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German Scientists Achieve Record 100Gbps Via Wireless Data Link

timothy posted about 6 months ago | from the telefunken-junction dept.

Networking 67

Mark.JUK writes "A joint team of German scientists working at the Karlsruhe Institute of Technology (KIT) have successfully achieved a new world record for wireless data transfers. The team were able to transmit information at speeds of 100 Gigabits per second by using a radio network operating at the frequency of 237.5GHz and over a distance of 20 metres (note: a prior experiment hit 40Gbps over 1km between two skyscrapers). The radio signals were generated by a photon mixer device that uses two optical laser signals of different frequencies, which were then superimposed on a photodiode to create an electrical signal (237.5 GHz) that could be radiated via an antenna. But the team aren't happy with breaking one record and their future attempts will seek to break the 1 Terabit per second (Tbps) barrier."

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Thank you porn. (0)

Anonymous Coward | about 6 months ago | (#45131363)

Porn video streaming is behind most, if not all of our technical advancements.

Re:Thank you porn. (4, Funny)

nospam007 (722110) | about 6 months ago | (#45131719)

"Porn video streaming is behind most, if not all of our technical advancements."

I see, that must be why the router said 'It hurts when IP'.

That is a lot of... (0)

Anonymous Coward | about 6 months ago | (#45131389)

That is a lot of kinky German porn per second.

Speed? (2)

Arker (91948) | about 6 months ago | (#45131407)

So sick and tired of people equating bandwidth with speed. Is a tractor trailer faster than a Ferrari?

So what kind of ping do they get on this link?

Re: Speed? (0)

Anonymous Coward | about 6 months ago | (#45131439)

The actual wireless link will have lower latency than fibre. However iy is possible that the electronics used could introduce delay due to the extra processing however I doubt it would be a significant amount.

Re: Speed? (1)

gothzilla (676407) | about 6 months ago | (#45133343)

With this technology, latency will be the least of your issues. 237.5GHz is in the upper EHF range and have a very short range because they get blocked by pretty much everything from molecules in the air, smoke, fog, rain, snow, humidity, and physical objects like walls and trees. In areas with high humidity you'd be lucky to get a signal to travel more than 1km and you still need line of sight. You won't be replacing fiber with this anytime soon.

Re:Speed? (2)

Trepidity (597) | about 6 months ago | (#45131571)

Eh, it's a pretty colloquialism even in other parts of science to use "speed" to refer to a rate rather than only a velocity.

Re:Speed? (1)

ballpoint (192660) | about 6 months ago | (#45136361)

Expressing proper units and dimensions seem to be difficult for the layman, the press and even for the /. audience. mWh, MW or kW/h, it's all the same. And every time a car is moving at a high rate of speed, Newton rolls a few radians in his grave.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45136505)

Speed is the scalar component of velocity, with the angular part being commonly known as direction, heading or bearing.

Re:Speed? (2)

operagost (62405) | about 6 months ago | (#45131597)

Well, the latency is ultimately going to be limited to the speed at which electromagnetic waves propagate through air, which at the refraction index of 1.0003 hardly differs from the 3x10^8 in a vacuum. Most of the latency will be introduced through the processing, although if there is much that would be trivial to address. I doubt processing power will be a difficult problem.

Re:Speed? (4, Informative)

Arancaytar (966377) | about 6 months ago | (#45131601)

Electromagnetic waves through air propagate at approximately .9997c.

Re:Speed? (1)

Arker (91948) | about 6 months ago | (#45133185)

Do you work for microsoft?

Because that fit the classic microsoft pattern - technically correct, but unresponsive/not relevant.

The time spent in the transmission of the signal is only one (probably the smallest one) of many factors that add up to produce the latency of the link.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45135685)

At 100 Gbps every millisecond of delay requires 12.5 MB of buffering, so it's hard to imagine any reason to use a chip to buffer so much data during transmission, or to imagine any physical component that would do this naturally. I'm afraid the burden falls on you to substantiate your worry.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45140423)

Dude, that's less than 1x. Get on with the times, even my grandpa's DVD can do 16x.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45131605)

The speed of electromagnetic waves significantly faster through air (very nearly c) than trough fiber, in which the velocity is c divided by the refractive index, which is, if memory serves me right, about 1.45 for normal glass fibers.

Re:Speed? (2)

timeOday (582209) | about 6 months ago | (#45132111)

On a semi-related note, why is the latency of WiFi so sucky? I recently tried to mount an NFS home partition on a WiFi with 50 Mb tested throughput, and it was noticeably bad, to the point I broke down and ran a cable. Granted, it's a pretty sad network filesystem that performs so badly with 1-4 ms of latency. But even that is much more than wired... why? It's obviously not the flight time of radio waves over 30 feet. There shouldn't be too much re-transmission at the wireless protocol layers, for such a good connection. More importantly, is there some combination of OS, drivers, and wireless router that provide near-wired latency for WiFi?

