'Whispering' Wireless Internet 134
Zondar writes "MSNBC is reporting about a new radio filtering technology allows an ISP to use already-occupied frequencies to transmit and receive data. From the article: 'xMax, the latest innovation in broadband communications, is a very quiet radio system that uses radio channels already filled up with noisy pager or TV signals ...' and 'xMax is trespassing radio frequencies, although trespassing is not the right word, because we're allowed to transmit a signal if it doesn't interfere with other, stronger signals...' Too good to be true? Sounds like it would just raise the noise floor, to me."
FCC (Score:3, Interesting)
FP?
Re:FCC (Score:5, Interesting)
Or will the TV stations roll out internet service themselves, since they have the license?
Re:FCC (Score:2, Informative)
Re:FCC (Score:2, Informative)
"Our technology uses a narrowband channel, and places a carrier there for an extremely precise clock in the receiver," says Bobier. "The transmitter also transmits information in side bands, at levels lower than ultra-wideband. We are able to get performance comparable to a wideband licensed trasmission."
The low-power channel it uses can overlap with other users, because it is below the noise floor, creating "dual use"
Re:FCC (Score:2)
This is a good idea, and FCC will probably welcome it. Though I'm sure there will be "some" problems from this broadcast type.
Just take a look at BPL. Sure it works, b
Re:FCC (Score:4, Informative)
UWB vs. xMax (Score:3, Informative)
An xMax-enabled system has several advantages of over a UWB network. Primarily, whereas UWB emissions require several gigahertz of spectrum, the "narrowband" version of xMax only requires sidebands on the order of several megahertz. The carrier synchronous nature of xMax also bests UWB, which uses thousands of pulses to represent one symbol.
Paradoxically, UWB is often designed as a PAN technology for use in the 3.1- to 10.6- GHz range and other li
Re:FCC (Score:5, Informative)
Typical transmissions use a center or carrier frequency and have what's called sideband noise, which is a fairly strong signal around the carrier frequency. This sideband is information needed as part of the primary transmission, but it is noise to its neighboring frequencies. This makes your 96.6 FM station really have an allocation of 96.5 to 96.7 MHz. The tuner locks into the carrier frequency and then gathers the information from the sidebands.
Ultra wide band distributes all of its information across several frequencies (generally near 1 GHZ of bandwidth with center frequencies varying from 3 to 10 GHz) without providing any RF power above the FCC limits for stray radiation, even at the center frequency.
xMax, however, is designed for sub-GHz channels. It places a significant amount of power on the center/carrier frequency like traditional transmissions. In contrast to traditional transmissions, however, xMax spreads the sideband information over a large bandwidth and thus the power amplitude per frequency is below the FCC mandated power limits for stray radiation (like UWB).
The net effect for xMax is that the primary signal it is so narrow that it can slip in between the existing allocated channels without emitting sideband information into neighboring, already channels. This makes it attractive for a way to cram more information into limited spectrum.
Re:FCC (Score:1)
"Chicken Lip Technology... Through the use of Chicken Lips we will give you Faster Data Speeds than you have ever seen before".
Re:FCC (Score:2)
Current limitations on UWB allow WLAN (802.11g) type ranges, though the levels people were hoping for would have allowed immense ranges. A company called Pulse~Link is doing the UWB WLAN research (Cringley told me about them in an email conversation), and I assume tha
Re:FCC (Score:2)
Mistake in your post (Score:2)
I wonder what FCC/ologopolies will have to say when someone else starts using their hard lobbied/bribed frequencies.
You meant to type:
I wonder what FCC/ologopolies will have to say when we starts using our hard lobbied/bribed for frequencies.
Re:Mistake in your post (Score:2)
"
We? Do you mean we as in "We, the People"? If so you are mistaken. We the people didn't lobby or bribe to obtain those frequencies, we already own them. Of course we did have to go through that little unpleasantless with England
Re:Mistake in your post (Score:1)
Spread-spectrum (Score:5, Informative)
Re:Spread-spectrum (Score:4, Informative)
Re:Spread-spectrum (Score:3, Interesting)
What is unique about the system is that it can emit signals that are too weak to be picked up by normal antennas, but that can be "heard" by special aerials which know where to "listen", thus enabling dual usage of the same scarce radio spectrum.
