ESTABLISHING WIRELESS COMMUNICATIONS SERVICES VIA HIGH-ALTITUDE AERONAUTICAL PLATFORMS - A CONCEPT WHOSE TIME HAS COME

Radio makes it possible to have communication ''without wires.'' This is a highly attractive proposition for mobile personal communications; it is increasingly an economic alternative to traditional wired phone systems, and is a potential technology for highspeed Internet access. But in the terrestrial environment, radio signals are subject to scat tering and multipath effects that limit the quantity of information po ssible to transmit in a given bandwidth, as well as the distances over which it can be communicated. In cellular and personal communication systems (PCS), radio coverage is deliberately restricted further to al low for frequency reuse. As a consequence, terrestrial wireless networ ks comprise numerous antenna towers, base stations, wired or microwave links, and mobile switching centers, all dispersed over wide geograph ical areas. Satellites can provide wireless coverage with much less te restrial infrastructure, but only by introducing considerably problems of their own. Geosynchronous satellites require expensive and bulky u ser terminals and introduce large signal delay because of their great distance. Nongeosynchronous satellites, because of their motion with r espect to points on the ground, greatly increase system complexity. Pr oposed high-altitude aeronautical platforms (HAAPs) are an intriguing alternative. From a communications perspective, they would have many a dvantages over both their terrestrial and satellite counterparts. If H AAPs prove to be reasonably stable, reliable, and not too costly, they will offerr considerable opportunities for wireless services provisio n, and introduction of innovative communications concepts such as cell scanning and stratospheric radio relays.