ADSL transmits at 60 Mbps over a POTS line

-- EDN, 12/9/1999

STMicroelectronics and Telia Researchdeveloped the Zipper-VDSL (very high-bit-rate-digital-subscriber-line) technology, which extends by an order of magnitude the capacity of asymmetric DSL (ADSL). The companies based the technology on the same discrete-multitone (DMT) technology that underlies ADSL. Telia originated the "zipper" concept from the way the strategy "zips" together the bands to use the telephone line in any configuration. It uses a filterless frequency-division-duplexing scheme that can freely assign the ratio between upstream and downstream capacity over the line. The total capacity comprises 2048 frequency bands that you can access individually to optimise capacity. The scheme is backward-compatible with ADSL and ADSL.Lite.

The companies based a prototype on a 0.25-µm CMOS chip they designed with France Telecom's research centre; STMicroelectronics targets an integrated single-chip implementation for commercial release early in 2001.

STMicroelectronics, www.st.com.

Telia AB, www.telia.se.

-by Graham Prophet