xDSL - Alphabet Soup Grows

Gentle Readers,

Firstly, read the "PS" if nothing else. Always some *GOLD* somewhere!!!

Holy Moly; he's back! Many may not know who I am as I have not posted on this subject in a while and there is a bit of churn here. Check the Archives, and, if you read them carefully, I fully guarantee that you can hold a head-to-head talk with most any telecom engineer. I get my information from them and have to sift out the wrong stuff that even they have to write.

Yes, the never ending saga of xDSL continues. When last we joined the telecommunications technology elite, they battled it out over CAP and DMT. The first was more suitable because of its lower power consumption and the latter, because of its stability in the correction of line noise and ability to degrade more *gracefully.* It turns out that, upon further reading during my hiatus from these posts, I find that both are fairly old by technology (computer) standards. Both, and QAM which has been linked with CAP, are older than Windows-based computing. Used in non-telecom areas; more of mixed-signal technology.

The telephone companies are limited to the power supply capacity in each rack at the switching office. Because of that it does not matter how physically small one makes an ADSL unit if it limits the number that can be put in a rack because of its power consumption.

Lucent owns the important patents on CAP and has licensed them to GlobeSpan, the only producer of chips at this time. Amati controls the patent licensing for DMT and has more suppliers of chips, but they have not reached the maturity of CAP; hence the power consumption issue.

This began as the telcos quietly moved T-1 and E-1 from 24 pairs of wires to two pairs in 1991 by using HDSL. This suited them well as it used one-sixth the wires while still bringing in a premium price for the high speed connection. A little more challenging to break it down into 24 voice lines, which is one of the things that T-1 is supposed to be able to do; or 32 for E-1. The same box could do either; it was all in the central office for the switching.

Well. now the plot thickens. Rockwell has introduce CDSL. Everyone needs another acronym, do they not! Consumer Digital Subscriber Line has some very compelling benefits.It offers 768 kbs coming downstream and 160 kbs going upstream. That is ISDN speeds leaving you machine and nearly five times that coming back. Yes, you can download the full version of IE 4.0 in 30 seconds!!!

So, what is so compelling?!? It can be done for about the price of a 56k modem! The implementation is so elegant that it requires minimal equipment at the central switch to off-load it onto digital lines. Regular touch-tone switches can handle the speeds at either end without problems. US West already offers it in Phoenix, Arizona for about double a normal voice line for a consumer. It comes in three flavors, Consumer, Business and Office with corresponding price and speed increases.

Which 56k modem technology wins just became moot; Rockwell has 56flex, which is far behind in the modem wars and 3Com has 56x, which is far ahead. Rockwell is quietly undercutting both its own and the market leaders footing with this new technology. Expect it to catch on quickly. It is not in trials!!! It is full blown implementation!!! It gives everyone a win-win situation. The consumer gets high speed access. The telcos do not have to buy lots of expensive equipment.

Fiber-to the-curb and VAST is still the future on the horizon at this time; but this is a viable and economical intermediate alternative.

Peace,
Clarke

PS Try going to IBM's DB2 Universal Database site and ordering the demo CD; get a free copy of Netscape 4.03 on it!!!

IBM DB2