SDSL is not new. It allows for approx. 1.8 Mbps downstream and upstream, and, thus symmetric. The ADSL-DMT advantage is that it allows for much greater speeds downstream (8-10 Mbps)than upstream (640 Kbps). If you use the internet a lot, then you probably already realize that you do much more downloading (ie. free software, articles, directories, etc.) than uploading (ie. sending commands to retrieve the info. from the net). ADSL also is excellent for movies on demand. SDSL is better for videoconferencing because of the bidirectional, "symmetric"/duplex bandwidth. Thus, SDSL would not be as useful as ADSL-DMT for everyday internet use.
The new tech. from Intel -- the MMX software/multimedia enhancement -- might be able to enhance the weaker upstream speeds of ADSL once it reaches the user. If this were true, then ADSL(esp.DMT) could possibly be as good as something symmetric for videoconferencing. This is only a guess. Presently though, for internet use, ADSL-DMT seems the best for reliability and performance. Also, GTE isn't testing SDSL in its current trial in Texas--it's testing ADSL. Why important? GTE Telephone Operations is the largest US-based local telephone co., providing voice, video and data products and services through more than 23 million access lines in portions of the US, Canada, South America, the Carribean and the Pacific. GTE is one of the largest publicly held telecommunications companies in the world. If they wanted to compare...they probably would have thrown in some SDSL products (they didn't).Everything herein, as always, IMHO.
Regards,
JPD |
