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CSIRO Demonstrates Fastest Wireless Link Yet

CowboyNeal posted more than 7 years ago | from the sky-is-the-limit dept.

Wireless Networking 94

rob101 writes "The CSIRO yesterday demonstrated the world's 'fastest' wireless radio link by transmitting sixteen full quality DVD streams over a 250m link and only using a quarter of the available bandwidth. 'The CSIRO ICT Centre today announced that it has achieved over six gigabits per second over a point to point wireless connection with the highest efficiency (2.4bits/s/Hz) ever achieved for such a system.'" CSIRO hopes to double the speed of this connection in the future, pushing twelve gigabits a second.

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Side benefit (5, Funny)

quokkapox (847798) | more than 7 years ago | (#17159412)

You can pop your microwave popcorn by just holding it up between the router and the TV during the FBI warning.

Re:Side benefit (2, Funny)

feld (980784) | more than 7 years ago | (#17159436)

try not to burn the butter this time

Re:Side benefit (2, Interesting)

imaginaryelf (862886) | more than 7 years ago | (#17159642)

I know you're just joking, but to clear up a common misconception, your microwave oven operates at 2.5GHz, which is why it interferes with current wifi stuff.

This technology operates at 85GHz, which is still in the microwave/radar band of the EM spectrum, so it's likely to interfere with radars.

Interferes with Radar? (1)

downhole (831621) | more than 7 years ago | (#17163326)

I've got it! The whole thing is really a plot by the MPAA. They want to be able to conduct airstrikes on your house while you're watching your pirated movies, so the made a wireless technology that will jam your radar while seeming to make it easier to watch the movies. Clever bastards...

Re:Side benefit (1)

Beryllium Sphere(tm) (193358) | more than 7 years ago | (#17164654)

Indeed, most radars are still lower than that. The W band is home to some cloud-studying radars and not much else.

Re:Side benefit (-1, Flamebait)

Anonymous Coward | more than 7 years ago | (#17159952)

I hope your mom dies.

Re:Side benefit (0)

dch24 (904899) | more than 7 years ago | (#17160726)

Sounds like flamebait to me.

Can't wait... (1)

Wizard052 (1003511) | more than 7 years ago | (#17159426)

...to get my new cellphone with the new network that uses this awesome technology!

Only to realise that the extremely high frequency is ionizing my head, and to make and receive my calls I use up all of 1 hundredth of its power.

That is progress indeed.

Funny, but misses the point. (4, Informative)

TapeCutter (624760) | more than 7 years ago | (#17159518)

Australia's network covers huge areas with a spare population, it uses radio and/or sattelite links to link remote exchanges to the trunk. During the late 90's I had extensive experience with an Australian wide mobile application, back then the radio links had a 2500 baud connection. Arguing about service to the bush is a political constant that hasn't changed in the last few decades.

Opps, hic, taxi!!! (1)

TapeCutter (624760) | more than 7 years ago | (#17160512)

That should read "sparse population", and "2400 baud" (aka, honey from the fridge).

Re:Can't wait... (3, Interesting)

jmv (93421) | more than 7 years ago | (#17159688)

Only to realise that the extremely high frequency is ionizing my head...

Actually, I wouldn't worry about ionizing radiation [wikipedia.org] as those only start at frequencies above visible light.

Re:Can't wait... (0)

Anonymous Coward | more than 7 years ago | (#17166728)

The Frequency wouldn't ionize your head. The power (dB)eminating from the atenna's might though.

Terminology (5, Funny)

nacturation (646836) | more than 7 years ago | (#17159454)

Sorry, I just don't understand this DVD streaming thing. Can someone translate this into Libraries of Congress per second?
 

Re:Terminology (-1, Troll)

Anonymous Coward | more than 7 years ago | (#17159482)

omg, this is so drunk. (I am really funny).

Re:Terminology (2, Informative)

Ryuu (742860) | more than 7 years ago | (#17159498)

Can someone translate this into Libraries of Congress per second?
Approximately 0.00003662109375 LOC/sec.

Re:Terminology (0)

Anonymous Coward | more than 7 years ago | (#17159594)

Well, unlike the Libraries of Congress analogies, their demo really did stream 16 DVDs at a time. It always makes a more impressive demo than "See this LED flashing 6 billion times per second?" or "See the bit-rate printed on the last line of this xterm?".

Re:Terminology (2, Interesting)

BigZaphod (12942) | more than 7 years ago | (#17159648)

Well, according to one page I found, the Library of Congress is (was?) around 10 Terabytes. Google says that equals 83,886,080 Megabits. Wikipedia says that DVD video can run at 9.8 Megabits/second using MPEG-2. So, my calculation is: (9.8 * 16) / 83886080 = 0.00000186920166 LOC/s. (Here's hoping I didn't make some stupid 2:30am math mistake here... :))

Re:Terminology (2, Informative)

Ryuu (742860) | more than 7 years ago | (#17159708)

Well, the result I found was 20 TB for the books (163840 gigabits) and they said in the article it was 6Gb/sec, so 6/163840=0.00003662109375 LOC/sec.

