Research On Spectrum Sharing Method Of Dual Satellite System Based On Distributed Satellite Formation

With the rapid development of space information network,more and more artificial satellites and spacecrafts are launched into different orbits.The construction of a satellite Internet system based on the low-orbit giant constellation makes the traditional static frequency allocation methods difficult to meet the increasing frequency demand.Exploring the spectrum resource sharing mode between LEO and GEO satellite systems has become a hot issue in the field of spatial information network.Aiming at the problems of weak perception,low spatial resolution and limited transmission performance of single LEO satellite,this article studies the cooperative perception and transmission technology based on distributed formation satellites in a dual-satellite system frequency sharing scenario.In the highly dynamic environment,make full use of the space domain resources of formation satellites,improve the spectrum perception accuracy of LEO satellite systems,reduce co-frequency interference of dual-satellite systems,and thereby improve the efficiency of spectrum use and transmission performance in satellite systems.This article mainly includes:(1)Aiming at the problems of LEO satellite with large beam coverage and weak sensing capabilities,this article proposes a blind beamforming spectrum sensing algorithm based on feedback control under the condition that the authorized user’s signal system is known.The cooperative satellites adaptively adjust the weighted values of the sensing signals through the sensing signal broadcast by central-satellite,so that the sensing signals forwarded by the distributed cooperative satellites are superimposed in the same phase on the central-satellite,which improves the signal to interference plus noise ratio(SINR)of the sensing signal,thereby improving the spectrum sensing capability.The simulation results show that the method proposed in this article effectively increases the SINR at the receiving end and improves the spectrum sensing performance.(2)Aiming at the co-frequency interference of GEO authorized user in the downlink and the co-frequency interference of LEO cognitive user,this article proposes a cooperative transmission method for formation satellites driven by transmission tasks.Utilizing the feature of flexible reconstruction of satellite formation,an optimization problem with the SINR as the optimization objective is established,and convex optimization and mixed integer programming algorithms are used to solve the problem.The simulation results show that the algorithm proposed in this article can obtain the optimal satellite formation and the weighted value of formation satellites that meet the needs of the transmission mission,effectively improve the SINR of LEO cognitive user,and reduce the interference to GEO authorized user.(3)Aiming at the problem of uplink co-frequency interference caused by GEO authorized user to LEO satellites,this article comprehensively considers the direction of arrival error caused by the outdated channel information of long-distance signal transmission in the satellite communication system,and proposes a robust adaptive beamforming algorithm based on linearly constrained minimum variance(LCMV).From the perspective of spatial isolation,the co-channel interference caused by GEO authorized user to low-orbit satellites is suppressed,and the spectrum sharing of the dual-satellite communication system is realized.Simulation results show that the proposed algorithm can effectively alleviate the problem of co-channel interference during uplink frequency sharing.