New Technology Could Kill WiMax?

GolygyddMax writes "Techworld reports that a Florida-based start-up, xG, has developed a technology that's a 1000 times more efficient than WiMax and which could, in theory, lead to wireless LANs being powered by watch batteries. It is still in early development, but this technology could allow anyone to set up as an ISP. This could kill WiMax before it even gets off the ground." From the article: "At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS, but had to take the 50mW base station - and its omnidirectional antenna - on trust, since it was at the top of an 850ft mast. The demonstration will be repeated for the US press next week. The system carried 7.4 Mbit/s per MHz per Watt, said Professor Schwartz. By comparison, GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz per Watt. "

Comments

ho!

[endersadvocate]

does this mean that i can use the internet while on the toilet, through steel walls?

3 your spelling/grammar

Re:ho!

[psyon1]

Yeah, I hate it when my porn gets blocked by the steel walls.

Re:ho!

[samkass]

use the internet while on the toilet

Sure, as long as you have handy an 850ft mas... ummm... nevermind.

Re:ho!

[Master of Transhuman]

Gee, when I was in Federal prison, they didn't let you use the Internet.

Have things changed there?

Are they still using stainless steel toilets which are harder to break when you want to flood your cell?

Re:ho!

[EnderWigginsXenocide]

Same here. My RV has been "up-armored" for my upcoming vacation in Iraq. The unfortunate side effect has been the blockage of wi-fi signals when war-driving. Ironicly getting a vehicle ready to war-drive in a war-zone has reduced my ability to war-drive.

1000 times for efficient than WiMax

[PIPBoy3000]

Must . . . resist . . . grammar . . . posting . . .

Re:1000 times for efficient than WiMax

[N8F8]

You mean spelling.

Re:1000 times for efficient than WiMax

[op12]

This is one of those cases when it could really be grammar or spelling (or both) :)

Re:1000 times for efficient than WiMax

[Anonymous Coward]

Speling is grammer ediot

Re:1000 times for efficient than WiMax

[CrazyBusError]

Take the keyboard away from her. Should do the trick.

Re:1000 times for efficient than WiMax

[Anonymous Coward]

Actually, no. Spelling and grammar are two different things, but they often go hand-in-hand.

Re:1000 times for efficient than WiMax

[Columcille]

but 'grammer' isn't spelling. Grammar, on the other hand, is spelled correctly. :) Hmm, this reminds me of something. http://www.sluggy.com/daily.php?date=051102

Re:1000 times for efficient than WiMax

[Anonymous Coward]

Funny---apparently more so than the average slashdotter realises.

FCC and cell phone companies will kill it

[Anonymous Coward]

Since a system like this working with IPv6 could potentially eliminate the need for telecom/cell service providers (since the power reqs are low, it won't be a problem for people to relay each others communications and act as peer to peer links ..using any of the already existing relay reward based schemes).. I could see how cell phone companies would want this technology neutralized.

Re:FCC and cell phone companies will kill it

[pvt_medic]

You'll see some legal challenges but not because it competes wil the telephone services. The real challenges will be related to 911. Since the telephone companies are required to provide E-911 data, how will these guys do this? Cell phone companies have invested lots to be able to ensure that when you dial 911 they can tell where you are calling from. WHile this technology isnt perfect yet and will be years before they have 100% compliance, its getting there. Imagine making a 911 call wirelessly via VOiP. there is no way that they can track you down (yes I am sure some people prefer it that way). But there no guarantee that your 911 call will be answered, be sent to the right state, and even if by some miracle they get you to a relatively close by dispatcher, they will never be able to tell where you are. and yes i am sure that the current phone companies will be the first to point this out to the FCC.

While I applaud these technologies, i also have dealt with the challenges of not being able to track down people who were in a car accident because no one can locate the caller.

Re:FCC and cell phone companies will kill it

[InvalidError]

There is a simple fix for that: use the phone's built-in GPS receiver.

No consumer-level data network (WiFi, WiMax, etc.) is aware of its location. Since VoIP goes through data networks which may be re-routed through other networks (someone routing calls using SSL to some other machine), it is impossible to determine the exact location based on the traffic's apparent point of origin.

100% 911-compliant VoIP is unlikely to ever happen because the 'line' is not tied to any fixed infrastructure. Cell phones have the towers, cable/dsl/phone have the coax/phone cable but VoIP is not tied to any particular endpoint/network/etc. anywhere on the planet. Even if a GPS receiver is built into the VoIP phones, these still depend on being able to detect the satellites and will fail to provide a location if there are a few reinforced concrete buildings around the area. Even if the GPS is cell-assisted, even cell phones stop working inside larger reinforced concrete buildings and there are dead zones all around towns too.

VoIP is not for critical calls. AFAIK, it was never intended to be and never will be. For VoIP to work, you have to trust that:
1) Your WiFi handset will work
2) Your WiFi router will work
3) Your ADSL/Cable/whatever modem will work
4) Your ISP link will work
5) Your VoIP company's servers will work
6) etc.

VoIP has more than double the number of middle-men compared to land lines and cell phones. Every link is a potential point of failure and any failure is very likely to lead to a dropped call, assuming the failure did not prevent you from placing the call in the first place. Last thing you want to have to do when you need to make an urgent call is troubleshooting your network.

Re:FCC and cell phone companies will kill it

[Anonymous Coward]

Just require the VOIP phone to contain/transmit GPS to be considered E911 compatible.

Re:FCC and cell phone companies will kill it

[c_woolley]

Not sure if cell companies would fight it or embrace it. More likely, if they took the buy on this tech, they could incorporate and become even more powerful financial entities. Bundle packages for wireless, cable and internet are right now a money making machine. This technology likely will not be available mainstream for another 5-15 years. That actually is pretty tight on time for planning and contract negotiations, but if communications companies took action on a breakthrough like this, it could stand to make a lot of money. As for the 911 emergency stuff, I do agree there could be a problem, but I feel that there is probably a simply GPS solution (as pointed out previously).

Re:FCC and cell phone companies will kill it

[c_woolley]

I just realized how tired I am and how much it affected my grammar on this post. :) Sorry to all the grammar Nazi people that are going to respond.

Re:FCC and cell phone companies will kill it

[Fordiman]

Of course the number of paralell middle men in a P2P-based VoIP reduces the number of points of failure. For example, the worst problem I've ever had with skype is a few clicks here and there.

Re:FCC and cell phone companies will kill it

[trippinonbsd]

There is a simple fix for that: use the phone's built-in GPS receiver.

I'm not sure if you have ever owned a GPS reciever, but GPS signals are very bad at going through solid objects. Getting a lock inside is quite difficult and when one is achieved it will not be very accurate (some inital testing on my GPS reciever inside my home reveals that the horizontal positioning error is on the magnitude of several hundred feet, not close enough to figure out where you are). That is why most cell phones use triangulation off of the cell phone towers to figure out where you are. It can be (and has to, legally) quite accurate, on my CDMA phone this is called gpsONE (despite not actually being GPS). I have made some test calls with it and the coordinates it gives me are dead on.

Re:FCC and cell phone companies will kill it

[InvalidError]

Although I have never owned a GPS locator, I have seen people have a hard time getting satellites even while standing in the middle of nowhere, I am betting GPS would be completely useless in a city. Sure, GPS' precision is limited... but even with a land line I may be placing calls from 100+ meters away using my long-range cordless phone.

I am not aware that precision localization was required by law... it is neither economically nor technically (and even legally) feasible for cellular operators to guarantee accuracy. All they can do is a reasonable effort using differential timings from multiple towers (at least three) that are in range but major cities are full of null-zones and other trouble spots (particularly around/inside sky-scrapers) that can easily throw off these computations by tens of meters.

How can they DO that?

[Bastian]

I am not a radio engineer, but here's what I read from "7.4Mbit/s per MHz per Watt." "At one watt, we can cram 7.4 bits into one cycle of a sine wave. At two watts, we can fit 14.8 bits into one cycle of a sine wave, and so on."

How does that work?

Re:How can they DO that?

[forand]

A Watt is a measure of power not the frequency of the carrier wave, i.e. think of this wattage as the amplitude of the sine wave. The frequency has to be much higher than than the number of bits being transmitted per second or at least the resonance modes needed to construct the square pulse from sine waves needs be.

Re:How can they DO that?

[Wesley Felter]

It probably doesn't work. Like everything else, the RF field is full of snake oil created by people who don't quite understand what they're doing. The stuff always demos well, but it never quite makes it into production.

Re:How can they DO that?

[Anonymous Coward]

They mean 1MHz as bandwidth, so if the signal is at 2.4ghz, data is on 2.400 to 2.401ghz (for example)

Re:How can they DO that?

[Trigun]

Maybe they're just using Clown Car bits?

Re:How can they DO that?

[jonesboy_damnit]

From TFA:

"xMax is unconventional," said Stuart Schwartz, professor of electrical engineering at Princeton Universithy, who has scrutinised xG's demonstration set-up, speaking at the xMax demonstration. "It is clever and innovative, but it is not magic. It uses single cycle modulation, and needs much less power than other technologies."
Single-cycle modulation is the invention of xG's chief technology officer Joe Bobier, with backing from Mooers Branton, a merchant bank, whose founder Rick Mooers also serves as xG's chief executive. The modulation scheme alters the frequency of individual cycles of the carrier wave, which has the effect of introducing very low power side-bands to the signal.

My take is that they're using the difference in frequency between the carrier frequency and the generated sideband frequency to represent a value (ie. +10kHz = 0001; +15kHz = 0010; etc.). This seems awfully similar to the SSB modulation commonly used in shortwave radiocommunications to me.

Since they're operating in the license-free 900mHz ISM band, it also *must* implement some sort of frequency-hopping (or direct sequence, I suppose) spread spectrum stuff in order to be legal. Could be kind of an interesting technology. I'd like to play with a couple of the radios and a good spectrum analyzer to see what it looks like.

In the interests of full disclosure, IANARE (but I played one at a job once for awhile).

-Matt

Re:How can they DO that?

[MindStalker]

Its all BS. Basically there is a standard MHz and a standard wattage that you really can't deviate much from. As well seval signals are being sent in neighboring MHz. Anyways the guy sent a 3.7Mbit/s signal using 1/20th of a watt using 900Mhz. To make the assumption that if use 20 times the wattage you could do anything but improve the distance/signal loss is rediculus.

Re:How can they DO that?

[Jozer99]

The "per watt" rating refers to power. The signal improves due to increased power because the signal is clearer, and therefore there is less interference and packet loss. As for the 7.4 bits per sine wave, I'm as stumped as you. Maybe they use harmonics or something.

Re:How can they DO that?

[LordKazan]

an EE here at work says you can fit multiple bits into a sinewave - the more you try to cram into a single cycle the elss flexible it becomes

Re:How can they DO that?

[qbwiz]

Of course, with twice as much power the S/N ratio can be twice as much, giving you more bandwidth. I'm not certain how much more bandwidth, as that depends on the current S/N ratio.

Re:How can they DO that?

[jonesboy_damnit]

Actually, increasing the transmit power *can* buy you greater data rates, as long as your data rate is limited by signal-to-noise ratio.

For example, let us build (in our minds) a transmitter/receiver pair which can encode/decode one symbol every second. OK? Every second we send one symbol (effectively a magic combination of waves which means something to a demodulator) from the transmitter, and every second we decode one symbol at the receiver.

If we have lousy SNR, we might only be able to differentiate between the most distinct two states of the transmitter (one bit per symbol: either 1 or 0), since all the noise impinging on our signal looks an awful lot like the more subtle states (or even worse, completely obstructs all states, making decoding impossible). This gives us a data rate of 1bps.

If we can increase the signal level at the receiver, thus increasing SNR (assuming we're not distorting the living hell out of our transmission, natch) but increasing our transmitter's output, we might be able to encode *two* bits per symbol (00, 01, 10 or 11) by adding two more symbols to the constellation. By doing this, we haven't increased our symbol rate (still only one symbol every second), but we *have* doubled our throughput.

Make sense?

-Matt

Re:How can they DO that?

[fatboy]

Since they're operating in the license-free 900mHz ISM band

Not a good band to be operating in for weak signal type stuff. The 300Watt paging transmitters operating in that band could cause them some trouble without the use of a helical front end on their receiver.

Re:How can they DO that?

[NardofDoom]

I am also not a radio engineer, but I'd imagine that it's calculated this way: Say you've got 1MHz of bandwidth (You 'own' the radio spectrum between 9MHz and 10MHz.) On that one band, you can transmit 7.4Mbps with a transmitter that uses one watt of power. If you double the Wattage, you double the bandwidth. If you get another MHz, you double the bandwidth again.

GSM uses 890-915MHz for phone transmit and 935-960MHz for base transmit, so this system could transmit 185Mbps with one watt, or 18.5Gbps with 100W

But, like I said, IANARE

Re:How can they DO that?

[MaceyHW]

The number is very impressive, but I doubt it's scalable.

Re:How can they DO that?

[tessaiga]

If we have lousy SNR, we might only be able to differentiate between the most distinct two states of the transmitter (one bit per symbol: either 1 or 0), since all the noise impinging on our signal looks an awful lot like the more subtle states (or even worse, completely obstructs all states, making decoding impossible). This gives us a data rate of 1bps. If we can increase the signal level at the receiver, thus increasing SNR (assuming we're not distorting the living hell out of our transmission, natch) but increasing our transmitter's output, we might be able to encode *two* bits per symbol (00, 01, 10 or 11) by adding two more symbols to the constellation. By doing this, we haven't increased our symbol rate (still only one symbol every second), but we *have* doubled our throughput.

