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DSL/vectoring/G.fast

BBWF 2010: NSN Takes DSL to 825 Mbit/s

PARIS -- Broadband World Forum 2010 -- The key theme emerging here in Paris is that fiber isn't the only physical medium that can deliver truly fast mass-market broadband.

In the past few days we've heard Dynamic Spectrum Management (DSM) specialist Assia Inc. talk about how it's working with more and more carriers to boost the speed and reach of their existing DSL lines, while chipmaker Ikanos Communications Inc. (Nasdaq: IKAN) has just unveiled its first G.vector products that will enable DSL speeds of more than 100 Mbit/s. (See BBWF 2010: Ikanos Boasts 100Mbit/s DSL and ASSIA Gets Behind DSL Management .)

Now Nokia Networks says it has achieved speeds of 825 Mbit/s over 400 meters of bonded copper lines, and 750 Mbit/s over 500 meters using a technique called "Phantom DSL." (See NSN Tests Phantom DSL.)

NSN isn't the first to use this technique, which combines "phantom mode" technology -- effectively turning two bonded copper pairs into three, the third being the "phantom" -- with G.vector capabilities, as Alcatel-Lucent (NYSE: ALU) and Ericsson AB (Nasdaq: ERIC) have both tested it in the recent past. (See Copper: Still a Precious Metal?, Bell Labs Touts 300-Meg DSL Test, and Ericsson: We Can Do 500 Mbit/s Over VDSL2.)

The key message from such tests and trials appears to be that broadband service providers don't need to invest heavily in fiber-to-the-home to be able to offer broadband speeds of more than 100 Mbit/s. And that, in essence, is good news for the operators, because FTTH involves a significant capital injection.

But what broadband speeds can be achieved in the "real" copper networks using Phantom DSL? The tests show what's theoretically possible over a relatively short distance, but use the same technology over thousands of copper pairs running from a central office/local exchange serving customers that are miles away, and what are the gains? And how much does Phantom DSL cost to deploy and manage?

Promoting Phantom DSL makes sense for NSN. It dropped out of the GPON market in mid-2008, announcing that it would concentrate on its DSL and "next generation optical access" products. That means VDSL2 and Phantom DSL for now -- NSN says it will incorporate its Phantom DSL technology into its hiX 562x/3x DSLAM products -- and WDM-PON in the future.

In his new report, "Next-Gen PONs & Fiber Access: A Market Perception Study," Heavy Reading analyst Graham Finnie notes that NSN is developing an "ambitious WDM PON product" called coherent PON. This has "attracted considerable interest" as, in theory, it can deliver 1 Gbit/s of capacity to each customer with a "splitter ratio" of 1:1000.

With WDM PON still not standardized, though, it could be some years before such a technology becomes a commercial reality. (See No Sure Bets in NG PONs.)

— Ray Le Maistre, International Managing Editor, Light Reading

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