Research On Network Coding Based Forward Erasure Transmission Protocol For S-IoT

Satellite-based Internet of Things(S-Io T)has obvious advantages over terrestrial Internet of Things in terms of coverage,communication capacity and network construction.Satellite communication systems can provide three-dimensional global coverage and have strong resistance to natural disasters.S-Io T can provide seamless and uninterrupted communication connection to people or things under various environmental conditions.In order to realize the high reliability,high energy efficiency,low delay and high time-efficient data transmission of the S-Io T network,network coding is adopted for the characteristics of frequent interruption,long delay and high bit error rate of the satellite-to-earth link or the inter-satellite link The NC HARQ(Network Coded HARQ,NC HARQ)transmission mechanism combining(Network Coded,NC)and Hybrid Automatic Repeat Request(Hybrid Automatic Repeat Request,HARQ)provides a performance analysis framework under the shadow Rice fading channel,and derives And get the theoretical expressions of energy efficiency related performance parameters in each scenario.First,starting from the typical application scenarios under S-Io T and combining the characteristics of network coding,a variety of unicast downlink transmission(Multiple-Unicast Downlink Transmission,MUDT)and network coding bidirectional relaying(NCBR)are designed.NC HARQ data transmission protocol under the scenario,the NC HARQ system model based on energy accumulation in S-Io T is established,the shadow Rice fading channel model and the indicators to measure the performance of the NC HARQ protocol are derived,including the expected number of transmissions,throughput and Energy efficiency.Aiming at the fading channel model,using the Laplace transform tool and the matrix exponential(ME)distribution,the relevant theorems for deriving the theoretical performance indicators of NC HARQ are given.Then,based on the expected number of transmissions in the NC HARQ system model and the theoretical analysis of energy efficiency,the ME tool is used to give a closed expression of the energy efficiency index of NC HARQ in the MUDT and NCBR scenarios.Then it discusses the optimization problem of NC HARQ protocol for maximizing energy efficiency in shadow Rice fading channel,fully considering the constraints of energy limitation and transmission reliability and adopting different optimization algorithms to solve the problem in different application scenarios.Provide feasible solutions for improving the energy efficiency of the system.Monte Carlo simulation is used to give the simulation results of NC HARQ performance indicators,and compare them with HARQ to verify the accuracy of the theoretical formula and also verify that NC HARQ can improve energy efficiency.Finally,in order to ensure the timeliness of S-Io T end-to-end reliable transmission of information,it is optimized based on the NC HARQ protocol,and a mixed transmission strategy of information packets and network coding erasure packets is reasonably designed to achieve a low peak information age(Age of Information,Ao I)NC HARQ forward erasure transmission protocol.This paper presents the detailed transmission process of the forward erasure transmission protocol model,and analyzes in detail the end-to-end transmission delay and Ao I performance indicators of the model.Taking into account the long delay and untimely feedback characteristics of the satellite-to-earth link,in order to better adapt to changes in channel conditions,the dynamic forward erasure transmission protocol is further designed,through the construction of a partially observable Markov decision process(POMDP)and Solving can get the optimal transmission strategy.In summary,the introduction of the NC HARQ transmission mechanism greatly improves the transmission efficiency of the S-Io T system,which can be applied to a variety of typical business scenarios,and effectively improves the system energy efficiency and information timeliness,which is important for achieving high reliability,high energy efficiency,The low-latency and high-efficiency S-Io T communication network has theoretical guiding significance.