Research On Space-ground Gateway In Space-ground Integrated Network

Since the rapid development of the Internet technology has made space-ground integrated network an inevitable trend of development in communication network, the gateway is becoming an indispensable component for the purpose of communicating between space and ground. TCP/IP procotols are typically applied to the ground network to realize network communication, similarly, TCP/IP system can be used in space communication to form a space-ground integrated network.This paper focuses on the main mechanisms of the existing TCP protocol used in ground network and the characteristics of the space-link with the influence on the TCP performance. On this basis, a protocol transition gateway scheme applied in space-ground integrated network is proposed.At first, combining TCP Splitting technique that belongs to one of dividing a TCP connection solutions, with end-to-end enhanced TCP methods, one TCP connection is divided into three sections by two gateways, TCP Reno protocol is applied to the ground LAN and the space LAN while the advanced TCP protocol is used in the satellite link. The enhanced TCP protocols are able to overcome the high propagation delay of satellite link with the help of the flow control mechanism driven by the receiver. And then, based on the improvement on the transmission layer of the gateway, another improvement is made to the link layer, which learns from the error-control idea of transmission protocol to design a kind of error-control mechanism called S-ARQ (Space-Automatic Request for Repetition) , whose aim is to overcome high space-link error rates. The gateway cross-layer solution is proposed, which is the integrated solutions that conbine the transport layer and the link layer. At last, simulation platform is established with OPNET, on which the improvement schemes on the transport layer and the link layer and the gateway cross-layer solutions are simulated and validated respectively. The simulation results are compared with experiments results of the American patent product SkyX, the improvement schemes on the transport layer and the link layer almost has the same performance enhancement and the proposed gateway scheme has even better performance enhancement on the transport layer under space experiment, which indicates that it is fit for space-ground integrated network.