Research On Dynamic Spectrum Sharing Technologies In Integrated Satellite-5G Networks

As people's requirements for communication areas become higher,achieving "seamless and all-weather" communication on a global scale has become the development direction of mobile communication in the future.Due to the different coverage and capacities between terrestrial networks and satellite,the combination of the two systems can provide users with more efficient and convenient communication services.Since 5G has become the standard of next-generation terrestrial mobile communications,satellite communications will play a key role in the 5G ecosystem.Spectrum sharing in the integrated terrestrial-satellites networks has become an urgent need for large-scale expansion of broadband services,which can mitigate spectrum scarcity and thus improve spectrum utilization.Therefore,this paper mainly studies the dynamic spectrum sharing technologies in the integrated networks.The domestic and foreign research status of the integrated systems and its spectrum sharing technologies were first discussed.Aiming at the current trend of satellite and 5G network integration,the application scenarios and architectures of the integrated system were analyzed,and the application strategies of spectrum sharing technologies from low frequency band to high frequency band were evaluated.Several typical cognitive radio-based technologies were introduced,and its advantages and disadvantages were analyzed and compared,which can provide the theoretical basis for the studies of energy detection algorithm and underlay algorithm in next sections.The energy detection algorithm for spectrum sensing in the integrated system were then analyzed in detail.By deducing the expressions of detection probability and false alarm probability,the perceptions of the cognitive users were analyzed and simulated,and the factors affecting the detection performance were determined.Aiming at the noise uncertainty and channel fading problem in energy detection,the solutions for using additional dipole antennas and applying cooperative spectrum sensing in cognitive users were respectively proposed.The simulation results have shown that using the dipole antenna at the receiver of the cognitive user can effectively avoid the appearance of the SNR Wall,thus avoiding the influence of noise uncertainty to some extent.The application of reliability based weighted algorithm for cooperative spectrum sensing can maintain a high probability of detection,thus avoiding interference to authorized users.Finally,in view of the limitations of energy detection in weak signal detection and node hiding,this paper has proposed the underlay algorithm,which aims to strictly control the transmit power of cognitive users to guarantee the expected QoS of authorized user.With the Meijer-G function,the asymptotic but concise expression of the outage probability of cognitive user was derived for the proportional interference constraint and the peak interference constraint at high SNR.The simulation verification of the algorithm performance was carried out in three typical satellite channel scenarios.The effects of various system parameters and constraints on the outage performance were characterized.Thus the validity of the derivation process was verified and the interference of primary user suffered is guaranteed below the threshold.