Re:Terminology (1)

BigZaphod (12942) | more than 7 years ago | (#17159924)

That's the problem with LOC/s... it's a moving target. :-) It reminds me of the era when measurements were based off the king's physical body. Like, the length of his foot might be a "foot" until he got replaced by a different king. Etc.

In any case, that 10TB number I found seemed a bit small and the page looked sort of old. So it's probably not very accurate - but that wasn't really the point. I hadn't looked at the article yet, either, and decided it'd be more fun to base it almost entirely on the bogus "16 DVDs" comment. Seemed appropriate given the silliness of using the Library of Congress as a measure in the first place. :-)

Re:Terminology (0)

Anonymous Coward | more than 7 years ago | (#17162376)

It reminds me of the era when measurements were based off the king's physical body. Like, the length of his foot might be a "foot" until he got replaced by a different king. Etc.

The mind boggles at the concept of a king running around all day measuring things out by pacing them off. How did any laws manage to get passed?

(grin)

Re:Terminology (1)

JohnFluxx (413620) | more than 7 years ago | (#17160402)

Good grief, there's 3 answers so far and all use 2 significant figures for their data, yet quote the answer around 10 significant figures!

Re: Significant figures (1)

Bozdune (68800) | more than 7 years ago | (#17161066)

"...all use 2 significant figures for their data, yet quote the answer around 10 significant figures!"

Which is why slide rules ought to be used in introductory science classes, not calculators. Slide rule use does two things: 1) enforces a basic understanding of significant figures, and 2) creates an ability to quickly calculate order of magnitude and therefore to quickly dismiss solutions that cannot possibly be correct.

However, I suspect that the parent posters know all of the above, and that this is just "cut and paste from the calculator" laziness. We're all guilty of it.

Re:Terminology (1)

scdeimos (632778) | more than 7 years ago | (#17169760)

How about 36.62 uLOC/sec?

(Sure would be nice if ampersand-mu or ampersand-#956 worked on /.)

Re:Terminology (1)

1310nm (687270) | more than 7 years ago | (#17159796)

Well, they do have an EWS (Entire Works of Shakespeare) reference available in TFA for you - the earliest known bandwidth calculator, dating as far back as the Renaissance Period, when RFC 1149 was in its infancy.

I always wondered why the rate of DVDs / t is used as a way of conveying bandwidth developments to the public. It's kind of a tease, as though there will be some point at which it will be legal to stream DVD-quality video in some way without giving up all your rights or paying more for the right to do so than the service carrying your bitstream.

Why don't we ever get more information with these reports, such as latency and tests at different MTUs and all that good stuff that might actually make these superficial tests meaningful to network engineers?

Re:Terminology (1)

James McGuigan (852772) | more than 7 years ago | (#17160196)

How about a wireless TV cable, between your set-top box/DVD player and your TV(s).

The MPAA may ask that this link be heavily encrypted, but it will make a nice CS hobby project in trying to decrypt it.

MPAA Warning (0)

Anonymous Coward | more than 7 years ago | (#17161010)

Wasn't this really the demonstration of the Fastest Violation ever of the DMCA over a Wireless connection? ...and 16 movie copyrights broken at the same time!

Ugh! (1, Interesting)

lordvalrole (886029) | more than 7 years ago | (#17159470)

I swear, none of this technology ever sees the light of day to the public. It is just astounding on how much bullshit that goes around in this country because of big business models. Something amazing like this should be rolled out everywhere. Even if this stuff costs a crap load atleast it is better spent on the public than a shitty ass war. It is nice to know US tax dollars go out the window where it could be actually funding programs like this and help roll out this tech. to communities. We have such a big business mindset in America that we end up going into tunnel vision.

I think I am frustrated paying $40 for a crappy Verizon connection that peaks about 120k/s and when I am actually downloading something and trying to browse the web, it ends up being slower than 56k.

This is a great achievement but it wont see the light of day in a very very long time if ever. (maybe our government will use it but not us)

Re:Ugh! (3, Insightful)

Anonymous Coward | more than 7 years ago | (#17159504)

I assume that you're speaking in general, but I would like to point out that the CSIRO (Commonwealth Serum and Industrial Research Organisation) is throwing Australian -- not US -- taxpayer's dollars out the window.

Re:Ugh! (1, Informative)

Anonymous Coward | more than 7 years ago | (#17159826)

CSIRO == Commonwealth Scientific and Industrial Research Organisation,.. and it does really good work, and provides more than the average bang for the buck. If only US companies would pay for using patented technologies the CSIRO develops Australia would have an even greater return on investment, or even more practical research to aid industry in Australia, and in turn the world.

