Multipath Channel Characterization in Realistic Non-Terrestrial Network Scenarios: Sounder Design, Chamber Validation, and Field Campaign

Non-terrestrial network (NTN) communication has emerged as a key enabling technology for future sixth-generation (6G) communication systems, owing to its capability to provide global coverage and seamless connectivity. To support system design, performance evaluation, and network deployment of realistic NTN systems, accurate and comprehensive knowledge of propagation channels is essential. However, multipath channel sounding and characterization in realistic NTN scenarios remain largely unexplored in the existing literature. This paper presents a comprehensive study on multipath channel sounding and characterization in realistic NTN environments. A self-developed multi-antenna channel sounder, equipped with dual-polarized antenna array and 56 parallel RF chains, is firstly proposed to extract the multipath parameters based on the passive channel sounding concept. Furthermore, the accuracy and robustness of the proposed channel sounder are thoroughly validated in a multi-probe anechoic chamber (MPAC). An extensive channel sounding campaign is conducted in realistic deployed NTN scenarios at the S-band, i.e., Tiantong satellite. The multipath parameters encompassing angular, power and polarization have been effectively extracted with the proposed channel sounder. The composite channel characteristics have been calculated and thoroughly analyzed using the extracted multipath parameters. Statistical models of these channel parameters are further established, enabling an accurate and comprehensive channel characterization for realistic NTN scenarios.