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WiFi, Light Bulbs, And The FCC
JFMulder writes "According to Cringely, 802.11 WiFi wireless networking is going to get in lot of troubles when Fushion Lightning starts marketting low-power light blubs which causes interferences with Wifi signals. Read about it at I, Cringely. Supposedly the new kind of light bulb is a real electricity saver and can wreck havoc to wireless networks in a half a mile radius. So what would you prefer? Wireless networks or low cost light bulbs all around the country to save more and more on electricity?" Update: 06/13 03:52 GMT by M : Cringely confused the FHSS-or-DSSS 802.11 standard with the DSSS-only 802.11b standard, but the general warning about the potential for interference is certainly troubling.
Well the answer appears very simple to me.
If these lightbulbs are emitting RF in the 2.4GHz spectrum then when will some smart-assed entrepreneur come up with the dual-function lightbulb/WiFi node?
Half the guts is already there -- the transmitter.
If every household and business had these bulbs, think of the massive 802.11 network we could build!
Each bulb could become a node in a new, better, "brighter" Internet.
Okay so I'm kidding!
Of course if that doesn't work -- why can't they just use some sheilding on these bulbs? A very thin (transparent) metal-film conductive coating (of the type they use on LCDs) should do the trick quite nicely and at minimal cost.
the 2.4ghz band is a mess. cordless phones, video transmitters (X.10!), 802.11, and Bluetooth all share that band of frequencies. Granted, this is what was pretty well inevitable with the FCC unrestricting the 2.4ghz band.
now there are technologies they never thought of, like interference from this light. I seriously have a problem with any of these 2.4ghz products: i'm not even guaranteed that my video transmitter will work with my phone without interfering.
i'll wait until Ultra Wide Band products become available. 3.1ghz phones are just around the corner. then watch us roll into GPS territory. maybe we should just switch back to carrier pigeons (:
Anyone know exactly how much power these lights are supposed to give off? If these are supposed to save power better than current technologies(e.g. florecent) they need to put out 12W. But the claim is that it interfers with 2.4GHz so how much power is going out in that band if the whole thing is only using 12W? It seems unreasonable that 12W falling off at 1/r^2(okay I assume a sphereical bulb) would have enough power to interfer with WiFi .5miles away. So does anyone know the power output(or usage) of these lights and exactly what intensity a WiFi will pick up?
I'd think that at some point wireless will be ubiquitous like cell bands and you won't need to broadcast your own.. isn't that what you meant by 'success story'.
Not broadcasting your own means much less interference AFAIK. This will happen soonest in tightly populated areas.. looked to Japan to be the first to have public access WiFI.
Course i have to ask how does WiFI scale to N users per square mile/km?
A fool throws a stone into a well and a thousand sages can not remove it.
To be honest, I hadn't even considered Part 18! So few devices qualify for Part 18 I don't really even think about it.
These lights could very well be Part 18, although RF lighting isn't mentioned specifically in the section.
I don't know the specifics of the design of these lights, so it's really hard to say. Shooting RF energy through a glass tube to excite a gas doesn't seem like it should radiate so much energy as to wipe out wireless networks for half a mile in any direction.
Personally, I'd have reservations about sitting under such lighting all day if it did!
Part 18 devices are limited to 2.4 GHz - 2.5 GHz, which unfortunately wipes out the entire Part 15 subband. They're also authorized a much higher field strength... at less than 500 watts (which we can assume these lights will be) it's 25 microvolts per meter measured at 300 meters.
However, I still don't see these fixtures being a problem for reasons aside from the Part 15/18 argument.
Properly designed, these lights should only emit spurious emissions at very low power and at specific frequencies and harmonics within the ISM band. Spread spectrum devices should see around this interference. Perhaps the range or speed would be a little more limited, it shouldn't be a huge impact unless your base station is sitting right under one of these lights (which is possible).
Also, you must consider market pressures. If they hope to sell these devices to businesses (the largest consumer of flourescent light bulbs) they simply have to consider wireless networks. By the time these fixtures are available on the market, wireless networking will only be more common.
No enterprise is going to purchase lighting devices that wipe out their wireless infrastructure.
All opinions presented here aren't mine.
Doh, just need to revise my previous post.
RF lighting IS specifically mentioned in Part 18 (it's early, sorry).
All opinions presented here aren't mine.