| Satellite navigation has been unable to meet people’s increasing demand for highprecision location services due to its insufficient coverage ability in indoor and other special scenes.Satellite communication has gradually become an effective supplement to satellite navigation owing to its advantages of high transmission quality,wide coverage and long transmission distance,and has been widely used in disaster warning,broadcasting,navigation,mapping and other fields.Therefore,the integrated communication and navigation system,which can provide navigation,positioning and data communication services at the same time,attracts a growing interest.In order to use wireless communication network to achieve high precision positioning and high quality communication,relevant technologies are introduced in this dissertation r to achieve integration of communication and navigation.Satellite-terrestrial links transmission models for different scenarios are established and optimized by using multiple input multiple output(MIMO),non-orthogonal multiple access(NOMA),unmanned aerial vehicle(UAV)communication and jamming technologies.The main work and conclusions are as follows:(1)Aiming at the mutual interference between communication and positioning signals in the integrated signal of communication and navigation,orthogonal frequency division multiple(OFDM)and NOMA technologies are introduced to optimize its communication and positioning performance.The research shows that the communication and the positioning performance of the integrated signal can be optimized by setting the bandwidth of the signal,the number of positioning users and the signal-tonoise ratio(SNR)of the positioning signal.Take the integrated signal of 10 d B as an example.The ranging accuracy can be improved by 68.4% when the total bandwidth increases from 10 d B to 30 d B;it can be improved by 42.26% when positioning users decrease from 30 to 10;it can be improved by 69.63% when the SNR of the positioning signal increases from 35 d B to 45 d B.(2)The physical layer secrecy performances of multi-satellite satellite-terrestrial links based on amplify-and-forward(AF)and decode-and-forward(DF)relay are analyzed and compared.The results show that: compared to the traditional single satellite link,the secrecy performance of the link can be optimized by increasing the satellites number and adjusting the channel parameters and relay mode of the link model.That is beneficial to the integrated system to obtain better transmission performance.(3)Given the advantages of multi-hop communication in indoor coverage and heavily shadowed areas as well as the influence of cooperative jamming technology on security performance,a multi-hop satellite-terrestrial link transmission model with jamming is constructed.The secrecy outage probability(SOP)and the asymptotic behavior in high SNR region are studied and the system throughput is discussed.The results show that: the link model can be optimized by setting hops,channel parameters and cooperative interference without increasing network resources,so as to improve the secrecy performance of the satellite-terrestrial link.(4)Based on multi-antenna and cooperative jamming technology,an optimization scheme of multi-antenna satellite-terrestrial link transmission model with jamming is proposed.The analytical and asymptotic expressions of SOP are given,and the secrecy performance of the system is further evaluated by diversity order and throughput analysis.The results show that: it is a better choice to configure the same number of transmitting and receiving antennas for improving the secrecy performance;decrease of the relay coverage airspace and jamming signal can provide better secrecy performance.(5)Transmission model optimization scheme of the hybrid satellite/unmanned aerial vehicle(HS-UAV)NOMA link is proposed by combining UAV and NOMA technologies with satellite communication.Based on the theory of spatial stochastic geometry,the SOP of ground NOMA users and the system throughput are investigated.The results show that the secrecy performances of near and far users are affected by the channel fading,UAV coverage,distribution of eavesdroppers,but the impact degrees are different.Parameters such as UAV coverage range and channel fading can be optimized to enhance the secrecy performance of the satellite-terrestrial link.In this dissertation,there are 44 figures,13 tables and 148 references. |
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