Design,Simulation And FPGA Verificationof Hybrid Routing Mechanism For Space Wire Networks

With the rapid development of space technology,requirements for aerospace bus technology are getting higher and higher,e.g.,to achieve high-speed data transmission,to adapt to high temperature,low temperature and other harsh environments,as well as to have strong antiradiation ability.SpcaeWire bus technology has become a hotspot in the field of space bus technology because of its characteristics of serial,point-to-point,full-duplex,high-speed transmission.However,with the expansion of SpaceWire bus technology,it can not guarantee the real-time transmission of control data owing to the uncertainty of the propagation delay of wormhole routing.Therefore,variegated busesare utilized in satellite network,which becomes the bottleneck of non-uniform interface and protocol of spaceborne network.In this thesis,dynamic routing and static routing are combined to design a hybrid routing mechanism that can make control data and payload data share the same network.And a simulation model for the network system is set up in OPNET to evaluate the proposed routing mechanism.In order to further verify the feasibility of the routing mechanism designed,we use the Very-High-Speed Integrated Circuit Hardware Description Language(VHDL)to design a SpaceWire router that can implement hybrid route transmission and build a simple network system on FPGA.(1)Related works of SpaceWire bus,router and routing mechanism are analyzed,and SpaceWire protocol and SpaceWire-D protocol specifications are given,which is the theoretical basis of hybrid routing mechanism design.(2)Based on the SpaceWire and SpaceWire-D protocols,a hybrid routing mechanism is designed to implement the shared network of control data and load data by combining static routing(time trigging)with dynamic routing(event triggering)mechanism.The static routing mechanism abides by the SpaceWire-D protocol to ensure deterministic data delivery,in which heuristic scheduling algorithm is adopted to realize multi-slot schedule for the first time,and the time-slot is designed by using greatest common divisor to improve the throughput.And the dynamical routing mechanism can insure the critical random event be processed preferentially when transmission routes conflict,by allocating priority levels to random event and payload data.(3)A simulation model for the network system is set up in OPNET to evaluate the proposed routing mechanism.And the results show that the throughput of the network is improved significantly during static routing time as comparing with the existing scheduling algorithm,and different transactions can be processed according to their priority during the dynamical routing time as expected.(4)A SpaceWire router capable of hybrid route transmission is designed using VHDL,and the design scheme is given.By increasing the router arbitration module and the priority recognition function,the critical random event be processed preferentially when transmission routes conflict,during the dynamic routing time.The transmission mechanism of the loop scheduling is avoided and the ISE software is utilized to simulate the router.(5)A simplified SpaceWire network system supporting the hybrid routing mechanism has been built up on the Xilinx Virtex-6 ML605 development board,which consistes of a four-port SpaceWire router and four SpaceWire nodes,and the proposed routing mechanism is verified.