KA band spectrum re-use for surrogate satellites on unmanned airborne vehicles

The use of airborne relays serving as surrogate satellites can provide battlefield connectivity and reduce traffic load on military satellite systems. Potential spectral re-use strategies require an analysis of interference effects associated with the operation of a surrogate satellite mounted on an unmanned airborne vehicle (UAV-SS). The ability to operate a UAV-SS at Ka band in the presence of other Ka band users, such as wideband Gapfiller system (WGS) terminals without creating and/or receiving unacceptable interference was assessed using a statistical mathematical model. Multiple scenarios, where parameters such as number of users, relative positions of UAV-SS and WGS terminals, mix of terminal antenna sizes and powers, traffic levels, etc., were investigated. Analysis results for the interferer-victim pairs are presented where the metric is percentage time interference levels exceed given criteria. The key finding is that under the strict constraints of spatially interspersed UAV-SS and WGS ground terminals sharing frequencies, the percentage of time high levels of interference at WGS ground terminals and at UAV-SS air occurred was unacceptable. The implication for potential UAV-SS use is that some relaxation of these constraints is necessary, either by separate frequency allocation, or spatial separation between the two user communities. The model provides guidance for determining the level of frequency/spatial separation necessary to achieve acceptable interference time percentages