You're missing the point. Yes, you can increase data rate by increasing power. However, by quoting a data rate per watt, they're claiming that power increase required is linear in the increase in data rate. It's well known that an exponential increase in power is required to increase your data rate. OP was pointing out that the data rate they reported has to be at a specific power level, and that you'd quickly discover it's not going to be very feasible to increase the data rate significantly beyond that by increasing power (contrary to what that "per watt" statistic suggests).

Re:How can they DO that?

[justnerds]

Frequency Hopping would be the most effecient approach. With FH a radio typically uses a 1MHz channel and stays there for approximately 200ms. Because the channel is so small, the FCC allows for higher TX power. In 2.4Ghz the 50mw limit for Spread Spectrum is compared to 500mw for Frequency Hoppers. The system must also change frequencies without repeating the same frequency again until 80% of the channels have been utilized in a sequence. This mitigates interference very effectively. Add something like OFDM and QAM128 and you have a very powerfull system.

Re:How can they DO that?

[WhiplashII]

An easy way to look at that is Amplitude Modulation (AM). Lets pretend that you have REALLY good signal to noise ratio - basically no noise. Use 44.1 KHz of bandwith, transmit CD quality sound, and you can get 44.1 KHz * 16 bits/Hz out of it.

Of course, in reality you use the time domain as well as the amplitude domain, but that is the idea.

Re:How can they DO that?

[WonderSnatch]

As some one above alluded to, you can use phase modulation, or QAM (quadrature amplitude modulation) to acheive this. You could also use AM. Let's say that you and I (TX and RX) agree that 1V is 0, 2V is 1, 3V is 2, 4V is 4. Each time you send a cycle of the sinusoid, you send one of those amplitudes, and I decode it to a 0,1,2, or 3 (the equivalent of 2 bits). That same can be done with phase modulation or a combination of the two.

Brett

Re:How can they DO that?

[WonderSnatch]

I think you're confusing bandwidth (measured in Hz) with channel capacity (measured in bits/second).

Brett

ps I am a radio engineer

Re:How can they DO that?

[TheSync]

7.4 Mbps per MHz per Watt is a silly way of saying things. The key is signal to noise at the receiver, which depends on signal loss and noise in the received spectrum where you are seeking the signal.

On their site, xG has a plot of bit error rate versus Eb/No (the energy in a bit over the spectral noise power, which is related to carrier-to-noise ratio as Eb/No=C/No - 10log(data rate)). It appears to perform as well as BPSK (binary phase shift keying). Although it doesn't make it clear how many bits per cycle (technically, bits per symbol) xMax is supposed to have.

You can transmit many bits per hertz. You can modulate between multiple amplitudes or multiple phases or a combination of both over a single sine wave phase. But the hit is that the more bits you send per hertz, the higher the bit error rate you get with the same amount of noise.

Re:How can they DO that?

[arjay-tea]

"At one watt, we can cram 7.4 bits into one cycle of a sine wave..."

They're probably talking about bandwidth, not base carrier frequency.

Re:How can they DO that?

[throwaway18]

"At one watt, we can cram 7.4 bits into one cycle of a sine wave.

Not quite. It suggests they can cram 7.4 bits into a 1Hz wide channel.
For example in theory you could descide to represent data using a carrier which
at any instant in time can be at one of 256 different power levels. That gives
you eight bits per symbol. To keep the frequency components of the signal within
a 1HZ channel you have to change the power level slowly which liits the symbol rate. For this to work you need the signal to noise ratio to be high enough that you can tell the difference between the different carrier levels in the time available. If you make the symbols longer you have more time to average out the noise.

Shannon's law gives the maximum amount of data that can be sent through a channel with a paticular bandwidth and s/n ratio.

Re:How can they DO that?

[NeedleSurfer]

Not really, consider that the signal sent is digital but the transport is analog, you could assign values to frequency shifts, phase shift and amplitude levels. Greater power permits greater amplitude, depending on the resolution of the A/D converter at the other end, greater amplitude can lead to more information channels. A 16bits A/D could therefore have a theoretical 65536 channels into which information could be extrated from frequency shifts and phase shifts, hence greater power=more information.

Of course this is purely hypothetical, but it illustrate that greater power can mean more information. I don't know if that is the trick used here I just say it's not as far fetched or impossible as you imply.

Re:How can they DO that?

[Guysmiley777]

It's easy. 7.4Mbit/s per MHz per Watt -> 23.1LOC/hh/kg (Libraries of Congress per hogshead per kilogram) -> 1,225Gbit/HP-ft-lb/AU. Once you get past the fact that you are comparing meaningless numbers, you can pretty much make up whatever you want.

Re:How can they DO that?

[elgatozorbas]

My take is that they're using the difference in frequency between the carrier frequency and the generated sideband frequency to represent a value (ie. +10kHz = 0001; +15kHz = 0010; etc.). This seems awfully similar to the SSB modulation commonly used in shortwave radiocommunications to me.

Actually this seems awfully similar to FSK (frequency shift keying) to me. And I am not sure that I trust it:

The modulation scheme alters the frequency of individual cycles of the carrier wave, which has the effect of introducing very low power side-bands to the signal.

Information is in the side bands (obviously not in the carrier because you can just generate one at the receiver side). Low side bands == not much information being transmitted.

Re:How can they DO that?

[saigon_from_europe]

Use 44.1 KHz of bandwith, transmit CD quality sound, and you can get 44.1 KHz * 16 bits/Hz out of it.

I am an EE, but my major is Power Engineering. But IIRC from my (short) telecomunication theory course, there is some limit of bits per hertz you can get. I really doubt if 44.1kHz bandwitdh could give you 44.1kHz*16bits.

Is there such bitrate/bandwidth limit or I am wrong?

Re:How can they DO that?

[rot26]

Not a good band to be operating in for weak signal type stuff. The 300Watt paging transmitters operating in that band could cause them some trouble without the use of a helical front end on their receiver.

That's the whole point. It's fairly conventional technology, but they've developed MAGIC TECHNOLOGY at the reciever that filters out the BAD signals (i.e. NOISE). Low operating frequency plus incredibly low S/N ratio equals efficiency equals range. They state on their website that they don't violate Shannon's Law (which was awfully considerate of them.) It's the MAGIC WAVEGUIDE TECHNOLOGY required on each reciever that looks pretty unlikely to me.

Re:How can they DO that?

[elgatozorbas]

"At one watt, we can cram 7.4 bits into one cycle of a sine wave. At two watts, we can fit 14.8 bits into one cycle of a sine wave, and so on." How does that work?

The easiest way (to explain) to make it work is to assume that for each period you change the amplitude of the sine wave, e.g. you transmit a sine wave of 1V, 2V, 3V... or 128V. At the receiver you measure the amplitude (number from 1 to 128) and this would allow you to transmit 7 bits. At the same time you can transmit cosine waveforms and play the same trick (another 7 bits). This would be one way to transmit 14 bits/Hz, albeit not what these guys (pretend to) do.

Re:How can they DO that?

[Matimus]

So, 7.4 bits in 1HZ of bandWIDTH, that doesn't mean that its a single sine wave, that means that a signal contained in the spectrum between XHz and X+1Hz can transfer 7.4bits/second. Make sense? Just as a side note, a single sine wave contains no information (chew on that for a while).

Re:How can they DO that?

[Jozer99]

Why 16 bits? Why not 17? That seems kind of arbitrary. Also, how do you FIT all those bits into one sine wave, without making the wave 16 times higher frequency?

Re:How can they DO that?

[WhiplashII]

I'm also an EE, hi there! Basically, that's why I said an infinite signal to noise ratio. Mbits/s does not scale linearly with MHz, but it does scale with signal to noise ratio. Essentially, snr defines the limit you are refering to.

Re:How can they DO that?

[qbwiz]

Yes, sorry, I was. I meant bandwidth in the colloquial sense of channel capacity, rather than in the actual, logical, technical sense of the width of the frequency band.

Re:How can they DO that?

[InvalidError]

Actually, how many bits you can cram in 1Hz of bandwidth depends on the SNR.

From Shannon: bps = BW * log2(1 + S / N)

So, with a 30dB SNR you get BW * log2(1+1000) = you could almost encode 10bits of data per Hz of bandwidth... a little under 10Mbps per 1MHz.

Since this modulation has smaller sidebands, more energy gets packed in a narrower band, enhancing the signal's strength while reducing the amount of noise picked up. It makes sense and I imagined something like this years ago. It looks basically like a single-cycle version of FSK or PSK but I think these should not look quite as clean as they did on their plots. (Well, they did stop at 100kHz resolution.)

As far as the signal generation goes, I am guessing they used an FPGA to drive an ADC and DAC for their prototypes and their 50mW is only the DAC's power output, not the entire receiver/transmitter power. They insist a lot on the signal's power but they say nothing about the system used to generate, transmit, receive and decode the signal.

Re:How can they DO that?

[Prof. Pi]

My take is that they're using the difference in frequency between the carrier frequency and the generated sideband frequency to represent a value (ie. +10kHz = 0001; +15kHz = 0010; etc.).

It's been a long time since I took Signals and Systems, but isn't there a principle whereby if you sample a signal over less time, there is more uncertainty as to what its frequency is? (It's analogous to the Heisenberg Uncertainty Principle, where the product of two uncertainties is a physical constant.) This puts a lower bound on how close the frequencies can be vs. how many cycles (or how much of one cycle) you use for one baud, even before taking noise into account.

Re:How can they DO that?

[StarsAreAlsoFire]

Which is where the 'power' comes in.

Contrary to the massive attack against the 'per watt' arguement, the wattage requirement *is* an important aspect of any wireless communication setup. Try doing uplink/downlink calculations for satellite communication -- power is *very* important.

And we are now starting to look at the whole MAN (bah, stupid name. Metropolition area network), where total coverage areas are within an order of magnitude of satellite communications distances.

Now, I'm not saying that this 'new tech' isn't BS. From the looks of it they don't provide enough data for us to be able to tell one way or another. Which is, of course, a good sign of BS.

Re:How can they DO that?

[lotus_out_law]

But, Why isn't anybody talking about Nyquist criterion here?
Should that be applicable here ?

Re:How can they DO that?

[Anonymous Coward]

As far as I can tell, what they are doing is individually changing the period of each cycle of the sine wave.
Thus, the signal transmitted will have frequency components significantly on either side of the nominal frequency,
and probably there is some issue in the way they calculate the amount of spectrum they are using, that explains
these anomalies. Per MHz here means per megahertz of spectrum used (a range, not a point in the spectrum); and presumably they are using more than they claim to be using.
But they may not be using *that* much more - they may still have impressive data rates.

Dan

Re:How can they DO that?

[fireweaver]

What they are probably doing is using the transmitted carrier as a clock for a synchronous detector. The actual information is spread out over a very wide band with very little energy at any particular frequency. If the data rate is somehow related to the carrier frequency in a way that is controlled by the carrier frequency, then you can suck a signal out of a lot of noise.

Of course, I wouldn't be surprised if the military or some TLA hasn't already had this for a while.

Re:How can they DO that?

[jamesh]

Alternatively, they could be using slashdot to come up with an idea of how their technology works, and then implement that :)

Re:How can they DO that?

[Fordiman]

*ahem*

With larger wattages you have better signal strength, meaning the modulations can be done at finer granularity. As such, more bits can be packed into a given interval of the signal.

Example: audio is a simple amplitude modulation air-compression signal. At 256 levels of granularity, you're using 8-bits per sample. At 64k levels of granulatiry, you're using 16-bits per sample.

That's where the log2 in Shannon's equation comes from. The higher the signal to noise, the more data you can pack in.

But that's not what this is about. This particular scheme works in a way to filter out noise that simply doesn't fit a given signature. It does this by a special antenna, and probably some sort of FFT analysis on the firmware end. My guess is that it produces/picks up only signals that produce a 1/2 Nyquist + 3i/4 Nyquist low voltage peak. Since simple sine waves don't produce this, and nor does noise (noise produces a relatively consistant FFT sig, focused mostly on the low end), one could pack a lot of data into those low-end side channels, by merely calibrating the FFT to nyquist on the carrier.

Ok, ok, I know that SOUNDS simple, but it's not as. It does take some clever detection routines to grab it. Personally I think this guy's a genius. It's easy to say "Hey! I coulda thought of that," after the fact. It's hard to actually think of it before hearing about it on Slashdot.

Re:How can they DO that?

[waynemcdougall]

For example, let us build (in our minds) a transmitter/receiver pair

Nice try Mr Jonesy boy! You can persuade me to build a transmitter receiver pair in my mind right after you pry the roll of tinfoil off my cold dead, head....ummm....no, wait...that's not actually an invitation....

Re:How can they DO that?

[Anonymous Coward]

For goodness sake, it's an average. It just shows that this is faster and less power-hungry than other technologies.

Re:How can they DO that?

