Interference avoidance beam planning method between NGSO constellation and GSO satellite

To address the increasingly congested spectrum resources resulting from the rapid development of non-geostationary satellite orbit constellation systems, a beam planning method based on spatial isolation zones was proposed to avoid interference in spectrum sharing between NGSO (non-geostationary satellite orbit) and GSO (geostationary satellite orbit) systems, utilizing a satellite-based phased array antenna. Through an analysis of the interference scenario between NGSO and GSO satellite systems, the Earth's surface was divided into grids by latitude and longitude for uniform spatial enumeration, which enabled the development of an aggregate interference analysis model for the NGSO system on the geosynchronous orbital arc based on time slices. According to the I/N interference threshold standard, an objective function was formulated for phased array antenna beam planning to facilitate frequency sharing between NGSO and GSO systems, revealing the mapping mechanism between spatial isolation zones and beam planning strategies. Consequently, a beam planning method was proposed to achieve interference avoidance. Through simulation experiments, the effectiveness of the method is validated, providing a reference for the design of low Earth orbit satellite constellation systems.

The measures currently proposed mainly target single-beam satellite constellation systems and impose strict requirements on constellation density and orbital positions. To ensure uninterrupted communication with ground stations, a reasonable constellation configuration is necessary. When the scale of low Earth orbit constellations is large, the complexity of the method increases, making it difficult to define spatial isolation angles and accurately determine exclusion areas. Moreover, the corresponding beam deflection or switching mechanisms become challenging to implement, reducing their practicality. Therefore, a novel interference avoidance beam planning method based on spatial isolation exclusion areas is proposed for spaceborne phased array antennas.

The method first analyzed the interference scenarios between the NGSO and GSO satellite systems. The ground was divided into several grids based on latitude and longitude, followed by spatial uniform enumeration. A time-slice-based analysis model was then established to assess the worst-case aggregate interference from the NGSO system on synchronized orbital segments. Next, based on the I/N interference limit standard, a phased array antenna beam planning objective function was constructed for frequency sharing between the NGSO and GSO systems. This revealed the mapping mechanism between spatial isolation exclusion areas and beam planning strategies, leading to the proposed beam planning method for interference avoidance. Finally, simulation experiments validated the effectiveness of the method.

Beam planning was carried out using this method, and the uplink and downlink carrier-to-noise ratios under the coverage of NGSO satellite beams were significantly reduced to below the threshold. After applying the beam planning interference avoidance strategy, no interference was present in any global region of the uplink and downlink scenarios across the global coverage of NGSO satellite beams. Additionally, the method demonstrated that the single-satellite beam utilization for both uplink and downlink links was higher than 38.9%, proving the effectiveness of the method.

Based on the quantitative analysis of interference avoidance isolation zones, a specific beam planning strategy was proposed. This strategy overcomes the limitations of traditional interference avoidance methods based on isolation angles or isolation zones, which require the shutdown of all satellite beams. It effectively avoids interference in regions exceeding the interference threshold under the coverage of NGSO satellite beams, providing a method reference and technical support for protecting communication links of GSO satellite systems while ensuring the operational efficiency of NGSO satellite systems.