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New Lighting Technology To Wipe Out Wi-Fi Access?
Richard Evans writes "Focus on Broadband Wireless Internet Access has an article
[cached by google ]
on the potentially catastrophic interference to Communications Users Of The 2.4 GHz Band e.g. Wi-Fi, DECT and Bluetooth by a new lighting technology called RF Lighting."
Steve Stroh
Independent Technology Writer
Specializing in Broadband Wireless Internet Access
P.O. Box 84
Redmond, WA 98073-0084
425-481-0600
www.strohpub.com
steve@strohpub.com
Presented in the Spirit of Sharing that was the most important part of the original Internet. It takes a certain minimum generosity of spirit to play the online communications game. Without it, you fail in the long run. - Jack Rickard
Focus
on Broadband Wireless Internet Access
Steve Stroh, Editor
This article is excerpted from the July/August, 2001 issue of Focus On Broadband Wireless Internet Access - www.strohpub.com/focus.htm and is offered as an example article.
Part 18 RF Lighting
A Potential "Extinction Level Event" For Communications Users Of The 2.4 GHz Band
The phrase "ELE - Extinction Level Event" entered the popular consciousness several years ago as a result of the popular movie "Deep Impact". In the movie, an enormous asteroid is observed to be on a collision course with Earth. The asteroid is sufficiently large that an impact on Earth will cause catastrophic effects, mostly a dust cloud that will block sunlight for many months if not years, triggering the death of plant life, and soon after most animal life.
The term ELE came to mind as I read about a new lighting technology from Fusion Lighting, Inc. (www.fusionlighting.com) that uses microwave energy in a new, very high-efficiency lighting system, dubbed "RF [Radio Frequency] Lighting".
An August 6, 2001 article in the Wall Street Journal titled "Energy-Saving Light-Bulb Maker Battles With Satellite-Radio Firms For Bandwidth describes a battle-in-the-making between Fusion Lighting, Inc. and two companies that plan to offer satellite-based broadcast radio - Sirius Satellite Radio, Inc. and XM Satellite Radio. At issue is the amount of interference that Fusion's new devices would cause to the satellite radio broadcasts at 2.32 - 2.345 GHz, which are considerably removed from the spectrum where Fusion's devices operate - 2.4 - 2.4835 GHz. The satellite radio broadcasters have concluded that Fusion's devices, as proposed, will cause substantial interference to their transmissions.
Left unmentioned in the WSJ article, and only now beginning to be noted by many users of the 2.4 GHz band is that if the Fusion devices are capable of causing such trouble for satellite radio broadcasting... what would the effect be to communications users of the 2.4 GHz band, where the Fusion devices will be operating?
2.4 - 2.485 GHz in the US is used by two very different types of equipment. The older, more well established use of the band is for Industrial, Scientific, and Medical equipment (ISM) such as household and industrial microwave ovens. Operations of such devices are governed under the FCC's Part 18 rules. Basically, Part 18 devices are expected to radiate only - not receive and thus, are not communications devices.
The second major use of the 2.4 GHz band is for license-exempt communications equipment governed under the FCC's Part 15 (15.247) rules.
Because the Part 15 rules specify "robust" modulation techniques such as Frequency Hopping Spread Spectrum (FHSS), Part 15 and Part 18 devices can generally co-exist, for example microwave ovens in a household rarely operate for more than a few minutes at a time, so cordless phones and wireless networks operating in the 2.4 GHz band can continue to operate. Conflicts were anticipated when the Part 15 operation was first envisioned, and the following requirement was levied on Part 15 devices:
(1) [Each Part 15] device may not cause harmful interference, and (2) [Each Part 15] device must accept any interference received, including interference that may cause undesirable operation.
Basically, buyer beware / use at your own risk.
Fusion's RF lighting system is a good example of a Part 18 device. RF technology is useful for any number of purposes other than communications, and the FCC and industry recognized this and set aside various chunks of spectrum for industrial use.
The problem comes that the 2.4 GHz band is now used by an incredible number of number of communications devices - cordless telephones, wireless Internet access networks, wireless Local Area Networks, and soon all manner of simple devices with Bluetooth embedded in them- with an accumulated investment of (at minimum) billions of dollars.
How we got to this situation is that there was steadily increasing demand by various companies for spectrum for wireless networking and related applications, but there were no large swaths of spectrum that were suitable. There were demonstrable needs for wireless LANs in warehouses and hospitals. There were demonstrable needs for temporary wireless links.