[tfoale]

It is very clever and takes the capabilities of radio to their theoretical limit, where every cycle can be a bit. It makes very efficient use of the radio spectrum, which is why there is so much interest. Normal radio works by modulating a carrier (the RF or radiofrequency) with a lower frequency (the IF or intermediate frequency) that is in turn modulated in a variety of possible ways by the data. This generates a shmear of radiation around the carrier frequency (called sideband) which is why spectrum is allocated in bands. At the receiver the received signal is demodulated with the carrier frequency to recover the IF with the data in it. The maximum datarate is related to the IF, not the carrier frequency. All recent developments have been aimed at cramming as much data into as small a part of the spectrum as possible and recovering it reliably, using this mix of RF and IF. The current state-of-the-art is probably represented by the Wimax and US 3G technologies. XG's technology requires as a minimum just two closely-spaced radio frequencies to transmit a bitstream, which can be at the same datarate as the radio frequency. It sends information by switching between the two frequencies at cycle boundaries (imagine a sine wave with some cycles stretched) and has no need of an IF stage. The economics are interesting - because it requires electronics that operates at the RF rate, I suspect (though I'm no radio engineer) that this is more expensive than the electronics of the IF stage. However, it is hundreds of times more efficient than current radio technologies. It also requires much less power. Will it kill Wimax? No more than it will kill any other form of radio communication. It takes spectrum cost out because you can cram a lot more data into the same bandwidth. I don't think the companies that have paid billions for portions of the radio spectrum will be too pleased - they will have to write down their spectrum asset. However, that is sunk cost paid for by shareholders, who are used to telecoms losses by now. It has to be converted to silicon, and the economics of silicon are volume-related. I see it being used in remote sensors and RFID rather than targeting relatively low volume applications like Wimax, although if the technology is as simple as they make out I can see it appearing everywhere eventually. It is certainly disruptive, but few Wimax service providers own any spectrum yet, so changing to a new technology just means dumping the old one. The low total cost of XG's system means that there's unlikely to be a market for second-hand equipment based on current radio technologies when it does hit - so long as it is capable of performing the same role.

It's you!

[tnk1]

Launch all ZiG 1000 times for efficent Justice!

Professor Schwartz?

[Morgalyn]

Here I was thinking, for a moment, that they were talking about UF's professor in the ECE department, but nope, the guy is from Princeton.

Re:Professor Schwartz?

[Anonymous Coward]

I did a double take when I saw Professor Schwartz and Florida. I had good old schwartz for MicroP and Digital Design

Re:Professor Schwartz?

[Morgalyn]

I'm glad I'm not the only one that made that connection, I was feeling a little foolish for providing all of /. with my gut reaction.

I had Gugel for MicroP and DL, and Lam for DD, but Schwartz was always involved in those classes. He had great office hours!

Re:Professor Schwartz?

[dokebi]

May the Schwartz be be with your wireless transmission!

Re:Professor Schwartz?

[rco3]

Yeah, but (no offense to Schwartz, I like the guy) but can you really see Schwartz designing a new communications modulation system? Ken O, maybe, or some of the people in John Harris's research group.

Re:Professor Schwartz?

[Morgalyn]

No! And that was one of the reasons I was surprised/curious. I doubt he'll make it out of academia, really. Now I could see Dr. Gugel doing something like this...

Re:Frothy piss

[XFilesFMDS1013]

At least the trolls are getting a little more complex...

"presumably using some kind of subtraction"

[Jim Morash]

Three orders of magnitude better than GSM or EVDO? There is no way this is true. What a load of bul^H^H^H marketing!

Re:"presumably using some kind of subtraction"

[jabberwock]

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong." -- Arthur Clarke ;-) Not saying you're elderly (leaving "distinguished" aside for the nonce) ... but suggest that there is not enough information for immediate acceptance or dismissal of the claim. That they have gotten this far -- I'll pay attention for a while, anyway.

Re:"presumably using some kind of subtraction"

[Jim Morash]

I am neither distinguished nor elderly, but ultimately aspire to both!

I agree with some of the other posters - the only way this is at all believable is if they're actually doing UWB and calling it ISM band.

Re:Frothy piss

[Anonymous Coward]

look at the parent's history of posts. wtf

Abort, Retry, Fail?

[Brunellus]

wait, WiMAX was alive in the first place? Either I'm actually living under a rock, or I haven't seen any significant real deployments of the technology outside of pilot programs. So from where I sit, WiMAX can't be killed, because it's not alive.

Re:Abort, Retry, Fail?

[IDontAgreeWithYou]

This could kill WiMax before it even gets off the ground.

FAIL

Re:Abort, Retry, Fail?

[rbanffy]

Don't think murder. Think abortion.

Re:Abort, Retry, Fail?

[Anonymous Coward]

It is still in early development

It can't kill anything yet.

And the parent is right...there's really nothing to kill. I don't think it will stop WiMax. When 14.4 modems came out, they knew there was something else faster in the pipe. If we didn't deploy technology because it might be made obsolete, nothing would ever get deployed.

Re:Abort, Retry, Fail?

[steveo777]

Same thing.

Good-bye Karma, I hardly knew ye!
Well... at least I have the balls to not post AC.

Re:Abort, Retry, Fail?

[Bun]

So from where I sit, WiMAX can't be killed, because it's not alive.

But it exits, so "un-dead" might be an apt description. Zombie-MAX (Z-MAX?), anyone? *ducks*

They need to sign a big contract.

[CyricZ]

They need to sign a contract with a large transportation provider in Europe and Japan, so as to provide this service on all buses, trains and other public transport vehicles. That would give people the incentive needed to purchase the hardware necessary to take advantage of this new system.

In other news...

[Mille Mots]

Infinium Systems announced the addition of wireless gaming to the panoply of features included in their phantom Phantom Gaming Console.

--
Who knows what evil lurks in the hearts of men?
The ShadowPhantom knows!

Re:In other news...

[cbreaker]

The funny thing about the Phantom is that it's basically an XP PC, and they can't get it out the door. How much R&D needs to be done to get a fairly standard PC shipped? They might claim it's the backend that needs most work, but it's just a network server that sends you files. They've been doing that since the inception of digital communications.

I don't know, I think the Phantom would be a cool toy to have. But after years and years it's just stupid now.

Let's not even mention Duke Nukem - that company must be two dudes in their basement laughing. How else could theykeep their doors open for 6 years and produce no product.

The real issue: interference

[rsborg]

From TFA:

not unlike a cordless phone base station, operating in the unlicensed - and crowded - 900MHz band, to send a 3.7Mbit/s data signal to a radius of 18 miles across the suburbs of Miami

and this:

Before any of this happens, more demonstrations are needed, to show the system is robust against interference and multipath, and can operate in an area more crowded than 18 miles of swamp. It will also need to be approved by the FCC and other regulators round the world.

Those are BIG if's. Most likely, if it can withstand a moderate amount of interference, this will mainly be used to support other technologies.

Yeah, an immersive internet would be awesome... but this thing still has some issues to be resolved.

Re:The real issue: interference

[JPriest]

RF engineering is nothing new. If they use a low power/high propigation (low) frequency, they run into interferance unless they are using very directional equipment. If they are using a high frequency (high power/low propigation), then they will need higher xmit power. These variables will not change.

What does change are advancements in modulation, DSP's, antennas, equipment cost etc.

More details here

[Anonymous Coward]

Lots more details in this article, and photo's here. Looks very interesting.

Re:More details here

[Anonymous Coward]

I don't see any more details, except "Does it work? Nobody can say for sure -- not even XG." Sounds like an investment scam to me.

It is still in early development

[pubjames]

It is still in early development...

I have a technology that's ten times better than this one, although it is in very early stages of development...

No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

Re:It is still in early development

[Anonymous Coward]

If you'd bothered to R the next F line -- they do have a working demo.

Re:It is still in early development

[bluelip]

>>No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

"At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS....."

Was the demo mention in the summary fictional?

Re:It is still in early development

[bhsx]

If you had RTFA, and g-d forbid, a couple of the links, you'd know that they gave a working demo. They will also be giving another "broader" demo next week. This is also backed by a Stanford prof who is taking a big risk here.

Re:It is still in early development

[pubjames]

No they don't. I was talking about a product demo, i.e. a working model of the final product. All their demonstration showed was that it is theoretically possible to create such a product.

Re:It is still in early development

[pscottdv]

"No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo."

You don't know much about raising venture capital, do you?

Re:It is still in early development

[Cid Highwind]

Was the demo mention in the summary fictional?

Pretty much, yes. In their demo, the alleged transmitter was up on an 850' tower. Reporters had to take it on faith that the signals reported by the recievers were really coming from that transmitter and that there wasn't a bank of car batteries and a 100W linear amp up there.

Until someone from outside the company can hook meters up to the transmitter and verify that it is really the source of the signal and that it's really using as little power as they claim, the demo is worthless.

Re:It is still in early development

[Capt James McCarthy]

Oh yeah, do you have the patent? I think that is the aim of most of these "next great inventions" anyway. That way when someone does pick up the technology and run with it, the base company waits until it has a large user base, then threatens legal action.

Re:It is still in early development

[Glog]

They have an effing demo. Did you RTFA?

Re:It is still in early development

[stienman]

No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

Unless they are looking for more funding because, apparantly, they don't yet have a genuine working prototype and have run out of money.

-Adam

Re:It is still in early development

[Anonymous Coward]

>> All their demonstration showed was that it is theoretically possible to create such a product.

You may be surprised to hear this, but that is often an important step in convincing people to fund the production of your product.

Re:It is still in early development

[Doctor Memory]

a bank of car batteries and a 100W linear amp

"Those are just for....backup. Yeah, that's the ticket -- backup."

Re:It is still in early development

[loose_cannon_gamer]

No technology company should make extravagant claims about the capabilities of their product until they have a genuine, working demo.

I think you're right, *if* said company wants to fork over all the cash for research, developing, and marketing. However, in our real world, almost nobody pays for anything up front that costs more than a few hundred dollars, and we're probably talking about several million to fully develop and market a seemingly cool technology.

All this really means is that they're trying to attract funding, be it from banks, venture capitalists, private and public investors, etc., as they probably don't have the resources to see it all through, or at least, not budgeted for that. I always view research announcements like this as a subtle request for a loan, or a precursor to such a request.

When the same thing happens for a finished product, they're usually just after free marketing and press time (and they usually get it).

That being said, I think research and paper launches are of some business value. If I'm a venture capitalist firm looking for the Next Big Thing, these kind of announcements can attract me to focus my research time better. These kinds of things can help connect investment opportunities with investors, especially higher risk / higher reward type investments like this one.

Two things

[aztektum]

There are two primary stumbling blocks before it will take over WiMax:

1) It actually does what the article says

2) It isn't bound up the ass by patents and doesn't require hefty fees to implement.

relay network

[TheSHAD0W]

There had been some discussion here in the past about using cell phones as network relays as well as end-points to increase range and reach, but one of the conclusions was that having cell phones constantly retransmitting data would run down the batteries too quickly. This technology might change the equation, making it possible to have an ad-hoc networking system shuttling data between portable devices rather than needing a lot of infrastructure.

Re:relay network

[fbjon]

ad-hoc networking system shuttling data between portable devices rather than needing a lot of infrastructure.

Won't somebody please think of the propagation time!

Re:relay network

[TheSHAD0W]

Depends on how well the network routes things. You can go a long distance in 3-4 hops. You could also design the protocol to act like a switch, with packets being relayed even as they're coming in.

Re:Frothy piss

[Anonymous Coward]

Haha. His subject lines are quite like spam - filthily worded but you still click.

Great ideas don't always make for great businesses

[GrAfFiT]

This tech may be better but given all the installed pre-wimax stuff and strong industry support I doubt that anybody will just scrap WiMax and restart all over... Betamax/VHS anyone ?

Nope, WiMax will come first

[EriktheGreen]

The poster of this article assumes that the technically superior solution will rise to the top. In fact, the administratively superior solution will... this means that if companies spend millions of dollars preparing a standard and products for market, they won't switch to something else automatically even if it's obviously better.

The reality of the situation is that if the new solution is exactly what it's sold to be (unlikely) then it probably will eventually break into the market, but even if it's made into a useable product immediately its use will be overshadowed by the well advertised and enthusiastically sold solution that the vendors are pushing instead. Vendors really don't care what's superior unless they're picking technologies from a menu and they have no interest in any of them (positive or negative). Vendors care about money, and if they've already spent some on one technology, they won't switch unless it's obvious that another technology will immediately dominate the market (VERY, VERY rarely does this happen).

Take off the rose colored glasses, people. Technically superior solutions MAY eventually win out over poorer ones if all else is equal, but all else NEVER is equal.

Plus, it's unlikely that this "breakthrough" is anything but some ambitious people trying to sell something inferior as if it's the solution to All Our Problems (tm).

Erik

Re:Nope, WiMax will come first

[ClickOnThis]

You're right, there are many factors that can determine whether a superior technology is adopted or not. (Consider Betamax vs VHS, cdma2000 vs WCDMA, etc.) But I think it also depends on the magnitude of the superiority of the new technology. A factor of 1000 improvement in bandwidth per watt (if it's true) is impossible to ignore, given the kinds of low-power, long-range devices it might support. I can imagine a great deal of commercial interest in dethroning WiMAX if the numbers add up for a substantially superior technology.

Re:Nope, WiMax will come first

[Anonymous Coward]

What is this "Betamax vs VHS" of which you speak?

