Interference Analysis Due to Spot Beams Drift in Integrated Satellite-Terrestrial Networks

Integrated satellite-terrestrial networks can improve both the service coverage and spectral efficiency in spot-beam-based mobile satellite service system (MSS). In an integrated satellite-terrestrial network, MSS frequency is reused in both satellite spot beams and complementary ground component (CGC). Due to reuse of frequency, co-channel interference is present in both intra-component (between CGCs) and inter-component (between satellite spot beam and CGC). Without spot beams drift, these interferences have tolerable levels for acceptable performance in voice and/or data communication. However, in practice, especially the inter component interference will start to grow if the spot beams drift from their nominal positions due to pointing error of spot beams. In this paper, we study the interference from the satellite component to the ground component when the drifted spot beams start to interfere with CGCs reusing the same frequency. The interference levels depend on the drift magnitude, drift angle, and also the protection ring size utilized by the ground component. Simulation results are provided for different values of these parameters and giving new insight into the effects of spot beam drifting in an integrated satellite-terrestrial network.