Eventually the FCC decided to offer a Faustian bargain: Industry could use the existing ISM spectrum if they adhered to certain technical limitations with no expectation of protection. It was clearly in the FCC's mind that there would relatively few Part 15 devices, and that for the most part they had heard the last from Industry. The Part 15 rules were tough, and it would be extremely challenging to make radios work under such conditions... and, they'd have to develop newfangled spread spectrum technologies that were previously used only by the military and developed at great cost.
But, Industry found the Part 15 "deal" to be perfectly acceptable. Industry understood the Part 15 deal better than the FCC did. Industry's major goal was to be able to offer wireless devices that did not require a license from the FCC, so that such wireless devices could be sold over the counter - to anyone, everywhere. Industry foresaw that there was a market for millions of such devices (I doubt that Industry, at that point, projected that such devices would rapidly number in the billions...)
That there were technical obstacles to overcome... well, that was just a barrier to entry for potential competitors. As we've come to expect, where there is a demonstrated demand, technology can overcome, and that's exactly what happened. The biggest factor that made the difference is the rapid increase in capability of application-specific integrated circuits, and digital signal processors. Taken together, spread spectrum radios could be built, at affordable prices, that met the FCC's Part 15 rules. Gradually, an entire Part 15 industry evolved... far beyond the wildest imaginings of the FCC.
What Will Happen? There are a number of factors at play, and very high stakes, so there are a number of possible scenarios. The first scenario is that, quite apart from its effects within the 2.4 GHz band, the effects of the new Fusion Lighting devices outside of the 2.4 GHz band must adhere to existing regulations. It's difficult to ascertain from what has been published to date (particularly when Fusion Lighting is being very circumspect with potentially damaging details of its proposed product), but it appears that Fusion Lighting claims to meet the "out of band emissions limits" for Part 18 devices.
The counter-argument from the satellite radio broadcasting companies is that even if Fusion Lighting's proposed products are within out-of-band emissions limits, their transmissions are still being impacted.
To which Fusion might be expected to reply (to the effect of) "If a satellite radio broadcasting system is too precarious to deal with other signals that should have been expected, then you didn't do your homework."
The satellite radio broadcast companies' position is that this kind of interference has never been previously been an issue. Etc. You can understand why this is such a hot issue at the FCC.
But, within the 2.4 GHz band... if a Fusion Lighting device is activated, it will severely impact the use of all manner of Part 15 devices in the area around it. For example, 802.11b is becoming very popular in both large and small companies, and becoming even more popular for home use (because to hook the kid's computer up to the cable modem doesn't require any new wires). Cordless phones are also increasingly using 2.4 GHz. What happens when a nearby gas station installs RF lighting... and all 802.11b devices and 2.4 GHz cordless phones for a mile in diameter stop working?
The RF Lighting issue is quite the dilemma for the FCC, which was hoping that Fusion Lighting would be willing and able to modify their device so that it wouldn't cause interference to communications equipment. But that appears unlikely, and Fusion Lighting appears to be within its "rights" to apply for an FCC Part 18 certification to begin manufacturing. But if Part 18 certification is granted and RF Lighting devices become widespread (and it appears very likely that they will, given their inherent energy efficiencies), is the FCC willing to "sacrifice" much of the utility of the 2.4 GHz band in exchange for one company's (at the moment...) product?
The group likely to be most severely impacted by Fusion Lighting devices are Internet Service Providers that are using wireless equipment to connect to their customers. The vast majority of Wireless ISPs (WISPs) use equipment that operates in the 2.4 GHz band. Some equipment is purpose-built for ISP use, and many others use modified Wireless Local Area Network (Wireless LAN) equipment. What all WISPs have in common is that their signals are relatively "fragile". The FCC's Part 15 rules apply equally to equipment used by Wireless ISPs, so the ISPs compensate for low transmitted power with high-gain, directional antennas. This approach allows them to have enough "signal margin" to achieve a reliable link... but if a source of interference appears nearby, the link will likely be disrupted.
It may well be possible to overcome interference in the 2.4 GHz band from RF lighting devices... but doing so won't be inexpensive or easy. For example, link margins can be improved by building multiple hub sites with short paths instead of just a few hub sites with relatively long paths. Another approach is to buy better 2.4 GHz band equipment that is more robust, such as that offered by WIMAN Systems (www.wiman.net).
