Electric light transmits data faster than Wi-Fi(techxplore.com)
techxplore.com
Electric light transmits data faster than Wi-Fi
https://techxplore.com/news/2023-12-electric-transmits-faster-wi-fi.html
72 comments
https://spectrum.ieee.org/lifi-standards
Wi-Fi consortium to the researchers: Stop trying to make fetch happen.
fetch?
Reference to a movie-quote, where a character is (unsuccessfully) trying to promote "fetch" as a new slang synonym for "cool." Implies a questionable and quixotic quest.
https://en.wiktionary.org/wiki/make_fetch_happen
https://en.wiktionary.org/wiki/make_fetch_happen
I cannot but feel that some part of the spectrum that is invisible, so it can work when the light is turned off, and is capable of penetrating the walls so as to not require an expensive wired repeater in every room, would still remain the best choice for providing local connectivity in general.
I can see applications for LiFi, but it will not replace WiFi any time soon.
I can see applications for LiFi, but it will not replace WiFi any time soon.
It's an advantage if your receiver is shielded against the neighbors transmitters by a wall. It allows better parallel reuse of spectrum from one room to the next.
> ...so as to not require an expensive wired repeater in every room...
Why do you speak of the feature as though it's a bug?
It's great for wiring contractors, great for LiFi vendors, what's the problem?
sigh
Why do you speak of the feature as though it's a bug?
It's great for wiring contractors, great for LiFi vendors, what's the problem?
sigh
What you are looking for is a spectrum of light known as subter-subter-infra-red which is around 2.4GHz.
> subter-subter-infra-red
To think that this was right there the whole time and we settled on "WiFi" instead!
To think that this was right there the whole time and we settled on "WiFi" instead!
It's still not to late to call it the internet's infra-structure.
The wifi name was created to be "a little catchier than 'IEEE 802.11b Direct Sequence'"
I don't think this is a candidate to replace wifi. But if it's cheap and becomes ubiquitous (unlikely) it would make wifi a lot better.
The advantage of the visible light approach is that it doesn't reach through walls.
It's inherently very dense, and can provide users in its footprint nearly unlimited bandwidth. If it reaches only 50% of users in a classroom or office building, then those 50% of users will have very fast connectivity, and wifi will be twice as fast for everyone else.
The advantage of the visible light approach is that it doesn't reach through walls.
It's inherently very dense, and can provide users in its footprint nearly unlimited bandwidth. If it reaches only 50% of users in a classroom or office building, then those 50% of users will have very fast connectivity, and wifi will be twice as fast for everyone else.
Right, it's another possible candidate for true high bandwidth "wireless wires" for applications like uncompressed video, external PCIe, high speed data access etc. Wearable displays are the most obvious candidate, it'd be very useful to be able to have the bandwidth on tap to perfectly replace DisplayPort/HDMI/Thunderbolt for 8k+ video while in an office, along with access to office NAS/SAN and potentially seamless use of other peripherals like GPUs. That would mean a wearable display could potentially function as a true no-compromise monitor/system replacement, and then transparently downgrade to independent mode when leaving. As you and others say that could even be an extra security advantage, that while sure there'd absolutely be authentication, it'd be an interesting capability that only a given light cell in a given room/cubicle/area could access particular VLANs or the like at all. The range being short doesn't negate the benefit of no wire, nothing to snarl or snag or get forgotten about. And the backbone aspect seems to be coming along as well. 40/50/100G is becoming surprisingly affordable even now, and in another 3-5 years as this cooks I don't think it'd be a blocker even if it was high end for a solid period of time like most new tech is.
There are other potential approaches but WiFi+LiFi hybrids could be neat. LiFi would also have the regulatory advantage of not needing to worry about typical licensing or bandwidth issues beyond basic emissions like anything with a power supply has, since those spectrums are of course fully public :). Although the industry could in principle muck the whole thing up with burdensome patents I suppose, but then again the basic principle are similar to fiber and free space optical transmission (including extremely high speed) has been done for ages so that might limit the scope of any potential claims to some degree.