Re:Nope, WiMax will come first

[GWBasic]

Usually when a technology makes it to market, there's better technologies in R&D. It appears that lessons from this technology could be used for WiMax v2 or v3.

Re:Nope, WiMax will come first

[EriktheGreen]

Yeah, I guess I meant to encompass that with the statement about "Immediately dominate the market". If a technology is orders of magnitude better, it usually will immediately dominate. Erik

Re:Nope, WiMax will come first

[Flunitrazepam]

How about the already deployed technology?

WiMAX doesn't even have a defined standard. The IEEE 802.16e specification is not a standard and probably won't be for a while.

Re:Nope, WiMax will come first

[chimpanzee00]

"People don't buy Good Products, they buy GOOD MARKETING" -- business saying

Could kill?

[vagabond_gr]

But the more interesting question is, could some technology X, that nobody has even though of yet, kill xG's technology before killing WiMax? And could another technology Y kill X before even being though of?

oh, come on, what's all this "could kill" mania lately?

Re:Could kill?

[Fhqwhgadss]

It's Zonk's shift today.

The overuse of the work "kill" is Zonk's attempt to overthrow his mentor Cmdr"killer"Taco. While Taco has made a fortune with his "foo-killer" rhetoric, Zonk is closing the gap with simple and elegant "kill" references.

You see:

Linux can't kill Windows but Microsoft can kill Linux or can it? Either way, Cheap, solid state computers could kill Microsoft and we'll all just Kill our PCs

I hear he's even closing the gap on dupes, despite Taco's valiant efforts to hold on to the title.

Florida-based start-up?

[Hoi Polloi]

This would probably one of the few Florida-based start-ups that didn't involve spam or real estate fraud. Maybe it is a breakthough in spam transmission!

Re:Florida-based start-up?

[Ctrl Alt De1337]

Hey, I'm a Floridian you insensitive clod! You forgot trailer park developments in coastal hurricane zones, sketchy interstate-side strip clubs that take out every billboard for miles in either direction, and the Tampa Bay Devil Rays!

Re:Florida-based start-up?

[mspohr]

Well, they are starting in a swamp...

Snake Oil!

[Anonymous Coward]

I've looked at this before. There's a lot of technbabble and nothing concrete. Some claims, such as "7.4 Mbit/s per MHz per Watt," are meaningless (distance is not part of the claim). The demonstration is not verifiable, "on trust, since it was at the top of an 850ft mast".

The only concrete claim, "3.7Mbit/s data signal to a radius of 18 miles across the suburbs of Miami, using 50mW and an omnidirectional antenna," is absurd...unless there is a REALLY BIG antenna at the other end.

Investors: avoid this like the plague!

Re:Snake Oil!

[yaff]

I don't think they're doing it with antenna size. Its height. You can talk to just about anyone from an 850 ft mast! That's line-of-sight to anywhere in the swamps below. Let's try this downtown, shall we? Multipath is the fun part of radio engineering (if you're a massocist.) And multipath is one of the major things that WiMAX has to deal with.

This all smells like the Ultra Wideband craze that went on about 5 years ago. And now UWB is relagated to a BlueTooth replacement because they violate FCC rules if you turn up the transmitters. I bet this bit of Snake Oil is a ploy to skirt the FCC rules, yet again.

IAARE.

This reminds me of Pixelon ...

[JoeGee]

And we all know what happened to them.

Snifffff

[DigiShaman]

That's the smell of BS.

Anyone else check their shoes? I think slashdot stepped in it again with this article.

If I'm wrong, then I will shut my piehole. ;)

SO....

[hurfy]

Either cut down the mast or file this under: Too good to be true......

Clearwater, Florida startup?

[Anonymous Coward]

That wouldn't be Clearwater, Florida, would it?

Can you spell mesh?

[Anonymous Coward]

Depending on the size of the r/t's themselves, this could be embedded in watches, using a wire in the wristband for the antenna and piggybacking off the watch battery for power.
Or as a not-so-radical theory, substitute cellular phone for watch in the above example.

How am I supposed to know without details???

[gd23ka]

Usually different modulation schemes are used tailored to the needs of he environment.
For example... your cable modem will most likely use QAM (Quadrature Amplitude
Modulation) because it doesn't have to expect a lot of interference on the
media. Your digital satellite feed and 802.16 Wimax use QPSK (Quadrature Phase Shift Keying)
because noise does not nearly affect carrier phase as much as the amplitude. None of
the modulation schemes today transmit information on the basis of a single cycle. A QPSK
transmitter will transmit thousands of cycles on one phase and then shift (if need be)
for the next symbol and send out thousands of cycles with that phase. Most textbooks
show just a handful of cycles in example graphs, which gives people the wrong impression.
In all cases this is done simply to reduce the error rate. As far as I can see a hell of a lot of math and thus computing power has to go into their receiver to get a decent rate unless you are just a few feet away from the transmitter.

Will this kill IEEE 802.16 ("WiMAX")...? No... not really. If really viable (and not the
usual crap hype) it will probably in a couple of years end up as an additional PHY.

More likely however, even though there is still a lot we could squeeze out of 1MHz of spectrum: it is hype but hey... surprise me...

Re:How am I supposed to know without details???

[markov_chain]

More likely however, even though there is still a lot we could squeeze out of 1MHz of spectrum: it is hype but hey... surprise me...

Is this true? I thought modern modulation/coding/etc. schemes were already close to the Shannon limit. Barring some serious MIMO trickery I doubt this company can do what they claim they do.

Re:How am I supposed to know without details???

[gd23ka]

A modulation scheme is not governed by shannon. A real life implementation of such a scheme is. You can for example try to shift the phase of your carrier with a symbol clock of say 1000ns or you can double the symbol rate by shifting phase every 500ns. Real world systems use conservative symbol rates which correlate to the quality and sophistication of the transmission and reception equipment and also to the environment (cable modem with shielded wire vs. satellite that has to punch through atmosphere).

Re:How am I supposed to know without details???

[markov_chain]

You can for example try to shift the phase of your carrier with a symbol clock of say 1000ns or you can double the symbol rate by shifting phase every 500ns.

OK, but doing that would increase the bandwidth. I don't think you'll be able to increase the spectral *efficiency* much, and especially not by orders of magnitude like these guys claim they can.

Re:How am I supposed to know without details???

[gd23ka]

I'll just have to admit that I have no idea how to squeeze a 7 some bits/cycle out of anything. Ask them, they're obviously a lot smarter than you and me :-)

the same way they...

[chomprock]

transmit 2.5 gb/s over the powerlines through microwaves guided by their magnetic fields while reading and writing them with quantum wells. then again, it could be the same way they run OS/X on a PC at 80% of the native speed. or how the nanotech sticker transmits an electric field that increases battery life by remotely altering the ion-exchange membrane in other words, another way-too-good-to-be-true tech claim. note how the base station and antenna were lofted onto an 850 foot mast. the hallmark of a bullshit invention is that nobody ever sees the device live and in person. i'll believe this when it gets multiple independent reviews

Re:the same way they...

[Anonymous Coward]

I'm inclined to agree with the parent, since the claims are not backed up by any calculation or information about how the values given in the article were reached. Essentially, I'm saying it's bullshit because I have no way of verifiying the accuracy of the article's numbers. Is there a whitepaper somewhere that I could look at, or some experimental procedure they followed that produced those numbers? If there isnt, then the article is meaningless.

One step closer to Borgdom

[Resident Netizen]

Cool! So we get these little transmitter-thingies that are super-efficient and then implant them and run them off of our own bio-electrical energy... then we just all plug in to each other!

I want a pony!

Re:One step closer to Borgdom

[indifferent children]

Resistance is futile. You will be assimilated.

Re:One step closer to Borgdom

[JFMulder]

then we just all plug in to each other!

I want a pony!

I don't like how you used those two comments of after the other...

The real truth is

[zappepcs]

That xMax technology is patented etc. It uses a low power signal to orchestrate the use of very low power signals in what is 'normally' the noise bands adjacent to the desired signal. That is to say, it uses multiple frequencies, but at such low power it only looks like noise. It is both clever and capable. The real trouble is that it

1 - is owned by a single vendor,
2 - has yet to be approved by the FCC,
3 - still needs to pass more testing stages before anyone will dare use it.

Even though it is a sound technology, it does something that other tech has not been allowed to do: use adjacent spectrum that is not licensed to the operator. There are significant hurdles to this technology being used.

Re:The real truth is

[Anonymous Coward]

Want to live a longer, healthier life? Check this out http://www.asomaworld.net/zinn

*cough* snake oil *cough*.

Sheesh, what is SomaLife gHP "Youth Formula" - regurgitated HerbaLife?

Re:The real truth is

[zappepcs]

No, its not old HerbaLife, and not snake oil either...

Re:The real truth is

[elgatozorbas]

The real thruth is that 'signals looking like noise' is an old idea, called spread spectrum, invented (among others) by actress Hedy Lamarr during the second world war.

Another real truth is that worldwide THOUSANDS of researchers are investigating digital communications and what these guys have come up with IS NOT NEW. Modulation has reached perfection with OFDM. The only things you can do (imho) to improve bit rates is use improved coding techniques or use multiple antennas (search for 'mimo transmission'). I am not saying that the stuff these people have made will never work, only that it certainly is NOT new or revolutionary. Especially the side band claim is ridiculous. As posted already: low side bands = low information rate.

Re:The real truth is

[ClickOnThis]

The real thruth is that 'signals looking like noise' is an old idea, called spread spectrum, invented (among others) by actress Hedy Lamarr during the second world war.

The "others", IIRC, is actually one other, namely composer George Antheil.

Re:The real truth is

[blincoln]

No, its not old HerbaLife, and not snake oil either...

On the other hand, it IS composed entirely of things you can get at your local health food store for significantly less money.

For the prices they're charging, you could be importing actual pharmaceuticals like Vasopressin and Piracetam from Europe. Assuming you're in North America, of course.

Offtopic, no karma bonus.

forgive me for possibly being redundant, but ....

[Randy Rathbun]

WTF does a watt have to do with bandwidth? This has got to be one of the stupidest things Slashdot has posted in a while.

How conveeeeeenient

[DSP_Geek]

The transmitter just happened to be atop an 850 foot mast so the reporter had to take the power and antenna descriptions on trust? Come on. They could've put KABC up there and no-one would be the wiser. I won't believe a word of it until they actually show actual hardware transmitting actual bits. Until then it's a press release.

Updates on WiMAX

[cciRRus]

While we get awed by this new wireless technology, let us also update ourselves on the developments of WiMAX here.

So is this what the singularity is?

[Anonymous Coward]

We have standards and ideas that are obsoleted before they even get implemented.
I have to wonder what will obsolete xMax before it even gets to market.

xG

[Professional Heckler]

So I should invest...?

Re:xG

[Anonymous Coward]

Yes, invest now, but, the day before the press conference, sell it all. Their performance claim is impossible.

Re:forgive me for possibly being redundant, but ..

[jumpingfred]

Transmission power has every thing to do with data bandwidth. You really need to read up about wireless communication before posting things like that.

Where does 7.4 come from?

[Anonymous Coward]

Assuming there's a shred of scientific validity to this claim, how does one convert to Mb/s per MHz per W? From the article, they are transmitting 3.7Mbit/s at 900MHz using 50mW. My attempt at normalizing it yields (3.7/900*20)Mbit/s per MHz per W, which is only about 0.082. What scaling factors does Professor Schwartz use to get 7.4 Mb/s/MHz/W?

Re:Where does 7.4 come from?

[dubiousx99]

The per MHz refers to the bandwith of the signal. 900 MHz is not the bandwith but the center frequency. Whats got me all sorts of confused is looking at their Spec Anny plots. The damn thing looks like a CW spike and not a modulated carrier. Plus the second plot located here http://www.xgtechnology.com/plots.asp makes it look like it has a carrier plus noise over noise of like 60dB. WTF?? Untill they actually release something more specific about their modulation technique I claim smoke and mirrors.

OverHyping will kill it

[Anonymous Coward]

TechnoGeek: Well there's this new technology that will destroy the telecom/cell phone industry.

Potential customer: Well were can I buy this wonder technology?

TechnoGeek: Er, well. It's not available yet.

Potential customer: Not available? Then what good is it to me then?

Plus I haven't even touched the other two issues. How well does this do with one or more moving target?

The other is best illistrated by a map. Preferably of a country with wide-open spaces between it's centers of populations.

Re:OverHyping will kill it

[fracai]

Overcoming the moving target problem solves the remote population problem.
Packets are stored on a bus, car, truck, plane, whatever that's leaving the remote area and offloaded as soon as the next connected population is encountered (duplicates on other cars, etc are discarded as soon as recognized). Responses are likewise loaded on the next available transports and offloaded at the destination as they arrive.

Finally, a world useable example of that "tape loaded station wagon" situation.

Of course, if these could be powered by watch batteries then they'd surely be powerable by a solar cell.

Its not math, its advertising.

[RingDev]

What they are actually saying is that it takes xwatts to transmit 7.4mbit/s over 900mhz. If you divide x by 900, then divide the transfer rate by that, and play with the numbers a bit you wind up with the "value" of 1 watt. Its usefully for compairing efficiencies, but it doesn't imply that you can simply increase the wattage to gain frequency or transfer speed. Its a formula that describes a senerio, not defines it.

