BT Runs an 800Gbps Channel On Old Fiber 127
judgecorp writes "BT has demonstrated an 800Gbps 'superchannel' on a 410km fiber in its core network, which was not able to carry 10Gbps channels using older technology. The superchannel is an advanced dense wave division multiplexing (DWDM) technique, created by combining multiple coherent optical signals into one channel, which had previously been shown in laboratory tests. BT ran the test on a fiber with optical characteristics (high polarization mode dispersion) that made it unsuitable for 10GBps using current techniques. That's a good result for BT, because it means its existing core fiber network can be upgraded to handle more data. It's also a good customer story for Ciena, which makes the optical switches used in the test."
Re:Great news for folks in Provo, UT (Score:3, Interesting)
For what it's worth, it's not providing any more bandwidth than the old technique, which had 80 channels at 10Gbps each. What it's doing is, instead of saying I have 80 channels, each of them needs to be clean in order to pass 10Gbps, it's saying I have these big channels which are noisy, but we have ways to mitigate that. Once all our mitigation is done you can expect 800Gbps (that may or may not be with error correction/other overhead factored in. Depends on the marketing department I suppose, but usually with fiber they give max achievable throughput)
The advantage in running unchannelized is on each 10Gbps channel they were holding extra bandwidth in reserve for error correction/overhead. With this you get the whole thing and your error correction is done on the aggregate, with less probable overhead and such.
Re:That's great and all (Score:5, Interesting)
Fibre providers have an ONU (optical network unit) supplied by the mains power on the property. Unless there's some kind of requirement for power-free phones I don't know about there really is no reason to run expensive copper wires.
Fairly sure there's a legal requirement for the telco to keep the phones working during a power outage. Certainly do-able with fibre, but would require a UPS and regular battery servicing - probably cheaper just to run copper.