Minn, HlaingGriffith, D. Todd2024-03-062024-03-062023-12December 2December 2https://hdl.handle.net/10735.1/9995Large-scale non-geostationary orbit (NGSO) satellite communication (SatCom) systems (SCSs) are emerging to play an important role for future global wireless communication. However, satellite communication systems with more than thousands of satellites raise a serious concern of radio frequency interference (RFI) to the ground-based radio astronomy system (RAS). This situation becomes more serious as the SatCom industry is rapidly expanding the number of communicating satellites which increases RFI, while the RAS is also advancing with enhanced radio astronomical observation (RAO) capability requiring better protection against RFI. To address this impending RFI issue, this dissertation focuses on two approaches, namely, space-based RAS and sky radio quiet zone. First, the satellite-based RASs including low earth orbit (LEO)-based or medium earth orbit (MEO)-based RASs are considered to lower the impact from SCSs on the higher orbit onto the ground RASs and the lower orbit RASs. We find out the required SCS emission mask for each RAS so that both systems can avoid RFI. Then, we investigate three typical radio astronomy metrics such as maximum baseline distance (MBD), the number of simultaneously observing telescopes, and the signal to interference plus noise power ratio (SINR) performance for NGSO satellite-based RAS. Additionally, we also explore the advantages of NGSO satellite-based RAS from a communication side. Our analysis shows that the large-scale NGSO satellite-based RAS can offer more spectrum access to both SCS and RAS. Secondly, we analyze RFI from the large-scale NGSO SatCom system to a ground-based RAS to identify dominant RFI contributors and then propose two types of sky radio quiet zone (SRQZ), namely, telescope-centered (TC)-SRQZ and RAO direction-centered (DC)-SRQZ. We investigate peak RFI and average RFI suppression characteristics of the two SRQZ types when applied individually alone and jointly. We evaluate the RFI characteristics with/without SRQZs for a few representative ground RAS receiver locations under a low earth orbit SatCom system as well as a medium earth orbit SatCom system. We present and discuss extensive RFI performance results and their dependency on the specifics of the RFI scenarios. These results show that appropriately designed SRQZs provide significant RFI suppression. We also offer guidance on the choice of SRQZ type/deployment, related parameter settings, and practical implementation aspects.application/pdfEnglishEngineering, Electronics and ElectricalThesis2024-03-06