| With the extensive construction of optical networks and the explosive growth of information carried by optical networks,the hazards of optical network failures are becoming more and more serious.Even a short moment of network failure can lead to huge amounts of data and information loss,causing irreversible and serious consequences.When a large-scale disaster(such as an earthquake)occurs,existing survivability technologies that rely only on terrestrial optical networks become powerless if parts of the network are completely isolated from other parts of the network.One possible solution is to use satellite optical networks to protect terrestrial optical networks.Thanks to the development of space laser communications and satellite optical networks in recent decades,it has become possible to build a space-ground integrated optical network to improve the survivability of the terrestrial optical network.In this context,this thesis investigates the shared protection technology in space-ground integrated optical networks,and the main work and innovation points are as follows.(1)The characteristics of satellite optical networks are analyzed,and the shared protection technology of the GEO satellite-based space-ground integrated optical networks is proposed to realize the protection of terrestrial optical networks in disaster situations,and it can effectively solve the isolation problem.The routing and wavelength assignment algorithm is developed,which can be completed in polynomial time.The results show that the proposed scheme has a low blocking rate.(2)A precomputed snapshot routing and wavelength assignment algorithm for link duration-aware dedicated/shared protection technology is developed for LEO satellite-based space-ground integrated optical networks.The algorithm selects the path with longer duration by sensing the link duration,thus reducing the number of path switches and avoiding frequent fluctuations in quality of transmission.By pre-calculating the handover process,resources are reserved to prevent requests from being forced to be interrupted due to insufficient resources during the handover process,ensuring a 100 percent switching success rate.The simulation results in the test network prove that the satellite coverage largely determines the availability of the protection technology of the spaceground integrated optical network,and the higher the satellite coverage,the lower the blocking rate. |
