| VDSL Doubling Works |
| Written by Dave Burstein |
 The speed fell from ~ 50 megabits to ~25 megabits when Chris Quonoey pulled one of the two lines connected to the new bonded VDSL2 modem from Nokia Siemens Networks. Then he plugged it back in and a few seconds later the speed went back up. Behind the door he showed me two spools of wire connected to two DSLAM-like ports. Zyxel's David Thompson had similar to show in the company hotel room. An engineer I trust is testing bonded modems in the field and tells me they are fine, although the price is currently too high.
Nearly every DSL connection that is 25 megabits or less can now be doubled in speed for less than $200 and typically less than $1/month in bandwidth. ASSIA's John Cioffi believes that will provide interesting competition for DOCSIS 3.0, especially as DSM provides further gains.The cablecos haven't yet deployed 3.0 upstream, although Tony Werner at Comcast tells me he intends to move aggressively in 2010 with upstream. NSN's list price for bonded VDSL2 today is ~$90, but the customers for this are so large they'll probably pay less. ADSL bonding is significantly cheaper and already in production use. I've previously reported the carriers expect rapid price declines. <A well-informed engineer> told me not to expect many in use until the middle of next year, after the carriers check them out, train their people, etc..The 25/50 megabit demo used 4,000 feet of copper but did not add interferers. A pessimist wouldn't plan for 50 meg total more than 3,000 feet and 25 meg 5,000 feet in the real world. AT&T has 5-15M U-Verse lines at 3-6,000 feet that need bonding to reach a solid 25 meg. They will need a million modems when they aggressively sell to those homes. AT&T's current plans are only to use bonding to get the 25 megabit TV package a longer distance, not to offer higher speeds, but that could/should change. The NSN units used an Infineon/Lantiq chip. Note that more advanced units will be required to take 50 megabit connections up to 100 megabits. The demo ran at the 8 megahertz profile, with something like 25 meg/line performance. The higher 17 and 30 MHz profiles would be required for more than 50 megabits. The higher frequencies attenuate very quickly. The 100 megabits works only a few hundred meters. Double your pleasure, double your fun.
|
