Comment Articles

Will wideband wireless be a DSL disappointment?

Rupert Goodwins AnchorDesk

Published: 20 Feb 2002 17:26 GMT

There's a new kid in town, and he's called UWB. Ultrawideband is the latest buzzword for wireless data fanatics -- with the US giving the technology the official go-ahead expect to be reading a lot more about it in the near future.

Unlike many over-hyped ideas, UWB is the genuine article -- a new way of working that could change everything. It's the biggest fundamental innovation in radio since Marconi invented the idea of tuning, and like Marconi's ideas it's come about at just the right time. And like many revolutions, it may be so scary to the existing order that it may get strangled at birth.

All good revolutionary studies start with a history lesson. Pre-UWB, all radio -- even the very clever stuff -- was fundamentally the same. The transmitter generates a signal called a carrier, which is analogue, continuous and at radio frequency. This carrier is coherent: it's millions upon millions of waves, all in step and all precisely alike, and the basic miracle of radio is that if you move electricity in the shape of a wave through a wire, that wire gives off a wave of radiation in the same shape. This electromagnetic signal -- be it long wave, short wave, or even microwave -- goes skittering through space: if it then hits another wire, the electrons in that wire start to move in sympathy. Houston, we have contact.

If you make small changes in the carrier before you transmit it -- modulation -- the receiver picks them up too. This modulation is usually information us humans want to move from place to place: with medium wave broadcasting, it's voice and music; with digital systems the information is ones and zeros, encoded as analogue shapes on that analogue carrier.

The radio spectrum has tons of room for millions of carriers, so you can put loads of different signals out at once. Everything works this way. Even wireless networking, which goes skipping around the bands trying to avoid interference, uses a series of carriers. A tiny burst of data on a wireless network rides on top of a chunk of carrier that has millions of waves all nicely lined up: the receiver tunes into the carrier and then pulls off the information.

Once your spectrum is full -- or if someone's already on your channel -- you're stumped, and that's why everyone's fussing about the analogue switch-off. New digital services need the room taken up by old analogue transmissions, and it's unfortunate for the people who still listen in.