Despite all the talk about broadband, only about7 percent, or 7.5 million, of U.S. households subscribed to high-speed Internet access services as of last June, according to a February report issued by the U.S. Federal Communications Commission (FCC). And the situation isn't much different elsewhere. Only a few countries with much smaller populations report somewhat higher percentages.

Lack of need is, of course, one reason for the unimpressive numbers. Outside of playing interactive games, which is hardly a universal activity, no broadband "killer app" has yet emerged. Another reason is difficulty in getting service. For a variety of reasons, many would-be subscribers have been unable to get cable or digital subscriber line (DSL) service. For them, a fairly new type of technology known as non-line-of-sight (NLOS) wireless may be just what they need.

At first, NLOS wireless may not sound like a big deal. After all, ordinary radios and cellphones are non-line-of-sight devices. But they don't carry broadband data [see , "What is Broadband?"]. What makes the latest generation of NLOS wireless technology worth talking about and having is that it delivers data at high rates over substantial distances. Moreover, most implementations do so without the need for a visit from an installation technician.

This last point is crucial. Previous attempts to provide wireless Internet access to the home failed in large part because their installation costs were too high. For example, multichannel, multipoint distribution service (MMDS), which operates at 2.5 GHz, delivers high data rates over tens of kilometers. But first-generation systems required a directional antenna to be installed on the subscriber's premises within sight of a base station antenna.

Since service providers often find out that a potential location has no unimpeded view of the base station only when they send an installer to the site, the average successful installation takes more than one visit. With "truck rolls," as technician visits are known, costing anywhere from US $300 to $800, it could take more than a year's worth of subscriber revenue just to break even on the installation.

Worse, line-of-sight (LOS) systems do not scale well. When a base station's capacity reaches saturation, the usual procedure is to divide the coverage area into two pieces, use the existing antenna to serve half of it, and put up a new antenna to serve the other half. With directional antennas, that means that the antennas at roughly half the existing subscriber locations will have to be re-aimed at the new base station site, necessitating truck rolls that bring in no new revenue.

That's why communications companies--from household names like AT and T, Sprint, and WorldCom to newcomers like Winstar and Teligent, all of which rolled out broadband LOS wireless Internet access services, principally in the MMDS band--have pretty much given up on LOS wireless, at least insofar as price-sensitive residential customers are concerned. Last year, AT and T stopped service to 47 000 customers, Sprint and WorldCom slowed or halted their development, and both Teligent and Winstar filed for bankruptcy protection.