A Novel Orthogonal LoRa Multiple Access Algorithm for Satellite Internet of Things

In recent years,LoRa has been extensively researched in the satellite Internet of Things(IoT).However,the multiple access technology of LoRa is still one of the bottlenecks of satellite IoT.To improve the multiple access performance of LoRa satellite IoT,based on the orthogonality of LoRa symbols in the fractional domain,this paper proposes a low complexity Orthogonal LoRa Multiple Access(OLMA)algorithm for multiple LoRa users occupying the same frequency bandwidth.The algorithm introduces the address code to divide the fractional bandwidth into multiple parts,and the OLMA users with different address codes occupy different parts to transmit the information code,thus avoiding mutual interference caused by collisions in the same frequency bandwidth.The multiple access capability of OLMA can be flexibly configured only by simply adjusting the length of the address code according to the actual application requirements of data transmission.Theoretical analysis and simulation results show that the OLMA algorithm can greatly improve the multiple access capability and the total transmission bit rate of LoRa IoT without changing the existing LoRa modulation parameters and process.

From Earth to Space:A First Deployment of 5G Core Network on Satellite

Recent developments in the aerospace industry have led to a dramatic reduction in the manufacturing and launch costs of low Earth orbit satellites.The new trend enables the paradigm shift of satelliteterrestrial integrated networks with global coverage.In particular,the integration of 5G communication systems and satellites has the potential to restructure nextgeneration mobile networks.By leveraging the network function virtualization and network slicing,the satellite 5G core networks will facilitate the coordination and management of network functions in satellite-terrestrial integrated networks.We are the first to deploy a 5G core network on a real-world satellite to investigate its feasibility.We conducted experiments to validate the satellite 5G core network functions.The validated procedures include registration and session setup procedures.The results show that the satellite 5G core network can function normally and generate correct signaling.

Adaptability Analysis of IP Routing Protocol in Broadband LEO Constellation Systems

With the inclusion of satellite Internet as the information infrastructure in China's "new infrastructure" category,relevant domestic industries and scientific research institutes have successively carried out the design of broadband low earth orbit(LEO) constellation systems and key technical research.As the core technology for the satellite-to-ground network communications of a broadband LEO constellation system,routing technology is extremely important for the efficient and reliable transmission of various service data.Focusing on the two important broadband LEO constellation systems in China,in-depth analysis and simulation of the high dynamics of the satellite-to-ground satellites are conducted in this paper to obtain more accurate network topology changes and characteristics;then the adaptability of the ground standard IP routing protocol to the broadband LEO constellation system is analyzed,and an LEO constellation simulation scenario is built with the Opnet software.The simulation results of the convergence performance of the standard IP routing protocol are produced.The results show that the IP protocol does not perform well for LEO satellite constellation networks.Based on the studies,some solutions are proposed to take full advantages of the characteristics of LEO satellite systems.These can also provide a reference for the choice of intersatellite routing architecture and protocol technology for broadband LEO constellation in the future development.