Re:Ugh! (0)

Anonymous Coward | more than 7 years ago | (#17159890)

It's Commonwealth Semen and Infertility Research Organisation

Re:Ugh! (3, Interesting)

TapeCutter (624760) | more than 7 years ago | (#17160738)

Radio comms has been a productive area of reasearch at CSIRO for decades. Politicians who ignore them are the ones who waste MY tax dollars. There are many examples that defend the CSIRO's enviable reputation for genuine science without political "fear or favour", ie a "model public service" (as opposed to the non-existant "perfected public service" or the ever present "public propoganda service").

To give an example of just one "public service": The CSIRO were the first to demonstrate to the world that radiation from atmoshperic testing of nukes was ending up as plutonium and other RA trace elements in childrens bones (MY bones considering the era). They found out by starting with an agricultural study into sheep near an Australian test site run by the Brit's and found the bombs were adding to a rapidly growing planet wide "haze" of radioactive dust.

Obviously they were not popular with the politicians of the day when their extrodinary claim was promptly backed with extrodinary evidence.

Re:Ugh! (1)

jonpry_oneword (317500) | more than 7 years ago | (#17159522)

Maybe they can buy everybody porsche's too.

Re:Ugh! (5, Informative)

phrasebook (740834) | more than 7 years ago | (#17159570)

CSIRO is Australian.

Your country does indeed take this sort of technology, and doesn't like to honour the patents [slashdot.org] on it either! So stop complaining.

Re:Ugh! (0)

lordvalrole (886029) | more than 7 years ago | (#17160278)

Yes I understand it is Australian and you completely missed my point.

It doesn't matter which country technology comes from it should be implemented into society. And excuse me I am going to complain because America actually gets the shit end of a lot of technology. The sad thing is that a lot of America doesn't know or doesn't care with the system we have today. So it ends up being fucked over by retards in Congress who make laws that not only affect the US but other countries as well.

Re:Ugh! (0)

Anonymous Coward | more than 7 years ago | (#17166222)

Honour isn't even a word! How could we possibly do that?!!?!!

Re:Ugh! (0)

Anonymous Coward | more than 7 years ago | (#17169822)

Honour [reference.com] is English, baka. Why should the rest of the world have to compensate for lazy Americans who drop letters from words just for the sake of convenience. (Colour is another of my favourite annoyances, too.)

Re:Ugh! (1)

desplesda (742182) | more than 7 years ago | (#17159624)

CSIRO is an Australian research organisation. The US government has nothing to do with it, and your tax dollars are not involved.

Re:Ugh! (2, Informative)

Anonymous Coward | more than 7 years ago | (#17159636)

Actually, the reason you won't have that at home is that it operates at 85 GHz, so it's only useful for line of sight communication. Think next-generation microwave towers, not WLAN.

Re:Ugh! (0)

Anonymous Coward | more than 7 years ago | (#17162488)

If you're limited by line of sight, why not just use lasers?

Re:Ugh! (0)

Anonymous Coward | more than 7 years ago | (#17162884)

IIRC, 85GHz is also used in RF crowd pacifier technology. Although US DND claims that it is relativley harmless form the number of surveys done, I'm not very excited about excessive RF radiation in that frequency band, as skin absorbs it very well.

How many tax dollars? (1)

TapeCutter (624760) | more than 7 years ago | (#17170750)

Like everyone else has said CSIRO is The Aussie science agency (capital 'T' since many countries have multiple agencies). However since I support my tax dollars going to CSIRO I wondered how many $ are going there? A quick check on the site supports their reputation for transparency and provides some numbers.

Total Income (including tax $'s): $929M Income from tax $'s: $250M ($12.50 per Aussie) Total expenditure: $947M Total Equity: $1126M

Not everyone is a taxpayer and many taxpayers would rather spend the money on public firework displays or a packet of smokes, personally I think it is worth more than my ~$50/year.

Rare, example of tech patents working (5, Insightful)

pingbot (1037186) | more than 7 years ago | (#17159530)

Remember this the Australian Government research organisation that has been defending there early 802.11a/g wireless patents against some mighty companies corps who want to avoid paying there dues http://www.theage.com.au/news/wireless--broadband/ csiro-wins-landmark-legal-battle/2006/11/15/116326 6614119.html [theage.com.au] .

Heartening to know the licence fees are not just going to the lawyers (something they have received some flack for in Aus), but getting invested in more research. More power to them I say.

Re:Rare, example of tech patents working (2, Interesting)

AlanS2002 (580378) | more than 7 years ago | (#17159838)

It's also a extremely good counter example to the small government argument that the private sector can always do anything better/more efficiently.

Re:Rare, example of tech patents working (1)

cperciva (102828) | more than 7 years ago | (#17160064)

This isn't really an example of patents working: The idea behind patents is that a guaranteed monopoly will encourage people to do and publish research, not to provide funding to people who have done good research in the hope that they will continue to do more good research.

A better example of patents working would be if CSIRO said "we're doing this because we think we can make money by patenting it".