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45132207)

It probably has to do with the CSMA-CA (the RTS/CTS packets) which is needed to make sure the spectrum is free at the receiver side.

Re:Speed? (1)

timeOday (582209) | about 6 months ago | (#45132229)

Full disclosure, I just remembered that it was a USB WiFi adapter on the client, which doesn't help latency any. Still, I have yet to use WiFi on any other computer that had near-wired ping times either...

Re:Speed? (1)

egcagrac0 (1410377) | about 6 months ago | (#45134965)

On a wire (or fiber), there is less contention for the available bandwidth. One device on each end of the string.

On WiFi, with everyone on channel 6, there can be interference and multiple devices having to wait their turn to talk.

Re:Speed? (1)

Arker (91948) | about 6 months ago | (#45133089)

It's a very good question. Often it has to do with obviously inferior/shoddy consumer electronics design, but even the better wireless hardware does still seem to impose significantly greater latency than an ethernet cable for the same distance, and even on the best of days.

On the worst of days, there is significant interference and that can cause a lot of retries and massive performance degradation, but that's a pile of different issues, whether sunspots or faulty wiring or the weather or whatever.

Re:Speed? (1)

ziggit (811520) | about 6 months ago | (#45133499)

If I'm not mistaken, WiFi has also traditionally been half duplex. This may have changed with some of the newer N stuff tho, I haven't really kept up. So that would definitely cause problems. That being said, if a half duplex link can kill NFS performance, I can only imagine what that would have been like in the days of thinnet.

Re:Speed? (1)

fatphil (181876) | about 6 months ago | (#45132131)

Are you trying to say that other RF comms technology is slower, but can carry more at the same time? Which wouldn't really stand up to much scrutiny at all.

A far better stupid analogy is to say that this is basically just the same as frisbeeing a dual layer DVD across a tennis court every 4 seconds.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45133415)

If you're transferring 100gb, that's 12,500MB/s, so 10ms of buffer is 125MB. So unless they have more than 125MB of buffer, the ping is probably 10ms or less.

Re:Speed? (1)

prefec2 (875483) | about 6 months ago | (#45133489)

The correct terms are throughput vs. response time. Throughput matters for many applications including video streaming. Only interactive applications, such as tele- or videophone require low ping rates, meaning low response time.

Re:Speed? (1)

Arker (91948) | about 6 months ago | (#45133905)

"The correct terms are throughput vs. response time"

Thank you. I actually misused 'bandwidth' egregiously in my initial post and I am shocked no one has flamed me for it yet, but at least you pointed it out, if indirectly.

Throughput just doesnt equate to 'speed' even approximately though. Response time (latency) does so it's hardly unreasonable of me to point out that marketing has no idea what they are talking about. Preserving the language of Shakespeare from these cretins is in everyones interest.

"Throughput matters for many applications including video streaming."

Yes, it does. But that doesnt mean it is accurately characterized as 'speed.'

"Only interactive applications, such as tele- or videophone require low ping rates, meaning low response time."

Eh, not really true. Those are typically the applications where you see the effect first, but latency matters in all kinds of applications. Excessive latency can have all kinds of negative effects, including effectively destroying your available throughput (look up TCP windowing and buffer bloat.)

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45134035)

You are right. I did not mean response time is unimportant, but the area of synchronous communication requires really low latency, while web-servers would work fine with up to 1 sec. However, the database behind the web-server together with all used services must be faster than that.

Re:Speed? (1)

wagnerrp (1305589) | about 6 months ago | (#45134081)

Low latency matters considerably depending on the type of protocol you're using. If you have any kind of congestion control, which you should always have unless you're using a fixed bandwidth dedicated link from end to end, high latency will cause some serious problems as soon as you start dropping data.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45135171)

Nice to find that there are some people who understand speed = latency and bandwidth = amount.

Of course if added with clock, wider bandwidth moves same amount data faster than narrower bandwidth but wider data transfer isn't faster than narrower data transfer.

Re:Speed? (0)

Anonymous Coward | about 6 months ago | (#45140387)

So sick and tired of people equating bandwidth with speed. Is a tractor trailer faster than a Ferrari?

Well, if the relevant task is transporting freight, yes it is. Which vehicle will transport sacks of sand *faster* from city A to city B? Here "speed" is defined as sacks transported per unit time (not distance over time). Technically the Ferrari transports them "faster", as each individual sack will travel at a higher speed. That is correct, but irrelevant. If your boss tells you to "transport those sacks of sand to city X as fast as possible" I suggest you do not use a Ferrari. You'd be a very technically correct unemployed.

Re:Speed? (1)

Arker (91948) | about 6 months ago | (#45147133)

So you are saying that bulk freight is faster than overnight air? Come now.

