Deutsche Telekom shatters data-transfer speed record

bealtine

http://www.theregister.co.uk/2012/03/07/deutsche_telekom_data_record/

"The bit boffins achieved a 512 gigabits-per-second transmission rate over a single optical fiber from Berlin to Hanover and back, a distace of 734 kilometers. Subtracting out the error-correction overhead, the total usuable bandwidth was 400Gb/s – enough, T-labs points out, to transmit a stream of data equivalent to 77 music CDs in one second."



"This tremendous transmission performance was reached using innovative transmission technology with two carrier frequencies, two polarization planes, 16-QAM quadrature amplitude modulation and digital offline signal processing for the equalization of fiber influences with soft-FEC forward error correction decoding in the receiver," T-Labs explains.

oscarBravo

This is cool stuff. There's so much potential to increase the capacity of fibre, compared to the hokum claims for being able to squeeze ever more capacity from limited radio spectrum.

To put it in perspective: they're pushing the envelope here by using 16QAM on fibre. We already use 256QAM on our radio links.

bealtine

oscarBravo wrote: »

This is cool stuff. There's so much potential to increase the capacity of fibre, compared to the hokum claims for being able to squeeze ever more capacity from limited radio spectrum.

.

Without question, it shows that all future investment should be in fibre and the more ubiquitous the fibre is the better for all concerned, Telcos ,Wisps and users. We should, as a country, be investing in our future, which is fibre and spreading out the fibre assets as close as possible to the users just like Finland did. The government promised to do this but to date all they have done is talk(consult). The NGN taskforce is supposed to be complete and the report is to be published on March 17th. Will be be another round of consultation short of actually doing something? Let's see.

Most of the spurious claims on the radio spectrum are just nonsense or marketing rubbish. Mostly those claims emanate from the marketing departments of big mobile players and have nothing to do with engineering.
The old pig in a bikini syndrome...

watty

Also with Radio you can only do 256 QAM for about 0.5% to 1% of the range! On mobile it drops to QPSK (4 QAM essentially) at cell edge. Robust Fixed wireless is often 16 QAM, and Digiweb Metro is 64QAM.

Cable can use 256 QAM downstream to EVERY connection and some systems on coax use 512 or 1024 QAM.

oscarBravo

watty wrote: »

Also with Radio you can only do 256 QAM for about 0.5% to 1% of the range!

...or all the time on a point-to-point link.

watty

Yes, but can always have a bigger tower and bigger dish once you are at max power on Point to Point....

I was thinking of point to many