Research On The Periodically Frame-generated And Virtual Channels Scheduling Algorithm Based On Poisson Flow In The AOS

In order to meet the requirements of increasingly complicated space missions and space systems,the Consultative Committee for Space Data Systems developed the recommendations of AOS.In AOS,the two-stage multiplexing mechanism,which includes the packet channel multiplexing mechanism and the virtual channel multiplexing mechanism,is adopted to make the multiuser,large capacity and high speed data share the same space physical channel dynamically,which can reduce the transmission time delay and increase the channel utilization ratio,the main contents are as follows:Firstly,the periodically frame-generated model with the finite buffer size was built;secondly,the theoretical calculating methods of buffer overflow probability and mean of packet multiplexing efficiency in this model were derived;thirdly,the simulation experiment was performed to verify the correctness of theoretical derivation;lastly,the application methods of this model and theoretical calculating formula were summarized.The research results can offer theoretical basis and reference for engineering design.In the design of satellite communication systems,the suitable buffer size can be set by applying these research results to obtain the system performance as expected.Secondly,a novel multiple-channels scheduling algorithm based on timeslot optimization is presented and its performance under the finite buffer size is also studied.Firstly,an optimized timeslot assignment method is designed based on both the ratio of synchronous frames arrival rate to asynchronous frames arrival rate and the allowable maximum time delay of synchronous VC frames.Secondly,the periodical polling scheduling strategy is adopted to schedule the synchronous VCs at the synchronous timeslots,and if there are no corresponding synchronous VC frames in a synchronous timeslot,another synchronous frame or asynchronous frame will be selected and scheduled according to the scheduling mechanism.Thirdly,a dynamic scheduling strategy based on the transmission urgency of VC is adopted to schedule the asynchronous VCs at the asynchronous timeslots.The research results show that the performance of the proposed algorithm is much better than that of the other scheduling algorithms in terms of the time delay and channel utilization rate.The proposed multiple-channels scheduling algorithm for the finite buffer size is extensively studied and the upper bound of rate of frame-lost timeslots of each asynchronous VC is concluded.