BDS Space Service Volume characterizations considering side-lobe signals and 3D antenna pattern

Abstract

Autonomous navigation based on GNSS (Global Navigation Satellite System) is an effective way for spacecraft operation without the assistance of ground facilities. The application of GNSS at high orbit has been defined as GNSS Space Service Volume (SSV). However, the SSV application is extremely constrained by poor satellite visibility. The GNSS side-lobe signals are considered as an effective way to enhance SSV availability. Although side-lobe signals have been utilized unconsciously for the high orbit autonomous navigation, characterizations for the side-lobe signals haven't been comprehensively analyzed. What's more, there is a lack of detailed specifications of GNSS antenna patterns which makes it difficult to have an accurate space mission design. In this paper, a comparative study of BDS-3 (the third generation of the BeiDou navigation satellite system) triple frequency signals with a combination of the main-lobe and the side-lobe for three typical SSV missions is conducted. A high-fidelity 3D BDS antenna pattern is reconstructed, and a comprehensive assessment of the received signal power, Doppler shift, receiver measurement errors, signal availability, etc. are carried out respectively. The simulation results show that the availability of 4 or more satellites and GDOP can be improved significantly as compared to the main-lobe alone case. The receiver measurement errors show that B1C and B3I signals perform better than B2a, and pilot signals are primarily recommended in SSV. The assessment in this paper can serve as the theoretical guideline for both GNSS-based space mission design and onboard receiver design.