Satellite constellations are promising in enabling the global Internet.However,the increasing constellation size also complicates tracking,telemetry and command(TT&C)systems.Traditional groundbased and space-based...Satellite constellations are promising in enabling the global Internet.However,the increasing constellation size also complicates tracking,telemetry and command(TT&C)systems.Traditional groundbased and space-based approaches have encountered significant obstacles due to,e.g.,the limited satellite visible arc and long transmission delay.Considering the fast development of intersatellite communications,synergy among multiple connected satellites can be exploited to facilitate TT&C system designs.This leads to networked TT&C,which requires much less predeployed infrastructures and even performs better than traditional TT&C systems.In this paper,we elaborate system characteristics of networked TT&C compared with traditional ground-based and spacebased TT&C,and propose the unique security challenges and opportunities for networked TT&C,which includes secure routing and trust mechanisms.Furthermore,since networked TT&C is a novel scenario with few relevant researches,we first investigate the current researches on secure routing and trust mechanisms for traditional terrestrial and satellite networks,and then accordingly deliver our security perspectives considering the system characteristics and security requirements of networked TT&C.展开更多
The safety of submerged buoy is higher than traditional buoy. The most important problem for submerged buoy is that signal will be attenuated greatly due to ocean wave fluctuation and seawater. On the basis of ocean w...The safety of submerged buoy is higher than traditional buoy. The most important problem for submerged buoy is that signal will be attenuated greatly due to ocean wave fluctuation and seawater. On the basis of ocean wave model, propagation characteristics of electromagnetic wave in seawater channel for submerged buoy is analyzed in this letter. It includes the propagation properties of electromagnetic wave in seawater and across the air-sea interface. The results show that the VHF frequency band, first order sea level and water depth of less than 10 cm are acceptable for submerged buoy.展开更多
基金supported by the National Natural Science Foundation of China under Grant 61971261/62131012Technology Project of the State Grid Corporation of China under Grant 5400202255158A-1-1-ZN。
文摘Satellite constellations are promising in enabling the global Internet.However,the increasing constellation size also complicates tracking,telemetry and command(TT&C)systems.Traditional groundbased and space-based approaches have encountered significant obstacles due to,e.g.,the limited satellite visible arc and long transmission delay.Considering the fast development of intersatellite communications,synergy among multiple connected satellites can be exploited to facilitate TT&C system designs.This leads to networked TT&C,which requires much less predeployed infrastructures and even performs better than traditional TT&C systems.In this paper,we elaborate system characteristics of networked TT&C compared with traditional ground-based and spacebased TT&C,and propose the unique security challenges and opportunities for networked TT&C,which includes secure routing and trust mechanisms.Furthermore,since networked TT&C is a novel scenario with few relevant researches,we first investigate the current researches on secure routing and trust mechanisms for traditional terrestrial and satellite networks,and then accordingly deliver our security perspectives considering the system characteristics and security requirements of networked TT&C.
文摘The safety of submerged buoy is higher than traditional buoy. The most important problem for submerged buoy is that signal will be attenuated greatly due to ocean wave fluctuation and seawater. On the basis of ocean wave model, propagation characteristics of electromagnetic wave in seawater channel for submerged buoy is analyzed in this letter. It includes the propagation properties of electromagnetic wave in seawater and across the air-sea interface. The results show that the VHF frequency band, first order sea level and water depth of less than 10 cm are acceptable for submerged buoy.
