Abstract: The standard of CCSDS AOS is used in space exploration because of the process of the standard airspace system. The spacecraft missions have used multi-protocol data unit (MPDU) to multiplex the package channels. The range of MPDU and the data are different in different spacecrafts. This process brings some problems in the maintenance and the correctness of the algorithms of virtual channel multiplexing in simulation system. The applications of CCSDS in the world were researched, and the general definitions of MPDU in these missions were described. A circle memory was given to buffer the data of MPDU, two general formats in the process of sampling MPDU were researched, an efficient and maintenance-free algorithm for unified sampling MPDU was designed, the efficient of time was analyzed, which proves its correctness in theory. The application of this algorithm was given, and the future application and work were pointed out.

Key words: AOS Standard, multiplex, MPDU, sample, algorithm, correctness