we use those as pseudo ethernet cables?" = powerline ethernet, which is fine and dandy. But "hey we've got energy emitters installed in every home, can we use those as pseudo wifi signals?" = let's make fun of this idea and dismiss it outright?
posted by thecjm at 4:36 PM on June 3, 2018 [3 favorites]


I'm not dismissing the idea. I'm dismissing the woo-woo fuzzy wuzzy writing of the article, and the implication it attempts to make that this will solve every problem. It won't. I like to work in a dark room. With the technology they're promising, I'll need to string a dongle out into a lit hallway to make the Internet work. One step forward, two steps back.

It's a marketing fluff piece with no detail, which implies to me that the tech is years away.

Anyone remember when frequency-hopping wifi was the future for wireless in the enterprise? How'd that go again?
posted by disclaimer at 4:42 PM on June 3, 2018 [1 favorite]


But "hey we've got energy emitters installed in every home, can we use those as pseudo wifi signals?" = let's make fun of this idea and dismiss it outright?

The problem is that while light may provide some extra bandwidth down the road, it is drastically inferior to the current WiFi solution now.

If the article had kept itself to just saying that I think there would be less scoffing and more "I hope that turns into something feasible." As it is the article is a bit of an over enthusiastic naive mess, so it’s definitely pulling the snark.
posted by Tell Me No Lies at 4:47 PM on June 3, 2018 [1 favorite]


In the 90s companies were experimenting with infrared light data relays. The xceivers were commercially available and for the most part sucked pretty badly in the "we're not yet certain if this is better than nothing" sort of way. If you were relaying through the windows of adjoining buildings, any dirt on the glass or heavy rain or even a passing bird was sufficient to disrupt data streams, sometimes requiring hardware reboots.

On the other hand I have some wireless headphones made before Bluetooth existed. The audio is transmitted over IR. They sound pretty good, and the coverage is surprisingly good since the walls in my office are white: I can stand behind the base station out of view of the transmitting LEDs without disrupting the audio.

So I dunno. I feel like some skepticism is called for, particularly since the bumf in the link doesn't provide any useful information other than that this technology is being trialed in an office somewhere, but padded out with no small amount of genuine bullshit. When you see "faster than light", read everything else with a heavy dose of cynicism.

But I also feel like it's something that could work. Line of sight does not literally have to be line of sight; those headphones I mentioned are a good demonstration. There are a pile of downsides, of course... nobody makes computers with optical receiver modules (unless this works through over-screen cameras; which sounds to me like opening a door on security problems that'll never be closeable), so this is going to be mean everybody gets network dongles. And there's the potential for both unintentional range restrictions and unintentional data leakage: The networks don't work outside of the rooms they're built in, but will people outside those rooms (in waiting areas, or standing outside the building) be able to snoop through windows and glass doors?
posted by ardgedee at 4:48 PM on June 3, 2018 [2 favorites]


Leonard Cohen-Fi: Like a bird on a wire it has tried in its way to be free, but the venture capitalists keep asking when they're going to get their return on investment.

There is a crack in everything, that's how the Li-Fi gets in.
posted by obscure simpsons reference at 4:50 PM on June 3, 2018 [9 favorites]


but how do you get the internet to the light fixture in the first place?

Well, presumably you get it to the light fixture the same way it gets to the light fixture right now in Philips Hue bulbs. There's a chip in the bulb and a bridge that you connect to your router. Presumably this would be a differently programmed chip.

Let somebody innovate, damn. People made fun of tablet computers for a decade before the iPad came out and now look where we are. No reason to preemptively pee in their Cheerios. Edison took how long to even make a working light bulb, I think we can afford to let Philips take a few turns. It's their nickel.
posted by Autumnheart at 4:53 PM on June 3, 2018 [2 favorites]


Let somebody innovate, damn.

