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AlcaLu Speeds Up Its VDSL2

Ray Le Maistre
9/22/2011

Alcatel-Lucent (NYSE: ALU) is heading to the Broadband World Forum show in Paris armed with a new DSLAM line card that should interest carriers deploying VDSL2 in their fixed-access networks.

The vendor has developed what it claims is the first VDSL2 line card for DSLAMs that incorporates vectoring capabilities -- that is, line cards that house chips based on the G.vector standard that reduces crosstalk (interference) between the copper pairs that are bundled together.

Vectoring was standardized by the ITU as G.vector, or G.993.5, in 2010 and is also known as Level 3 Dynamic Spectrum Management (DSM) by DSL players such as Assia Inc. (See Ikanos, ASSIA Get Tighter on Vectoring.)

Adding vectoring to VDSL2 can, in theory, boost the speed of a copper broadband connection to 100 Mbit/s downstream (at line length distances up to 400 meters), compared with the current maximum VDSL2 speeds of 40-50 Mbit/s.

The benefits aren't as great over longer copper line lengths, however. At 1,000 meters, VDSL2 with vectoring can enable downstream speeds of 40 Mbit/s compared with 25-30 Mbit/s from regular VDSL2 lines.

Stefaan Vanhastel, marketing director at AlcaLu's Wireline Fixed Access division, tells Light Reading that the company developed its own silicon and software for the vectoring algorithms and that the line cards will be commercially available in December.

The line cards (with 48 line ports) can be housed in existing VDSL2 DSLAM chassis and come in two formats: board-level vectoring, with all the capabilities housed on a single line card; and system-level vectoring that, with the use of a dedicated vectoring processor board, enables the higher-speed capabilities across multiple line cards and nodes. In the latter scenario, up to four line cards (192 ports) will be supported by a single vectoring processor board when the products are launched later this year, but this will double to eight line cards (384 ports) in 2012, says Vanhastel.

The AlcaLu man notes that the introduction of vectoring impacts not only individual line speeds but also enhances the utilization of capacity across all the lines supported from a single DSLAM. For example, if just a few of the lines activated from a non-vectorized VDSL2 DSLAM are affected by crosstalk and can only achieve a maximum of 20 Mbit/s downstream, then that's the maximum speed a service provider can market to customers in that area, even though some customers would be able to get higher speeds. By deploying vectoring, all the lines are boosted to their near maximum potential, increasing the opportunity to market higher broadband speeds and offer more bandwidth-hungry applications such as HD IPTV.

Of course, it's not as simple as swapping out some line cards. The VDSL2 vectoring line cards cost more than regular VDSL2 boards and customer premises equipment (CPE) would need to be upgraded to support vectoring. Vanhastel says most current VDSL2 CPE units are upgradeable to support vectoring and wouldn't need to be replaced by the operator.

So is there any demand for these capabilities? Vanhastel says that, with FTTH taking a long time to deploy, operators are looking to get the most out of their copper plant and offer as broad a range of services as possible until they deploy fiber all the way to customers' premises. "This solution offers a faster time-to-market and a faster return on investment than with FTTH," says the marketing man, before remembering that he also has some GPON kit to sell. "Of course, operators need to start building out their FTTH capabilities now, too, because it's going to take a long time to build out … but operators need greater bandwidth now" to remain competitive and offer the highest-value services, he adds. (See BBWF 2011: Who Needs FTTH? )

He says there is strong interest in the new products in Western Europe and North America, with trials taking place with the likes of Belgacom SA (Euronext: BELG), Orange France , Swisscom AG (NYSE: SCM), Telekom Austria AG (NYSE: TKA; Vienna: TKA) and Türk Telekomunikasyon A.S.

The vendor, which currently boasts about 70 regular VDSL2 customers (deployments and trials) amongst its hundreds of fixed broadband engagements, will announce its first VDSL2 vectoring customer in Paris next week. (See PTCL Bonds VDSL2 With AlcaLu, STC Picks AlcaLu for GPON, VDSL2 and AlcaLu Takes VDSL2 to China.)

It's clear that most broadband network operators know they need to invest further in their copper plant to boost their line speeds (especially in markets where the cable operators are deploying Docsis 3.0) while they figure out the full cost and regulatory implications of FTTH deployments, so technology advances such vectoring, bonding and "Phantom DSL" are of interest to carriers. (See Turk Telecom Checks Out AlcaLu's Phantom DSL, BBWF 2010: NSN Takes DSL to 825 Mbit/s, Copper: Still a Precious Metal? and Ericsson: We Can Do 500 Mbit/s Over VDSL2.)

It's also clear that AlcaLu isn't the only DSL vendor that will be plugging VDSL2 vectoring in Paris this year: Expect the topic to emerge again during next week's event. (See Huawei Boosts DSL Vectoring and ZTE Unveils VDSL2 Vectoring Prototype.)

— Ray Le Maistre, International Managing Editor, Light Reading

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