On the effect of interference from a cluster of spread spectrum stations

With the advent of micro earth stations using spread-spectrum (SS) technology, a victim terrestrial radio receiver is likely to be subjected to uplink interference from many earth stations, especially near metropolitan areas. Statistical methodology is used to characterize the intermittent use of SS transmitters, making it possible develop a model for the interference generated from such a cluster of transmitters. It is shown how current coordination and design procedures must be revised if one wants to optimize the use of SS technology without harmful interference to victim terrestrial receivers. For example, for a cluster size of 50 and activity factor of 10%, it is shown that the effective number of exposures can be taken to be 15. This numer is not exceeded 99.99% of the time when one or more transmitters are active and transmitting