Rim Semiconductor Company (fka RSMI)

[THOROFTHUNDER]

From dsl prime.
ADSL2 - it matters
Reach, testing, power and noise savings
I thought ADSL2 was "ho hum," but I now see it will be a powerful source of opex savings, not just an increase in speed to 12M. I recommend you insist on it as soon as the last kinks are resolved, no later than June of 2004. Here's why:
Reach on long loops improves 2,000-3,000 feet, demonstrated on a line simulator by Analog Devices. Real world results may not be as good, but any reduction in long loop problems saves money. If you extend your servable customers 1,000 feet, that's significant growth in sales.
ADSL2 test modes give you a much clearer picture of what customer problems can be, providing much better data on the loop near the customer. Spirent, using Aware's Dr. DSL test software, showed how you can quickly pinpoint problems like bad in-home wiring. These are now among your costliest to troubleshoot and solve. This will only take a software upgrade on the gear most U.S. telcos already own.
Powerdown does more than just save on electricity costs, although that's significant as well. Unnecessary power use create interference on other lines, hurting performance in the field. (Telcos are telling me this is a major problem.) Reduced power/heat is especially important in remotes. Infineon is ready to test powerdown with telcos.
Dozens of small improvements are incorporated in the new chip sets. Better filters and hybrids, improved design algorithms, and much more were all possible under ADSL1, but have not been incorporated until the newest designs. I'm hearing from many sources the modems are significantly better.
I was long confused between ADSL2 and ADSL+, and owe David Benini's white papers a thank you for explaining. The new design features are part of the ADSL2 spec, which is settled and in advanced interoperability testing at UNH. Speeds go up to 12M. ADSL2+ also doubles the frequency range, with the higher frequencies as much as doubling performance on short (less than 10,000 foot) loops. 2+ goes to 24 mbps, and 26 mbps with non-standard tricks.

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ADSL2+ isn't working yet; ADSL2 has problems to solve
24-26 meg Japanese service all proprietary
They're actively selling 24-26 mbps in Japan, but I was wrong to report it as ADSL2+. It's the ADSL2+ chips running in various incompatible and non-standard modes, while ADSL2+ is far from an interoperable standard. I confirmed with several chip guys: ADSL2 interoperability is still a way off, ADSL2+ even further out. This email questioned my item "Here Comes VDSL2"

"My reaction to this is 'Oh No'. As an integrator of DSL chipsets, I'm already at the point where I believe that chipset companies and standards bodies have already raised expectations too high with ADSL2. Now they seem to be pushing VDSL2. To explain my angst, let me say that I do not believe that there is any technology provider in the market _right_now_ that has an ADSL2 solution. Interoperability hasn't been worked out. Recent evidence from UNH would indicate there are still chipset vendors that can not synchronise with any other parties, so other ADSL2 features just can not be developed yet.

The NTT solution is NOT ADSL2. It is a chipset-proprietary implementation of something named G.992.1 Annex I, to aid in the current Japanese bitrate war. This would definitely not work with any other chip vendor, as there are many proprietary "features" in the product.

The feature sets of ADSL2 are complex, so are being rolled out in different phases. This is a nightmare for CPE equipment manufacturers, as Telcos are expecting "ADSL2" CPE now. These same CPE may not be compatible with later phases.

Similarly, VDSL still isn't mature enough to guarantee interop. between chipsets. There are companies that can't even agree on what bandplans to use. For example plan 997/998 won't cut the mustard for ethernet at anything but short reaches, so companies are inventing proprietary bandplans to cover this gap. These bandplans will only work on same chipset deployments. This isn't "VDSL". ADSL2+ is supposed to be G.992.5. Yahoo will deploy GSV "G.span" technology, which is not 992.5. I guess this is just NTT and Yahoo scoring points (maybe striking sparks???) off each other.

Therefore, for T1E1 to start talking VDSL2 is all fine and dandy. Maybe when the industry _actually_ catches up with other developments, such as ADSL2, we can start worrying about 'new standards.' Meanwhile, of course, the telcos are still listening to the standards and marketing guys and demanding these new technologies, which can't be delivered."

I believe the payoff from ADSL2 is so high these problems must be solved, but that's why I urge a changeover over the next 9 months rather than immediately. db

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Al d.