Research On Space Communication And Networking Technology

The development of space exploration makes space mission more and more complex. Thelegacy point-to-point communication mode can not meet the demands of current and futurespace missions. The space communication paves its way to the direction of high levelnetworking. However, the broad margin between the cost and demand of space communicationmakes it urgent to provide efficient and economical communication method. The developmentof the technologies in Internet and commercial satellite communication presents a new meansof space communication. It is a hot topic at present to research on how to use the noveltechnologies from Internet and commercial satellite communication to provide satellite basedspace communication, and go a step further, to construct a unified networking environmentincluding both ground and space links. This dissertation analyzes the characteristics andrequirements of space communication, discusses the feasibility of using IP technology in space,and focuses on the communication model, networking infrastructure and technologies for QoS(quality of service) support in the information transmission of space missions. The majorcontributions of the dissertation are summarized as follows: (1) The dissertation presents a kind of communication mode which decouples the basiccommunication from space missions and provides space information transfer service based onIP technology;offers the related communication model using the Internet method and IPtechnologies. The dissertation analyzes the development trend of space communicationstandards, the principle of IP and its technology evolution, the advancement of space wirelessand optical technology, and points out that it is urgent to provide mature networking protocoland technology in response to the increasing demands of space communication, andemphasizes that IP can be adapted to the space communication environment and merged intospace communication standards. The dissertation suggests that the future space communicationshould be independent of space missions, be provided by Internet provider, and take the way ofcommercialization. (2) The dissertation analyzes the mechanism and architecture which is used in Internet tosupport QoS, proposes the QoS model for space information exchange that uses the Internetmethod. Basing on this model and the characteristics of space links, the dissertation proposes akind of algorithm for the hierarchical link-sharing and link bandwidth reallocation adapted tothe dynamically changing bandwidth. The algorithm employs the classical method of controltheory, finds out by viewing the dynamic condition the variation of link bandwidth due to themitigation, and informs the packet scheduler to adjust the scheduling time. It adopts adomain-based bandwidth reallocation mechanism to reallocate the bandwidth according to theneeds of the users, can share the link among different uses, provides QoS support, and stillachieves high link utilization efficiency. The feasibility of the algorithm is approved bytheoretical analysis and simulation.(3) The dissertation examines the current space network of NASA, the principle of commercialsatellite constellation, and analyzes the problems discovered when they are used in spacecommunication. Based on the analysis of characteristics of space communication, thedissertation proposes a communication model which is based on satellite ring (SR) withlayered architecture. The model is space mission oriented, and is based on SR which iscomposed of several satellites linked by intraplane intersatellite links (ISL). SRs provide accessservices to the spacecraft that rotate in the same direction and keep the angles between theirorbit planes within a certain limit. The SRs of higher layer provides connection services to theSRs of lower layers as well as to the connection services between ground facilities and lowerSRs through inter-orbit ISL and earth-space links. In this way the proposed model can reducethe negative effects of handoff and velocity variation caused by the relative motion betweenspacecrafts and satellites, and can raise the service capacity the communication system offers tousers. The work of the dissertation has constructed a simulation environment to demonstratethe reasonability of this model and will be a foundational platform for further research.