Re:Rare, example of tech patents working (1)

TapeCutter (624760) | more than 7 years ago | (#17170564)

"A better example of patents working would be if CSIRO said "we're doing this because we think we can make money by patenting it"."

They have been around for nearly a century, they have "lost" heaps by under-selling or giving patents away (particularly in the area of drug research). In the 80's there was a drive to get more "value" from their inventions and they are a bit wiser in that area now. However the CSIRO is still a "public service" (and a good one at that), similar to NASA and other US agencies it's aim is not to be self-funding but they do realise there is a buck to made and are less inclined to "throw things away" these days.

It's stated purpose is to..."Deliver great science and innovative solutions for industry, society and the environment." Note it says nothing about profit or cost, however it has grown into one of the largest and most diverse scientific agencies on earth. As a political statement it is a prime conter-example to the false notion that capitalism and socialisim are two sides of a binary choice.

PS: If you want a entertaining insight into the CSIRO, there is an excellent movie called "The Dish".

Re:Rare, example of tech patents working (1, Interesting)

Anonymous Coward | more than 7 years ago | (#17160418)

The irony is that the CSIRO is in the red on this one. So far their legal fees trying to defend the 802.11 patent substantially exceed their receipts. There is quite a bit of controversy with claims that the legal battle is draining research funds. Thus even this rare example is broken.

(2.4bits/s/Hz)? (1)

rootEToTheIPi (937469) | more than 7 years ago | (#17159672)

(2.4bits/s/Hz)
bits per second per hertz? Wouldn't that just be bits?

Re:(2.4bits/s/Hz)? (3, Informative)

John Miles (108215) | more than 7 years ago | (#17159744)

A "hertz" is a cycle per second, so what they're really saying is that they're getting 2.4 bits per cycle of the carrier. I agree that bits/sec/Hz is a ridiculous term for someone to have made up, but they would probably justify it by pointing out that there's not just one effective "carrier" in a modern modulation scheme.

In any event 2.4 bits/s/Hz is nothing special, unless it applies to individual subcarriers in an OFDM-like scheme. 802.11g sends 54 MB/sec in a channel about 20 MHz wide, for a bandwidth efficiency of 2.7 bits/second/Hz. Sounds like they basically threw a metric assload of RF bandwidth at the problem (another technical term found in relatively-few EE textbooks).

Re:(2.4bits/s/Hz)? (2, Informative)

squizzar (1031726) | more than 7 years ago | (#17160192)

I might be wrong, radio comms stuff is not a strong area of mine, but I thought the intention of numbers such as these was to provide a view of the efficiency of the system. For example a QAM system gets 4 bits per cycle, 64-QAM gets, well, 64 (I think it's used in DVB broadcasts in the UK, don't know about elsewhere).

As the amount of information per cycle goes up, the risk of noise and corruption increases, since they have a more significant effect on the signal. Seeing as there is usually a fixed frequency band to work with, then it is necessary to increase the number of bits/cycle in order to increase the throughput.

It sort of reminds me of the clocks per instruction measure for cpus.

Re:(2.4bits/s/Hz)? (1, Informative)

Anonymous Coward | more than 7 years ago | (#17161742)

For example a QAM system gets 4 bits per cycle, 64-QAM gets, well, 64

Not so fast, you're forgetting a logarithm (base 2) here: 1 bit gives 2 possible values, 2 bits give 4 distinct combinations etc...
So QAM, using 4 distinct phases of the carrier transmits 2 bits per cycle. 64-QAM requires you to distinguish between 64 different possibilities for each cycle, and that gets you 6 bits. Whether it is actually possible to distinguish the different possibilities depends on the signal-to-noise ratio.

Re:(2.4bits/s/Hz)? (0)

Anonymous Coward | more than 7 years ago | (#17160830)

I don't believe that saying they mean bits per cycle of the carrier is correct. I believe its as you mention later, it's bits/sec per each Hz available in the channel width. This is frequency domain stuff, not more than one carrier as you suggest. In this case, the speed increases as the width of the channel does.

Re:(2.4bits/s/Hz)? (1)

cnettel (836611) | more than 7 years ago | (#17160834)

802.11g is 54 Mbit, not 54 MB/s. Your calculation seems to be based on the latter. That means that this technology is a significant improvement, while not something ground-shattering. (And, for those wondering, this would also beat 802.11n, but the margin gets thinner.)

Re:(2.4bits/s/Hz)? (1)

John Miles (108215) | more than 7 years ago | (#17166074)

(Sorry; I just hit the Shift key one time too many when typing 54 Mb/sec. The calculation is right but the 'M' is wrong.)