...it's not like a cranky thread on MeFi -- wherein the crankiness is largely directed at the clickbait-slash-breathless-marketing aspects of the reporting -- is gonna stop Philips or anyone else, though? It's not like Frans van Houten is gonna stumble across this, start crying his poor little heart out in a crisis of confidence and, between body-wracking sobs, wail 'those haters are right, it'll never work, CANCEL ALL OUR INNOVATING'

let people complain about daft marketing, damn
posted by halation at 5:11 PM on June 3, 2018 [7 favorites]


That isn't a marketing article. Marketing is when the company who produces the technology writes the article. And no, Philips isn't going to stop the project just because some people are all "This is weird and doesn't make sense to me, make it stop" but that doesn't make those people the voice of reason.
posted by Autumnheart at 5:30 PM on June 3, 2018


Let somebody innovate, damn.

If you're not prepared to have your ideas ruthlessly dissected, do your best not to have a PR hack produce a fluff piece on them.
posted by Tell Me No Lies at 5:30 PM on June 3, 2018 [7 favorites]


Well, presumably you get it to the light fixture the same way it gets to the light fixture right now in Philips Hue bulbs. There's a chip in the bulb and a bridge that you connect to your router.

What that chip does is called "radio." And Hue is using some kind of low bandwidth mesh network. All it needs to do is poll bulb status and send control signals, etc.

There's no advantage to this over WiFi if the connection at the AP isn't wired. At least in terms of complexity, cost, or performance.
posted by snuffleupagus at 5:32 PM on June 3, 2018 [2 favorites]


just wait until fast co finds out about microwave transmissions.
posted by nikaspark at 5:38 PM on June 3, 2018 [4 favorites]


It's weird that such an old technology is being written up breathlessly as the next big new thing. I remember reading articles about wireless internet over light being a big up-and-coming technology back in the early 2000s, if not in the 1990s. I guess the dramatic reduction in the cost of high-power LEDs over the last several years probably opens up some possibilities, but my understanding is that wireless optical data transmission has some intrinsic limitations, the biggest being the line-of-sight requirement. Losing your network connection every time a shadow passes over the transceiver makes it annoying and unreliable.

This isn't to say there's not some great potential use cases for data-via-lightbulbs. Taking the streetlight example, I think casual Internet-users gaining much benefit is unlikely, but suppose maintenance workers can retrieve diagnostic data from the streetlights by pointing their tablet PC at it. The very line-of-sight nature of the communication channel becomes a benefit, preventing interference from neighboring lights. I think it's likely that "Li-Fi" is going to end up finding its role in relatively more niche applications like this one.
posted by biogeo at 5:45 PM on June 3, 2018 [1 favorite]


pfft, li-fi's got nuttin on fi-fi.
posted by mwhybark at 5:47 PM on June 3, 2018 [1 favorite]


prn. fye-fye, kthx bye
posted by mwhybark at 5:48 PM on June 3, 2018


On a more personal note, from the Phillips press release:

Philips Lighting leads the way in offering seamless hand-over between light points; meaning that as a user moves from one side of a large office to another, they maintain their connection as one light point hands off to another.

Guess who has two hands, wrote a fairly broad mobile networking patent 16 years ago, and will be demanding business class tickets if they want to depose him in the U.S.?

<points thumbs at self>

This guy!
posted by Tell Me No Lies at 5:48 PM on June 3, 2018 [14 favorites]


I doubt Philips is planning to connect the bulbs to the network via radio. It is probably powerline. The bulbs are already screwed into AC and powerline has a lot of bandwidth. In an industrial or office application, the light fixtures could well be wired with Ethernet.
posted by chrchr at 6:07 PM on June 3, 2018 [1 favorite]


The very line-of-sight nature of the communication channel becomes a benefit, preventing interference from neighboring lights.

