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Siemens Develops 1 gbit/sec Wireless Link
jonknee writes "Siemens has developed mobile wireless technology with transfer rates as high as 1 gigbit per second. This blows the doors off of '3G' technology, or EV-DO (the high-speed data technology used by Verizon Wireless and soon by Sprint PCS). Not all the specs are out yet (more info is expected early next year), but it uses three transmitting and four receiving antennas. With any luck the phone in your pocket will have a gigabit link by the year 2015."
according to the article, the bandwidth is only 100 MHz for the experimental setup that they have running.
1Gb/s is supposed to be what it's capable of in the future - or at least that's how I read it
Multiple antennas.. sounds like a variant of BLAST:
http://www1.bell-labs.com/project/blast/
They claim >20bps/Hz by making lemonade out of multipath's lemon.
RTA. They're multiplexing; using several different channels to allow many different streams of data simultaneously. Yeah, it makes it a bit more complicated and error prone in the protocol specs, but it means a faster signal. And yes, to some degree, it will make other mobile broadband solutions obsolete, that is until they spec out the next generation of wireless to use similar methods. Remember, this is something that's going to be rolled out 10 years from now. I'm sure wifi is going to get a lot better in that time.
Marxism is the opiate of dumbasses
Given the number of receiving and transmitting antennas, it would sound like they are using a variant of BLAST - this is a technique that uses multipath to enhance the signal - think of it as doing spatial-domain multiplexing. By using multiple antennas, and using the multipath time difference on the signal, they are able to discriminate signals in the same band of frequecies based upon the physical location of the antennas.
However, the odds that this will fit "in your pocket" as the story poster said are pretty slim - the physical seperation of the antennas would tend to preclude that.
www.eFax.com are spammers
shannon's law and all - of course we haven't approached those limits yet (I think)
the DVB-S2 standard (with devices due in 2005) comes within 1.0-0.7db of shannons law. Also, another company has come within 0.1db (or 0.01db, i forget) and might be even closer now at this point to shannons law. This is the real thing and is being adopted in broadcast networks for transmission to stations. PDF here on the new tech. On page 11 they list the 1.0-0.7db figure. Not sure how large it is Unfortunately in order to use a full transponder at full capacity and speed you would need a few of these since it appears they do not have the processing power to do more than ~50 megabits/sec. A full transponder under one of these would run around 180 Megabits/sec (36Mhz*5bits/mhz) .
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
Well most wireless data systems are rate adaptive, so to be able to use new high speed services you will require very strong signal coverage (even more radiation). 2G and 3G will still be there, plus all the other radio systems.
Never heard of bluetooth or PMCIA cards?
3G phone in pocket. Bluetooth on. PC talks to phone, makes connection. Done.
Not hard.
This is a multiple-antenna technology, called MIMO for Multiple-Input-Multiple-Output. Instead of modeling the "medium" (electromagnetic spectrum) as a "box" taking a single signal as input and outputting a single signal, the medium is modelled as a matrix taking multiple signals on input and outputting multiple signals, on the same frequencies and at the same time.
The capacity increase is *theoretically* limited by the max number of antennae in input or output: say there are N transmitters and N receivers, if you assign each transmitter to a receiver and place a shielded coax cable between the pair instead of relying on em free-range transmission, there should not be much interference for sure. Thus you have N times the throughput, and that's how MIMO throughput numbers are computed *for PR purposes*...
In practice, when you use the air medium, there is a good deal of interference between the antennae, but research can derive some increased capacity (by "diagonalizing" the MIMO channel, i.e. identifying linearly independent sub-channels in this matrix of channels).
However, the practical increase is *in no way* linear as a function of the size of the MIMO array as some would obviously like other people (press, stock analysts, investors...) to believe. Additionally, MIMO works best in certain environments; independent sub-channels are best created by channel irregularities that are at a distance comparable to the scale of the antenna array. It means, for instance, that MIMO does not generally improve much the capacity of line-of-sight transmission but provides better improvements indoors!
It's not oversimplified to say that, in fact it's a common practice. In QAM modulation systems (Quadrature and Amplitude Modulation), "complex amplitude" (i.e. amplitude + phase) modulates a waveform with not just two values (+1 and -1) but four values (1, i, -1, -i) or more...
The set of amplitude values is represented in the complex plane as a "constellation". At the receiving end, you have to "recover" the amplitude and the phase of the emitted signal, which is the process of synchronisation.
In cable (coaxial) networks, where attenuation is lower than in free-range transmissions, 64-QAM or even 256-QAM (a modulations with 256 complex values, an 16x16 square in the complex plane) is commonly used.
Power and range do limit the effectiveness of modulations. In GPRS/EDGE packet radio, for example, QAM schemes are varied as a function of radio conditions to avoid using too ambitious of a modulation for what the channel can support.
they might have to compensate for the higher speeds with stronger signals
It uses 2.4 GHz at 1 KW.
Good news: The transmitting hardware is inexpensive because it's already used in microwave ovens.
Bad news: Battery life is gonna really suck.
>> My ultraviolent Linux switch video.
Uncertainty principle, as in Quantum Mechanics?! That's a really funny one! The only thing fundamentally limiting signals transmission is noise, which in electromagnetic transmissions comes in its most unavoidable form from thermal noise. There are other sources of "noise" or "interference": depending on the environment, interference can come from other communicating devices, a car's engine ignition sparks, thunder, a static discharge, a microwave oven... And worsening it all, media also always attenuate the signal, more or less, therefore weakening the Signal-to-Noise ratio which along with the available bandwidth determines the theoretical capacity of the transmission system. The uncertainty principle has nothing to do with it.
;-) -- or to update this one.
Any good introductory course in Digital Communications will cover this, and introduce the notion of QAM and constellations in passing. May I suggest this Digital Communications OpenCourseWare module (viva MIT) or, for a gentler introduction that might not be as complete, this set of slides (viva University of Cambridge).
And once you've read all about it, be sure to write up an entry about it in WikiPedia
Radio systems utilizing multiple antennae (MIMO), may "trump" this to some extent by playing on the fact that spectrum is a three-dimensional medium and not a one-dimensional medium (contrary to twisted pairs or coaxial cables). On that, you may want to read this intro.