Wireless data can be delivered by lights, anywhere: call it ‘Li-Fi’

Originally posted by DaRAGE

Originally posted by metalshredmetal
Duh, all electromagnetic communication is light..radio waves and ultraviolet waves included. Its just not light in the human visible spectrum.

So your telling me that if i have my phone locked away in the glove compartment of my car that light from the LEDs in a street light, could interact with my phone? I doubt it. But i sure know what could... Radio Waves...

Sure they are both Electromagnetic waves, but one stops (light) when it hits matter like a glove box, and the other (radiowaves) can go through that glove box and interact with the phone.

That depends on the material that surrounds the device. Put your phone in a glass box and light will quite happily still reach it. Put your device into a box made of a fine copper mesh (sometimes called a farady cage) and light will get to it but radio waves wont.

Impractical, for many reasons:

• The only type of illumination medium presently known that could handle such data transmission would be LED. LED bulbs are still in their infancy, with the only bulbs I can find locally being 40W or less. Street lights are typically high-power halogen or mercury-vapor units of 500W or more.
  
  
• Car headlights are also extremely powerful bulbs, far beyond the ability of LED bulbs using present technology while still remaining economically viable.
  
  
• Visible light is easily blocked by anything opaque, interrupting the flow of data. This was the major drawback of IR remotes back in the day... they required line-of-sight communication.
  
  
• AC signals are noisy and subject to interference from any metallic, magnetic, or electrical medium surrounding them. This is the major difficulty implementing data-over-power internet access. The same difficulty would apply to any light-based transmission source that was powered by AC power, aggravated by the need to regulate power inputs to a device that is required to deliver kilowatts of light energy, instead of milliwatts.
  
  
• Vehicle electrical systems are also very noisy and subject to interference, primarily due to the close proximity of the circuitry to rapidly spinning pieces of metal and high-voltage medium-frequency ignition pulses. That's why high-performance car stereos have such huge filters on the power inputs and why controller circuits are low-speed processors and also highly filtered on the power inputs.
  
  
• "Li-fi" would require a two-way communication medium, meaning that signals would have to be pretty much omnidirectional, further exasperating the problems with opacity.
  
  
• This also means every street light and car headlight would also require a reception mechanism.
  
  
• Light scattering would mean that amplification requirements would have to cover an immense range from negligent to astronomical.
  
  
• Tying data transmission to lighting requirements would mean that the ambient light level would be dependent on the binary stream emitted at any particular time. Lighting would become very hard on the human eye, as it constantly tried to adjust to changes in the ambient light level.

There seems to be a move in society toward one item that does everything, a'la the iPod, iPad, SmartPhones, etc. This is a completely impractical model. In the first place, one malfunction equates to the loss of a myriad of functions, and in the second place, upgrades require the replacement of a range of functions that are not directly affected. In the old days, we called this approach "putting all your eggs in one basket", implying that if that one basket were dropped, all the eggs would be broken. In financial circles, the concept of not doing such is called "diversification" and is considered one of the best investment strategies available.

In any (realistic) server configuration, there are multiple APUs designed to operate should one fail; there are multiple servers, each one capable of picking up the load when one fails; there are multiple hard drives arranged in RAID configurations, designed so that any one can fail without loss of data. So why do people keep trying to tie everything together in other areas? A better, cheaper, simpler, and more reliable solution would be to mount wifi antennas on every street light and on every PC or laptop. The transceiver mechanisms are already standardized through 802.11a/b/g/n, the upgrade would be just that instead of a refit of the existing lighting system, a loss of one service would not necessarily affect the other, repairs and maintenance would be simpler, and the problems of opacity and scattering would become moot subjects.

Jeff Goldblum said it best in Jurassic Park: "Just because one can do a thing, it does not necessarily follow that one should do a thing."

TheRedneck

reply to post by TheRedneck


Whilst I agree with everything else you have said, I have to correct you on two points:

1. LED street lights are in use in plenty of places, and are becoming more common, which is a god-send for us amateur astronomers as they are also bringing down light pollution. I have seen several pop up round several towns in my county, and I would imagine lots of other places in the UK too.

2. Plenty of reasonably priced cars use LED headlights, a ton of people have them round my town, and it's not one of the richest towns in the UK.

reply to post by woogleuk



I knew there were people working on high-powered LED lights, but I had no idea they were in use already! Can you give me a starter link maybe to catch up on this?

As for the headlights... same thing. LEDs are lower voltage, meaning easier to implement in a vehicle, and they are pretty voltage-tolerant, meaning no problems with the noise of the electrical supply (thus the widespread use in taillights), but I was not aware they had powerful enough systems inexpensive enough to use as headlights.

TheRedneck

reply to post by TheRedneck


Sure, at a quick search:

gemma lighting

LED Car Bulbs

The light they produce seems much cleaner and natural too.

Originally posted by SLO7H
reply to post by mwuhi

 

Actually, there are many cars that is starting to use LED lights now

Ya, tail lights, but not head lights.

reply to post by mwuhi


No, ALL lights, front, read and side.....see the link in my last post. I have seen plenty with my own eyes.

Originally posted by TheRedneck
Impractical, for many reasons:
Jeff Goldblum said it best in Jurassic Park: "Just because one can do a thing, it does not necessarily follow that one should do a thing."
TheRedneck

Exactly. For things to succeed they have to be practical, especially if they want wide spread adoption. And this Li-Fi to be successful needs total wide spread adoption everywhere. Devices like smartphones, computers, to have this Li-fi technology AND every damned 14.5 billion light bulbs (that must be connected to the internet...)