Architecture Research For Low Earth Orbit Satellite Internet Of Things

The Internet of Things(IoT)has a pround impact on peoples' s lives and working methods.However,the world of “Internet of Everything” portrayed by the IoT cannot only rely on the ground network to meet the growing demand.Satellite communication can achieve global seamless coverage,which greatly expands the scope of the ground IoT business.Compared with the terrestrial IoT,Low Earth Orbit(LEO)satellites have the advantages of wide coverage,large link capacity and strong reliance.Furthermore,compared with traditional Geosynchronous Earthquake Orbit(GEO)satellites,LEO satellites have unparalleled advantages,such as low loss,low delay,wide coverage,and large orders of magnitude.These characteristics make the LEO satellite IoT the best way to achieve global coverage of the IoT.At present,in the field of satellite IoT,most focuses are on communication link and channel design,lacking of overall architecture design,Therefore,it is necessary to analyze and demonstrate the architecture of the LEO satellite IoT as a whole.Based on the research of satellite mobile communication system and ground IoT,a preliminary architecture of LEO satellite IoT is proposed,which focuses on its constellation design,network architecture,transmission system and interference analysis.Moreover,aiming at the business characteristics of LEO satellite IoT,it also combines Satellite Tool Kit(STK)and Matlab simulation software to improve a business simulation method.The specific details are as follows:(1)Analyze the network architecture of Iridium and Orbcomm in satellite mobile communication system and the system characteristics and network architecture of Narrow Band Internet of Things(NB-IoT)and Long Range Radio(LoRa)widely used in terrestrial IoT.Through research and comparative analysis,a reasonable research direction for space segments and ground segments is proposed: the design of the space segment can refer to Iridium,and Orbcomm focuses on the short data transmission method closer to the application scenario of the LEO satellite IoT.At the same time,the IoT access segment can adopt the LoRa system,while NB-IoT is more suitable for high level protocols.(2)A novel star-ground fusion architecture with separation of forwarding and control is proposed,and then the system composition and core network design of the architecture are analyzed in detail.A viable constellation scheme is given,and its coverage characteristics are simulated by STK.The business transmission is improved to adapted to the application.In the meanwhile,a proxy caching scheme is proposed to improve the incompatibility of NB-IoT and LoRa,which can reduce the pressure of space segment.(3)On the basis of summarizing the characteristics of LEO satellite IoT traffic,an algorithm for analyzing satellite traffic is improved.The simulation results show that the buiness distribution of LEO satellite IoT has great suddenness and change in time and space.Since the unevenness is not conducive to the improvement of system performance,it is necessary to study the resource management strategy with the change of business volume according to the distribution characteristics and laws of the business.