Research On The Key Technologies Of Satellite Delay Tolerant Network Information Transmission

At this stage,all countries in the world are actively exploring the space environment and setting off an upsurge.Drawing on the matured information transmission technology of the terrestrial Internet and applying it to the space environment,it has become the research focus in this field to establish the integration of the sky and the deep space exploration system.However,due to the large delay of satellite deep space exploration environment,frequent links and disconnections of links,high bit error rate,and limitation of storage devices and computing power on the satellite,the United States pioneered the concept of delay tolerant networks to solve this problem.Satellite delay tolerance network has become the current research hotspot in various countries,such as Mars exploration,deep space exploration and space travel and even space immigration base.The most important factor in delay tolerant networks is the routing of satellite nodes and the reliability of transmission.In this thesis,we will study from the following two parts.For satellite delay tolerant networks with poor communication conditions and long communication intervals,the delay tolerant network transmission congestion avoidance and network transmission quality issues are studied.Based on the congestion problem of satellite delay-tolerant network transmission,the Earliest Arrival Optimal Delivery Ratio routing algorithm in satellite delay tolerant networks is improved,and an optimal arrival rate routing algorithm based on network transmission quality awareness is proposed.The algorithm avoids congestion by predicting satellite link congestion and prioritizing dropping packages with low reach.This algorithm is a satellite delay tolerant network congestion avoidance algorithm.It avoids congestion by predicting the congestion of each link in advance.When the satellite network is heavily congested,it preferentially discards the packages with low arrival possibility to improve the arrival ratio of the entire network.For satellite delay-tolerant network link frequent on-off and limited on-board storage capacity,the problem of satellite delay tolerant network hybrid routing is studied.Considering that although the globally optimal route can select the earliest path to be reached globally,it cannot be flexibly modified in such an environment with many problems and the path information may be outdated,and timely and effective path information cannot be obtained.The local optimal path can be changed in time according to the real-time situation during the path transmission,but it may cause the route to be oscillating or unreachable,and the timeout reaches the end point.Combining the respective advantages of the two routes and using the real-time node information in the network,a satellite delay tolerant network hybrid routing algorithm is proposed to improve the package transmission efficiency and transmission quality of the entire network.The network information used in the delay tolerant network hybrid routing algorithm includes the node's last encounter time interval,link connectivity rate and congestion probability.The network information is used to select the next hop node that is most suitable for package delivery.