Obviously there can be tradeoffs between wide pipes and fast pipes for different applications. If you are trying to move a large number of sandbags across the country and speed is less important, you want bulk freight. But not because it's "faster."

Damn it. (4, Funny)

fuzzyfuzzyfungus (1223518) | about 6 months ago | (#45131427)

Oh for the days when our German scientists where better than their German scientists. Truly a golden age for American Innovation.

Re:Damn it. (1)

atomicxblue (1077017) | about 6 months ago | (#45131515)

Even our movie stars were inventing the beginnings of wireless networks.

Re:Damn it. (2)

weav (158099) | about 6 months ago | (#45131639)

You talking about Hedy Lamarr here?

Re:Damn it. (1)

Anonymous Coward | about 6 months ago | (#45131907)

Who was, of course, one of our German actresses (actually, Austrian, but the countries are very closely associated...)

The Americans owe a lot to the Europeans. I seem to recall that the Brits gave us the Jet engine, Radar, Sonar and the start of the Atomic Bomb project (Tube Alloys, which changed into the Manhattan Project) during the war.

They tried to give us the Convoy System as well, but our admiral hated the Brits so much he preferred to have American ships sunk by U-Boats rather than take British advice....

Re:Damn it. (0)

Anonymous Coward | about 6 months ago | (#45132663)

Most Americans ARE Europeans...ethnically at least.

Re:Damn it. (1)

fuzzyfuzzyfungus (1223518) | about 6 months ago | (#45146099)

That was the great thing about 20th century Europe: brilliant enough to invent all kinds of neat stuff, theoretical and applied; but dumb enough to fight two nigh-apocalyptic meatgrinder wars of unprecedented brutality for reasons somewhere between 'kind of silly' and 'so baffling that historians have made entire careers out of them', thus driving much of said brilliance to the US! It'd be pretty sociopathic to suggest as a deliberate talent-recruitment strategy; but as an accidental side effect it served us pretty well.

Re:Damn it. (0)

Anonymous Coward | about 6 months ago | (#45134075)

> You talking about Hedy Lamarr
It's not "Hedy", it's "Hedley".

Re:Damn it. (0)

Anonymous Coward | about 6 months ago | (#45131705)

Maybe if you accuse them of some non existent human rights violation and offer their scientists asylum you might climb back on top?

Re:Damn it. (2)

K. S. Kyosuke (729550) | about 6 months ago | (#45132857)

Oh for the days when our German scientists where better than their German scientists. Truly a golden age for American Innovation.

Don't feel bad. They have had hundreds of years of experience with German scientists, whereas the Americans with mere decades are relative newcomers in this field.

Innovation (1)

benjfowler (239527) | about 6 months ago | (#45131491)

At least SOMEBODY in the West remembers how to make things and innovate (and I don't mean 'innovate' in the sense of wizarding up even more financial and managerial bullshit).

Management and finance don't create value, techies and innovators do. Unfortunately, stupid, spoilt rich kids head into law and finance, so our clueless overlords prioritize that.

Re:Innovation (1)

operagost (62405) | about 6 months ago | (#45131631)

Management and finance obtain the funding and drive the demand for the technology. This is what you call a "necessary evil".

Re:Innovation (0)

Anonymous Coward | about 6 months ago | (#45131807)

There's still the problem of deciding in which projects we should invest to maximize innovation. Some finance people do something similar: they invest in companies and try to maximize profits, but since innovation is one way to get profits, the investments tend to indirectly maximize innovation.

Re:Innovation (1)

prefec2 (875483) | about 6 months ago | (#45133539)

Tools are made by engineers. They shape the options to manipulate our environment. Our elite overlords determine how they are used. Sometimes they miss something and we get printing or the Internet out in the public ;-)

Re:Innovation (0)

Anonymous Coward | about 6 months ago | (#45135209)

Innovation is taking one invention from one product, and apply it with a another kind product.
Innovation =! inventing new things.

So is this innovation? They used existing technologies to get a gear what managed them to get something on networking what was not possible previously. So yes, it was innovating but not inventing anything new.

the tech is great, but (3, Funny)

P-niiice (1703362) | about 6 months ago | (#45131587)

I'd hit my cap in 20 seconds

Re:the tech is great, but (0)

Anonymous Coward | about 6 months ago | (#45139835)

20 seconds? I'll have to jump onto your ISP; Comcast caps out at 250 gbps, or roughly 2.5 seconds on this connection.

High attenuation (0)

Anonymous Coward | about 6 months ago | (#45131643)

The atmospheric attenuation at these frequencies is several dB per km (from losses due to O2 and H20 resonances, aside from the 1/distance squared losses), so it can only be used for relatively short range links. Still awesome though.