-Ruck

Re:Its not math, its advertising.

[Fordiman]

That may be true, but the math is correct to the Shannon equation. Mr. Professor Man just stated it poorly.

900MHz band, to send a 3.7Mbit/s @ 50mW
BW=Freq*log2(S/N+1)

We can assume N to be a nonzero constant, to avoid having to split those annoying infinitives. Now, let us solve for N.

N=S/(2^(BW/Freq)+1)

N=0.05W/(2^(3700000baud/900000000Hz)+1)
N~=0.025W

Now note that that means this particular scheme, in this particular environment, was able to deal with a 2.0 S/N ratio (or 3.0db). Recalculating to 1MHz at 1W to get BW

BW=Freq*log2(S/N+1)
BW=1000000Hz*log2(1/0.025+1)
BW~=5,350,000baud

Hm. I get about 5.1Mbaud at 1 Watt with the same noise characteristic. Apparently this guy can't do math. Still impressive, assuming that this system is able to intrinsically filter out most noise and just deals with less than, say 0.05-0.10W (1Mbit signal) of interference in a RF-crowded environment. If not, than this is a stupid pipe dream.

Impressive, because once applied to a spread spectrum, every 5kHz or so, you get another 1Mbaud of bandwidth to be shared by the geographically local group...

Capitolism

[GuitarNeophyte]

This is the joys of capitolism. For those of us who haven't yet invested in WiMax, this is just good news. Go ahead, kill WiMax. Give me something better. It's just fine with me.

Re:Capitolism

[Rei]

Wouldn't capitolism be communism? :)

Re:Frothy piss

[P3NIS_CLEAVER]

I think somebody should create a "bird penis", or "revenge of the penis" asci image. Trolls need to diversify.

Reading assignment for today

[Rorschach1]

Your assignment for today is to read up on the Shannon-Hartley theorem. Then ponder the sort of signal-to-noise ratio required to do what they're saying. I'm just not seeing it happen. And the explanation of changing the frequency of individual cycles - that doesn't make any sense to me. That's just FM, not a novel modulation technique.

Also, consider the black-box demo - so typical of snake oil these days. If it was an actual, novel system, you'd probably have a custom board with a pile of FPGAs and such in there. No amount of staring at it would tell you anything significant about how it works. On the other hand, if it's a commercial WiFi board with 'Netgear' plastered all over it, it's going to be pretty obvious. So what are they hiding?

Re:Reading assignment for today

[Lexic0n]

I am not an engineer, but does this sufficiently address the potential problem the parent post brings up? (from http://www.xgtechnology.com/faqs.asp#q7)

Q: What is Shannon's Law?

A: Shannon's Law is the relationship between channel capacity C (bits/sec) or maximum data rate, bandwidth B (Hz) and Signal to Noise power ratio S/N, as summarized in the Shannon-Hartley Theorem: C = B log 2 (1+S/N). The narrowband channel allocation that xMax uses to coordinate reception of its wideband xG Flash Signal is not the system's information-bearing bandwidth. xMax does not violate Shannon's Law.

Re:Reading assignment for today

[YU Nicks NE Way]

Things which talk about not violating Shannon's law make me think of other things which talk about not violating the Second Law of Thermodynamics.

"In the house, we obey not only the Second Law of Thermodynamics, but Shannon-Hartley as well!"

Re:Reading assignment for today

[photon317]

From the technical details available, it seems they are actually transmitting on multiple channels at a time. They're making a parallel bus out of the airwaves, so to speak. There's a control frequency that informs the other side what to look for on which of the sidebands. It's not revolutionary, it's just a rehash of other radio ideas that have been around for a while, but rehashed in a new and potentially useful way.

So basically, we've got a relatively low-power low-bitrate transmitter, transmitting "words" split up into bits on several of these relatively low-bitrate channels at once to achieve a remarkable-sounding aggregate bitrate for the amount of power being used (or if you prefer, for the acceptable s/n ratio)

This brings to mind something I see in wired communications all the time. Seems all communication technologies (but especially the various cables and busses in computers) go through this cyclic parallel/serial dance. It goes like this:

1) We push the data rate on our serial line as high as we can go, until it's just not practical for us to make it any faster, because we're outpacing fundamental tech. So we invent a parallel technology with N (8, 16, 32, 64, ...) channels operating at the old speed /N/2, giving us twice the bandwidth we had before.
2) We push the data rate on our parallel line as high as we can go, until it's just not practical for us to make it any faster, because we're outpacing the fundamental tech. So we invent a serial technology with 1 channel running at a blazingly-fast data rate compared to that serial technology.
3) Goto 1

In reality, our fundamental ability to push data (either parallel or serial) slowly gets better over time regardless of these switches. But for some reason (maybe not rational), we jump back and forth as we progress. I guess it's a kind of meme-boredom or something. Or maybe just the companies that set the standards do this to force cyclic upgrades.

But while we'll fight all day long switching back and forth between parallel and serial copper cabling for data tranmissions (and the inherent problem, the reason parallel isn't just flat out superior, is because of inductance/capacitance issues specific to putting several copper conductors in parallel)... nobody seems to be interested in parallel fiber. Fiber doesn't have any issues going parallel (other than cost). Why hasn't Cisco gone and strapped 32 fiber strands together into a special connector for proprietary 32Gig-Ethernet that sends 4 bytes at a time in parallel? It might be expensive, but you know someone would buy it versus trying to trunk 32 individual Gig-E ports.

Wow, I've wandered way off topic :)

Re:Reading assignment for today

[acaspis]

So what are they hiding?

Nothing: The journalist reveals that the transmission is highly directional. You could beat that with laser-based communications.

AC

Re:Reading assignment for today

[Rorschach1]

See OFDM. Frequency multiplexing alone is NOT enough to account for a 1000-fold increase over current modulation schemes, many of which use OFDM schemes already.

Finally at last, I can go home now!!

[gd23ka]

From the marketing blurb: "by combining advanced technologies"... aha! I knew it! I can return to the future now, Looks like I found my ship!!

Relevant Patent applications

[TheSync]

20050008087 Tri-state integer cycle modulation

The invention disclosed in this application uses a method of modulation named Tri-State Integer Cycle Modulation (TICM) wherein a carrier signal, comprised of a continuum of sine waves is modulated such that spectrum utilization is minimal. A modulation event is imposed upon the carrier signal by modifying the carrier frequency at precisely the zero crossing point or the zero degree angle. The method of imposing the modulation event is by increasing the frequency of the carrier for one or an integer number of wavelets then lowering the frequency of the carrier for one or the same integer number of wavelets then returning to the carrier frequency to derive the modulation event. The main carrier frequency is only modulated beginning at the zero degree phase angle and ending at the 360-degree phase angle.

20050007447 Modulation compression method for the radio frequency transmission of high speed data

20040196910 Integer cycle frequency hopping modulation for the radio frequency transmission of high speed data

Re:forgive me for possibly being redundant, but ..

[Anonymous Coward]

WTF does a watt have to do with bandwidth? <== This has got to be one of the stupidest things Slashdot has posted in a while.

Black Box

[GungaDan]

"At this stage, with patents pending, the technology behind this is very much under wraps, and was literally present at the demonstration in a 'black box.'"

Wait... I've heard this one before. Recently. $10 says there's a midget with a chess set inside that box.

Re:Black Box

[nmos]

$10 says there's a midget with a chess set inside that box.

Q: What's the chess set for?

A: To keep the midget from getting board.

Re:Black Box

[sgt scrub]

Exactly! "OK folks. You can see the output from the perpetual machine but you are not allowed to see inside the box"

Patent?

[Anonymous Coward]

Doesn't the fact that they have a patent pending keep them safe from possible thieves of this technology? What does it matter if they tell us how it works now or next month?

BS Detector To Full Power!

[FrankDrebin]

By comparison, GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz per Watt.

In a world where CDMA EV-DO with Turbo Coding comes within 1-2dB of the Shannon Limit, xG claims their system is 1000x (60dB) better. Perhaps they are modulating the tachyon-neutrino field? Ensign, Crusher... evasive maneuvers!

Re:BS Detector To Full Power!

[ichigo 2.0]

Wow, that's a lot of decibels! Reminds me of my old 2400 bps modem, now that bugger was loud! Does this mean I can wardrive around and find unsecure wlans by looking for a loud high-pitched beeping sound? One should probably avoid the loudest ones though, because they're downloading porn and would have lousy ping!

Re:BS Detector To Full Power!

[acaspis]

In a world where CDMA EV-DO with Turbo Coding comes within 1-2dB of the Shannon Limit, xG claims their system is 1000x (60dB) better.

Excellent point. But does CDMA EV-DO use directional antennas too ?

AC

Zuh?

[Hershmire]

If everyone is an ISP, who will be the subscribers?

Trust but verify...

[digitaldc]

"At the demonstration with other reporters, we were able to verify that the signals were being sent wirelessly, and checked the distance by GPS, but had to take the 50mW base station - and its omnidirectional antenna - on trust, since it was at the top of an 850ft mast. The demonstration will be repeated for the US press next week.
Before any of this happens, more demonstrations are needed, to show the system is robust against interference and multipath, and can operate in an area more crowded than 18 miles of swamp. It will also need to be approved by the FCC and other regulators round the world."

It sounds like a great idea, power-efficient and cheap technology will be widely used. But will the FCC approve or will they somehow change the spectrum licensing?

From: http://www.xgtechnology.com/faqs.asp#q16
"Some of the uses their website proposes are: The initial market applications are expected to include, but are not limited to, the following:
Broadband Internet
Beyond 3G - Mobile Broadband
Cellular Telephones (800 MHz - Upgrade to Digital High-Speed Broadband)
Cable TV - Wireless
Cable TV - Wired
HDTV - Wireless
HDTV - Wired
Public Safety Communications (i.e. Police Cars, Fire Trucks, Ambulances, etc)
Satellite
Phones, TV, Radio
Broadband
Wireless LAN
Wireless ATM Circuit (622Mbs)
Ultra fast Bluetooth
Home Automation/Wireless Appliances
Ultra fast DSL
Video on Demand"

Pretty soon everyone will have a wireless network.

Algorithm

[azatht]

The per per part, didn't make any sense for me, so I just had to check it;
TFA states '7.4 Mbit/s per MHz per Watt'
I read it as (7.4 Mbit/s) per (MHz per Watt)
So we have ((7.4 Mbit/s)/MHz)/W = (7.4 Mbit/s) * (W/MHz) = 7.4 bitW/sHz
sHz = one revolution of some kind, so we have 7.4 bitW/revolution
This make it intresting, if we lin W -> 0 we get infinet bandwith, and if we linit rev -> 0 we get some strange event :)

Re:Algorithm

[ichigo 2.0]

Hz = s^-1

7.4 Mbit/s per MHz per Watt = ((7.4 Mbit/s) / MHz) / Watt = ((7.4 * 10^3 bitHz) * 10^-3 s) / Watt = 7.4 bit per Watt

Now that's pretty damned inefficient :D

Not Joe Bobier's First "Marketing" Ploy

[Anonymous Coward]

Joe Bobier is behind this technology, and it's not his first time of trumping up "new" ideas.

His last venture was to "revolutionize" wireless networks by "inventing" Wireless to home users. He did this in Parkersburg WV using Wirefire Internet Service. It worked moderately well, though line of sight transmissions caused a problem, since the system required bulky exterior antennas, and trees blocked signal nearly universally. He claimed to have invented the system, even though the equipment was actually off the shelf Breezecom cards and radios talking to APs housed on terrestrial based radio and water towers.

Before Megafire (as it was known) failed, he convinced a Sarasota company iDigi to buy it. iDigi was owned in part by the Mooers company, referenced in the article. They funded the creation of a company named Island Labs, who's sole purpose was the create wireless that worked.

Joe is a smart guy, but he takes too much credit for things he didn't do. This may be another of those cases. I have heard of another technology very similar to this that didn't work either. I'm going to try to find it. If I do, it will be a reply to this post.

Re:Not Joe Bobier's First "Marketing" Ploy

[Anonymous Coward]

Amazingly enough, I am from Vienna, WV (nextdoor to Parkersburg) and lived about a mile directly west (on the same street) as the antenna Wirefire placed on top of the town water supply. The service sucked. It still sucks. The antennas REALLY suck. I won't comment on Bobier's marketing ability other than to say when I was living hand to mouth, apartment to apartment, living with friends, I got myself a Bobier pager because they were the only name I knew.
Thank god I escaped West Virginia. Verizon is installing Fiber to my neighborhood lately, I'm waiting impatiently for some serious high speed Internet access!

Just Think How Great This Is

[SkyDude]

Spam, porn and malware anywhere you are. I can't wait!

New Technology to kill WiMAX?

[Anonymous Coward]

Either this is vaporware, or so innovative that Big Brother and his cousin The Man will crush this before it even gets off the ground.
Don't expect to see this for another 20 years if it even exists....
How long has powerline internet been in the works, and only .005 of the world population is even using it, even though it's faster and easier to implement than Cable/DSL so we're told....

Somebody set up us the bomb.

[randomErr]

Operator: We get signal.
Captain: What !
Operator: Main screen turn on.

Go look up some basic communications theory

[Andy Dodd]

And look up Shannon's Law.

Guess who the stupid one is in this case?