Re:(2.4bits/s/Hz)? (1)

John Miles (108215) | more than 7 years ago | (#17166902)

Er... the 'B' is wrong. Just, just... forget I said anything. :)

Re:(2.4bits/s/Hz)? (2, Interesting)

GrizlyAdams (999280) | more than 7 years ago | (#17159814)

Multiply the frequency of the channel being transmitted on by 2.4 and you get the bit rate. Supposing you were transmitting on 2.434 GHz you could get about 5.8 Gbit/s one way. at 85GHz thats 204 Gbit/s. Mind you this is not your actual sustainable data rate. You would likely be limited to 1/4th to 1/10th this by noise, packet overhead, latency issues, etc. A this kind of frequency anything getting in the line of site can kill your signal, of course, your signal can likely kill anything staying too long in the beam as well. I don't really even understand how you can encode 2.4 bits per Hz, cause thats a bit much data to be packing into a single oscillation.
Disclaimer: I am not a HAM, or anything approaching an EE, just someone who likes math / science.

Re:(2.4bits/s/Hz)? (3, Informative)

Anonymous Coward | more than 7 years ago | (#17159870)

No, not the frequency of the channel - the width of the channel.
Look up the Shannon-Hartley theorem on Wikipedia for some context. It establishes the theoretical maximum capacity given the signal to noise ration and the width of the channel.

Re:(2.4bits/s/Hz)? (1, Informative)

Anonymous Coward | more than 7 years ago | (#17159908)

That's bits per second per Hertz of BANDWIDTH, not transmission frequency. Or at least it better be, because that's the only thing which makes any sense to consider (the carrier frequency has no bearing on the data rate).

No, no, no NO!!!! (4, Informative)

Andy Dodd (701) | more than 7 years ago | (#17160864)

God, I wish there were a -5 "Totally Wrong" moderation.

Carrier frequency has nothing to do with how much information a channel can carry. Channel bandwidth (spectrum used on each side of the carrier frequency) is what matters.

For example, a 6 MHz channel at 450 MHz and one at around 800 MHz have the exact same channel capacity (assuming that the SNR at the receiver is the same on each channel.)

To be specific, the formula for maximum channel capacity of a communications channel is given by Shannon's Law:
C = W log (1 + Eb/No), where Eb/No is the signal to noise ratio of the channel and W is the channel bandwidth.

Maximum C for a given SNR and W (or minimum SNR for a given C and W) is not achievable in practice, but recent advances in error control coding techniques such as LDPC and turbo codes have allowed people to get to within just 1 dB of the minimum SNR for a few years. (And yes, this technology is in cell phones. If I recall correctly, turbo codes are used on some cell phone downlinks when transmitting image data that is not latency-sensitive. Unfortunately both turbo codes and LDPC both introduce pretty high latency to a communications system.

2.4 bits/sec/Hz is nothing new. As others have pointed out, plenty of other systems have been doing this for quite some time.
Cable modems - I believe the DOCSIS maximum limit is 36 Mbits/sec over a 6 MHz channel. 6 bits/sec/Hz - the nice thing about cable distribution is that the inverse square law goes bye bye and high SNRs are easily achievable.
ATSC digital television - 8VSB provides 19.2 mbits/sec over a 6 MHz channel. Just over 3 bits/sec/Hz over relatively long free-space distances, although transmitter power is measured in kilowatts.

There isn't really enough information to figure out exactly what they did, but it looks like the CSIRO people just threw a massive amount of channel bandwidth at the problem. 2.4 bits/sec/Hz means their SNR was not that high.

BTW, yes, it IS true that at higher carrier frequencies, there is more free spectrum available to use wider channels, but there is no direct link between carrier frequency and channel capacity as you claim.

Re:No, no, no NO!!!! (1)

expatriot (903070) | more than 7 years ago | (#17164472)

To be fair, there is some relationship, so maybe it is only -3 Totally Wrong
You can't have 2MHz of bandwidth on a 100Hz center frequency. It would be more correct to say in this case that the center frequency is somewhere around 1MHz.
As you increase the information content by modulating the carrier, the channel bandwidth increases. The AM, FM, or phase modulation creates sidebands.
The main reason higher carrier frequencies are used is so that it is easier to create large bandwidths. (I know that this is a generalization with lots of exceptions, but due to practicalities in circuit design, it is easier to get 50M baud over a 100MHz carrier than it is on a 10MHz carrier.)

Re:No, no, no NO!!!! (1)

Andy Dodd (701) | more than 7 years ago | (#17166000)

Well, I did mention that in my post - "BTW, yes, it IS true that at higher carrier frequencies, there is more free spectrum available to use wider channels, but there is no direct link between carrier frequency and channel capacity as you claim."

In addition to there being more free spectrum, it's also true that many aspects of transmitter and receiver construction become more difficult as the ratio of bandwidth to carrier frequency increases. i.e. an antenna covering 1 GHz of bandwidth with a 2 GHz carrier frequency would be rather difficult (without the antenna being severely nonoptimal for its size at any part of the covered frequency range), while 1 GHz bandwidth with a 50 GHz carrier is much easier.

