A Simplified Method for the Laboratory Determination of Multipath Outage of Digital Radios in the Presence of Thermal Noise

Multipath fading at microwave frequencies causes highspeed digital radio systems on line-of-sight paths to experience outage, where outage is defined here as the number of seconds in a month that the bit-error rate (BER) on an unprotected hop exceeds a threshold. The expected or predicted outage of a radio system may be calculated using a statistical model of fading in conjunction with characteristics of the radio determined by stressing it with a multipath fading simulator in the laboratory. To determine the effects of transmitted power levels (or nominal received carrier-to-noise ratio) on outage may require the simulation of 500-1000 channel conditions to characterize the radio completely. This paper describes a method of generating the complete characterization from a reduced set of simulation measurements; the method reduces the required number of measurements by a factor of about 20. Over a wide range of operating conditions, the outage calculated with this simplified method differs by less than 25 percent from that obtained with the complete characterization.