Re:Spread-spectrum (Score:5, Informative)
-Peter
Re:Spread-spectrum (Score:3, Insightful)
One thing that I find interesting is that her role as a scientist was somewhat celebrated. The wikipedia article still focuses on her celebrety as a movie star but I found myself most interested in how intensely driven she seems to have been.
Re:Spread-spectrum (Score:3, Funny)
That's an interesting way to describe her pic... Who says geeks aren't gentlemen?
I disagree (Score:1)
Re:Spread-spectrum (Score:2, Interesting)
Re:Spread-spectrum (Score:1)
Re:Spread-spectrum (Score:1)
Seems to fit the defintion put forth in the article. In what way do you disagree?
-Peter
Re:Spread-spectrum (Score:2)
1) Spread-spectrum transmits the signal over a very wide bandwidth (hence the name), as opposed to frequency hopping, which (in her case) used narrow-band transmission, albeit on a changing frequency.
2) Spread-spectrum is particularly useful for multiple local, short distance transmissions that do not interfere with each other. Think of DECT phones and all the other stuff in the 2.4GHz band (it has other uses as well).
Re:Spread-spectrum (Score:2, Interesting)
Re:Spread-spectrum (Score:1)
Cool.
-Peter
Re:Spread-spectrum (Score:1)
Re:Spread-spectrum (Score:1)
Re:Spread-spectrum (Score:1)
-Peter
PS: Proving, once again, that there should be a "-1: I don't get it" moderation option.
-P
Re:Spread-spectrum (Score:2)
*bangs head against desk*.
NEWSFLASH: You are a stupid fuck.
Re:Spread-spectrum (Score:2)
Cue goatse jokes.
Re:Spread-spectrum (Score:1)
Re:Spread-spectrum (Score:2)
There's also work being done to free up unused UHF TV space for WISP's.
Re:Spread-spectrum, NOT! (Score:2)
again? (Score:1, Interesting)
Re:again? (Score:3, Informative)
Interesting, but possible problems? (Score:4, Interesting)
Re:Interesting, but possible problems? (Score:4, Informative)
The problem they had was that the regulators looked in the regulation books, and discovered that the only category that really fitted was spark gap transmitters, which were banned outright (spark gap transmitters transmit across all the wavelengths simultaneously and can cause enormous interference).
However it seemed a bit ridiculous, because the powers intended to be used for spread spectrum are really minute, and unlikely to cause interference, nevertheless 'rules are rules'.
Recently the argument was made that hairdryers often produce sparks from the brushes in the electric motors, and these don't produce significant interference, and these aren't banned; hairdryers are basically spark gap transmitters; and spreadspectrum produces much less interference than hairdryers.
The regulators hmmed and hahed, and it's looking like spreadspectrum is being permitted at very low powers in America.
Other countries like the UK have followed suit.
Incidentally, the noise floor often isn't affected measurably by this stuff, except at very close range. Noise doesn't add linearly and many of these systems are well below the noise floor. Also see Shannon Hartley theorem [wikipedia.org].
Re:Interesting, but possible problems? (Score:2)
Re:Interesting, but possible problems? (Score:2)
Re:Interesting, but possible problems? (Score:2)
It's neat to see the technology be developed though. After all, there's going to be a huge opening of spedctrum soon... it would be nice to get the ball rolling for the public to get some real benifit from some real quality spectrum...
Re:Interesting, but possible problems? (Score:1)
Techdirt article on xMax (Score:1, Interesting)
Check out
http://www.techdirt.com/news/wireless/article/5617 [techdirt.com]
Re:Techdirt article on xMax (Score:3, Interesting)
Best quote from that article:
Instead, they quote the technology's inventor and the executive chairman of the company, while a man presented just as "an electrical engineering professor at Princeton University" actually sits on the company's board of advisors. None of these three, of course, have a vested interest in pumping up this new technology.