As others have said, 2.4 bits/sec/Hz isn't particularly amazing, although that number implies over 2 GHz of actual channel bandwidth for a 6 gigabit/sec channel, which IS rather impressive, if only for the fact that a receiver for that signal would have to do baseband processing of at least 4-5 gigasamples/sec of data (2x the channel bandwidth at a minimum), and a 4-5 gigasample/sec ADC is no small feat, neither is the processing power needed to deal with the output of that ADC. It's not something that we will see any time soon in the real world though - any part of the RF spectrum below 10-20 GHz is too crowded to have routine usage of a communications system with 2 GHz of raw channel bandwidth, and above those frequencies you start running into severe line of sight restrictions and high path losses due to water absorption in the air. Not too big of a problem for point-to-point links with fixed high-gain antennas, but a big problem for mobile devices, and mobile devices are the future of wireless. (In my opinion, freespace optical and/or plain old optical fiber buried in the ground are far better options for fixed point-to-point links.)

Re:No, no, no NO!!!! (1)

elgatozorbas (783538) | more than 7 years ago | (#17165606)

2.4 bits/sec/Hz is nothing new

Indeed, to digital communications people this is nothing special. Moreover: it is rather meaningless to say how many bits/s/Hz you get without any mention of distance, power or SNR (signal to noise ratio). I don't think the achievement has anything to do with clever modulation techniques, just with the large bandwidth emerging from just one transmitter. Just like a 1000 ton car consuming 1000 liters of fuel per km is no great technological achievement (in terms of theoretical efficiency), but a 1000 car would be the biggest ever made and not easy to construct.

Re:No, no, no NO!!!! (1)

GrizlyAdams (999280) | more than 7 years ago | (#17168408)

Like I said, I'm not an EE or HAM. I didn't even think about the channel bandwidth, thank you for pointing that out.
If you managed to have a 2.5GHz channel bandwidth at 2.4bits/s/Hz that would be the ~6 gigabit/s they claimed as data throughput. At 85GHz that would be from 83.75GHz - 86.25GHz.

Re:(2.4bits/s/Hz)? (1)

Idbar (1034346) | more than 7 years ago | (#17161666)

In a digital communication system you transmit symbols instead of bits, that is to take advantage of your bandwidth. For example, on your carrier of 2.4GHz you are allowed to use only a band of frequency, and you want to transmit the higher amount of data per second as possible, so you might thing about transmitting sinusoids of 128 different amplitudes (in the physical part) and that could represent 128 different symbols. You are not transmitting binary (only 2 amplitudes) and consequently, you have a more efficient system.

Unluckily, that doesn't always work, and in fact many systems decide to use less than one bit in order to avoid other several problems like ISI (Inter-Symbol interference) which is, in the case of wireless, the effect of reflections against walls, etc.

So many wireless systems use suboptimal (in terms of symbols) to achieve longer distances or reduce interference due to moving objects, etc. That is why a modulation system can be expressed in terms of bits/sec/Hz and it's in some sense a measure of efficiency of the system, however, an interference study has to be performed, and for sure it will be tough getting long distances if there is not a good coding scheme to avoid the ISI.

In conclusion, not everything is attenuation, but also reflections and systems have to be robust to these effects.

Can somebody please tell me? (0, Redundant)

warrior_s (881715) | more than 7 years ago | (#17159696)

What was the link capacity in xxx Gbps or Mbps ?

Re:Can somebody please tell me? (1)

HazE_nMe (793041) | more than 7 years ago | (#17159782)

CSIRO hopes to double the speed of this connection in the future, pushing twelve gigabits a second.
From the sounds of it ~6Gbps

Re:Can somebody please tell me? (1)

tpgp (48001) | more than 7 years ago | (#17159868)

What was the link capacity in xxx Gbps or Mbps ?

Perhaps read the first sentence of the article? (six gigabits per second)

Useless description of speed (0)

Anonymous Coward | more than 7 years ago | (#17159800)

"transmitting sixteen full quality DVD streams over a 250m link and only using a quarter of the available bandwidth"

Without a time scale, this is a totally useless description to give any feel of the speed.

Re:Useless description of speed (1, Insightful)

Anonymous Coward | more than 7 years ago | (#17159888)

The data was streaming so there is no requirement for a timescale.

Shannon (0)

Anonymous Coward | more than 7 years ago | (#17159880)

Am I missing something or 2.4bits/s/Hz packs 2.4 bits on each cycle of the carrier? Doesn't the carrier freq needs to be > 2 times the data per Shannon?

So, unless using some sort of compression on the data prior to transmission, what's the trick?

Re:Shannon (0)

Anonymous Coward | more than 7 years ago | (#17160324)

No, just look at your standard telephone modem. On a 300Hz to 3kHz channel they get 56kb/s worth of bandwidth. They do things like phase offset to achieve these rates. I wish I could explain more but it's been almost 10 years since I learned this stuff...

