Think DSL's fast? Watch VDSL

Summary:It won't happen tomorrow, but urban dwellers will be talking megabits, not kilobits, for their broadband connections after Ikanos successfully demonstrated VDSL-DMT.

The next generation of broadband came closer last week when Californian chip company Ikanos demonstrated Ethernet at 50 megabits per second (mbps) download speeds over a kilometer of copper wire.

The new technology, VDSL-DMT, also allows up to 28mbps uplink, and conforms to Plan 998--a standard for using radio frequencies over telephone cable. Aimed at in-building and densely populated urban applications, VDSL--very high speed digital subscriber line--is designed to connect buildings through telephone lines to nearby hubs in exchanges, or on the street, containing fibre backbones.

It will provide high-quality video on demand, broadcast TV, and much faster digital media delivery, as well as better Internet access, but only for sites within a mile of a hub.

As always, the politics of which standard to adopt is as important as the technology, and Ikanos is preaching flexibility. "It is absolutely essential that VDSL chip suppliers be familiar with both ATM (the standard telco voice and data protocol) and Ethernet, particularly for central-office applications," Richard Sekar, vice president of marketing at Ikanos, told industry magazine EE Times. "Over time, Ethernet may be preferred for its familiarity and lower cost," he said, but many deployments, particularly in Europe, "will be using ATM in the near term."

The demonstration took place at an FS-VDSL committee meeting in Colorado. The FS-VDSL committee is an industry group of some 70 companies dedicated to a speedy roll-out of much faster broadband, and includes BT, Deutsche Telekom, Bell Canada, Qwest Communications and many equipment manufacturers.

Although VDSL-DMT hasn't yet been chosen as the standard for VDSL the decision is due to be taken soon, and Ikanos hopes that showing working silicon will help it press its suite. VDSL-DMT is compatible with existing ADSL, and can support existing DSL modems where the higher speeds of VDSL aren't possible. Ikanos is working in co-operation with Alcatel, Globespan/Virata, STMicroelectronics, IBM and Ericsson among others.

At the end of February, the FS-VDSL committee successfully demonstrated delivery of high-quality video and fast Internet access over a test network designed to simulate actual working conditions: systems interoperability demos have been installed at five sites around the world, including on a BT site.

The tests were designed to show real-world use, including acceptable response when viewers were channel-zapping, and also demonstrated high quality videoconferencing, broadcast TV, and video-on-demand. The emphasis is as much on integrating the new services with existing telco systems as the new services themselves, using lessons learned in the first wave of DSL deployments.

Although the technology may still be some time away from commercial release, some DSL providers are experimenting with other ways of boosting bandwidth. The UK's Easynet is planning to offer businesses in metro areas up to 8mbps of uncontended bandwidth (where the bandwidth is not shared with other customers), and has been experiminting in the lab with bundling DSL cables together to achieve bandwidths of 50mbps.

Topics: BT, Broadband, Networking

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