Ka-Band Inter-Satellite Link System Design for MEO Navigation Satellites Constellation

Inter-satellite links (ISLs), the essential part of global navigation satellite systems (GNSS), enhance the autonomy and flexibility of the constellation under the minimal distribution of reference monitoring stations. ISL is generally designed to cater to ranging, communication and autonav requirements for medium earth orbit (MEO) navigation satellites. ISL assists the communication need by transferring primary navigation parameters and ranging parameters across the satellite constellation at faster rates. The code division multiple access (CDMA) based ranging assists precise orbit de-termination and time-transfer requirements for autonav operation. We propose the radio frequency (RF) ISL system for navigation satellites constellation considering the low data rate requirements and ranging accuracy for orbit determination & autonav requirements. We present the onboard system design of RF ISL with Ka-band active phased array antenna. Inter-plane RF ISLs, which connect satellites from different orbital planes, are greatly dynamic and are considerably affected by the higher Doppler shift. We also present link design for various ISL distances, the required transmit/receive antenna requirements & power amplifier rating, Doppler shift, and the number of ISLs for a given MEO satellite constellation. The proposed RF-ISL provides the ranging accuracy of approximately 13.6 cm for MEO navigation satellite constellation system.