There are other potential approaches but WiFi+LiFi hybrids could be neat. LiFi would also have the regulatory advantage of not needing to worry about typical licensing or bandwidth issues beyond basic emissions like anything with a power supply has, since those spectrums are of course fully public :). Although the industry could in principle muck the whole thing up with burdensome patents I suppose, but then again the basic principle are similar to fiber and free space optical transmission (including extremely high speed) has been done for ages so that might limit the scope of any potential claims to some degree.
A hybrid with radio WiFi could be interesting. You could set up the usual ceiling light panels as a big fat downlink and use WiFi as an uplink. Would be pretty useful for public areas.
I think an uplink with visible light might be too much to ask, but if we could just glue these two networks together, it becomes a lot more useful.
I think an uplink with visible light might be too much to ask, but if we could just glue these two networks together, it becomes a lot more useful.
There are lots of technologies where uplink and downlink are asymmetrical since downlink is used to consume data, and significantly more of it.
I wish more technologies could do one-to-many broadcast. for example a live video stream that many were watching, or tv/movies/presentations where many people were listening to the same audio with headsets or earbuds.
I wish more technologies could do one-to-many broadcast. for example a live video stream that many were watching, or tv/movies/presentations where many people were listening to the same audio with headsets or earbuds.
One place where it would work well is offices. Office buildings have drop ceilings that make it easier to mount devices on the ceiling. Then have one Lifi in each office or pretty dense in open plan offices.
This could solve the problem of getting reliable speeds to devices without Ethernet, that are either hard to wire or don't want to plug in.
This could solve the problem of getting reliable speeds to devices without Ethernet, that are either hard to wire or don't want to plug in.
The speeds would be completely reliable until somebody starts walking around the office, disrupting the line of sight to the lightspot in the ceiling.
Like, sure it'd vary by office, but a lot of us are in spaces with pretty high ceilings and even a very tall person wouldn't be able to disrupt the view of most lights. I think the assumption here is LiFi, or other highly directional tight beam possibilities, would require significantly more density of WAPs. Maybe not every light replaced but a solid grid in most spaces, and then clients would be regularly connected to different ones and rapidly jumped between them as needed due to movement/obstruction (conceptually the same as Starlink for example which constantly connects, tracks, and rapidly jumps between sats which are LEO and thus constantly moving over the horizon). Part of the implementation standard would be handling all the packet shuffling for that, which will have to be enormously better then WiFi Roaming.
Higher density is more costly too of course, but even so depending on the performance that might well still be cheaper/easier then fiber drops everywhere, plus it'd avoid some of the minor but sticky end user physical interface issues of fiber connections. Whether the value is there remains to be seen and will no doubt vary, but as others have said a lot of typical office plans (with drop ceilings, ceiling rails or other designs meant to enable more modular ceiling use) on the surface seem pretty amenable to such an approach.
Ultimately all depends on what the actual implementations look like though, and at what cost.
Higher density is more costly too of course, but even so depending on the performance that might well still be cheaper/easier then fiber drops everywhere, plus it'd avoid some of the minor but sticky end user physical interface issues of fiber connections. Whether the value is there remains to be seen and will no doubt vary, but as others have said a lot of typical office plans (with drop ceilings, ceiling rails or other designs meant to enable more modular ceiling use) on the surface seem pretty amenable to such an approach.
Ultimately all depends on what the actual implementations look like though, and at what cost.
LiFi signal bounces off walls. It doesn’t need direct line of sight. Think a light bulb lighting a room. But it doesn’t go around corners and through walls like WiFi.
If you have quick enough failover to wifi-- who cares. I'll happily take 75% availability of dedicated 2gbps and less-congested wifi the other 25% of the time.
Isn't this solved by POE? For an office building which already has extensive electrical/networking/plumbing needs, pulling one dedicated wire for a robust networking connection seems worth it.
It will work well in a lot of places where lag is an issue.
Should make lag-free wireless video game controllers and full-bandwith lag-free headphones a reality.
at least until the shadow IT crew starts bringing in their LiFi lamp shade routers
Yeah, because everyone needs fluctuating light 8 hours a day. It is like seating do not destroy your health enough. /s
WiFi negotiates connections to determine the best frequency range to use. It could support line-of-sight visible light if it works for that particular setup, or fallback to 2.4/5Ghz when it doesn't.
