An Unscented Kalman Filtering Based Bundle Delivery Time Estimation Algorithm In Space Delay/disruption Tolerant Networking

With the further development of space exploration,the establishment of Air-space-ground of integrated information communication network has become a trend.As the characteristics of high bit error rate,long delay and frequent interruption,the traditional terrestrial of TCP/IP protocols was no longer applicable.For the challenged space communication environment,the network architecture of Delay/Disruption Tolerant Networking(DTN)is proposed,which is more suitable for space communication.DTN through added the "bundle layer" between the application layer and the transport layer,solved the problem of communication space environment,and the custody transfer mechanism made the reliable transmission of space communication link be possible.However,as high-speed on-orbit relative motion between space communications satellite nodes,the communication distance between satellites was changing rapidly.In addition,the space communication environment is affected by many factors,delivery time estimation of the bundle becomes more difficult,but delivery time of link was a very important indicator of measuring network,traditional delivery time estimation algorithm base on static environment,the status of the link between the nodes was static,the set of link parameters(bit error rate,propagation delay,queuing delay,etc.)was a constant,In this thesis,we propose a delivery time estimation algorithm to track the real-time state of link,analyze the characteristics of communication environment and its impact on communication.Based on the impact of the communication environment on the link and the transmission characteristics of custody transfer mechanism,and based on Unscented Kalman Filtering(UKF)algorithm designed the trace bundle transmission delay estimation model.The basic model can be divided into a system model describing the state change of the link communication and a measurement model which obtain ed round trip delay measurement information.In the process of link state estimation,according to the characteristics of bundle actually round trip delay variation,the UKF estimation algorithm based on an unequal-interval measurement values be proposed,and optimizes the algorithm of custody transfer countdown timer.Through simulation shows that the UKF algorithm proposed in this paper can effectively track the change of link state,and the custody transfer countdown timer algorithm can predict bundle actually round trip delay more accurately,and improve the network's Goodput.According to the characteristics of custody transfer,the paper also analyzes the process of message transmission in BP-layer under multi-hops environment.In addition,we provide the relationship between single-hop and multi-hop delivery time estimation.On this basis,the paper deduces the file transfer delivery time in the multi-hop environment and the reliability of the models were verified by simulation.