With the booming development of terrestrial network, scaling terrestrial network over satellite network to build Integrated Terrestrial-Satellite Network(ITSN) and meanwhile to provide the global Internet access, has ...With the booming development of terrestrial network, scaling terrestrial network over satellite network to build Integrated Terrestrial-Satellite Network(ITSN) and meanwhile to provide the global Internet access, has become ever more attractive. Naturally, the widely and successfully used terrestrial routing protocols are the promising protocols to integrate the terrestrial and satellite networks. However, the terrestrial routing protocols, which rely on propagating routing messages to discover New Network Topology(NNT) in the terrestrial network with rare topology changes, will suffer from overly numerous routing messages in satellite network whose topology frequently changes as satellites move. In this paper, a Topology Discovery Sub-layer for ITSN Routing Schemes(TDS-IRS) is firstly proposed to avoid the propagation of numerous routing messages by taking advantage of the movement predictability of satellite and the requirements of routing schemes to discover NNT in advance of topology change. Secondly, a Weighted Perfect Matching based Topology Discovery(WPM-TD) model is designed to conduct the NNT discovery on the ground. Thirdly, this paper builds a testbed with real network devices and meanwhile interconnect that testbed with real Internet, to validate that RS-TDS can discover NNT immediately with the less on-board overhead compared with optimized routing schemes. Finally, different network scenarios are applied to validate the WPM-TD, i.e., the core module of TDS-IRS. Extensive experiments show WPM-TD can work efficiently, avoiding the invalid NNT discovery and decreasing 20% ~ 57% of potential topology changes, which can also improve up to 47% ~ 105% of network throughput.展开更多
This paper focuses on studying a new energy-work relationship numerical integration scheme of nonholo-nomie Hamiltonian systems.The signal-stage numerical,multi-stage and parallel composition numerical integrationsche...This paper focuses on studying a new energy-work relationship numerical integration scheme of nonholo-nomie Hamiltonian systems.The signal-stage numerical,multi-stage and parallel composition numerical integrationschemes are presented.The high-order energy-work relation scheme of the system is constructed by a parallel connectionof n multi-stage schemes of order 2,its order of accuracy is 2n.The connection,which is discrete analogue of usual case,between the change of energy and work of nonholonomic constraint forces is obtained for nonholonomic Hamiltoniansystems.This paper also gives that there is smaller error of the scheme when taking a large number of stages than a lessone.Finally,an applied example is discussed to illustrate these results.展开更多
基金supported by State Key Program of National Natural Science of China (91738202)Science &Technology Program of Beijing (Z171100005217001)
文摘With the booming development of terrestrial network, scaling terrestrial network over satellite network to build Integrated Terrestrial-Satellite Network(ITSN) and meanwhile to provide the global Internet access, has become ever more attractive. Naturally, the widely and successfully used terrestrial routing protocols are the promising protocols to integrate the terrestrial and satellite networks. However, the terrestrial routing protocols, which rely on propagating routing messages to discover New Network Topology(NNT) in the terrestrial network with rare topology changes, will suffer from overly numerous routing messages in satellite network whose topology frequently changes as satellites move. In this paper, a Topology Discovery Sub-layer for ITSN Routing Schemes(TDS-IRS) is firstly proposed to avoid the propagation of numerous routing messages by taking advantage of the movement predictability of satellite and the requirements of routing schemes to discover NNT in advance of topology change. Secondly, a Weighted Perfect Matching based Topology Discovery(WPM-TD) model is designed to conduct the NNT discovery on the ground. Thirdly, this paper builds a testbed with real network devices and meanwhile interconnect that testbed with real Internet, to validate that RS-TDS can discover NNT immediately with the less on-board overhead compared with optimized routing schemes. Finally, different network scenarios are applied to validate the WPM-TD, i.e., the core module of TDS-IRS. Extensive experiments show WPM-TD can work efficiently, avoiding the invalid NNT discovery and decreasing 20% ~ 57% of potential topology changes, which can also improve up to 47% ~ 105% of network throughput.
基金supported by National Natural Science Foundation of China under Grant No.10672143the Natural Science Foundation of Henan Province under Grant No.0511022200
文摘This paper focuses on studying a new energy-work relationship numerical integration scheme of nonholo-nomie Hamiltonian systems.The signal-stage numerical,multi-stage and parallel composition numerical integrationschemes are presented.The high-order energy-work relation scheme of the system is constructed by a parallel connectionof n multi-stage schemes of order 2,its order of accuracy is 2n.The connection,which is discrete analogue of usual case,between the change of energy and work of nonholonomic constraint forces is obtained for nonholonomic Hamiltoniansystems.This paper also gives that there is smaller error of the scheme when taking a large number of stages than a lessone.Finally,an applied example is discussed to illustrate these results.
