Research Of The AOS Multiplexing Simulation System Based On HLA-RTI

With the continuous development of space technology, the spatial datacommunication system proposes new requirements to data processing. Therefore,Consultive Committee for Space Data System(CCSDS) developed the AdvancedOrbiting System(AOS) protocol to adapt the multi-source, large-capacity and high-ratedata transmission system of the complex spacecraft.Traditional distributed simulation is unable to meet the requirement of large-scaleand complex simulation system, therefore, U.S. Department of Defense proposed HighLevel Architecture (HLA) for modeling and simulation. By providing general andrelatively independent Run-Time Infrastructure (RTI), HLA separates emulation,simulation run management and underlying communication transport, achievesinteroperability and reusability of different simulation system.First of all, the AOS multiplexing simulation system is overall designed in thisthesis, and the system is composed by four federates: including source coding federate,packet channel multiplexing federate, virtual channel multiplexing federate and addingASM federate. The simulation system achieves the hardware design by using three hosts,writes the function of each federate and the system communication interface by usingVC. Designing federate lifetime and federal time management, then achievingconnection of the AOS multiplexing simulation system by RTI.Secondly, designing each federate of the AOS multiplexing simulation system, thedetails are: The department of source coding federate, analysis of text, images, audio,three kinds of source model, and encoding them by using positive and negativeencoding, contrasting the relationship between information bits and supervision bits;The department of packet channel multiplexing federate, packing three encoded sourcesinto CCSDS package of version1and multiplexing them into the MPDU by using highefficiency frame generation algorithm, then generating VCDU by adding the MPDU ledhead, then generating data frame by adding the frame head and frame tail; Thedepartment of virtual channel multiplexing federate, describing four kinds of classicalscheduling algorithms, the superiority of the static priority scheduling algorithm is analyzed, dividing three different priority virtual channel by according to therequirements of real-time transmission of the source, and transmitting data frames byaccording to priority level; The department of adding ASM federate, selecting the bestframe synchronization flag as Attached Synchronization Marker in according to thecharacterisitic of perfect ASM, then adding ASM to the header of the data frame inorder to achieve frame synchronization better at the receiving system.