Willy

Re:Shannon (4, Informative)

Andy Dodd (701) | more than 7 years ago | (#17161094)

"Doesn't the carrier freq needs to be > 2 times the data per Shannon?"
No, that's Nyquist sampling. To sample an analog signal without aliasing, the sampling rate needs to be 2x the bandwidth of the input signal. Doesn't directly apply here, although it does govern how fast a receiver ADC must be for a software defined radio. NOTE: Carrier frequency does not impose any requirements on the ADC, only channel bandwidth. i.e. an ATSC digital television signal needs at least a 12 MHz sampling rate to be properly sampled, as it is approximately 6 MHz wide regardless of channel carrier frequency.

Shannon's Law states:
C = W log (1 + SNR)

C = channel capacity
W = channel bandwidth
SNR = signal to noise ratio of the channel

Thus, achieving 2.4 bits/sec/Hz is easy - just increase your transmit power or your channel gain to increase SNR. This is why cable modems easily achieve 6 bits/sec/Hz (DOCSIS upper limit is 36 Mbits/sec over a 6 MHz channel, any lower speed is an artificial cap from your provider) - when you are transmitting over a cable instead of free space, losses are (comparatively) low and hence high SNRs are not difficult to achieve.

In this case, it appears the CSIRO guys just threw a lot of bandwidth at the problem (large W).

Easier said than done in the real world. Fixed point-to-point links are easy (directional antennas reduce multipath significantly, what multipath does remain does not change rapidly so requires little receiver processing power to estimate and compensate for.) Mobile environments with rapidly changing high amounts of multipath are where the real challenges are, and thanks to Moore's Law, technology is growing by leaps and bounds in this regard. Error correction techniques known since the 1960s but not implementable until recently (such as LDPC) are now in regular use thanks to increased computing power.

Re:Shannon (0)

Anonymous Coward | more than 7 years ago | (#17187238)

"In this case, it appears the CSIRO guys just threw a lot of bandwidth at the problem (large W)."

Yes, a few people have said this. They did throw a lot of bandwidth at the problem - but its not like thats an easy thing to do.

Although the power can be increased rather than the bandwidth to increase the data rate, there is a diminishing gain in data rate since the Shannon capacity of the channel increases logarithmically with the added power. Nonlinear amplifier effects stop you pumping through as much power as you would like.

The achievement here is that they were able to pump out a lot of power over a very large bandwidth.
Bandwidth = Data rate (bits/s) / Spectral efficiency (bits/s/Hz) = 2.5GHz. Thats 125 times the bandwidth of a 20MHz 802.11a/b/g device! (Note that the comparison with Wireless LAN devices is not fair as they are required to work under multipath, delay-spread channels whereas a point-to-point link is not).

The amplifiers must be pumping out a lot of power at very high frequencies (60-80ish GHz?), over a large bandwidth, without nonlinear effects. Also, although the spectral efficiency is not remarkable, we don't the SNR the system is running at, so it would be unfair to say there is much innovation here in terms of coding or modulation. Besides it would only mean there is more room to improve before they reach the Shannon limit.

On top of this, there must also be some fairly fancy digital modem hardware to pump all that data through.

Tell me when it hit's five times that speed (0)

Anonymous Coward | more than 7 years ago | (#17159904)

........that's the speed at which I like my p0rn

Old news! (1)

Xhris (97992) | more than 7 years ago | (#17160076)

This is old news - it was demonstrated (at least privately) two days ago, not yesterday!!!!

Unfortunately I missed my only chance of slashdot fame by deciding to drink beer at our staff Christmas party rather than witness the demonstration. Oh well

Re:Old news! (1)

allrong (445675) | more than 7 years ago | (#17160284)

It was quite impressive, though the heat generated by the demo PC's caused a few problems in a neighbouring server room. I also submitted the story yesterday (once the press release was made public) and it was rejected.

Wow, finally a technology.... (3, Funny)

jocks (56885) | more than 7 years ago | (#17160172)

....that will keep Windows Vista patched in real time!

Sometimes you forget to think 'wow!' (2, Insightful)

clickclickdrone (964164) | more than 7 years ago | (#17160556)

Back in 1989 I had a 48Mb SCSI hard drive on my Atari ST. That loaded files at 350k/sec. That was fast back then.
Now we have data going through the air at 6Gb/sec. It's all too easy to get used to the steady stream of new stuff but every now and then you need to stop, think about how much has changed in the last 15 years or so and think.. 'Wow!'

Re:Sometimes you forget to think 'wow!' (1)

clickclickdrone (964164) | more than 7 years ago | (#17160564)

It's also all too easy to forget to close the bold tag and not bother to preview. Sheesh. God job it's Friday.

Re:Sometimes you forget to think 'wow!' (1)

Threni (635302) | more than 7 years ago | (#17160968)

And easy to forget your units. "350k/sec". 350,000 what? bits? Bytes? Underpowered Amiga competitors?

Only a quarter of the available bandwidth... (3, Funny)

Xolom (989077) | more than 7 years ago | (#17160566)

why don't they try using the rest?