I'm surprised (Score:3, Interesting)
Re:I'm surprised (Score:1)
Re:I'm surprised (Score:5, Informative)
A better approach is to have each receiver (not transmitter) indicate where and when it is listening so that other transmitters can avoid interfering with it. Busy Tone Multiple Access (BTMA), proposed way back in the 1970s, is probably the earliest such scheme. The MACA (Multiple Access with Collision Avoidance) scheme I invented for amateur packet radio circa 1990 that found its way (with enhancements by others) into 802.11 is basically time-division BTMA on a single channel.
A few years after I proposed MACA, I also suggested a more general purpose dynamic frequency coordination scheme for the amateur service based on packet radio. It was inspired by the backlash to the proposals to broaden the use of spread spectrum on the ham bands. You'd have a coordination channel on which receivers would broadcast the frequencies and times that they were listening so that nearby transmitters could avoid interfering with them. You could get fancy and have each transmitter send a test transmission to see if a receiver is bothered by it, and if not then that transmitter would not have to defer to that receiver.
Naturally this never went anywhere because the vast majority of hams are not really interested in any kind of technical innovation. They didn't want to have to do anything new just to continue using the frequencies they've always used, which they tend to treat as their own personal property. The spread spectrum proposal was eviscerated, and I let the idea drop. I wouldn't be surprised if the xG guys are now trying to patent my ideas. Wouldn't be the first time companies have tried to claim innovations placed into the public domain by hams as their own.
Re:I'm surprised (Score:1)
Re:I'm surprised (Score:1, Funny)
Re:I'm surprised (Score:2)
Read his article on MACA, his invention. You will be impressed if you have any understanding.
-Billy
Re:I'm surprised (Score:3, Informative)
Not only that; I most remember using his early dos-based TCP/IP stack and tools (repackaged by Demon Internet in the UK, BackInTheOldDays) which, while minimally friendly, were damn fine.
App
Hooray! (Score:2, Funny)
Re:Hooray! (Score:4, Funny)
"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.
Re:Hooray! (Score:1, Informative)
Area = pi * r^2 (Score:3, Interesting)
Re:Area = pi * r^2 (Score:2, Informative)
from a random wireless advisor post [wirelessadvisor.com]
from an article on Yale's website "The Physics of Cellphones" [yale.edu] (but dated 2003) :
"Trespassing" (Score:1)
Re:"Trespassing" (Score:1)
Technical Information (Score:4, Informative)
Will we become invisible to ET SETI searchers? (Score:5, Insightful)
I wonder if each civilization goes through a short RF-detectability phase before they so densely pack the spectrum with so many emitters that they become invisible, too.
Re:Will we become invisible to ET SETI searchers? (Score:3, Insightful)
Saying that wide band communications is less visible than narrow band communications is like saying that white light is less visible than red light. You'll still be able to see the 'noisy' white light in the field of gray and black, and perhaps more easily than the red light.
-Adam
Re:Will we become invisible to ET SETI searchers? (Score:2)
Re:Will we become invisible to ET SETI searchers? (Score:3, Interesting)
> it will be generating much more radio noise than
> the surroundings.
Not true. The total output of all the radio transmitters in use today is much less than the thermal radiation from the Earth integrated over the same band. If all those transmitters were using UWB the effect would be to raise the apparent noise level by an imperceptible amount.
> Saying that wide band communications is less
> visible than narrow band communications is like
Re:Will we become invisible to ET SETI searchers? (Score:2)
Which band? 1MHz to 10GHz? Where are you getting your data about thermal radiation output of the Earth?