Re: High attenuation (0)

Anonymous Coward | about 6 months ago | (#45132181)

At that kind of frequency the loss will be much higher than a few db/km. I doubt they would use an omni directiinal antenna so the distance squared loss does not apply.

Re: 1/r^2 still true (2, Informative)

Anonymous Coward | about 6 months ago | (#45132311)

The recieved signal strength would be multiplied by the antenna gain, but the distance square loss always applies, even with a strongly directional antenna. Even if the beam width is 1 degree across, the "area" taken up by that 1 degree increases with the square of the distance.

The headline should read RF Wireless (0)

Anonymous Coward | about 6 months ago | (#45131671)

or something to that effect. Lasers are wireless and have been used to push over 25Tbps ... just sayin

Skyscrapers? Really? (0)

Anonymous Coward | about 6 months ago | (#45132307)

a prior experiment hit 40Gbps over 1km between two skyscrapers

Really? I never knew there were scyscrapers in Karlsruhe

Re:Skyscrapers? Really? (2)

SuricouRaven (1897204) | about 6 months ago | (#45132827)

It's a good application for short-range, high-capacity wireless. The cost of laying fiber in a city is ridiculous - closing roads, digging trenches, disrupting business. Tall buildings give good line of sight. One modestly-high comm tower in the middle of the city (Something like BT Tower?) could serve all the other major buildings. Even if they don't want to depend on radio exclusively due to the risk of atmospheric disruption, it'd serve as good backup connectivity option removing the need for redundantly-pathed fiber.

Re:Skyscrapers? Really? (0)

Anonymous Coward | about 6 months ago | (#45133123)

I know all that, it just a joke about skyscrapers in Karlsruhe. I lived there. There are no skyscrapers there. There's hardly any building taller than 5 or six floors.

Re:Skyscrapers? Really? (1)

prefec2 (875483) | about 6 months ago | (#45133579)

They most likely mean the high rise buildings in Karlsruhe, like the library. Most German skyscrapers are located in Bankfurt (alias Frankfurt). They are used as phalli for the finance industry (http://en.wikipedia.org/wiki/List_of_tallest_buildings_in_Germany).

Is there a theoretical maximum bandwith? (1)

deathcloset (626704) | about 6 months ago | (#45133409)

Slighly tangential line of thought here:

Let us imagine a cylinder of empty space with radius r = 5mm and length l = 10 meters. Allowing for any kind of medium in this space (fiber, copper, neutron-star matter, etc...), what is the maximum throughput in principle of this communication channel?

In other words, I've been wondering lately if there is an upper-bound (in principle) on bandwidth. Like how there is a speed limit for light, is there something similar for information transmission?

Re:Is there a theoretical maximum bandwith? (2)

wagnerrp (1305589) | about 6 months ago | (#45134395)

You've got the Shannon limit, describing the ultimate channel capacity in terms of bandwidth and signal-to-noise ratio. You can increase your bandwidth, but your transmission medium will eventually impose attenuation limits. You can increase your power output, and thus your SNR, but you eventually reach a saturation limit from blooming, ionization, or melting of your medium. There is no theoretical limit on channel capacity, unless you want to go into information theory and figure out the maximum amount of data that can be stored, if your power source is the entire quantity of mass-energy in the known universe, and transmit it over Plank time, but there are functional limits.

Re:Is there a theoretical maximum bandwith? (0)

Anonymous Coward | about 6 months ago | (#45136977)

But channel capacity increases with the log of radiated power, so you quickly lose if you try and increase your channel capacity that way.

If X-ray lasers weren't ridiculously expensive and infeasibly large (and look at solid-state free electron lasers for reasons that might not be true in future), and we had spallation detectors with fast enough slew rates, we could build channels through freespace that would well exceed our present ability to keep them fed with information. The fastest commercially available electrical SERDES is 28Gbps, to pump a 100Gbps QSFP+ takes 4 parallel SERDES. I'm not so sure we want xray comms beams shooting all over our cities, but I think FEL lasers will play a major role in future communications systems, owing to their extremely large tunable wavelength.

The present limitation in fiber optical networks is the bandwidth of Erbium doped fiber amplifiers, which limits the number of channels to 48x40 in the general case, 96x100 in special grade fiber (closer channel spacing, less dispersion). Future research is on using Raman amplification to add more bands, which can also be DWDM, but this is more like linear scaling than the exponential scaling we've come to expect from electronics and communications. Other approaches are to use spin and multilevel coding (already used extensively in electrical systems), but both of these introduce significant challenges to amplification technology.

In freespace optical networks, the limiting factor is detection and filtering, that is, being able to find your line amongst all the stray light entering the receiver, this is made more difficult by the line not being a constant wavelength due to uncontrolled drift in the transmitter. An additional challenge is optical attenuation, something the 240GHz band doesn't seem to be so affected with.

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