Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure. Routing aimed at satellite networks has become a hot and challenging research topic. Satellite networks, which are special kind of Delay Tolerant Networks (DTN), can also adopt the routing solutions of DTN. Among the many routing proposals, Contact Graph Routing (CGR) is an excellent candidate, since it is designed particularly for use in highly deterministic space networks. The applicability of CGR in satellite networks is evaluated by utilizing the space oriented DTN gateway model based on OPNET(Optimized Network Engineering Tool). Link failures are solved with neighbor discovery mechanism and route recomputation. Earth observation scenario is used in the simulations to investigate CGR’s performance. The results show that the CGR performances are better in terms of effectively utilizing satellite networks resources to calculate continuous route path and alternative route can be successfully calculated under link failures by utilizing fault tolerance scheme. 相似文献
Space satellite observations in an electron phase-space hole (electron hole) have shown that bipolar structures are discovered at the parallel cut of parallel electric field, while unipolar structures spring from the parallel cut of perpendicular electric field. Particle-in-cell (PIC) simulations have demonstrated that the electron bi-stream instability induces several electron holes during its nonlinear evolution. However, how the unipolar structure of the parallel cut of the perpendicular electric field formed in these electron holes is still an unsolved problem, especially in a strongly magnetized plasma (Ωe > ωpe, where Ωe is defined as electron gyrofrequency and ωpe is defined as plasma frequency, respectively). In this paper, with two-dimensional (2D) electrostatic PIC simulations, the evolution of the electron two-stream instability with a finite width in strongly magnetized plasma is investigated. Initially, those conditions lead to monochromatic electrostatic waves, and these waves coalesce with each other during their nonlinear evolution. At last, a solitary electrostatic structure is formed. In such an electron hole, a bipolar structure is formed in the parallel cut of parallel electric field, while a unipolar structure presents in the parallel cut of perpendicular electric field.