A long term solution to interference issues in the 2.4 GHz band is to begin using equipment that operates in the 5 GHz band. In the US, there is a total of 300 MHz of spectrum available for license-exempt wireless devices at 5 GHz. 100 MHz of this spectrum is also ISM spectrum, with the potential of industrial devices being operated there also. But the other 200 MHz is "virgin" spectrum and reserved exclusively for communications.
A number of companies now offer equipment for the 5 GHz band, and as the price of RF components for 5 GHz continues to fall, more and more equipment will become available. The emergence of equipment compliant with the 802.11a Wireless LAN standard is expected to play a major role in increasing the popularity of equipment for the 5 GHz band. Where 802.11b offers (theoretical) speeds up to 11 Mbps and operates in the 2.4 GHz band, 802.11a offers (again, theoretical) speeds up to 54 Mbps and operates in the 5 GHz band.
If RF Lighting is an "ELE" to communications users of the 2.4 GHz band, at least there is time to begin "planning for survival" - planning for migration to 5 GHz, study of new equipment, lining up additional financing, etc.
Filename: 0701feat.htm This page is one of a series of pages from www.strohpub.com. This page, and all subsidiary pages associated with it (not including links to other World Wide Web pages) are Copyright © 1997-2001 by Steven K. Stroh. To contact the author, send e-mail to steve@strohpub.com. This page was last updated September 5, 2001.
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The website it cites: Link is *still* blank at least a year after it was cited.
The article also goes into very little detail as to *why* this new lighting technology will be either popular nor necessary. It's vaguely referred to as "very high efficiency."
Summary: Call us when you have real news.
That's why 2.4 GHz will rapidy become unreliable for wireless LANs.
Luckily, 5 GHz wireless LAN products (802.11a) are now becoming available (called WiFi-5, I believe). Since they
do not use the 2.4 GHz frequency range, they will not be affected by this issue.
http://www.fusionlighting.com/technology.htm
Read the article:
Eventually the FCC decided to offer a Faustian bargain: Industry could use the existing ISM spectrum if they adhered to certain technical limitations with no expectation of protection.
In other words, as long as you stay within the 2.4 GHz spectrum, you can do what ever you want, as long as you didn't expect to be protected from interference from other devices.
Bluetooth and 802.11B have already violently clashed in this space already. I have seen it myself - with a 802.11B card in one PCMCIA slot, as soon as I turn on a bluetooth card in the other slot, my average ping time on the 802.11B goes up considerably.
Do you have Linux and a DotPal? Click here now!
The company I used to work for did the very first large scale (non-test) installation of their lighting products in the US. It sounded like an awesome product. It would provide MORE light for LESS power with LESS maintenance.
:)
We installed a HUGE area with this stuff (took many months to do the install). A year later we ended up yanking every bit of it out. Why? Well, there were SEVERAL technical problems with these things that they hadn't worked out. The short version of how they work is that they irradiate a glove with some sulfur in it with microwaves and turn it into a glowing plasma. Well, that stuff is a bit hot, so you have to continuously rotate the 'bulb' This rotational part breaks, so the light breaks.. the reflectors can't stand the heat, etc.
so don't worry.. they are in bankruptcy...
This looks like a niche product. It's not even clear that Fusion Lighting is still in business. Their web site is essentially defunct. Their web site used to have some nice pictures of glass bulbs and more info, but now, it's just a starter page.
The really stupid part about that is eventually 5 GHz will have the exact same problem.
Read the article more carefully. It states a section in the 5 GHz range reserved for communication devices only.
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- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
Yeah, those were the promises. I really wish it would have worked out better. a few details of the problems:
#1 - the BULBS might last 11.4 years, but the magnetron that shoots the microwaves into the bulb, and the motor that turns both the fan (that cools) and the bulb (to prevent the plasma from burning through the glass of the bulb) burn out VERY fast. 1st generation units had 50% of the magnetrons burn out within 6 months. We were told this was due to the power supplies. 2nd gen units seemed much more solid in the power department.
#2 - the fan motor / bulb turner would break/no longer rotate. It didn't appear to us that they had a high enough quality motor on these... a large percentage of them would break within 3-6 months. If the motor stops turning that bulb it goes POOF when the plasma burns through.