Re:forgive me for possibly being redundant, but ..

[Husgaard]

The more power, the more bandwidth you get. This is a fundamental fact of telecommunications.

As a rule of thump (when the signal to noise ratio is high) the usable bandwidth is raised by a constant factor every time you double the power of the signal.

Carrier frequency vs. signal bandwidth

[Andy Dodd]

The carrier frequency is in the 900 MHz range, but the signal bandwidth used is signficantly less than that.

That said, any performance metric for power/spectral efficiency that doesn't involve SNR at the receiver is worthless. Any performance metric that states a linear relationship between wattage and achievable data rate is total bullshit, given that the relationship between achievable data rate and SNR is logarithmic, not linear.

Also, I don't know how far away WiMax is from the Shannon limit, but I'm 100% positive they're less than 30 dB away. Thus, it is impossible to be 1000 times more efficient than WiMax, because that would require this new technology to be breaking Shannon's Law.

Prediction: This is a scam

[Teilo]

Ok. I could eat my words, but this thing has all the marks of a major scam. This reminds me of the Madison Priest Magic Box hoax.

is xG VMSK

[TheSync]

I thought it sounded like Very Minimal Shift Keying (VMSK), then I saw this at VMSK.org:

"XG technologies goes on the air with their method in November from an 800 foot tower..."

More info on VMSK here and here. The first paper states "no ultra narrowband modulation method, which includes VMSK and VPSK, can have substantially greater efficiency than conventional methods, such as QAM, in transmission in the same frequency band".

Florida = Fraud

[irritating environme]

just like:
Texas = Fraud
Telecom = Fraud

Why do you think the bushies control these states? They're corrupt as hell, but unlike the rest of the corrupt south, these two states have money.

Don't get me started on Telecom.

Whats the catch?

[petantik f00l]

My lecturers teach me one thing. Whenever something new comes out that seems to be so fantastic as to be miraculous ask one question

Whats the catch?

I'm doing engineering and i'm alway wary about such claims

where else/how much have they tested it?
How much does weather affect its operation?
How much will it cost?

Of course. i'm not saying that they are lying, they have achieved an engineering marvel that can only change things for the better. can you imagine how useful this would be in the developing world and rural areas where bandwidth is expensive or non-existent

IPV6 is plainly stupid and adds nothing to this

[postbigbang]

You've been missing the discussions for years that prove that IPV6 is plainly far too much, and that IPV4 needs to be fixed via re-allocation of huge A B and C block and CIDR allocation madnesses that were doled out in the early DARPA days of the Internet.

What's nice about the posted technology is that its encoding methodology might answer some prayers that neither WiFI or WiMax does. But it's all still unproven, and still far into the future. I like the low battery consumption side of it, as WiFi sucks the very life out of my notebooks and makes it impossible to realistically use PDAs of any kind with it-- save for short durations of frustration.

Re:IPV6 is plainly stupid and adds nothing to this

[rtb61]

IPV6 is inevitable because of it's scope every device can be uniquely identified and it will be far cheaper than IPV4 (supply and demand).

I not sure if this is going to be that popular with the tin foil hatters, ultra cheap, ultra pervasive wifi and low powered ;-).

Re:IPV6 is plainly stupid and adds nothing to this

[postbigbang]

What??!!!??? The billions of networks (before NATting) won't be enough??!!?? IPV6 is absurd. Look at it closely, and justify the fact that it has more addresses than the amount of molecules in your body. The answer, I promise, won't be the source of amusement for the next few days.

Re:IPV6 is plainly stupid and adds nothing to this

[trippinonbsd]

IPV6 is absurd. Look at it closely, and justify the fact that it has more addresses than the amount of molecules in your body.

Why are you SO concerned that there are more IP addresses in IPv6* than we would ever use? This is the POINT, to not run out. To make all of the IPv4** addresses usable would take a lot of work and it would also take a lot of work to implement IPv6. So why not just fix the problem with IPv6 which is superior.

There are 281,474,976,710,656 (2^48) possible MAC addresses, why don't you complain about that as well?

* IPv6 has 3.4 × 10^38 addresses.
** IPv4 has 4,294,000,000 possible addresses, not even enough for one per person.

Wikipedia: Mac address
Wikipedia: IPv6

I propose a new Slashdot section -

[bizitch]

I know this was posted under "hardware.slashdot.org" - But I propose a new section for this item

How about "vaporware.slashdot.org"?

Re:I propose a new Slashdot section -

[Anonymous Coward]

>How about "vaporware.slashdot.org"?

Maybe snake-oil.slashdot.org?

ubiquitous internet wifi, 100% coverage (metro)

[Khopesh]

This is something I dwell on, from time to time (I posted this comment on "Peer-to-Peer Cell Phones" in 2002):

A small number of people have a direct connection to the internet and share it with anybody within a large range, to wireless devices that not only use it, but also share it to others, thus further extending the range. With enough such devices, an entire metropolitan region can get blanketted in internet access. Sure, the connection would be slow, but eventually, everybody would be connected wirelessly and the initial small number of people will be less significant (and more plentiful, anyway).

The largest flaw in my design has been the battery power needed to broadcast indefinately, but if a tiny watch battery can do it, then a broadcasting managed by a dumb routing program should require very low power. As the parent post notes, this would also require IPv6.

Oh, and one more thing...

[xactuary]

This way to the Egress.

P.T. Barnum used a sign with the above printed on it, which of course caused people to hurry on the next, and perhaps even more amazing exhibit. Soon enough they realized that egress means exit in French.

If you think about it, maybe this post is on-topic.

Re:Oh, and one more thing...

[manarth]

Egress...isn't that a female eagle?

(ok, Pratchett came up with that one first :)

Re:Oh, and one more thing...

[pkhuong]

Really? Weird. Doesn't look French to me, a native speaker.

Dict.org says:

    Egress \E"gress\, n. [L. egressus, fr. egredi to go out; e out +
          gradi to go. See Grade.]
          1. The act of going out or leaving, or the power to leave;
                departure.
                [1913 Webster]

Fully English, although the word does have a latin origin.

Re:Oh, and one more thing...

[xactuary]

What can I say, other than pardon my French? ;>)

People go hunting out there all the time

[CiXeL]

just get one of the seminole indians on the reservation to shoot it off the pole and mail the remains to slashdot.

Re:Great ideas don't always make for great busines

[Anonymous Coward]

WiMax isn't the only thing it can obsolete.

How about FM radio? I'm sure a lot of radio stations would love to replace their 10kW, analogue transmitter with a 200mW digital signal and still have the same coverage. The electricity bill would pay for itself in 5 minutes.

Any suitably rigged...

[Alioth]

When I saw this on the front page - with the thing about the 850 ft tower it IMMEDIATELY brought the phrase "Any suitably rigged demo is indistinguishable from magic".

There have been cases of this before - very convincing demos done that have turned out to be snake oil, or perhaps have the kernel of truth behind them (and the demo used to drum up capital - at which point the inventors HOPED they could make the technology actually do what the rigged demo showed).

Basically, I'll believe it when you can buy it, not before. At the moment it sounds like a rigged demo.

Re:Any suitably rigged...

[TapeCutter]

Yes, you will never see a magician invited to a magical demo.

Re:Any suitably rigged...

[jabberwock]

I don't believe or disbelieve -- I'm just weighing what I read. In particular, as regards magic: "xMax is unconventional," said Stuart Schwartz, professor of electrical engineering at Princeton Universithy, who has scrutinised xG's demonstration set-up, speaking at the xMax demonstration. "It is clever and innovative, but it is not magic. It uses single cycle modulation, and needs much less power than other technologies."

IAARE

[elgatozorbas]

I am a radio engineer...
well, not professionally but I know what it is about.

Digital transmission works as follows: you select a certain waveform out of a set and transmit it. At the receiver you try to figure out which one it was. Unfortunately the reception is distorted because of noise you pick up, such that the distinction is not perfect (e.g. in case you can reliably tell 8 possible waveforms apart three bits will be conveyed each time you do this). Using more power will lead to a better distinction and therefore higher bit rate. Using a larger (RF) band width allows you to send more waveforms per second hence also increasing the number of bits transferred (this is simplified somewhat).

Shannon left us a nice formula to calculate the capacity aka maximum possible throughput EVER, but first you need to calculate the signal and noise power you receive.

1) If we assume the waves travel in free space, the received signal power will be dependent on
- transmit power
- transmit antenna gain (dish is more focused than dipole etc.)
- free space loss (FSL, i.e. field strength getting weaker far from the source because the energy is spread out in all directions)
- receive antenna gain
This is an optimistic assumption because their setup takes place in suburban territory!

We can assume both the antenna gains are 0dB, being small and probably not perfectly matched.
The FSL is equal to: R^2*4pi^2/lambda^2 (R=distance, lambda=wavelength)
At 900 MHz lambda=0.33m, R=18 miles=29e3 m.
FSL= 3e11(in 'power') or 115dB.
The transmit power was 50mW, i.e.17dBm, the total received power will be 17-115=-98 dBm. The thermic background noise is equal to -173dBm/Hz (best case, due to ambient temparature - this is a bit optimistic too because other wireless devices are transmitting there too).

2) The channel capacity is given by Shannon as C=B*log2(1+S/N), where C=capacity (bits/sec), B=bandwidth (physical, in Hz), S=signal power (-98dBm), N=noise power (-173dBm/Hz*B).
You can now play with the bandwidth to influence the capacity. To a certain extent an increased bandwidth will increase the capacity but after a while you are just catching more noise while the signal will be spread out in frequency, so this saturates.
For these numbers the (theoretical) maximum capacity would be about 4.5e7 bits/sec or 45MB/sec. But even to achieve the 3.7Mb mentioned you already need a bandwidth of 700kHz (rough estimate, I made a plot in matlab).
At that point you transmit 3.7Mb/(50mW)/(0.7Mhz)=100Mb/s/W/MHz, so their figure of 7.4 MB/2/W/MHz is not impossible. However it will be difficult to achieve. We have made some assumptions (especially about the loss in the urban envorinment), and their bit rate only has a 'margin' of a factor 12 (45 to 3.7). There you have it.

Re:IAARE

[leighklotz]

We have made some assumptions (especially about the loss in the urban envorinment),
I would echo the optimistic assumption you mentioned earlier about the noise floor at 900Mhz, which is much higher in an urban environment than in the middle of a Florida swamp. I would suspect these two (signal loss, noise gain) will easily eat up the 10dB margin you calculated (factor of 12).

Re:IAARE

[fishybell]

Here's a general question about the Shannon limit. You seem to know your stuff, so I'll ask you.

Does the Shannon limit take into account software error correction at all? As far as I can tell, the Shannon limit gives you the maximum throughput of error-free data. What if it doesn't matter whether the data is error-free or not? For example, if I can only get 50% of the way to the Shannon limit using hardware in a real-world environment, could I boost that number by ignoring symbols that are indistinguishable and just let error correction (like reed-solomon) take care of the missing parts?

Re:IAARE

[SpiritStranger]

Shannon left us a nice formula to calculate the capacity aka maximum possible throughput EVER

This formula however assumes the AWGN channel (additive white gaussian noise) which is a worst case channel. Typically more realistic radio channels will have a better theroretical capacity limit than this. I think your analysis is quite good though. These results must be hoax.

Re:IAARE

[kaleth]

The critical point here is that the Shannon limit doesn't give you a maximum data rate - it gives a maximum _information_ rate, a subtly different thing. No matter how you encode the data, you can't get more information through the channel than the Shannon limit gives. In this case, adding error correction reduces the number of bits available for trasmitting your data, and lowers the overall data rate.

Re:IAARE

[elgatozorbas]

Indeed the Shannon limit gives you the maximum number of bits you can transmit per second with an 'arbitrarily low probability of error' (error free). So maybe you will need infinite processing power or an infinite time etc, but this is what you can ultimately get. Any bit rate above this limit can NOT be realised with an arbitrarily low probability of error. The Shannon limit doesn't care how you do this although Shannon gave some clues.

So it matters that the data is error-free.

Your question is a bit unclear to me. In case you mean that the bit rate is 50% of the Shannon capacity and these bits can even be corrupted, the final throughput will obviously be even lower. First of all because some bits will be invalid (and these don't count) and moreover because you even don't know which ones! In the extrenme case the channel has a 50% bit error rate it is perfectly worthless because you could as well toss a coin at the receiver (also 50% chance of being accidentally the same as the bit you transmitted).

Symbols that are indistinguishable will generally not be discarded. Say you transmit 2 bits and either expect a receive signal of (e.g. in volts) 0,1,2 or 3, you could argue that a received '1.51' is hardly convincing. This is exactly where coding comes into play.

Older coding systems (such as Reed-Solomon) decided this counts as a 2 just as much as 1.9999 would have, called 'hard decoding'. Newer techniques use 'soft decoding' and take into account the probability of the decision (so in out example the decoder "wouldn't be so sure" about the 2). You can intuitively see that this will perform better. To exploit this additional knowledge about the 'reliability' of the decisions, some redundancy is added at the transmitter (i.e. some 'logic' is introduced between succesive symbols). Due to noise mistakes will be made at the receiver and the 'logic' will be violated. The receiver will now revise some of its decisions to comply to the logic again, and the best candidates to revise will be the decisions with low reliability. Even though additional redundancy was introduced, there will be an overall gain.