Further, UWB means that a single radio is going to cover less than a few hundred MHz. Due to mass production it is unlikely that we will spread these radios out in such a manner as to cover the entire band evenly. There will be large spikes of activity
Lower power, not greater bandwidth (Score:2, Interesting)
As an aside, the transition to heavily encoded packet RF also reduces our signature to ET. Anyone with a long enough wire and a speaker can pick up analog TV or radio and recognize it as synthetic. Can the same be said for highly dense encrypted digital traffic
Re:Will we become invisible to ET SETI searchers? (Score:2)
Re:Will we become invisible to ET SETI searchers? (Score:2)
This also brings out some of the problems with wireless technology in general. It is convenient and n
Re:Will we become invisible to ET SETI searchers? (Score:2)
You would be looking at easily multi-gigabit wireless that wouldn't have too many users per node. The problem of course is that this whole scenario
Re:Will we become invisible to ET SETI searchers? (Score:5, Informative)
I've heard people say "But the Earth radiates as much RF as a star" - BULLSHIT. The Earth doesn't even radiate as much as Jupiter. The only thing is that the Earth's radiation is in narrower bandwidths and thus more detectable.
However, ignoring losses due to the inter-[planetary|stellar] medium, the signal strength of ANY signal goes down as the square of the distance (even highly collimated signals still diverge, and thus quadruple their area as distance doubles once you get out of the near-field effects).
Do the math: Assume a gigawatt transmitter. Assume that this transmitter is collimated to the point that at 100,000,000 kilometers the beam is 1 kilometer wide, and treat the transmitter as a point source. (BTW - that is an power density of just under 1.3 kilowatts per square meter - about the same as the total solar power at the Earth's surface).
At just ONE light-year the signal is just over nine billonths as strong - call it 10 microwatts to keep it to about 2 significant digits. At 4 light years, it is down to less than a microwatt per square meter. At 100 light years, it is one nanowatt per square meter.
And remember, we started with an INCREDIBLY collimated, INCREDIBLY powerful emission - normal transmissions are a thousandth this powerful, and a million times more diffuse.
The SETI project is NOT looking for alien TV or broadcast radio. SETI is looking for a Mount Arecibo class radio telescope transmitting a narrow bandwidth high power signal designed especially for a SETI system to see.
Re:Will we become invisible to ET SETI searchers? (Score:2, Interesting)
What does that mean in practise, not many stars within that range, so it isn't to much help. So to have any real chance you would need a space based telescope that is much much larger to seriously increase sensitivity. But that won't happen for a
Re: (Score:2)
It doesn't matter. (Score:2)
Re:Will we become invisible to ET SETI searchers? (Score:2)
Whatever happens, you will still see 50 and 60 Hz..
Technical details (Score:2, Informative)
In the faq http://www.xgtechnology.com/faq.htm [xgtechnology.com] there is a brief description. Note that the spectrum plot shown is basically worthless because it does not show any signal details.
Here is a magazine article http://www.mwee.com/showArticle.jhtml?articleID=16 3700624 [mwee.com] that has a little more information.
Note the following: In the first is the statement that Shannon's theorem is not violated but no justification is given. In the second it says that most p
Signals below the noise (Score:3, Interesting)
Shannon's law describes the amount of data you can send as a function of the signal to noise ratio. As long as you are willing to put up with low bit rates it is no problem to use a signal below the noise floor.
Several of the posters have assumed that these guys have re-invented cdma. That's not necessarily the case (although it might be).
Re:Signals below the noise (Score:1)
For that matter, you don't even need the signal in the first place.
More relevant now than ever (Score:1)
Lobbyists for spectrum license holders have written thousands of pages of F.C.C. comments ridiculing proposals to allow low-power transmissions (whispering) within their frequency bands. For example, highpower TV broadcasters argue that such low-power unlicensed underlays for uses such as WiFi would create harmful interference with their signals and lead to an inefficient allocation of resources. By lobbying against unlicensed underlays, they
Re:More relevant now than ever (Score:2)
Yeah, we wouldn't want to add any noise to those analog NTSC transmissions. They are practically noise free!
Re:More relevant now than ever (Score:2)
HF spectrum? (Score:2)
How much info can a cell carry (Score:1)
On key piece of information I go looking for in new wireless schemes like this is how much information a "cell" can carry. For example, from memory a GSM cell carries about 400 kbps, a 3G cell carries 4 Mbps, a WiMax cell about 70 Mbps. The figure gives you a feel for how useful the technology will be for broadband.
