Defining Availability for High-Rate Data Links with Fading

Future wireless military data links are being designed to transmit packet data at rates of hundreds of Mb/s and higher. Link technologies that are liable to signal fading, such as free-space atmospheric optical technology, are also expected to gain in importance over the next decade, especially for very high-rate links. These developments require reevaluation of the traditional criteria used for determining the availability of such communications links. This paper examines some traditional criteria for defining link availability, both in the military and commercial arenas, and analyzes their shortcomings for defining link availability in future systems. New classes of error-rate-based availability definitions are presented, along with analysis showing that their characteristics are particularly suitable for the high-rate, possibly fading, data links of the future.