The Design Of Transmission And Scheduling Algorithm Of The SpaceWire Network Based On Time-Triggered Mechanism

SpaceWire, based in part on the IEEE 1355 and ANSI/TIA/EIA-644 commercial criterion, is a communication standard specifically for aerospace applications. It is coordinated by the European Space Agency(ESA) in collaboration with international space agencies including NASA, JAXA and RKA. Within a SpaceWire network, the nodes are connected through bidirectional, full-duplex, high-speed(200MHz), point-to-point serial links and packet switching wormhole routing routers, which are the reasons which are reasons for its popularity and broad application prospect in the aerospace industry.However, the SpaceWire standard only supports event-triggered messages. In the eventtriggered network,all the end systems randomly send messages according to the operation of the application. Because of lack of advanced plan, it is easily leading to network resources conflict and link obstruction. At the condition of end systems sharing only one output of the router,transmission delay can’t be determined because of the network resources contention between nodes. The communication delay and time jitter can’t be determined in the eventtriggered network, that is to say, the event-triggered network can’t provide Qo S Guarantee to the specific service, which is intolerable for the transmission of important information on aircraft.To overcome the application bottlenecks that transmission delay can not determined in SpaceWire network, we introduce Time-Triggered Protocol on the basis of the SpaceWire standard, enabling it to provide strict Qo S Guarantee to specific service.Based on the analysis and comparison of various bus used in aerospace field and the analysis of the technology status abroad and implementation principle of SpaceWire bus, proposed Time-Triggered SpaceWire network structure. The key technologies of TTS network we study futherly include layered structure, system components, the packet transmission principle. The scheduling algorithm of TT-transferred frame is improved. Besides, the preemption mechanismis of TT-transferred frame and discontinuous transmission mode of ET-transferred frame is innovatively proposed. Then, a general framework design is proposed for Time-Triggered SpaceWire end system and Time-Triggered SpaceWire switch. And the function model of them are made in detail. Finally, the simulation model of TTS network is established to simulate the scheduling algorithm of TT-transferred frame, the preemption mechanismis of TT-transferred frame and discontinuous transmission mode of ET-transferred frame. The feasibility of this design is analyzed based on the simulation result.