DSL 2013: Double and Triple Speeds Possible, Limited Deployment

Claude_Shannon_sets_limitsJohn Cioffi amazed the FCC hearing with talk of 200 megabit bonded VDSL with DSM3, which one carrier believes will make fiber unnecessary. Infineon and ECI in Paris both demonstrated working DSM3, although field units are a few years away. Infineon and ECI in Paris. VDSL bonding is working according to carrier engineers testing it in the field. Over modest distances like 1,000 feet two pair can deliver 200 megabits without breaking Shannon's Law.

But rather few homes are likely to be offered more than today's 10-20 meg in the U.S. Few in Europe will be offered double speed bonding. DSM3 will come from the labs to practicality over the next few years and likely be standard on new DSLAMs. Few carriers will replace existing DSLAMs any time soon and it will probably be a decade before most homes are upgraded. Working technology doesn't mean anything if the carriers don't deploy it.

10-15% with marginal IPTV speeds are likely to be offered bonded service. AT&T almost certainly will use bonding offer TV to homes that can't get 25 megabits without it. That's typical of homes 3,000-5,000 feet from a U-Verse DSLAM. There may be as many as 10M homes that need bonding to receive U-Verse, three or four times as many as the first U-Verse planners expected. DT and others offering HD TV will probably do similar although for fewer homes.

Virtually no carriers today have plans to offer bonding except to bring distant homes to 20-30 meg for HD TV. The current RFPs, which are for the equipment for the next 2-5 years, almost never are planned for widespread bonding. With massive firings of network staff continuing, they are reluctant to make changes in their system. One regulator thinks it's a good idea to offer a second line to the lowest speed homes, but doesn't expect that to be required.

For the TV homes using bonding, about half of the bandwidth will be dedicated to TV. So even for those home, the effective download speed will be 10-15 megabits and upload will be 1-3 megabits. Except for fiber to the basement huge in Japan and now beginning in New York and other American cities - the hybrid DSL/FTTN offering will be closer to 1 up, 10 down the 100 megabits routine with fiber home.

DSM3 noise cancellation, the other major improvement likely, is 1-3 years from the field. Because it requires replacing the line card or the entire DSLAM, it will mostly go to new builds. The 40-50 million homes passed by U-Verse and similar cannot be inexpensively upgraded. There's no reason to think many will be replaced in less than 5, or perhaps 10 years. So DSM is crucial for new equipment and particular situations, but it will be a decade before it has much of an impact in existing deployments.

I probably underestimated the cost of bonding when I said it was $200 right now but likely to go down towards $50 fairly quickly based on the increased cost of the modem and extra DSLAM port. Stagg Newman reminds me that it requires a technician to the home in most cases. If they are installing IPTV, they need that truck roll anyway. But for an upgrade, especially from a U-Verse field terminal, that also requires a technician.

Takeaway: DSL, except from the basement, should be considered as 5-15 meg of data down, 1-3 meg up. Networks take a decade to rebuild, so there's no magic coming from the technology. Written by Dave Burstein


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