DSL

DSL Prime News Weekly: The Inside Source —continued

Panasonic Jetstream: It's a Phone!

$15M to Bandspeed for faster DSL chips
Michael Dell, Cisco put in funds
The race is heavy for improved DSL chips, with Alcatel, Conexant, and Globespan all looking to migrate theory to your modem and DSLAM. Bandspeed is an Australian outfit, with technical roots in the military, that has released only limited details of their technology. They speak of crosstalk silencing, noise mitigation, channel equalization, timing synchronization, and adaptive frequency hopping.

The providers badly need that extended reach. Ameritech's initial DSL deployment was ruined financially, when they decided to cut the maximum distance from 18,000 to 12,000 feet because of unreliable service at the longer distance. This reduced the potential customer base by nearly half, making impossible to reach customer goals. SBC had been considering service to 17,000 feet, but now cuts off at 14,000. Repeaters are now also working as well.

No retail, no 3Com
Drops entire line of cable and DSL modems
Products reach end of life, apparently, and 3Com has apparently decided that US Robotics modems will not survive into the broadband era. Amid massive corporate losses, they decided that there would not be enough retail sales of either for them to make any money at it, and they've generally failed at OEM sales because they could not compete on price.

Lack of standardization is not the only reason retail hasn't made it. Free modem offers are currently outstanding from Verizon and others, and subsidized modems, direct from the provider, seem a requirement of most sales. So where is there room for 3Com, whose strength is premium retail products.

No Alcatel modems, either
Moves bestselling brand to partner Thomson
Consumer electronics giant Thomson and Alcatel have joint ventures in space, broadcast video, telephones, and DSL, and Alcatel has an investment in Thomson. With today's low modem prices, Alcatel decided to get out of the market, and moved the product line to their partner for $400M more in stock.

So long, EDSL
Orckit writes off basement DSLAM vendor
Once a large provider chooses a DSLAM vendor, it's hard for another vendor to win them over. The result, last year, was a rush into the expected market for basement DSLAMs, looking for a new groups of customers, the BLECs (building LECs). Orckit bought an Israeli company, EDSL, which had an Ethernet like system, but never was able to find customers. The result: a $23M writeoff.

Actelis: Interesting Product, Extraordinary Hype
Adds error correction to bonded DSL lines for multimegabits
Actelis' incredible claims to "turn copper into fiber" overstate their apparent real achievement, error correction across multiple wires. They base that on a low bit error rate, one of fiber's characteristics. But we can't accept "turn copper into fiber" unless they deliver gigabits, not megabits, over a single strand, for which they make no claim. (Later versions, with better signal processing, are targeted for twice the current copper capacity, but haven't yet emerged from the lab.)

The theory is well established: find some way to characterize the noise in the binder, and you can considerably speed up DSL. Depending on the distribution of noise in the actual circuit, this can lead to a significant increase in throughput. The entire industry is working on ways to characterize noise. If noise is random, we are close to the Shannon limit on maximum rate, and unable to obtain more than the 15-25% improvement due in the next few years. Noise in the real world is not perfectly random, so approaches that characterize and compensate are the most promising hopes for the next performance leap. I don't have many of the technical details of how Actelis's system works, but measuring patterns of noise across multiple lines is an obvious means of achieving their results.

Without error-correction, of course, DSL itself would be impossible. Actelis has taken the obvious step of implementing error-correction across multiple lines, producing a bit error rate in certain unspecified conditions that is very low. Good work, assuming the product works as well as it did in a one month trial at a small telco. Bonding multiple lines together where copper is available cheaply is a good way to reach speeds of 5 megabit and more, as demonstrated previously by Copper Mountain and Netopia. The technique is common enough to have a name, inverse multiplexing. With today's chip's processing power, it becomes practical to do adaptation to line noise in real time, which is well recognized for potential improvement.

Molly Miller of GPR is the most effective pr person in this business, and this time she's promoting Actelis as making copper act like fiber. Molly handled Redback when they were crowned The next Cisco, which was worth $billions to their market price; created a category business DSLAMs so client Copper Mountain could be the leader; and brought Tollbridge to the center of the then hottest spot in the industry, Voice over DSL, although their product was closer to the Voice over IP category. If we ever have a pr budget, we want Molly.

Advanced Software Will Drive Voice Over DSL
Voice compression can deliver surprising quality at 16K
Click over to http://dslprime.com/a/advsoftware_VoDSL.html for an article by Keith Buchanan of TI/Telogy. It covers key issues, including compression, echo cancellation, adaptive compensation for packet loss and network problems, and tone processing. Units like the Panasonic broadband phone, above, become very attractive if you can squeeze four voice channels into 64K of upstream bandwidth, and the demonstrations from Telogy are impressive.

DSL Prime welcomes articles that are readable, relevant, and free from sales pitches. If they relate to your products, they should let the facts speak for themselves. TI, in this case, sponsored a mailing that brought it directly to readers—but we edited the article to make sure the content was strong and useful.

Copyright 2001 Dave Burstein.
The DSL Prime Newsletter is reprinted with permission.

"The power of the printing press belongs solely to those who own the presses"
—A.J. Leibling

The Internet is the cheapest printing press ever invented.

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