Evaluating the Influence of Satellite Systems on Terrestrial Networks: Analyzing S-Band Interference
Lingrui Zhang, Zheng Li, Sheng Yang
TL;DR
The paper tackles NTN-to-TN interference in the S-band by modeling NTN signals with the ITU-R P681-11 two-state model and examining how satellite–TN geometry, especially misalignment and elevation, affects interference at TN UEs. It combines a detailed link-budget decomposition, an antenna-pattern model, and ITU-based channel statistics to simulate interference across slant ranges and separation distances, deriving a minimal separation distance to keep INR under $0$ dB. Key findings show that the interference level is highly sensitive to the angle between the TN UE direction and the sub-satellite point, and that the required separation to maintain acceptable INR varies with slant range and satellite direction, with a transition around certain ranges. The results provide actionable guidance for spectrum sharing in the S-band, highlighting when and where NTN deployments could disrupt TN performance and identifying directions for effective interference mitigation in practical networks.
Abstract
The co-existence of terrestrial and non-terrestrial networks (NTNs) is essential for achieving comprehensive global coverage in sixth-generation cellular networks. Given the escalating demand for spectrum, there is an ongoing global discourse on the feasibility of sharing certain frequencies currently utilized by terrestrial networks (TNs) with NTNs. However, this sharing leads to co-channel interference and subsequent performance degradation. This paper specifically investigates the interference caused by NTNs on TNs in the S-band and its relationship with the relative position between satellite and TN user equipment. We analyzed the transmission mechanisms of satellite signals and employed the ITU two-state model for our interference analysis. Through simulations, we evaluated the interference intensity at different separation distances and slant ranges. Our findings reveal that the angle between the user equipment direction and the sub-satellite point direction from the beam center significantly influences the interference level. Furthermore, we determine the minimum separation distance needed to keep the interference-to-noise ratio of NTN interference below 0 dB.