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.

基于GNSS（全球导航卫星系统）的自主导航是航天器运行的有效方式，而无需地面设施的帮助。GNSS在高轨道上的应用已被定义为GNSS空间服务量（SSV）。但是，SSV应用受到卫星能见度差的极大限制。GNSS旁瓣信号被认为是增强SSV可用性的有效方法。尽管旁瓣信号被无意识地用于高轨道自主导航，但尚未对旁瓣信号的特征进行全面分析。而且，由于缺少详细的GNSS天线方向图规范，因此很难进行精确的太空任务设计。在本文中，对三个典型的SSV任务的BDS-3（北斗导航卫星系统的第三代）三频信号进行了比较研究，该信号具有主瓣和旁瓣的组合。重建高保真3D BDS天线方向图，并分别对接收信号功率，多普勒频移，接收机测量误差，信号可用性等进行全面评估。仿真结果表明，与仅主瓣情况相比，可以显着提高4颗或更多卫星和GDOP的可用性。接收机测量误差表明，B1C和B3I信号的性能优于B2a，并且在SSV中主要推荐使用导频信号。