Research On Frequency Compatibility And Coexistence Between Low Earth Orbit Satellite Internet Constellation And Geostationary Satellite System

With the continuous development of low earth orbit communication satellites,the construction of satellite Internet constellation by low earth orbit satellites is on the upsurge all over the world.Commercial aerospace companies such as One Web,SpaceX,Telesat and Kepler are developing their own Internet constellations in the hope of providing global broadband services.Low earth orbit satellite systems can greatly reduce communication delay and radio transmission loss,and the system performance will be more stable.However,frequency bands such as Ku and Ka et.al.used by low earth orbit satellite are also widely used by Geostationary Orbit(GSO)satellites,which are prone to inter-system interferences.With the deployment of Internet constellation in low orbit,the frequency compatibility problem with GSO satellite systems will become more and more serious.This paper first analyzes key research points of co-frequency interference between satellite systems,including causes of co-frequency interference,key factors of scene modeling,evaluation indicator and calculation of interference,as well as statistics and analysis of interference.Secondly,a downlink interference mitigation method between satellite systems is proposed,including the definition and mathematical modeling of the NGSO satellite exclusion zone,proposing the overlap criterion of satellite beams,designing the adaptive beam control method matching exclusion zone,and using MATLAB and Satellite Tool Kit(STK)joint programming techniques to verify the effectiveness of the method.Thirdly,a uplink interference mitigation method between satellite systems is proposed,including the strategy design of dynamic separation angle,software simulation with One Web and SinoSat-5 systems as examples,discussion of simulation results from multiple dimensions,and verification of effectiveness of the uplink interference mitigation technology.The results show that the proposed downlink interference mitigation method joint exclusion zone and adaptive beam control,and uplink interference mitigation method based on the strategy of adaptive separation angle can effectively reduce the I/N value,interference frequency,interference probability,as well as the communication link C/(N+I)degradation at the GSO satellite and earth station receiver.The proposed methods can be used to protect GSO satellite system from NGSO satellite system.