Research On Optimal Energy Management For Fractionated Spacecraft Network Topology

Fractionated spacecraft is a highly innovative and revolutionary distributed system, all module spacecraft connect to each other to form a space wireless communication network through intersatellite links. which is equivalent to a traditional large satellite and execute some complex space missions such as detection and communication.Network technology is one of the important technologies of Fractionated spacecraft,in this thesis, Fractionated spacecraft is constituted of Cubesats that their standard structure is 2U or 3U, and so the volume and solar array area of solar panels is very limited,which leads to the energy consumption is serious. Therefore, for the Fractionated spacecraft network, the problem that need to be resolved of limited energy is significant to extend the working hours of Fractionated spacecraft in orbit. Taking into account energy efficiency, this thesis aim to build an efficient, stable and reliable Fractionated spacecraft network to balance and optimize energy efficiency dynamically.During the high-speed movement of Satellite in orbit, intersatellite links switch frequently, some satellite nodes’ join and quit fractionated spacecraft system, which fully reflect that the fractionated spacecraft network topology is highly dynamic and cyclical. From aspect of the relative motion between satellites, the establishment of intersatellite links and energy consumption of nodes, this thesis analyze fractionated spacecraft network characteristics. Then, according to the Graph theory, fractionated spacecraft network model is established.Based on analysis of Ad hoc technology, this thesis proposes a satellite-cluster network management theory. On research of the classic clustering algorithm LEACH, optimize clustering algorithm LEACH according to energy efficiency of nodes to elect master satellite in a cyclic manner. Therefore, updating dynamically master satellite of network the LEACH optimized balance and reduce the energy consumption.On basis of multi-hop path and single-hop path, this thesis analyze that the number of hops has an impact on energy consumption in network. The classic shortest path algorithm---Dijkstra, proves that the multi-hop path is superior to single-hop path in energy efficiency, then, the optimal number of hops is determined,Lastly, with the characteristic that the fractionated spacecraft network topology is highly dynamic and cyclical, network cycle is divided into several time slots according to the moment of switch of intersatellite links. Consequently, corresponding dynamic network topology can be represented by a sequence of static graph over a period of time among fractionated spacecraft for the reason that every moment corresponds to a static network topology. Based on the neighbor nodes of satellite, the proved shortest algorithm that is proposed for fractionated spacecraft network has better energy efficiency in the presence of satellite mobility.