If you follow the links already posted here, you will see it has FCC approval, it travels a looong way at low power levels, the chip set is expected to be under $10, has bugger all side-band
Re:How much info can a cell carry (Score:1)
Replying to my own post, this article http://news.com.com/An+energy-conscious+wireless+t echnology/2100-1039_3-5778423.html?part=rss&tag=57 78423&subj=news [com.com]
answers that question and a lot more. (Beware the extraneous spaces slashcode sticks into the link.)
This Will Bring Inexpensive & Free InterNet To (Score:1)
The speed I would think- could be anything up to the speed of light, limited by factors that normally bottleneck tcp.
if they say broadband, they mean broadband, which is anything faster than 56kB.
Even if it's slow like isdn, it will still ad to the luster of having access points everywhere, which can only be good.
I would like to take a guess and say it will compete with wimax, etc, but be slower because it will have to default to whomever has first usage rights on whatever particular Frequency it happ
Narrowband pilot + low-level UWB or SS (Score:2, Informative)
So, it's a very narrowband pilot signal plus low level wideband signal with some new filtering/shaping tricks and maybe frequency agility on the wideband part.
The pilot is strong, easy to find, on a known frequency, shaped to occupy minimum bandwidth, and carries low-bitrate control info - like where and when
Re:Narrowband pilot + low-level UWB or SS (Score:1)
I smell a SCAM (Score:2)
Here's another: http://www.sec.gov/litigation/litreleases/lr15898
"Never give a sucker an even break." (W.C. Fields)
Re:I smell a SCAM (Score:1)
Funny thing is, the description the xMax people give of their modulation doesn't claim they are really squeezing multiple Mbps into the narrowband portion, but in the very low level, wide sidebands.
It does smell at least just a bit fishy.
Sounds like... (Score:1)
Re:Sounds like... (Score:2)
Re:Sounds like... (Score:1)
Trespassing? (Score:4, Insightful)
Damn right it's not the right word, and it wouldn't be even if it weren't legal to transmit on those same freqs. You can't trespass on frequencies because frequencies are not anyone's property. We gotta shake off this relentless trend of treating rights and licenses as property. To use a more familiar example, nobody "owns" music, not even the composer. Rights holders don't own anything at all, they merely control the rights to do specific things for a limited time.
The distinction isn't semantic nitpicking, it's very important because treating rights as property gives the copyright control industry an unfair advantage in any public discussions about rights issues. They like to play the part of the plucky little old lady chasing down a purse snatcher, or the outraged homeowner defending his castle against burglars and government goons. They get away with it because the public has been taught to overlay the simple and familiar concept of property on much more complicated issues. Treat rights as what they are -- temporary conditions set by the government -- and various rights and DRM issues suddenly require a lot more thought, which they should.
Re:Trespassing? (Score:1)
I think you're missing the important point that with spread spectrum, you can have multiple users of the same frequency, so there doesn't need to be a single owner. With old style modulation, that is not the case, so there does.
But the channel still has a capacity limit - if too many people use it the noise floor will rise.
It reminds you of the Shanno
The floor? (Score:2)
little girl: "There is no floor."
This reminds me.. (Score:1)
In wait-and-see mode (Score:2)
There are a couple of interesting things about this. On one level, it's a UWB-like system that promises to do longer distance, by the use of a narrowband licenced channel for a timing signal.
So far, it's only been demonstrated indoors (and that's the basis of its support by Stuart Schwartz, the Princeton professor). The people involved have a history that I am still disecting.
All of which mak
Re:Range? (Score:3, Informative)
The first xMax network is currently being built in Miami and Fort Lauderdale where one base station can deliver broadband Internet over a 40 square mile area.
But with that much area, you need to start worrying about capacity. What good is it to cover 40 sqmi when you can't get a packet through:
The capacity of that wireless network is not bigger than any other wireless technology, which means that more base stations need to be added if a certain number of people are using the network
Re:Range? (Score:3, Insightful)
Re:Range? (Score:2)
Re:MOD PARENT UP!!!!! (Score:1, Funny)