Research On The Key Technologies Of Access And Transmission For The Integrated Sky-Earth Internet Of Things

The Internet of Things(IoT)interconnects and converges the separated cyberspace and physical world,driving the third wave of the information industry revolution.With the exploration of the physical world and the deepening of IoT applications,more and more vast uninhabited areas(e.g.marine,desert,etc.)require information monitoring and collection.The traditional infrastructuredependent IoT has limited coverage and cannot meet the sensing and transmission needs in large scale scenarios.As an important direction of the new generation network,the Space-Earth Integrated Information Network will effectively improve the network coverage capability and provide a new way to solve the interconnection problem of heterogeneous network elements in infrastructurefree areas.Therefore,this thesis integrates the Space-Earth Integrated Information Network with the Internet of Things(IoT)and conducts a study on the Integrated Space-Earth Internet of Things(abbrivate as ISE-IoT).Due to the high mobility of satellites and other nodes in the ISE-IoT,the lack of collaboration in link heterogeneity,and the large difference in transmission overhead,it makes the challenges in access QoS guarantee,low latency and low overhead transmission.Therefore,this thesis focuses on the high quality access between space-based networks and user terminals represented by low-orbit satellite networks,and the integrated transmission with air and ground-based networks as the core,and researches the low-orbit communication satellite beam switching strategy,joint MAC layer method,and heterogeneous delay-tolerant economic routing protocol,and verifies the effectiveness of the method through simulation experiments.Specifically,the main contributions of this thesis are as follows.(1)Beam switching strategy for low-orbit communication satellites for the ISE-IoT.As an important component of the IOT,high-throughput low-orbit communication satellites have different beam structures from traditional satellites to meet their large bandwidth and low latency data transmission,and such differences make this type of satellite require more complex beam scheduling strategies to meet the needs of user terminals.In this thesis,we firstly propose a beam switching strategy based on the fixed IP of user terminals to achieve seamless switching of user terminal services;secondly,we propose a geographical location priority beam load balancing strategy to optimize the beam allocation of high-throughput low-orbit communication satellites for user terminals.These strategies and mechanisms ensure the link quality of satellite beams when serving user terminals,while reducing link congestion caused by excessive load on individual beams and improving system service quality.(2)Joint MAC layer transmission method for the ISE-IoT.MAC layer protocol is the key to realize efficient interconnection of heterogeneous networks for ISE-IoT.This thesis proposes a heterogeneous MAC linkage optimization method based on high-throughput low-orbit communication satellites called JTDMA,which combines the transmission characteristics of high-throughput low-orbit communication satellites with the MAC protocols of terrestrial IoT devices to realize large-scale information transmission.Meanwhile,this thesis also proposes a continuous forward time slot allocation strategy-CFTSA,which makes full use of satellite resources to ensure that the collection of IoT data reaches saturation each time a satellite time slot comes.These strategies can effectively reduce the system latency of the ISE-IoT,and also reduce the energy consumption of the system and improve the utilization of satellite resources.(3)The heterogeneous delay-tolerant economic routing protocols of the ISE-IoT.The routing protocol carries the transmission quality and performance of the heterogeneous links in the IoT,which is the key optimization object to achieve high-quality communication.In this thesis,DHOR protocol is proposed,which can make full use of the different transmission characteristics of satellites,aircraft and vessels in the system to ensure efficient transmission while reducing the system overhead,thus achieving economic routing.At the same time,this thesis also proposes an adaptive link scheduling algorithm and link prediction strategy based on data demand for the DHOR protocol,which enhances the link sensing and processing for data demand,resulting in effective improvement of link utilization and further reduction of system overhead.In summary,this thesis presents a series of theoretical models,algorithms,strategies,etc.from three aspects,namely,low-orbit communication satellite beam switching strategy,joint MAC layer method,and heterogeneous delaytolerant economic routing protocols,and provides theoretical basis and technical support for the development of the integrated IoT technology and related services.