Research On Random Access Technology Of Satellite Internet Of Things Based On CRDSA

The design of satellite data access scheme based on random access is a hot spot in the field of satellite Io T research.Compared with the existing satellite communication network,the satellite Internet of Things has more severe challenges in how to use limited channel resources.The number of Internet of Things devices is growing rapidly,and satellites need to provide access services for a large number of ground Internet of Things devices;most of the data packets generated by Io T devices are short data packets with a relatively low duty cycle,and the transmitted data is not continuous,making it difficult to allocate channel resources in advance;data is mostly burst data,which is prone to channel resource preemption and data conflicts.Satellites have insufficient ability to resolve data conflicts.Therefore,how to design an effective random access scheme,propose an algorithm for resolving data conflicts,and enhance the satellite's ability to support random access,so as to achieve concurrent transmission of multiple Io T devices is a problem that must be resolved in the satellite Io T.Starting from the CRDSA random access protocol commonly used in satellite communication networks,this paper systematically studies the problem of random access by multiple users concurrently transmitting data in the satellite Internet of Things.Through the analysis of the data sending and receiving process of the CRDSA protocol,the above data sending and receiving process is designed based on the sparse code division multiple access technology,the CRDSA random access protocol is improved,and the SC-CRDSA data packet decoding algorithm is proposed,which improves the throughput performance of the access system.The specific research process includes: Analyzing the "deadlock" problem in the CRDSA protocol and the reasons for the degradation of throughput performance and proposing solutions;at the sending end,the data to be sent is processed according to the codebook information in the sparse code division multiple access,which includes encoding and resource mapping operations;the SC-CRDSA unpacking algorithm is proposed at the receiving end according to the multi-user data access model.The SC-CRDSA algorithm effectively solves the decrease in throughput caused by the "deadlock" phenomenon in the CRDSA protocol,improves the concurrent data receiving capability of the satellite receiving end,and enhances the performance of the random access system.Based on the CRDSA protocol enhanced with sparse code division multiple access,in order to solve the problem of serious data conflicts in the network under high load transmission scenarios and maintain the efficient performance of the random access system,this paper proposes an improved CRDSA protocol transmission control algorithm.The algorithm uses a cascade of BP neural network and NAR neural network to predict the actual load on the ground in real time,and then ground users obtain transmission control information based on the predicted information.The BP neural network is used to obtain the actual connection after the transmission control is executed.The load accessed into the satellite can provide a basis for accurately judging the network load status.The simulation results verify that the algorithm can enhance random access in high-load transmission scenarios,and improve the compatibility of the improved CRDSA protocol under different network loads.