The benefit of LiFi would be the exact opposite: in a congested signal space, that it's actually easy to mostly shield an area from it - i.e. you and your neighbor can have LiFi APs screaming out signal and a simple plasterboard wall would almost completely shield the interference.
It strikes me that 400nm UV LEDs would be a good choice for this application: we can't perceive 400nm, it doesn't penetrate cells (FYI: this is why all "LED" sterilizers are snake-oil), and most importantly the UV spectrum is almost entirely blocked by regular glass-windows so the sun wouldn't interfere and the signal would attenuate to nothing at the bounds of a building.
It strikes me that 400nm UV LEDs would be a good choice for this application: we can't perceive 400nm, it doesn't penetrate cells (FYI: this is why all "LED" sterilizers are snake-oil), and most importantly the UV spectrum is almost entirely blocked by regular glass-windows so the sun wouldn't interfere and the signal would attenuate to nothing at the bounds of a building.
400nm UV is still probably bad for your eyes.
> (FYI: this is why all "LED" sterilizers are snake-oil)
Most are snake oil, but there are definitely UV-C LEDs out there.
IMO, we should just use ordinary white LED lighting for this. Easy to ensure that no matter what the data, the lights are at 80% DC brightness, and you can still get an absurd amount of data throughput per light fixture.
> (FYI: this is why all "LED" sterilizers are snake-oil)
Most are snake oil, but there are definitely UV-C LEDs out there.
IMO, we should just use ordinary white LED lighting for this. Easy to ensure that no matter what the data, the lights are at 80% DC brightness, and you can still get an absurd amount of data throughput per light fixture.
The wired repeater could in theory just be a light bulb and power line networking
Power line networking will be crap until we start delivering all our power via network cables.
You could just connect the bulbs with WiFi!
How are they crap? Some places have interference but in situations where they work, they seem to be fairly well liked.
Most people are not streaming 8k VR.
Most people are not streaming 8k VR.
For one thing, it's a bit silly to set up a fancy new wifi alternative with much better signal isolation between APs and then run it over backhaul with none.
> Some places have interference but in situations where they work, they seem to be fairly well liked.
But that is the problem....
Power-line networking both suffers FROM interference, and causes interference TO licensed services. When it works, it works well, until randomly it stops working.
You can't expect to reuse allocated spectrum without encountering serious problems.
But that is the problem....
Power-line networking both suffers FROM interference, and causes interference TO licensed services. When it works, it works well, until randomly it stops working.
You can't expect to reuse allocated spectrum without encountering serious problems.
I see this as a move ch better repeater, both in homes and even more so in large office/mall settings.
https://spectrum.ieee.org/lifi-standards
> The new standard for Li-Fi, IEEE 802.11bb, is designed to provide a global framework to deploy light-based devices that are compatible with each other. It was ratified in June [2023] ... Li-Fi simply appears as if it was another band of Wi-Fi ... It can achieve data rates of 1 Gbps or more from a range of 20 centimeters to 3 meters.
> The new standard for Li-Fi, IEEE 802.11bb, is designed to provide a global framework to deploy light-based devices that are compatible with each other. It was ratified in June [2023] ... Li-Fi simply appears as if it was another band of Wi-Fi ... It can achieve data rates of 1 Gbps or more from a range of 20 centimeters to 3 meters.
I would hope for bandwidths much higher than 1Gbps... Assuming conservatively you can do 1 bit/sec/Hz, we should be able to get an easy 300 Tbps in the visible light spectrum.
Any thats a low estimate, because physics lets you do massive MIMO, polarization, etc to get even more throughput.
Any thats a low estimate, because physics lets you do massive MIMO, polarization, etc to get even more throughput.
We are currently seeing 200 Gbps sat-to-ground but Li-Fi is targeting much lower bandwidth, as the application is different. https://www.nasa.gov/centers-and-facilities/ames/nasa-partne...
or like, lasers.
