7 ms·

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 t

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.

Syonyk 3y ago
> ...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
osigurdson 3y ago
What you are looking for is a spectrum of light known as subter-subter-infra-red which is around 2.4GHz.
- nwiswell 3y ago
  > subter-subter-infra-red To think that this was right there the whole time and we settled on "WiFi" instead!
  - whatshisface 3y ago
    It's still not to late to call it the internet's infra-structure.
  - twelvechairs 3y ago
    The wifi name was created to be "a little catchier than 'IEEE 802.11b Direct Sequence'"
mlyle 3y ago
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.
- ianburrell 3y ago
  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.
  - cornholio 3y ago
    The speeds would be completely reliable until somebody starts walking around the office, disrupting the line of sight to the lightspot in the ceiling.
    - xoa 3y ago
      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.
    - mlyle 3y ago
      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.
XorNot 3y ago
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.
- mlyle 3y ago
  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.
eternityforest 3y ago
The wired repeater could in theory just be a light bulb and power line networking
- thfuran 3y ago
  Power line networking will be crap until we start delivering all our power via network cables.
  - JoBrad 3y ago
    You could just connect the bulbs with WiFi!
  - eternityforest 3y ago
    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.
    - thfuran 3y ago
      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.
    - Johnythree 3y ago
      > 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.
yalogin 3y ago
I see this as a move ch better repeater, both in homes and even more so in large office/mall settings.
tesdinger 3y ago
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.

Syonyk 3y ago

> ...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

osigurdson 3y ago

What you are looking for is a spectrum of light known as subter-subter-infra-red which is around 2.4GHz.

nwiswell 3y ago
> subter-subter-infra-red To think that this was right there the whole time and we settled on "WiFi" instead!
- whatshisface 3y ago
  It's still not to late to call it the internet's infra-structure.
- twelvechairs 3y ago
  The wifi name was created to be "a little catchier than 'IEEE 802.11b Direct Sequence'"

mlyle 3y ago

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.

ianburrell 3y ago
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.
- cornholio 3y ago
  The speeds would be completely reliable until somebody starts walking around the office, disrupting the line of sight to the lightspot in the ceiling.
  - xoa 3y ago
    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.
  - mlyle 3y ago
    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.

XorNot 3y ago

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.

mlyle 3y ago
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.

eternityforest 3y ago

The wired repeater could in theory just be a light bulb and power line networking

thfuran 3y ago
Power line networking will be crap until we start delivering all our power via network cables.
- JoBrad 3y ago
  You could just connect the bulbs with WiFi!
- eternityforest 3y ago
  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.
  - thfuran 3y ago
    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.
  - Johnythree 3y ago
    > 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.

yalogin 3y ago

I see this as a move ch better repeater, both in homes and even more so in large office/mall settings.

tesdinger 3y ago

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.