Re:IAARE

[leighklotz]

>For example, if I can only get 50% of the way to the Shannon limit using hardware in a real-world environment, could I boost that number by ignoring symbols that are indistinguishable and just let error correction (like reed-solomon) take care of the missing parts?

Yes, it's called "coding gain" and it can be measured in dB. If you want to get the results you would have had with twice as much signal to noise ratio, you need 10*log(2)=3dB coding gain. Unfortunately, putting in forward error correction reduces the data rate or increases the bandwidth, so you need to make sure you're coming out ahead.

If you're interested in experimenting with these topics, try reading about ham radio digital modes for HF (3-30Mhz). The cost of entry is low, and with open source software such as gMFSK it's possible to do your own experimentation. You might start with this historic article that started a new set of experimentation on a phase-shift keying modulation scheme called PSK31, which packs all the power into a tiny 31Hz wide bandwidth. You can read a less technical description, or read about other modulation techniques using multiple carriers (MFSK, Olivia, which uses Walsh functions for FEC and can be copyable with low power in noisy conditions).

For a long overview of HF digital mode performance in practical circumstances, see this paper from the Radio Society of Great Britain.

There's also plenty going on in UHF as this 900 Mhz work is doing, but it's a little harder to experiment there, but if you are already comfortable building 802.11 equipment and have the skills necessary there, there's plenty to do. Some hams recently conducted Earth-Moon-Earth bounce communcations using 47GHz (which I heard one of the 24GHz pioneers say would never happen!).

And at the other end of the spectrum, US, Australian, and European hams are experimenting with LF in the 137KHz region (under special license in the US) and have made super-slow communications across the oceans. There are challenges here as well, and the data rates are extremely low, not unlike the 76KHz signal that we used to send to our nuclear submarines underwater, which I think is roughly one bit (a repeated "don't-blow-it-up don't-blow-it-up don't-blow-it-up...).

Re:IAARE

[acaspis]

this is a bit optimistic too because other wireless devices are transmitting there too.

You bet ! If you assume 10 active transmitters per square kilometer in a 29 km radius, then the receiver is getting at least -54 dBm of additional noise, and the theoretical maximum capacity drops from 45 Mbit/s to 50 kbit/s. And that might still be optimistic for a metro/suburban area.

Isn't that an obvious, inherent problem with shared-spectrum modulations ?

As usual the early adopters will get a free ride. Then the bands will get crowded, and customers will have to purchase new technologies on new bands or with more aggressive frequency hopping. See 802.11b versus Bluetooth versus 802.11g in dense office areas.

Of course wideband modulations could still be useful for broadcasting - but it would be totally unfair to compare that with GSM and CDMA/EV-DO.

BTW some textbooks use R^2*(4pi)^2/lambda^2 as the formula for FSL. Dunno which is right, but that would be 120 dB instead of 115. Apart from that, your calculations seem to be correct, and I enjoyed redoing them.

AC

Re:IAARE

[chrisuhlik]

Free Space Loss applies only in free space. Over a Florida swamp, the radio signals reflect off the ground and interfere with each other. A better path loss calculation would be to use COST-231/Hata rural. This model is for 500--2000 MHz so the 900 MHz ISM should be well represented. Florida fits the Hata "rural" definition. One parameter left out is the receiver antenna height --- I'll use 1 meter.

PathLoss = 46.3 + 33.9 log10(f) - 13.82log10(hb) - ((1.1*log10(f) -0.7)hr - (1.56log10(f)-0.8)) + (44.9 - 6.55log10(hb))log10(d)

d = 18 miles = 29 km
hb = 850 feet = 259 meters (base-station height)
hr = 1 meter (receiver height)
f = 912 MHz

PathLoss = 46.3 + 33.9 * log10(912) - 13.82*log10(259) - ((1.1*log10(912) -0.7) - (1.56*log10(912)-0.8)) + (44.9 - 6.55*log10(259))*log10(29)

PathLoss = 157 db

I think they are missing at least 35 dB and the demonstration is bogus.

Chris

Re:IAARE

[acaspis]

The article says the receiver antenna is 20 feet up. That's still 144 db according to your formula.

Also, the receive antenna is "the size of a small paperback book", which is pretty big when compared to a 900MHz phone. So maybe the transmitter actually is omnidirectional, and it's the receiver that has directional gain.

AC

Re:IAARE

[chrisuhlik]

At 900 MHz, a directional antenna the size of a paperback book might have a gain of ~6dBi. To get the necessary 30 dBi I think it would take a dish several meters in diameter. I don't know how to do this calculation, but my intuition suggests that you'll need a few hundred square wavelengths (a few hundred square feet of collector area at 900 MHz or a ~3+ meter diameter dish) to have a gain of ~1000 or 30dB.

Chris

It smells fishy

[CiXeL]

or swampy, whichever you prefer but I wouldnt be surprised if we got some legitimate startups out here.

My girlfriend and I moved from LA and now we're seeing new california license plates out here every week as well as recent transplants from colorado and oregon. Theres alot of opportunity out here because it isn't built up yet and realestate prices are cheap.

The thing is you know these people moved here and aren't realestate speculators because they wouldnt move their car cross country, they would just fly out. In addition you know they're recent because the state here has a law where you have to get your new florida plates in 30 days.

No, three

[dpilot]

"but this technology could allow anyone to set up as an ISP."

I'm sure there are some heavily-moneyed parties who would rather not see things de-centralize. This is part of a larger losing picture for the whole computer/networking technology arena. We've become everyone's beating boy, and so far everyone has succeeded in doing this. If only our industry had a fraction of the clout of the NRA. If only the Founding Fathers had understood the concept of end-to-end networking. Oh well. We'll probably figure out that making computer/networking technology responsible for everyone else's woes was a bad idea, after it's too late. (If it isn't already)

WiMAX lives

[magli]

So from where I sit, WiMAX can't be killed, because it's not alive.

WiMAX is simply a term used to denote appliances which have been certified by the WiMAX Forum
From their FAQ:

"The WiMAX Forum is an organization of leading operators and communications component and equipment companies. The WiMAX Forum's charter is to promote and certify the compatibility and interoperability of broadband wireless access equipment that conforms to the Institute for Electrical and Electronics Engineers (IEEE) 802.16 and ETSI HiperMAN standards"

They have started testing loads of equipment from various manufacturers, as part of their "certification" process. These products should have been certified before the end of the year. Here are some examples:

Siemens "WayMax"
Alvarion BreezeMax

WiMAX is very much alive.

Maybe I didn't understand it?

[Anonymous Coward]

Is the claim really that for the same spectrum, you get 1,275 times the bit rate. Is that what they were saying?

"The system carried 7.4 Mbit/s per MHz....GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz..."

So are they saying that where now a GSM call uses around 25kbs for voice and signalling and error correction, in that same spectrum, they would now be able to give that caller 32 gigabits/sec?

Must have not understood.

What about MIMO?

[Captain Perspicuous]

What about Multiple-input multiple-output? I hear it's the hottest topic in wireless research at the moment and looks very promising.

Re:What about MIMO?

[Erich]

MIMO increases SNR mainly by adding transmit and receive diversity.

A good example of receive diversity is the "rabbit ears" on a TV antenna. Signal that is faded to one antenna is likely to not be faded on the other.

Also, SNR on a wireless LAN is much better than SNR on a WAN like a cell. Which means that it is easier to acheive higher data rates on a LAN. This is why 802.11[abg] has good data rates and also why you can't use it over long distances very well.

With multiple antennas you can also do beamforming, which changes a signal for a user to be more directional. This decreases interference for other folks.

But, of course, you don't have to worry too much about other's signals, their walsh coded signals won't correlate with yours. :-)

So far, nobody has been able to break Shannon's Law. There is no magic wand.

Here's how it does it

[Dster76]

"xMax is not a compression technique, but rather a synergistic mix of two well-established communication approaches that dramatically improves spectrum utilization." - from the company's FAQ.

Doesn't everyone know that, therefore, xMax is a communications protocol for quickly generating excessive media interest and venture capital?

Brings to mind VMSK

[w9ofa]

Phil Karn debunked the claims about VMSK here:
http://www.ka9q.net/vmsk/

I AM a radio engineer, and I am extremely dubious about some of the claims in the article/website/etc. The thin line on the spectrum analyzer looks alot more like a sine wave than a system that "modifies each cycle of the sine wave". Others have pointed out that this is another way of stating the essence of phase/frequency modulation, a very old modulation technique.

On the xG website there is a press release that has some tortured details:
http://www.xgtechnology.com/newsitem.asp?id=21

"xG's Flash Signal technology, which utilizes single-cycle waveforms to transmit information at a minimum effective rate of 1 MB/s for each megahertz of spectrum"

Well, to me, you take away the "megas" and you get 1 bit/sec/Hz for the spectral efficiency .. .the same as BPSK.

The only important technical point I can find in the article is this one:

"Moreover, because the receiver -- the design of which is xG's most-guarded intellectual property -- includes a passive wavelet path filter that acknowledges only single-cycle waveforms, all other RF signals are ignored."

My guess is that he has an antenna/feedline scheme that cancels signals that cross correlate with a 1 cycle delayed version of themselves. Most likely, he does this by using two antennas and a bit more coax (at a particular design frequency) on one antenna to cancel any signals that are coherent with themselves for some integration time. This is not a particularly new or cleaver idea, but I suppose you could use it with the modulation scheme to increase the SNR of the signal (assuming of course that most signals are not like yours).

Also, if this is the case, then the geometry of the antenna array relative to the transmitter will be important, because at the wavelength used (900 Mhz) the configuration of the antennas will yeild different phases depending on how they are aligned relative to the transmitter. I take further proof of this in the zdnet article which describes the signal as degrading when the antenna is pointed away from the transmitter. (near the end)

ZDNet UK saw that the bitstream vanished when the receiving antenna was moved out of alignment with the distant transmitter

http://news.zdnet.co.uk/communications/wireless/0, 39020348,39235645,00.htm

This scheme will yield better performance, that is.. until everyone is using it. If there are many signals that are not coherent with themselves over the integration time of the circuit, then the supposed advantages in terms of interference rejection will disappear.

In summary, if everything is as I have guessed, this technology is about the same as using a better antenna for a regular wifi system ... it will get better performance, but at the cost of requiring knowledege of where the base station is located relative to the mobile unit. Also, if the technology is what I have guessed, it will be easily copied if the market finds it to have great value, of which I am dubious. I could be wrong about all of this, but it would be interesting to see more technical information rather than a few plots and a dog-and-pony show. Appeals to authority fail to be very convincing when you are talking about claims in a field with well-known laws limiting performance.

Sounds like bollocks to me!

[Anonymous Coward]

This sounds like bollocks. In fact this sounds very similar to the bollocks that was VMSK. In VMSK, the low level sidebands contained the data, but its inventor tried to dismiss them. In this case the inventors acknowledge the sidebands. It still doesn't smell right though.

I realise that most of /. readers are not technical. They like to think they are but they aren't. The amazing technology being described sounds very much like something that is called "transmitted reference CDMA".

Perhaps people would like to Google for such terms and read the rebuking of VMSK before they believe the hype of this latest wondermode.

What kind of comparison is that???

[Anonymous Coward]

GSM vs EV-DO. Has nothing in common, EV-DO is a data medium, GSM a Voice medium.
GSM vs CDMA is however more correct and would be similar in performance - Why are we even talking about GSM - It's so pre 2000. Since GSM we used GPRS and EDGE and are currently using UMTS moving towards HSDPA.

Er...where was this demo, exactly?

[Control Group]

since it was at the top of an 850ft mast

Anyone know where they held this demo that they could put the transmitter on top of a seventy-storey building??

Re:Er...where was this demo, exactly?

[Anonymous Coward]

joe doesn't stray anywhere far from FL these days. Bet on a radio antenna in Sarasota

Re:Er...where was this demo, exactly?

[SpinyNorman]

They said mast, not building, and sure enough if you click through the links in the article, there's a picture of it.

http://www.techworld.com/mobility/features/index.c fm?FeatureID=1939

Re:Er...where was this demo, exactly?

[juggledean]

It's the WTVJ (was WCIX) tower here

Re:forgive me for possibly being redundant, but ..

[Anonymous Coward]

The more power, the more bandwidth you get. This is a fundamental fact of telecommunications.

As a rule of thump (when the signal to noise ratio is high) the usable bandwidth is raised by a constant factor every time you double the power of the signal.

Which works, unless the noise is due to your own signal (multipath, your signal interfere with itself because of transmission delay), or due to transmissions of your neighbors. In which case you are doubling your noise too.

Power and Bandwidth are Independent Parameters

[Junior Samples]

The system carried 7.4 Mbit/s per MHz per Watt, said Professor Schwartz. By comparison, GSM would have around 0.0058, and CDMA/EV-DO about 0.0085 Mbit/s per MHz per Watt.

These units of measurement are not meaningful. Transmission Bandwidth and Transmission Power are two independent parameters that do not interact. Increasing the transmission power will increase the signal field intensity at the receiver and thus increase range. Increasing the modulation bandwidth will allow higher transmission speeds. Increasing the power will not increase the transmission speed (assuming adqeuate signal levels are available to prevent interference from noise).

Will Google Snatch Up This Technology?