I would expect that widespread assumptions about the limited range of these things could lead to some interesting security exploits, perhaps along the lines of those already seen for range-extended operation of wireless EFTPOS cards and car key fobs.
posted by flabdablet at 6:19 PM on June 3, 2018


DDoS'd by THE SUN
posted by glonous keming at 6:47 PM on June 3, 2018 [7 favorites]


"I heard that turning up the TV brightness is really good for your eyes!"


https://xkcd.com/654/
posted by Tell Me No Lies at 6:54 PM on June 3, 2018


Up to a megabit or two, this sort of thing works reasonably well in an open room. There's kit from the 90s that use various IR protocols to network with in a room. I recall a few Ethernet bridges, even.

Going faster is hard with light, especially in a room where reflections are an issue without having many colors and therefore more transceivers.

It's not so much that it's a silly idea, it's that significant development in manufacturing capability would be required to make it cost effective at a reasonably modern data rate.
posted by wierdo at 6:56 PM on June 3, 2018 [1 favorite]


And for pretty much any use case where it would be cost-effective, what would be even more cost-effective is just building a low-powered WAP with a shitty antenna into the bulb or whatever. Wifi chips are already super-cheap because volume, they're easier to design into equipment casings because you don't need to provide an optical pathway through it, and it's pretty easy to make wifi not punch through concrete walls either especially at 5GHz.
posted by flabdablet at 7:32 PM on June 3, 2018 [1 favorite]


Seems eavesdropping on the signal could be done from a great distance with a telescope and a window—even ones with blinds. Maybe even satellite distances.
posted by bz at 8:28 PM on June 3, 2018 [1 favorite]


Eavesdropping is always a problem with wireless networks. That's what encryption is for.
posted by Tell Me No Lies at 8:41 PM on June 3, 2018 [1 favorite]


I believe that one not too distant benefit of autonomous vehicles will be a reduction of infrastructure such as street lamps and the resultant lowering of light pollution.

How does that follow? I’ve always thought of streetlights as being more for human pedestrians and already pretty unnecessary for cars that have headlights.
posted by stopgap at 9:01 PM on June 3, 2018 [2 favorites]


It would require a major rework of power systems to pull off. It’s not just the multiple circuit problem, it’s that both the mains and the backup supply in an Enterprise often include scrubbers to smooth out the power (or so it was explained to me, I’m not an EE). Tweaking the scrubbers to not interfere with data was not a sure thing.

This "scrubbing" is called power conditioning in case you want to learn more about it. (When that article talks about "inductive loads", it's mostly talking about motors: air conditioners especially, but refrigerators, vacuum cleaners, fans etc. as well. Inductive loads are hard to get current going in, but once the current is going it doesn't want to stop. As inductive loads are added and removed from the grid, they cause voltage levels to fluctuate.) Power conditioners are there to make sure that, whatever else is happening on the grid, everybody sees a nice consistent 60Hz 120V at their outlet. But nice consistent waves- having as little bandwidth as possible- do not carry information.
posted by Jpfed at 9:28 PM on June 3, 2018 [1 favorite]


Spectrum isn't a problem, WiFi has got a 60 GHz band that'll support gigabits to lots of users, And it works in the dark.

The problem with 60 GHz is that it is getting short enough in wavelength that it is starting to behave more like Li-Fi than microwaves. The 801.11ad standard is only good for about 30 feet, is highly directional, needs direct line of sight and can't penetrate a door let alone a solid wall. In other words, it's a lot like light. And the routers currently cost hundreds of dollars.
posted by JackFlash at 10:17 PM on June 3, 2018 [2 favorites]


This "scrubbing" is called power conditioning in case you want to learn more about it.

Interesting. Thanks for the pointer!
posted by Tell Me No Lies at 10:22 PM on June 3, 2018


ArsTechnica had a good article on 60 GHz wifi.
posted by RobotVoodooPower at 10:28 PM on June 3, 2018 [1 favorite]


As the VR nut that I am, I could see Li-Fi help making headsets cordless. The Vive, for example, already uses infra-red laser projection for its positional tracking system, and it's plausible that it could be extended to include Li-Fi like data transmission. Direct line-of-sight isn't strictly necessary, the headset can see the IR patterns being projected on the walls, and multiple projectors help cover any blindspots. It doesn't really need a return channel either, as the vast majority of that data is the video signal going to the headset, the smaller flow back to the computer can go over bluetooth or whatever.

