5 ms·

This does not mean much until we learn how much spectrum they used. We need more efficient use of spectrum not raw download speeds.

by hristov 12y ago

ArkyBeagle 12y ago
This claims 100MHz bandwidth: http://www.ispreview.co.uk/index.php/2015/02/university-of-surrey-claims-1tbps-speed-over-future-5g-mobile-tech.html http://www.ispreview.co.uk/index.php/2015/02/university-of-s...
- japhyr 12y ago
  Is that good or bad?
  - ArkyBeagle 12y ago
    It's 100 times a Bluetooth channel. So for deployment, that rounds down to "bad". It might makes sense for tightly controlled point-to-point.
  - wmf 12y ago
    100 MHz is a lot. It's wider than the entire 2.4 GHz band and each cellular carrier has less than 100 MHz of spectrum. http://www.fiercewireless.com/special-reports/how-much-lte-spectrum-do-verizon-att-sprint-and-t-mobile-have-and-where http://www.fiercewireless.com/special-reports/how-much-lte-s...
- jpmattia 12y ago
  Not really, according to the update the entire result is sim. From your link: > According to Tafazolli, the new class of Detector (a completely new approach) was tested through computer simulations (these simulated a real mobile/wireless environment) and were found to achieve the 1Tbps rate claimed. In our view that’s quite a bit different from conducting a practical test. It doesn't look like there was any actual lab result.
  - ArkyBeagle 12y ago
    Argpfhh! I didn't scroll down to the update. I just saw "measured at" and took them at their word. So vapor again. sigh. At least until they actually measure it. Good eye, sir.
- darkmighty 12y ago
  How is this even physically possible? Is this for a small mobile device? It would imply a spectral efficiency of 10000 bits/s/hz. To put in perspective [1], 4G claims a best case spectral efficiency of 30 (!) bits/s/hz using 4x4 MIMO. I'm not sure there are even enough physical degrees of freedom to allow that with a small device, given the wavelength of light at the Ghz range is ~10cm (i.e. sure, if you use 10000 antennas over a large area, you can have 10000 b/s/hz!; in this case, I would estimate it to need ~2000 antennas). To be clear, for a single "degree of freedom" you are limited by the Shannon capacity [2], which we are pretty close to already in most technologies. So I'm skeptical. It's either a nice optical link, a massive device, or some high freq. radiation I'm not familiar with. [1] http://en.wikipedia.org/wiki/Spectral_efficiency http://en.wikipedia.org/wiki/Spectral_efficiency [2] http://en.wikipedia.org/wiki/Channel_capacity#AWGN_channel http://en.wikipedia.org/wiki/Channel_capacity#AWGN_channel

This does not mean much until we learn how much spectrum they used. We need more efficient use of spectrum not raw download speeds.

by hristov 12y ago

This does not mean much until we learn how much spectrum they used. We need more efficient use of spectrum not raw download speeds.

ArkyBeagle 12y ago

This claims 100MHz bandwidth: http://www.ispreview.co.uk/index.php/2015/02/university-of-surrey-claims-1tbps-speed-over-future-5g-mobile-tech.html http://www.ispreview.co.uk/index.php/2015/02/university-of-s...

japhyr 12y ago
Is that good or bad?
- ArkyBeagle 12y ago
  It's 100 times a Bluetooth channel. So for deployment, that rounds down to "bad". It might makes sense for tightly controlled point-to-point.
- wmf 12y ago
  100 MHz is a lot. It's wider than the entire 2.4 GHz band and each cellular carrier has less than 100 MHz of spectrum. http://www.fiercewireless.com/special-reports/how-much-lte-spectrum-do-verizon-att-sprint-and-t-mobile-have-and-where http://www.fiercewireless.com/special-reports/how-much-lte-s...
jpmattia 12y ago
Not really, according to the update the entire result is sim. From your link: > According to Tafazolli, the new class of Detector (a completely new approach) was tested through computer simulations (these simulated a real mobile/wireless environment) and were found to achieve the 1Tbps rate claimed. In our view that’s quite a bit different from conducting a practical test. It doesn't look like there was any actual lab result.
- ArkyBeagle 12y ago
  Argpfhh! I didn't scroll down to the update. I just saw "measured at" and took them at their word. So vapor again. sigh. At least until they actually measure it. Good eye, sir.
darkmighty 12y ago
How is this even physically possible? Is this for a small mobile device? It would imply a spectral efficiency of 10000 bits/s/hz. To put in perspective [1], 4G claims a best case spectral efficiency of 30 (!) bits/s/hz using 4x4 MIMO. I'm not sure there are even enough physical degrees of freedom to allow that with a small device, given the wavelength of light at the Ghz range is ~10cm (i.e. sure, if you use 10000 antennas over a large area, you can have 10000 b/s/hz!; in this case, I would estimate it to need ~2000 antennas). To be clear, for a single "degree of freedom" you are limited by the Shannon capacity [2], which we are pretty close to already in most technologies. So I'm skeptical. It's either a nice optical link, a massive device, or some high freq. radiation I'm not familiar with. [1] http://en.wikipedia.org/wiki/Spectral_efficiency http://en.wikipedia.org/wiki/Spectral_efficiency [2] http://en.wikipedia.org/wiki/Channel_capacity#AWGN_channel http://en.wikipedia.org/wiki/Channel_capacity#AWGN_channel