AlcaLu Develops 'SmartDSL'
Speaking here Wednesday, Danny Goderis, director of product marketing at AlcaLu’s Access Division, said the technology cuts down the level of “noise,” or interference, on a DSL line, freeing up vital chunks of bandwidth that can be used to provide more, and better-quality, services over a broadband connection.
Such a development could be critical to carriers that are offering multiple, bandwidth-hungry services, such as IPTV and online gaming, across DSL lines, as it would allow them to provide a better quality of service across existing connections and add more services or video streams over a single DSL line.
It’s also noteworthy that this development, which is applicable to existing DSL equipment deployments as well as new deliveries, is being launched by AlcaLu, which has a massive installed base of more than 150 million DSL lines around the world. (See AlcaLu Claims DSL Lead.)
Goderis said the technology is being trialled by five broadband access customers currently (though he wasn’t allowed to identify them), and is generally available from today in the ETSI region (Europe and Asia/Pacific) as part of the vendor’s IP-based ISAM (intelligent services access manager) multiservice access node product line.
“We’ve done quite a lot of field testing before making this generally available,” he added.
The technology will also be available to AlcaLu’s large installed base of ATM-based DSLAM customers (outside North America) from around the middle of 2008 as a system software upload, added Goderis.
Goderis noted that, in North America, AlcaLu uses line-bonding technology to boost broadband access speeds. That’s a technique already being deployed by AlcaLu customer AT&T Inc. (NYSE: T), which takes two copper lines to each of its U-verse customers.
Masking the noise
SmartDSL is a software product integrated into a DSLAM, and works closely with various OSS products, such as broadband line measurement and network provisioning tools. Goderis noted that while AlcaLu has optimized its own OSS, such as its network analyzers, to work closely with the core SmartDSL software on the DSLAM, carriers can still use their existing OSS to reach the same goal.
In simple terms, the SmartDSL software deliberately creates a “noise mask” -- a low level of interference on a DSL connection that masks “crosstalk” noise, which can deplete a DSL line’s available bandwidth by between 20 percent to 30 percent on an ADSL2+ line that is carrying IPTV traffic. Masking out that noise can, according to AlcaLu’s field trial results, lead to a significant increase in available capacity on a DSL line.
The problem of noise interference on a DSL line can currently be dealt with by increasing the line’s “noise margin,” but as the noise margin is increased, the available stable bandwidth decreases.
Goderis gave the example of an ADSL2+ line that, using the “noise margin” method, can deliver 7.3 Mbit/s (across an unknown length of copper loop) of stable bandwidth. With SmartDSL deployed, Goderis said that same line, under the same conditions, would have 11.6 Mbit/s of stable available bandwidth.
To see how AlcaLu is positioning this technology officially, check out this page on its Website.
Differences between ADSL and VDSL
There are differences between the method of deployment in ADSL networks and VDSL networks, however.
The ADSL version of SmartDSL involves software being added to the DSLAM only. This sends “artificial noise” across the line, which is then recognized as actual noise on the line by the DSL modem at the customer’s premises. That artificial noise acts as the mask that blocks out other dynamic noise on the line.
That version of SmartDSL is a proprietary solution, stated Goderis.
In the VDSL world, though, the method is an option that is part of the completed standard. Here, there is a software module on the customer premises equipment (CPE), too. The DSLAM software sends data to the CPE that creates “virtual noise” on the line, which acts as the mask. “This is part of the standard so it is well understood by other vendors,” said Goderis, “but as far as I know we are the first to make this technology commercially available.”
Measuring up against DSM
SmartDSL isn’t the only development that’s aiming to increase DSL line capacity. Dynamic Spectrum Management (DSM) is another technique that has been in development for several years, and which is being trialed by AT&T.
Startup Assia Inc. is one of the leading DSM lights, while ECI Telecom Ltd. is also working on the approach, and has even referred to the technology as VDSL3. (See Assia Adds Execs, Assia Finds Licensees, DSL Group Forms, and Valley Wonk: DSL Man.)
AlcaLu is also backing DSM, but believes it’s some way off being commercially available.
Goderis said DSM is a different approach that “shows promise,” but added that the rival approach is “still a bit science fiction -- this [SmartDSL] is real.” Chipsets that enable DSM are still some way off, and likely won’t be in mass production until next year or even 2010, predicted the AlcaLu man.
— Ray Le Maistre, International News Editor, Light Reading