Nokia has reached a connection speed of 5 Gbps-around 625MB / sec-over 70 meters with a conventional copper telephone cable, and 8Gbps over 30 meters. The study used a new Protocol Digital Subscriber Line (DSL) called XG.fast (aka G.fast2) .

XG.fast is the likely successor to G.fast, which has been successfully tested in some countries over the past two years and will soon begin to be marketed initially in the UK and then in all other countries. Both G.fast and XG.fast are “VDSL

pontenziati.”

In essence, this means that a VDSL2 signal frequency maxes out at around 17MHz, while G.fast part by 106MHz and reaches twice, XG.fast comes between 350MHz and 500MHz.

This translated indicates that there is much more bandwidth and that, consequently, the speed of data transferred is higher.

For example, the VDSL2 can reach 100Mbps a17MHz through this channel; G.fast instead can reach 700Mbps at 106MHz; XG.fast and up to 10 Gbps at 500 MHz with two related telephone lines.

G.fast uses much more bandwidth, but as a result the signal is attenuated over a distance much shorter.

The problem with higher frequencies, however, is that the problem dell’accavallamento and the interference created by copper wires, it becomes an important issue, as it weakens the DSL signal very quickly. To combat the interference, and G.fast XG.fast use both ‘the vectoring to keep the signal that is reasonable distances.

The Vectoring, works similar to the headphones with noise cancellation: The DSLAM (the network kit at the other end of the telephone line) constantly crosstalk currency on a given bundle of telephone lines, and then generates an anti-phase signal that cancels most of the interference.

Even with vectoring, however, the maximum distance of G.fast and XG.fast is rather short: about 100 meters to 700Mbps G.fast, and only 30 meters for 10 Gbps XG.fast. This means that the DSLAM must be approached very (generally located under the sidewalk or to a telephone pole). And ‘it required a higher density of DSLAM, and then turn out to be much higher infrastructure costs. But despite this it is argued that it is still convenient to use this method.

Following a graph showing the effect of vectoring technology, and the new “Vectoring 2.0” tech Nokia that is used in G.fast and XG.fast.

This vectoring to 5Gbps Nokia’s more than 70 meters is quite impressive; The original plan for XG.fast was only 2 Gbps to more than 70 meters, and would allow you to connect to a few tens of houses / buildings to the same DSLAM in an urban environment.

Like other forms of DSL, and G.fast XG.fast are adaptive and can be used at low speeds over long distances.

BT, the operator has committed to roll out G.fast to 10 million homes in the UK by 2020, initially offer a max of about 300 Mbps, with DSLAM every few hundred meters . Clearly the goal is to help the principal competitor Virgin Media.
Presumably also other operators (such as AT & T in the US), will follow the footsteps of BT, using G.fast, increasing the density and DSLAM, and then ensure a high speed.

Francesca Lacorte SOURCE

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