Communication Link Measurement And Visualization Technology For LEO Constellation

With the prosperity and development of the satellite industry,some problems brought by it have attracted people’s attention,such as complex inter-satellite link design,difficult data supervision,difficult routing selection,and time-varying network topology.Digital twin technology provides a new solution to this problem by simulating and predicting the behavior of physical entities through data.So how to measure the internal state of the loworbit constellation network efficiently and accurately is particularly important for the recovery of the twins.Traditional network measurement is limited by routing protocols and autonomous systems,which brings difficulties to the measurement.As a result,a new protocol-independent network measurement technology,Network Tomography(NT),has emerged,which can infer the performance indicators of the entire network link through partial end-to-end measurement values.Since the LEO satellite network adopts a centralized routing mechanism based on virtual topology,which means that it does not support the source routing mechanism,it is necessary to infer the satellite link performance through passive measurement.In this paper,how to use the fewest possible number of detection paths to measure all satellite link performance indicators,such as link delay,packet loss rate,etc.,and display the low-orbit satellite network model and its network measurement scheme through visualization technology,is the research question of this paper.The work of this paper includes the following three aspects:(1)Through the study of network tomography technology,based on the linear system model,a detection path generation algorithm is implemented,which can expand the detection path of satellite links.Since there are too many routing strategies calculated by the centralized routing mechanism based on virtual topology,all of them participating in the calculation will greatly increase the time cost of the algorithm.Therefore,this paper proposes a routing strategy selection method,which ensures that all inter-satellite links can be identified.Under the conditions,the necessary routing paths are selected to participate in the path calculation.(2)The relationship between the detection path and the target link is reflected by the bipartite graph model,and a greedy algorithm is used to select the detection path corresponding to the target link.Considering the problem of time consumption caused by redundant detection paths in the end,the detection path selection algorithm based on bipartite graph proposed in this paper ensures that the detection cost and time cost are relatively low.Inter-satellite link detection scheme calculation.(3)Visualization is an indispensable part of digital twins.In this paper,the relevant parameters of low-orbit satellite orbits calculated by TLE data and the SGP4 model library provided by the Python scripting language are based on the CZML language specification and the SSE technology provided by HTML5.Carry out data transmission,and then use the Cesium digital earth platform to achieve low-orbit satellite orbit simulation and visualization,and display the results of tomography technology calculations together.Experiments show that in the low-orbit satellite network,the algorithm proposed in this paper can measure all satellite link performance indicators with as few detection paths as possible under the condition that the time requirements are met.Finally,combine Cesium,an open source 3D js library,to build a visualization platform.Visualize the satellite network topology and detection path strategy.