There's not too much point though, as like everyone else is saying, the 60GHz wifi tech is already here and probably works better.
posted by Eleven at 6:37 AM on June 4, 2018 [1 favorite]


I guess another thing to keep in mind is that historically, proprietary network protocols have rarely been competitive, and even more rarely lasted long once the flood of products built on standardized alternatives flows in.

So Philips has to publish their work; they can opt for a piece of a large market or monopolize a nonexistent market.
posted by ardgedee at 7:41 AM on June 4, 2018


60 GHz is just getting going. With beam steering/MIMO, which becomes much more interesting at these very short wavelengths, we'll see much better range and total throughput. There'll be plenty of things it can't do better than 5 GHz, but that's still there; I can't think of any advantage Li-Fi has over 60 GHz - well, it probably goes through thick glass better. But the killer advantage of 60 GHz is that it's in the standard and on the shelf.

When Li-Fi first appeared, I thought it was mildly interesting, but my antipathy to it has grown with each pulse of aggressive hype. It's not a new idea, the problems it claims to solve aren't really there, and the incumbent wireless data technologies are extremely capable and still developing. This is an environment in which Li-Fi really has to demonstrate one of an extreme cost advantage, extreme performance advantage, or unique use cases impervious to existing technologies: it has none of these. But it has plenty of disadvantages.

I'm sure that Philips buying into it is going to hasten its demise. Perhaps it can be made Zigbee compliant, just to make sure.
posted by Devonian at 10:05 AM on June 4, 2018 [2 favorites]


There are already some interesting 60GHz products out, like Mikrotik's "wireless wire," which does a couple hundred feet as long as there isn't a wall in the way. A window is fine, though. Even does PtMP.

They even have a version with a dish that's good for a few miles and has much less fresnel zone hassle than 5GHz thanks to the smaller wavelength.

That's pretty much the opposite of what Lifi would be useful for, though. Lifi would be good for constant low data rate connectivity. If it were actually lower power than a modern wifi chip, it could be very useful for devices to use when they are mostly idle and are only really exchanging notifications and such.
posted by wierdo at 10:56 AM on June 4, 2018 [1 favorite]


That isn't a marketing article. Marketing is when the company who produces the technology writes the article.

Here’s how this stuff works:
Step 1: company’s public relations agent issues press release
Step 2: “news” outlets print that press release virtually verbatim under the byline of some “journalist” with a thesaurus

Barely rewording a press release doesn’t magically make it *not* bald-faced PR bullshit.
posted by Sys Rq at 3:45 PM on June 4, 2018 [3 favorites]


Step 1: company’s public relations agent issues press release
Step 2: “news” outlets print that press release virtually verbatim under the byline of some “journalist” with a thesaurus


Dateline on the press release: March 16, 2018.
Date of the press conference: March 19, 2018.
Dateline on the Fast Company story: March 21, 2018.

The Fast Company story repeats several point from the press release (great for hospitals! use a dongle!) and the press conference ("smart poles" with li-fi in cities!).

And then there's stuff in the story that is just plain bizarre. There's the above-mentioned flickering that allegedly occurs at "ten times the speed of light." The story also claims that "Li-Fi can actually still operate in sunlight by filtering out the sun's part of the light spectrum." Sunlight is full-spectrum; the result of filtering it is called "shade."
posted by compartment at 1:28 PM on June 5, 2018 [1 favorite]


Sunlight is full-spectrum; the result of filtering it is called "shade."

Clearly they operate at the precise frequencies of the Fraunhofer lines.
posted by clawsoon at 4:18 PM on June 5, 2018


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