Research Of The Congestion Control Technology Based On Storage Management In Space Networks

The rapid development of aerospace technologies and spatial applications accelerate the step of informationization in space network, so more and more countries and research institutions dedicate to exploring the integrated approach of the space network, the sky network and the land network. Because the space network exists similar problems to DTN (Delay/Disruption Tolerant Network), such as huge link delay, lack of end-to-end transmission path, storage resource constraints, the existing applications of Internet architecture, protocol and congestion control technology based on TCP/IP face serious challenges in space network.This thesis introduces the basics and the network architecture of the space network, and analyzes the characteristics of the space network as well as the research topics background. After combining DTN researches and the existing congestion control technologies, this thesis focus on the existing space network congestion control problem, and proposes a combined algorithm of congestion control based on storage management, called CACC-SM algorithm, for the Head-of-Line congestion problems from the custody transfer mechanism.Firstly, the combined algorithm differs the multi-copy packet from single-copy packet. For the multi-copy packet, this algorithm uses a"Condition Selections"mechanism to select the packet and drop this packet based on"Drop"strategy . For the single-copy packet, this algorithm combines the transferred packets and proxy nodes"condition selection"mechanism. This thesis uses the"Push"strategy to transfer packets, which was borrowed from M.Seligman's passive congestion control mechanism-"storage routing"approach. For the fact that the space network links often interrupted, this thesis proposes a multi-stage processing strategy of transferred packet by adding a mechanism of HELLO polling message based on the"Pull"recovery operation of the original transferred packet. The combined algorithm effectively integrates the network storage resources from the perspective of the overall space network, achieves optimal allocation of storage of the communications node, reduces the congestion of space network and improves the network reliability. The combined algorithm is universal to the current routing protocols in space network, and adapt to the features that node storage resources are limited in space network.We build a space network simulation environment with ONE (Opportunistic Networking Environment) simulator. In order to validate the performance of the CACC-SM algorithm, we compare and analyze the packet transmission reliability under different conditions by changing the simulation time, packet size and TTL situation. The simulation results show that under the First Contact routing mechanism with CACC-SM algorithm, the ratio of transferred packets can be increased by about 25%, however the average network delay can be increased by less than 1%, while the ratio of packet loss and network overhead can be reduced by about 14%. Besides, with the Epidemic routing mechanism with CACC-SM algorithm, the ratio of packet transfer can be increased by about 20%, however the average network delay can be increased by less than 1%, while the ratio of packet loss and network overhead can be reduced by about 18%. The simulation results proved that the CACC-SM algorithm is effective on solving the congestion problems of space network with different routing mechanisms.