Ready to upgrade 3M/year. Kevin Foster of BT minced no words. "G.fast must deliver speeds over longer distances ~ 350m (0.5mm Cu.)" BT's original plan was to support G.fast from 4M distribution points, for speeds of > 500 megabits. The finance guys decided to go only to the neighborhood cabinets, requiring 95% fewer installations and minimal new fiber. That raised the typical loop length from 35 meters to 350 meters.
To get even the lowered speeds (~300 megabits) at 350 meters is pushing the state of the art. The change in requirements has delayed most work from early this year to end of this year. The tests are going well to over 4,000 homes, at least at short distances.
Kevin thinks it can be done. He believes engineers can:
- Enable higher bits per tone
- Improve the receiver sensitivity (noise floor)
- Increase the transmit power
- Optimise the frequency usage with VDSL ? Increased vectoring group sizes ?
Rami Verbin of Sckipio saw the same possibilities in an interview last June. Some of them should be close to delivery by now. Foster also demanded "G.fast units must have a higher DPU port density (typically 48/96 ports.)" Fortunately, Huawei tells me they expect a 96 port unit late this year. Alcatel should be on par with them.