Research On Fractionated Spacecraft AD-HOC Network Properties And Topology Control Algorithm

As a new generation of distributed satellite system, fractionated spacecraft has a great breakthrough in ways of designing and function realization. It is no longer rely on one core spacecraft, and each module in this fractionated network shares the same status and works together to accomplish the space mission, which greatly improves the survivability and scalability of spacecraft system, but also it faces many technical problems.Networking technology is one of the key technical problems to be solved in fraction-ated spacecraft. From about four aspects of network properties, topology control algorithm evaluation index, topology control scheme and hardware-in-loop simulation platform, this thesis focuses on the research of fractionated spacecraft networking and topology control technologies.Similar to wireless sensor networks, fractionated spacecraft also shares some same properties of ad-hoc network, such as none central node, multi-hop in information trans-mission, topology changing over time and etc. Based on analysis of different perfor-mance in hierarchical and planar structure of sensor networks and also combined some features and function requirements of the fractionated, this thesis considered the planar as basic configuration in fractionated spacecraft. Then, according to the proximity graph and probability theory, the accurate variation of expected communication distance in relation to maximum communication distance and node distributed density is given on research of the fractionated communication network model, and for the certain network, the expected value is constant. From aspect of energy efficiency, three network life cycle evaluation indexes of minimum (maximum), summation and mean square error are proposed for the purpose of analyzing the influence of topology control algorithms on network life cycle.On the basis of traditional topology control algorithm, F1YG, expected communica-tion distance and topology survival time, this thesis puts forward both an improved algo-rithm and a topology construction scheme and also simplified selection method of most dangerous path due to C-W equation and algorithm complexity. Then, through some sim-ulations, it is pointed out there exists some deficiencies in tradition algorithm and the improved algorithm has better energy efficiency which lead to longer network life cycle.Lastly, with combination of improved topology construction scheme and Wi-Fi ad-hoc communication protocol, some simulation programs are established to test perfor- mance of fractionated spacecraft networking and topology control technology. This thesis uses programmable low power RF chip to design fractionated spacecraft hardware-in-loop simulation platform’s communication module, and by built-in AT instruction set, con-trolling software has been programmed. Through simulations, the feasibility of improved topology control scheme and ad-hoc networking technologies have verified.