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looks like the aim is to replace IrDA not current usage of wifi
Interestingly, optical was one of the PHYs for the original 802.11: indirect (diffuse) infrared. I think the idea was that the AP and the individual nodes would communicate by scatter off the office ceiling.
(The other two PHYs were FHSS and DSSS on 2.4GHz, the latter of which morphed into the 802.11b that gained wide popularity.)
(The other two PHYs were FHSS and DSSS on 2.4GHz, the latter of which morphed into the 802.11b that gained wide popularity.)
While cool I am skeptical on this tech given the light propagation. How many LiFi APs would I need to buy for a full office compared to existing WiFi?
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The higher speed comes from visible light having a higher frequency than radio.
> Notably, Li-fi ensures robust security by exclusively transmitting data to areas illuminated by light.
Can someone explain how this ensures security?
Because hackers always work in the dark? /s
Can someone explain how this ensures security?
Because hackers always work in the dark? /s
It might enable security but I wouldn't say it _ensures_ it.
It just means that visible or IR light (What are they using?) won't leak through walls the way Wi-Fi does. Depending on how wide the beam is and exactly how it all works, it _might_ still leak out of windows and under doors. But it's not like someone casually wardriving outside your house will get as much as they would from Wi-Fi, I would think.
It just means that visible or IR light (What are they using?) won't leak through walls the way Wi-Fi does. Depending on how wide the beam is and exactly how it all works, it _might_ still leak out of windows and under doors. But it's not like someone casually wardriving outside your house will get as much as they would from Wi-Fi, I would think.
Yeah, you'd want blackout curtains (or better, paint) on your windows. Still cheaper and easier than making your office into a Faraday cage.
Working graveyard and renting, I learned aluminum foil is perfect.
cheap, trivial to install and remove. and perfectly opaque.
That assumes that Li-Fi doesn't leak RF still.
Can encryption not be used with LiFi?
How can visible light pass from a core of a star or planet to the outside, but some routers light not? I guess it's just super duper faint?
Visible light does not pass from the core of a star to the outside.
The sun has a radius of about 700,000 km. Only a few hundred km is transparent enough for light to pass through and has a density of about 300 mg per cubic meter. Roughly the density of air at the altitude where airliners cruise.
The photons you see originate from a layer that’s just 0.5% of the radius of the sun. That layer is heated with other photons from inside. The core temp is 15 million K while the photosphere is around 5800 K. The spectrum of the core were the rest of the sun transparent would be much different and … unsafe. (Not that this really makes sense, if the rest of the star was transparent it would go nova)
The sun has a radius of about 700,000 km. Only a few hundred km is transparent enough for light to pass through and has a density of about 300 mg per cubic meter. Roughly the density of air at the altitude where airliners cruise.
The photons you see originate from a layer that’s just 0.5% of the radius of the sun. That layer is heated with other photons from inside. The core temp is 15 million K while the photosphere is around 5800 K. The spectrum of the core were the rest of the sun transparent would be much different and … unsafe. (Not that this really makes sense, if the rest of the star was transparent it would go nova)
Using light to heat up the walls of a home enough to start emitting significant black body radiation poses some additional engineering challenges.
The house's thermal mass would also limit the data rate.
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I think that yes, compared to the core of a star, a LiFi AP is aptly described as "super duper faint".
> security
Wi-Fi passes through walls, can be used to remotely infer keystrokes, human biometrics, position and activity.
> dark
Li-Fi can use infrared light, does not pass through walls.
Wi-Fi passes through walls, can be used to remotely infer keystrokes, human biometrics, position and activity.
> dark
Li-Fi can use infrared light, does not pass through walls.
Poor wording. I think what they're getting at is that, unlike wifi, light doesn't pass through walls, floors, ceilings, etc. Anything that isn't directly illuminated by the light beam will have effectively no signal, making it less likely to be picked up from (say) five offices away.
Though if there's a window around that light might go further than 60GHz, which is presumably the best competitor for same-room high-bandwidth links.
Please can we call an Electric Light LAN an "Orchestra"?