#3 - the light is NOT white. it is kinda green.. pretty noticibly green actually. People do not seem to like greenish light. Most of us are used to either a yellowish or blueish tint. We had several people complain of feeling sick.. Dunno why green light would do it, but it didn't make our customer happy.
#4 - the high temps that these units achieve lead to a break down in both the reflectors and in plastics used to feed the light into useful places. We replaced many lights with one of these units (like a 5 to 1 ratio maybe) and then used a plastic tube as a 'light pipe' to deliver the light where it was needed. The material in the reflector would either a) degrade, or b) get deposited on the plastic tube due to the high temps. Also the plastic joins on the tubes would degrade seriously in a short (months) time frame. Maintenance costs were incredibly high.
In short: great idea, bad implementation. I have no doubt that if the engineering of these untis was higher (with the subsequently higher cost) that these would work. But then these already pricey (very) units would not be able to compete with existing technologies (like metal halide).
Crow
You obviously don't know much either. Incandescent and flourescent lighting both "flicker" because they are powered by alternating current. Incandescent lights work by heating a wire so hot it glows white (that's what "incandescent" means). Flourescent lights work by using high voltage to excite a gas. That gas emits UV light which strikes phosphor compounds on the inside surface of the tube. These compounds emit visible light when struck by UV (they "flouresce," hence "flourescent").
Whether or not flicker is visible depends on the "persistence" of the phosphors and the cooling rate of the incandescent wire. They all flicker. The flicker is a result of the alternating current. Of course, you can use DC to make an incandescent bulb work. You can't do that with flourescent lights because AC is required to keep high voltage coming out of a transformer (transformers only work with changing magnetic fields - put DC into them and you only get output voltage when DC comes on and again when it shuts off).
I'm not an RF expert, but I'll tell you why I personally don't worry. The 2.4GHz band was set aside as an ISM band precisely because it is very well absorbed by water. Which is how a microwave oven works. The several hundred watts of microwaves emitted inside of the oven will bounce off the metal walls until they get absorbed by something. Usually this is your food. Or more accurately, the water in the food. Which is why it heats it up so well.
You don't want to be around the output of a microwave oven for precisely the same reason you don't want to stick your hand on the stove when it's on. You'll get burnt, plain and simple. With microwaves, you could actually get burnt on the inside. Most internal organs don't like extra heat. Witness how little of a fever you have to have before it becomes life threatening.
Now, back to wireless devices. The power output of your typical 802.11b device is between 30mW and 100mW. A typical microwave oven will produce up to 1000W of power. 10,000 times the power of your wireless card. Can the output of your wireless card or phone heat up your head? Of course. Will it heat it up enough to matter? Not likely.
I've found the description at PhysicsClassroom to be useful for explaining light. Now, it's geared toward high school students, and as such is not strictly accurate (most notably, light is a transverse wave, whereas the picture seems to imply that it is longitudinal), but at the least it answers the often asked question of "why does light only travel at c in a vacuum". It's a good site overall, I'd definately recommend it.
Effectively, a particle in quantum physics is a cohesive bundle of energy. We measure the mass of that energy in "electron-volts" (eV), which you can think of as a electron-level volt-meter. It's similar to measuring the voltage of a battery; we can't directly see how much charge is in a battery, but we can see how hard it pushes / pulls a test charge. Likewise, we can't see how big a proton or electron or up-quark is, but we can see how it affects other particilars of similar size (e.g. an electron as a reference point). Due to the massive deviances in particular masses, it's hard to know for sure if a photon is truely massless (even though it carry's energy). post-modern quantum physics speculates that photons, neutrino's, and even gravitons have mass. (Yes, this does imply that gravity has a weight of it's own. More precisely, the emision of the force of gravity adds weight to the space between two particles.)
The substance of the particle is subject to debate. String theorists believe (if I'm not mistaken), that all particles are made of strings of something (which we'll never know), and that those strings wrap around space (which we also can't know it's consistency)- warping it and being stretched by it.
