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The Last Mile
Wireless techologies may be the wave of the future

It was just over ten years ago that Nicholas Negroponte of MIT's esteemed Media Lab made the prediction that became known as the Negroponte Switch. The basic premise of Negroponte's prediction went something like this: Traditionally, mass communications (point-to-multipoint) such as radio and television have been transmitted over the airwaves while interpersonal communications (point-to-point) such as telephone transmissions have been transmitted via wires. The development of new technologies makes possible a "switch" between the two that creates a more rational system. In other words, bandwidth-hungry mass communications will be delivered via wires (or cables) and relatively low bandwidth transmissions like phone conversations will be delivered via the airwaves.

At the time, Negroponte had every reason in the world to believe that such would be the case for the foreseeable future, and almost everyone agreed with him - his word became gospel in industry and academe. After all, cable television throughout the 1980s was becoming the dominant force in the entertainment industry that it is today. One coaxial cable coming into your house was capable of delivering 60 or more television channels, as opposed to the three or four you could receive over the air. Fiber optic cables, in increasingly widespread use since the early 80s, had been developed to the point that they seemed to promise almost unlimited bandwidth. On the flip side, cellular telephone use had grown through the 80s to the point that it was clear that cell phones (or something like them) would one day become ubiquitous. By 1989, of course, there was already extensive use of satellite and microwave relays (using over the air transmissions) in the public phone system.

Negroponte's prediction was based on an important concept that was a fact of life at the time - the scarcity of spectrum space. Simply put, the usable part of the electromagnetic spectrum was too valuable to devote to a relatively few very high bandwidth channels like television signals. Something had to be done about this situation before we could enjoy genuine broadband access for work and entertainment. With this scenario looming, techno-pundits began exploring ways to bridge the critical "last mile" to the residence or business. The best possible case, bandwidth-wise, was the installation of fiber to the door, but that would cost multi-billions of dollars to implement and was an unpleasant and perhaps unworkable prospect. Technologies that made use of existing twisted pair phone wires were developed, but they were, and are, simply transitions to more satisfactory bandwidth.

Negroponte had the distinction of being known as a savant for at least three or four years before technology put the Negroponte Switch out to pasture as an idea for the future. By 1994 or 95, it was becoming increasingly clear that the genuine broadband revolution, in terms of the "last mile," would be one powered not by wired technologies, but by wireless technologies. However, there would be many obstacles to overcome, not the least of which was developing a whole new system of "broadcasting" in a much higher portion of the spectrum. But making use of higher and higher frequency ranges has been the history of the evolution of our use of the spectrum, and the 1990s have seen some of the most dramatic developments to date, making possible a wide new range of services for home and business in the very near future.

The next few columns will explore the use of wireless networking in a variety of contexts - from your corporate local area and backbone networks to neighborhood television and Internet access and beyond, to global wireless service provided by fleets of low-orbit satellites. Stay tuned.