Re:Only a quarter of the available bandwidth... (2, Funny)

Hanners1979 (959741) | more than 7 years ago | (#17160838)

By the time they'd finished starting up the 16th DVD stream, the MPAA were hammering on the door...

Re:Only a quarter of the available bandwidth... (3, Interesting)

jmv (93421) | more than 7 years ago | (#17161088)

Cost of the LCD screens. I'm not joking.

Re:Only a quarter of the available bandwidth... (1)

sharkey (16670) | more than 7 years ago | (#17161678)

Because the resulting 24Gbps would make their stated goal of reaching 12Gbps seem kind of pointless to fund.

Re:Only a quarter of the available bandwidth... (1)

Chris Shannon (897827) | more than 7 years ago | (#17164118)

I thought about that too. An RF channel isn't a perfect window in frequency. The further you put your information from the carrier frequency, the more distorted it becomes. This is mostly due to non-linear components. My guess is that the 3/4 of the bandwidth that they didn't use offers too much distortion or loss. Diminishing returns kicks in the further you get from the centre frequency. The marketing people would rather let the reader extrapolate the results. "Wow, if they used the whole bandwidth, they'd get 4 times the rate."
I'm sure if they could use the whole bandwidth, they would have.

Re:Only a quarter of the available bandwidth... (1)

PurifyYourMind (776223) | more than 7 years ago | (#17166476)

I know you're just joking, but blah blah blah +5 insightful.

And Still... (0, Redundant)

sycodon (149926) | more than 7 years ago | (#17161146)

...my Windows XP box takes 15 seconds to show me what is in a folder.

Data Gravity (1)

Doc Ruby (173196) | more than 7 years ago | (#17161556)

What's happening at a rate of "b:s:Hz"? "b:s", or bps, is a rate of data transmission. "b:Hz" is a rate of data processing, like the typical 0.5b:Hz CPU performance on a fixed clock. b:s:Hz sounds like the acceleration of bits on a clock, as if the last bit travels faster than the first after the system runs a while.

Does this fiber have to warm up like my old B&W TV?

Re:Data Gravity (1, Insightful)

Anonymous Coward | more than 7 years ago | (#17162902)

Bits/second/Hertz is a measure of spectral efficiency [wikipedia.org] .

In other words, since they say their spectral efficiency is 2.4b/s/Hz and their link rate is 6 Gb/s, their system must use 2.5GHz of RF spectrum to accomplish that. The article says the system operates at 85GHz, so technically it probably emits energy along the entire range from 83.75GHz to 86.25GHz, assuming the bandwidth is centered at 85GHz.

Also, this is wireless technology, not fiber, although that doesn't affect the above.

Re:Data Gravity (1)

Doc Ruby (173196) | more than 7 years ago | (#17163652)

Ah, it's not Hz of actual cycles, it's Hz of literal bandwidth, simultaneously transmitted on multiple frequencies.

Too bad. I'd love to see a physical example of bits per second per second, data acceleration. Especially traveling at the constant speed of light.

Pshaww.... (2, Funny)

Quixote (154172) | more than 7 years ago | (#17162854)

Not to rain on their parade, but bear with me:
A DVD is 4.5GB (say). So 6Gb/s means a DVD can be transferred over the distance (250m) in 6 seconds.
In my backpack, I can put a 100 DVDs (a spindle). Assume I'm not in shape and can't carry more. I can walk the 250m in just over 4 minnutes (at a leisurely pace of 1m/s).
So if I carry my 100 DVDs the distance, I'll cover it in 250 seconds, which works out to a speed of 14.4 Gb/s, more than double of what these boffins are getting.

Never underestimate the bandwidth of a backpack full of DVDs....

Re:Pshaww.... (1)

catprog (849688) | more than 7 years ago | (#17168902)

What about burning speed?

Use a real datarate! (1)

tbcpp (797625) | more than 7 years ago | (#17165452)

What one earth is the datarate of a "full quality DVD?". Why not use a datarate everyone knows like "Library of Congresses per half day"?

What is really funny about this article... (0)

Anonymous Coward | more than 7 years ago | (#17169500)

... is that the CSIRO is the Australian Government Tech Labs, yet Australia has the slowest/most expensive broadband in the developed world. A result of too many years with our fat and lazy government sitting on their asses(arses).

http://www.smh.com.au/news/Business/Trujillo-agree s-broadband-a-disgrace/2006/11/29/1164476260911.ht ml [smh.com.au]
http://www.smh.com.au/articles/2006/12/05/11650809 44848.html [smh.com.au]

They fixed it (1)

Sivar (316343) | more than 7 years ago | (#17170470)

The article initially said:
"Multi-gigabit links operate at speeds that leave current wireless networks far behind. For example the entire works of Shakespeare could be transmitted over this six gigabit link in under seven thousandths of a second or a full DVD movie in just over three quarters of a second."

Oops. I think that the marketing people at a networking products company should get this kind of thing, above all else, correct. Especially when transmission speed is the focus of the announcement... :)
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