Another point of view is that of Ether, which we tend to hold on to, since quntum physics is so similar to our percieved world that it would be a shame that such patterns could not be known to persist at different scales. One theory that I like is called
Aethero-kinematics. It's based on the idea that tiny hard balls (perfectly elastic, like steel) bounce about in different patterns (mostly vortexs, like in a drain). All energy is in the form of the kinetic energy present from these bouncing balls. The cohesion allows for quantum particles. The augmentation / contraction of mass (via Einsteins special relativity) is explained away the same as Mach-theory (where an the air-resistance increases exponentially as you exceed the speed of sound). The "speed of light" is merely the average velocity of the balls. The explained reason why we can't perceive relative motion against the ether of space is that earth is not moving with respect to the ether about it; nothing does. Motion is only ever a small fraction of a difference in speed from it's surrounding ether. Lastly, the concept of experimentally determined transverse nature of light is nicely explained away in Aethero-kinematics in common sence ways. (having to do with the probability distribution of collisions of particles in an ideal gass)
Modern quantum physics simply ignores the what's and hows of particles, and simply says they exist with certained measured properties.. That's it, that's all, that's ugly. Because of this, I tend to look at models like the above (so long as they fit the experimental data) as a way of putting my mind at ease. The problem is that until the theory's demonstrate validity, we can't take the analogies they present (ideal gas, or strings) too far in extrapolation / interpolation.
As for waves (also questioned in this thread): a wave is a regular periodic fluxuation. Longitudal waves are like a wripple in a violin string or cresting waves on the ocean. If you just look at a single water molecule, however, you'll see that it doesn't move forward, but instead up and down (just like a boat). You could also look at a police-car flashing light. The color of the light slowly fluxuates from red to blue and back again in a definite period. If you took a cardboard box and punched a hole through it, you'd see on a wall the color fluxuation. If you look more closely, the fluxuation is merely caused by a rotation of two light bulbs. Photonic transverse waves are the fluxuation of the state of the photon from electric to magnetic (hense the phrase, electro-magnetic). An electron sitting still has only an electric field (which applies force to other adjacent electric objects (pretty much anything but a neutron; and even it, if you break it down into quarks). When an electron moves in a circle, it applies a strange perpendicular force which only affects other spining electrons. You can understand that it's different than charge because two electrons are attracted to each other when they counter-rotate (or rotate, I forget which). It turns out that rotation has nothing to do with it; it's the motion of the electrons (but the math gets harder). So here are two completely independent characteristics of a charged particle. As it turns out the transmission of photons accounts for both activities, so the photon is both a messenger particle for magnetic fields and charged-fields (electric-fields). Since a photon must always travel at the speed of light (relative to it's medium), it should be apparent that it works within a magnetic context (e.g. charge in motion). It seems that the photon fluxuates between the two in a sinusoidal pattern with respect to time (independent of it's physical motion). The "frequency" of the photon is the speed at which it oscilates a full transition between electric and magnetic. Such a periodic transverse wave-pattern has many astonishing properties. Most notibly that the same beam of photons when reflecting back apon itself can have interference patterns; namely that the waves can cancel each other out (or amplify one another). The best example of this is to take a beam of monochromatic polarized light and send it through a cardboard box with two slits on it. On the other side of the box, you should see a periodic pattern of light and dark spots.
I'm not a physisist, but I am an electrical engineer, so I have more than a lay understanding of the principles.
-Michael
-Michael
I have no vested interest in Wi-Fi. I personally am waiting for Ultra Wide Band devices to become prevalent. These devices supposedly cannot be jammed by something like RF lighting or other current methods.
I say do your homework *before* investing in the latest technology, or face being screwed in the arse later. If you can't afford to switch to technology that actually works, then don't buy into the one that does not. Simple? I think so. Reasonable? Definitely.
Here's your requested correction.
: users.ox.ac.uk/~jsw/Schroedinger.html+schroedinger %27s+cat&hl=en
Schroedinger's cat test is a little more sadistic than that.
You have a box you can't see into. Inside the box you place a vial of deadly poison that will produce instant death if it's broken. Close to the vial you position a hammer that's cocked. It can go off and break the vial at any time.
After you stick the cat in the box, you close it up. What follows is an incredibly simplified base for Quantum physics.
At any time, the hammer is both cocked and uncocked, the vial both broken and unbroken, the cat both alive and dead. None of the objects are in a definite state until you take a measurement, in which case you determine all three.
The nature of light is similar. It is both a particle and a wave, depending on how you measure it. In most experiments, researchers focus upon either light's particle aspects (by counting photons, for instance) or wave aspects (by measuring an interference between electromagnetic fields, to cite a simple example). Hence the dual nature of light and the relation to Schroedinger's cat experiment.
A good page with further explanation is cached at google here http://216.239.35.100/search?q=cache:fbyF8_1R6_4C