Capacity Analysis And Resource Management Of Space Information Networks

Space information network(SIN)is an important infrastructure,which includes geosynchronous orbit satellites,medium and low orbit satellite,stratospheric airships,manned or unmanned aerial vehicles,other space platforms and ground networks.These components interchange information with other through the hierarchical and dynamic space links.With the rapid development of space science and information technology in recent years,space information network has played a more and more important role in national security,aeronautics and astronautics,environment monitoring,traffic management,industry and agricultural,counter-terrorism,emergency rescue and disaster relief and so on.Compared with traditional ground networks,SINs have many characteristics,such as limited orbital position and spectrum resource,limited payloads of satellite platforms,high investment and long launch period of satellites,and difficult to on-board maintenance and upgrade.Therefore,it is very difficult to increase the service capacity of SINs by directly increasing the number and service capacity of space nodes.That is to say,different from the terrestrial networks,SINs need an even more accurate design stage.To cope with the growing demand of missions,network capacity is becoming an important parameter for designing SINs.However,SINs have high-dynamic nodes,complex actions in space and time and sparse network structure.Moreover,it is difficult to find a permanent end-to-end path between two nodes and most of the network packets are delivered to the destination node through the store-carry-forward paradigm in SINs.Therefore,it is very important to propose a mathematical model to characterize the resources of SINs,which is the theoretical basis for accurately analyzing the network capacity and improving resource utilization of SINs.To this end,in this paper we first propose a graph model to characterize the resources of SINs,then,based on the model,we analyze the network capacity and develop efficient mission planning strategies.The paper is organized as follows:1.We develop a multi-dimensional resource representation model for SINs,which reveals the relevance and conflict relationship of the resources on time and space dimensions.Faced up with the disadvantages of traditional time-expanded graph in modeling space information networks,we develop the time varying resource graph(TVRG)for jointly representing the resources of observation,computing,storage and communication resources in SINs.It reveals the relevance of different resources in both time and space dimensions,and provides the theoretical basis for exploring the intertwined impact of different resources on mission implementations.We propose a time varying resource conflict graph(TVRCG)to model the conflict relationship generated from the different resource scheduling process.Moreover,it reveals the characteristics of time variation and the relevance of resource conflict and as well provides the theoretical basis for the conflict-free resource scheduling scheme.2.We study the capacity of SINs,and investigate the effect of onboard image compression capability,storage capacity,battery capacity and other parameters on the service capability of providing efficient information to users.Based on the definition of communication capacity,we define information capacity to represent the capability of SINs for providing efficient information to users.Then,we employ TVRG to model the effect of onboard image compression capability,storage capacity and link bandwidth on mission scheduling of SINs.On the other hand,we develop an energy-flow time-expanded graph to model the effect of energy harvesting and management process on the mission scheduling.Based on the graph models,the network capacity of SINs is modeled as a multi-commodity flow problem on TVRG and energy-flow time expanded graph.Simulation results validate the theoretical analysis of our proposed scheme and show the guiding significance of information capacity on the design of SINs.3.We investigate efficient mission planning strategies of SINs.We first propose a mission planning scheme for earth observation system which considers the effect of image compression on mission implementing process.We employ TVRG to model the effect of compression ratio on the delivery process of mission data,and model the impact of the time taken by adjusting satellite attitude based on the TVRCG.Based on the mentioned models,we model the multi-resource synergistically planning of earth observation system as a mixed integer linear programming(MILP)problem,and then develop a polynomial time heuristic algorithm.Simulation results show that this scheme not only increases number of successfully scheduled missions but also improves the quality of the images down to the earth.Moreover,we develop a mission scheduling scheme for data relay satellite systems,which considers the time taken by slewing antenna among different users.By modeling the network resource and the conflict between different resources by TVRG and TVRCG,the optimal scheduling scheme is modeled as the combination of multi-commodity flow problem and independent set problem.The simulation result shows that the proposed scheme can effectively improve the number of successfully scheduled mission in the network.