[Daedius]

(Google + xMax) == Free Wireless ISPs?

Re:Frothy piss

[kevinwal]

I was wondering what had happened to Dan Quayle.

Living in Sarasota

[Anonymous Coward]

Being that I live in Sarasota.. This company is fairly close to another Tech company downtown.. named Infinium.. I will believe it when I see it deployed..

Licensing will decide how fast this kills anything

[dtfinch]

If, like most failed revolutionary new technologies, they aren't flexible and reasonable in their patent licensing, this can take a long time to reach wide market acceptance. Experience tells me that new technologies are expensive through the roof, even if the cost that went into it isn't. It all depends on if they want to price for business or consumer use.

Not a WiMax killer

[MicroBerto]

WiMax is about to "cross the chasm", and companies successfully installing it out there aren't going to wait around for something better. WiMax is here and it works. Yes, it'll get replaced someday, but it has the momentum and the marketing hype, and I don't see anything beating it out anytime too soon.

Similar, but not quite the same.

[XNormal]

VMSK was just phase modulation with very small modulation index. While the bandwidth between the -3db points is indeed very narrow (apparently breaking the Shannon limit) the actual information was carried in the sidebands. This means, of course, that the central carrier is just a waste of transmitted power.

This "xG" modulation seems to be a more subtle variation on the same idea as VMSK: the central carrier is in the 900 mHz band, where you are allowed to transmit quite a lot of power without a license. Unlike VMSK it's not totally useless since it is used as a timing signal to help the receiver synchronize. It is also used as a regulatory fig leaf (see below). The rest of the data is carried on very wide sidebands that leak hundreds of MHz outside the 902-928MHz unlicensed band. The total power of these sidebands is just tens of milliwatts and they are spread over hundreds of MHz so the power density at each frequency is below the level that devices like your PC are allowed to emit as background noise.

So xG is ultrawideband plus a pilot signal in the 900MHz band.

Ultrawideband is real. It can transmit a lot of data at very low power levels. But current FCC rules only allow UWB operation above 3.1GHz (up to 10GHz) and places additional restrictions like limiting it to indoor operation (outdoor operation is allowed for handheld devices, not fixed installations). One problem with these high frequencies is that they do not penetrate walls very well. UWB has been demonstrated below 1GHz and it works extremely well at these lower frequencies - but that's not allowed by part 15 of the FCC rules.

So how can xG legally transmit UWB in the coveted first GHz of the spectrum? By twisting the rules a bit. A device is allowed to emit low levels of RF energy all over the spectrum as noise (like your PC) but it's not allowed to transmit in these frequencies an an "intentional radiator". But there's another way in which a device may transmit small amounts of power in an otherwise restricted band: as sidebands of a carrier which is centered inside a legitimate band. This is what xG is doing - they claim that this wideband signal is the sidebands of the central carrier in the unlicensed 900MHz band. And it really is. That's what you get when you modulate a 900MHz signal with sub-cycle pulses.

So xG may meet the letter of the law but probably not the intent.

Simple really - Evil bits

[JonTurner]

"It's a simple concept but the actual implementation gets a little complicated. In short, we alternate good bits with Evil bits so they cancel each other out in a matter/antimatter sort of way. It's real "star wars" technology and I can't comment further due to patents pending.

(mumble) Damn engineers. Always ruining the fun. Quit asking questions and just buy some shares in the company so I can cash out and retire at 40.(/mumble)

Hey, did you notice my thick hair and shiny teeth? Let's move on. Yes, you, there in the back. A question? ..."
--salesman

Re:More details here - here's the trick

[acaspis]

Even more interesting than the photos is this statement at the end of the second article:

ZDNet UK saw that the bitstream vanished when the receiving antenna was moved out of alignment with the distant transmitter

In other words, this is a highly directional transmission. That's why they need a GPS to make the demo work. And when they say "omnidirectional antenna", either they are lying, or they mean it's a phase-array antenna that can be tuned to transmit in any direction (but not all directions).

The bullshit about a revolutionary modulation technique is probably just that. There's no way you can beat state-of-the-art modulations by 1000x.

Oh, and the demo seems to be a one-way transmission. Dunno how hard it is to do a phase-array receiver with the same gain as a phase-array transmitter.

In other words - nothing new here.

AC

Some history of the principals...

[Anonymous Coward]

Back in 2002, the Sarasota Herald Tribune did some stories about a predecessor to xG called iDigi, and some of the people involved. Richard Mooers, the xG CEO, and Joe Bobier, the xG CTO, both feature prominently.

Here's a Google cache link to one of the stories.

Choicest quote:

Karason said he found out later that the whole demonstration was fraudulent, "using illegal power, illegal equipment, preloaded stuff on computers that we were told was downloaded over the system, etc., and in fact the Icelandic system did not work at all, as the people running it found out after the presentation -- when the 'magic dust' had disappeared."

They may have the real thing this time, but... (An account of the story much friendlier to Mooers appears on his website.)

I don't know if this will

[Solr_Flare]

beat out WiMax in the near future, but this does indicate that there is a lot more we can do with the techology. Plus, at the rate wireless is developing, I don't think it would be too surprising to see how it will someday replace landline connections once the technology truly gets "good enough".

It still has a ways to go, but it is catching up quickly. It certainly would be nice if we can some day see a world where, outside of possibly power, all our other forms of communication are done wirelessly. Anyway, I'm glad to see the technology advancing. Between this and WiMax, we should be able to close that last mile in no time.

your should be lucky you can make a 911 call

[cheekyboy]

Dude, if you can make a 911 call, then use your damn brain and say

"hey im at 21st and 85th street tower, floor 54"

No system is perfect, and its better to get some call in than nothing.

GPS is easy, even if you loose sat contact, then duhhh, you have a record of the last 10mins of avail signal, so you
can locate yourself roughly.

And, if you are in a building, then damn pick up the normal phone, not every phone will be voip.

If your in a forest, then yeah, gps will work, and im sure the cell phone wouldnt.

ANd with camera phones, well, you can take the photo of wher eyou are and send it to 911 too, if they can recieve
them.

If voip has double the middle men, then why arent land line calls and cell phone calls DAMN DIRT CHEAP????

coz they are raking it in.

Re:your should be lucky you can make a 911 call

[InvalidError]

I do not necessarily know/remember the address of the place I went to... I only remember the turns to take to get there or simply followed someone there and did not note the address or forgot it.
I do not own a GPS phone.
I do not own a camera phone.

In a building, there may not be a nearest open (pay-)phone.
Yes, GPS usually works in forest but (as you presumably implied) pretty much nothing else does.
Yes, baby Bells & co. do rake it in, that is why some of them are plotting to charge fees to third-party online service providers to recover their lost LD income.

Land lines go through the POTS. The costs of establishing and maintaining a dedicated virtual circuit through the POTS scale with the number of traffic exchanges and length fiber/copper the call goes through. With POTS, you are guaranteed a steady audio stream under all but the worst conditions thanks to the static virtual circuit (reserved bandwidth) established when the call is initiated. With VoIP, any change in IP routing from source to destination can cause packet loss and out-of-order reception that will cause skips or delays in the audio streams.

VoIP is fire&forget, the network operator does not have to make any delivery guarantees. POTS calls however requires that a whole virtual circuit (64kbps each way) be reserved for the duration of the call. On most fibers, telephony traffic has absolute priority over IP and POTS pay for that privilege. This is a large part of why LD over POTS is much more expensive. Meeting POTS' zero-tolerance requirements in data delivery is much more expensive than meeting VoIP's "whenever".

Re:Frothy piss

[Lil-Bondy]

obviously this troll is jealous of geek supremecy :) like gabe from penny arcade said "in the real world, we run shit."

forget US market, go ASIA, 10x more people.

[cheekyboy]

Asia , where regulations are easier and less legacy to interfere with, and where physicical networks
are too hard to build because of land mines or swamps or 1000s of islands. This stuff will succeed there
and overshadow any US corporate FCC approved monopolist buddy systems.

Besides electricity will get more expensive and low power will win.

how can we buy stock?

[elucido]

Which company? are they on nasdeq?

Good luck

[Dwonis]

No doubt they'll screw it up by patenting it to death...

Here are the patent applications

[mccoyspace]

He has two applications pending.
Modulation compression method for the radio frequency transmission of high speed data
Tri-state integer cycle modulation
Can anyone summarize and/or give an informed opinion of them?

Re:Here are the patent applications

[armag]

It's a scam. I read the first patent application a while ago: he has "re-invented" amplitude modulation. (The same thing used by Marconi and in every AM radio.) All he does is set the modulation frequency equal to the carrier frequency, but this is still AM. The USPTO must have been asleep at the switch. There are certain laws of physics (and Shannon's law) that you can't get around. The claims they are making for the technology are completely bogus.

Re:Here are the patent applications

[WiMAXPro]

Before xG is either accepted at face value or rejected summarily, idiots (we are all idiots) should read the patents currently issued to xG as well as the applications pending. Reciting Shannon's law or other axiom of the trade is childish nonsense: UWB technology was thrown out by similar arguments. The criticisms from some lazy RF engineers who failed to think out side their boxes fell silent once the technology was demonstrated and now proven to work in chips and devices destined for PAN applications. A few years ago some fellow engineers said that OFDM FFT based wireless would never be practical in our life times: "to do effective OFDM would take a $300 DSP!.. it just isn't going to happen (fool)" Well, it did happen starting on a large scale with 802.11a and then .11g and now multi-mode chips are selling for the cost of popcorn at the movies (or less). The point being that everyone in the industry needs to do a periodic rethink about what is possible and practical: many basic assumptions were made because of the inability to design using digital methods or being able to sub-sample (wavelets) at sufficient clock rates to make these differential signaling methods practical. The basic theories behind wavelet transforms, single cycle (limited cycle) modulation methods, etc. have huge potential benefits, much greater magnitude of benefits than, say, OFDM over WCDMA. It is just recently that wavelet pulse, wavelet transform, single cycle signaling methods could be considered in the realm of being practical for mainstream wireless applications. Oh sure, Shannon's law, signal propagation properties and waveform physics are still the same as they were in the days of Marconi. But the body of wireless theory and practice could not have dreamed of over-sampling single cycle waveforms. Who knows, maybe xG has something, maybe not. The answer isn't going to be found on web boards.

Now you get my point.

[postbigbang]

IPV6 is irrelevent.

IPV4 has only 4.3 billion addresses. Behind unroutable NAT tables, how many more? How many more factorial numbers do you need? Ok, ok.

Now mulitply the MAC address combos with all of those. Ok ok.

Now add back the IPV4 behind the unroutable NAT nexus points, informing a router that on this side, bogus NAT addresses and please proxy, and on that side is the real Internet. Ok ok.

Unique MAC: IP combos are limited by 2^48 addresses. Pairs are limited by the smaller number. Ok ok.

Do this again on this translated side, an infinite number of times. Trump infinity, please. 3.4*10^38 vs infinity. Ok ok.

Now take the IPV6, nearly infinite as it is, and use its non-routable equivalents: look! Mulitple Infinities! It's like a Nissan parking lot!!!!

Somewhere, somebody on a side street sold you this book. You looked at it, genuflected and adopted IPV6. It is good, pronounced some twittering pooh bah that doesn't understand the difference between IPV4, IPV6, and a deep dark hole. They saw: ugh, heap big more numbers. Must be good. Like 64-bit. Hmmmm. Buy this, must be good. Make heap big more router sales. Good for industry. And you bought the argument. There were a few verses in this bible about how much better life would be, and holy for there were more numbers, and routing could be done like the Sistine Chapel, on your back, staring at a ceiling.

Overnight and behind your back, the Internet grew up. A few more dragons need to be slain, but overall, we won't run out of unique addresses... and the ARP and DNS tables will keep things nice and honest. It's all working today, but we need to hurt some fat Class A and B network block owners to make them cough up a few. This will become really necessary given current growth characteristics about the year 2050 from estimates I've seen. I'm 96 and dead by then. Sorry. I'll hit the morphine drip and let my great granchildren figure it out.

Re:Now you get my point.

[Anonymous Coward]

You're posts REALLY don't make much sense. It's not even worth the effort to correct.

New Technology Could Kill WiMax?

[Anonymous Coward]

My first comment .. If the technology really is what i think it is, then the spectrum must be measured with a fast peak-holding analyzer to get meaningful values. The "sidebands" will exceed legal maximum values significantly, but only for a short time. This will NOT show on an average (slow) instrument, but will corrupt other services on the same frequency for this short time. Does this hurt ? I dont know.

Re:forgive me for possibly being redundant, but ..

[Randy Rathbun]

True. But power out does not mean squat! Just because I have a million watt transmitter does not mean, based on this "7.08 Mbps per MHz per watt" or whatever it is, that all the receivers are going to be receiving data at 7.08 x 10^6 bps.

The key words in Shannon's Theorem are "signal to noise ratio".

The farther out you go from the transmitter, the worse the s/n ratio is going to be. Likewise a crappy antenna. Or crappy obstructions. Or crappy weather. Or a damn bird flying right between the transmitter and receiver. It doesn't matter how much power is being used - if any of the crappy things above happen, the s/n ratio is going to go down.

Instead of saying "7.08 Mbps per watt per MHz" or whatever it was, they need to instead say something like "7.08 Mbps per MHz with a S/N ratio of whatever-it-was."