Blind Spot of Spectrum Awareness Techniques in Nongeostationary Satellite Systems

Spectrum awareness techniques have been proposed as a promising solution to improve the utilization of available spectrum bands. However, few works have discussed the feasibility of spectrum awareness techniques in satellite systems. In the scenario of spectrum coexistence between geostationary (GEO) and nongeostationary (NGEO) satellite systems, this paper investigates the issue of blind spot where the spectrum awareness techniques may fail to identify the spectrum holes. Both the uplink and downlink transmissions are analyzed and three key parameters, i.e., altitude of NGEO satellite and antenna diameters of NGEO and GEO earth stations, are considered. Simulation results show that in the uplink, when the NGEO satellite approaches to the GEO satellite with a certain heights, there exists the situation of blind spot. In addition, this paper also provides a specific method to eliminate or reduce the range of blind spot.