Research On Efficient Narrow Beam Transmission For Terahertz Inter-satellite Communication

With the emergence of various new mobile communication requirement,the deficiency of the terrestrial mobile communication system in terms of coverage capability is becoming more and more obvious.Considering the unique advantage of satellite communication in coverage,using satellite network to assist terrestrial mobile network to provide global Internet services is the future development direction of mobile communication system.Inter-satellite link is not only a key technology for the satellite Internet and future satellite-terrestrial integration network but also decisive for satellite network capability.Terahertz is in the spectrum between microwave and laser.It has the advantages of microwave and laser communication.The advantages include high operating frequency,large available bandwidth,excellent directivity and higher energy efficiency than laser communication.So it is a key potential technology for inter-satellite link.At present,there is a lack of research on terahertz inter-satellite communication,and systematic research and analysis are urgently needed.In this thesis,we firstly analyze the characteristics of terahertz transmission in the space environment and verify the feasibility of inter-satellite terahertz link and then carry out systematic simulation analysis of inter-satellite terahertz communication in terms of links and networks.Finally,an energy-efficient space-borne transmitter architecture for inter-satellite terahertz communication is designed by using intelligent metasurface.It meets the requirements of energy-efficient communication and follows the development trend of miniaturization and low cost of satellite equipments.The details of the research are as follows:(1)Systematic simulation research of inter-satellite terahertz communication.This research is mainly carried out from the following three aspects:analysis of inter-satellite terahertz narrow beam propagation characteristics,simulation of terahertz inter-satellite link and terahertz inter-satellite directional organizing network.For the analysis of inter-satellite terahertz narrow beam transmission characteristics.Firstly,the transmission characteristics of terahertz in atmosphere and space environments are analyzed and simulated to prove the feasibility of inter-satellite terahertz link.Secondly,the unavoidable beam misalignment is modeled to lay the foundation for the subsequent link analysis.For the simulation of terahertz inter-satellite link.Firstly,the terahertz beam characteristics are analyzed by phased array technique.Secondly,the model of inter-satellite terahertz channel is proposed on the basis of inter-satellite beam misalignment and solar scintillation effect and the simulation of link performance is carried out accordingly.Finally,the model of inter-satellite Doppler shift is proposed based on ephemeris information.For the simulation of terahertz inter-satellite directional network,the actual satellite constellation is constructed by using STK software and then the time slice topology routing algorithm designed in this thesis is simulated by using OPNET software to analyze the performance of inter-satellite terahertz dynamic directional network.(2)Energy efficiency evaluation of terahetz inter-satellite communication with the help of intelligent metasurface antenna.In order to solve the problem that terahertz massive active array antenna has complex structure and bad energy efficiency performance,with considering the advantages of intelligent metasurface antenna in cost and energy efficiency performance,an energy-efficient terahertz inter-satellite communication scheme based on metasurface antenna transmitting architecture is proposed in the thesis by using the metasurface antenna as the space-borne terahertz transmitter antenna.Then the energy efficiency performance of the proposed scheme is comprehensively evaluated.The results show that compared with the traditional massive array antenna,the metasurface antenna transmitting architecture can effectively reduce the complexity of the transmitter feed network and the system cost and improve the energy efficiency performance in the inter-satellite terahertz communication scenario.