| The amount of data transmission during mission to mars is greatly increased.To accommodate the requirements on communication equipment,relay communication such as lander-satellite-earth links are used.A new procotol,Proximity-1 Space Link Protocol,is developed by Consultative Committee for Space Data Systems(CCSDS)in order to provides short-range communication among landers,probers and orbiting relays.On the basis of the general communication system,an implementation,testing and evaluation system of the Data Link Layers of the Proximity-1 Space Link Protocol is developed.Firstly,a detailed design of the Proximity-1 Space Link Protocol is proposed based on the specific content of the protocol in this report.The implementation,which consists of two Proximity-1 protocol units and one On-Board Computer(OBC),can initiate a communication session with a remote entity,transfer data and reconfigure the parameters of transceivers if needed.Secondly,three types of Automatic Repeat-reQuest(ARQ)schemes are compared.Under the limitation of spacecraft resources,a system based on Go-Back-N ARQ(GBN-ARQ)is designed and implemented.And the sliding window size is also analyzed under the equation.Thirdly,the communication unit and control unit are designed on MFC and Labwindows/CVI according to the principle of softwave design,to realize the Proximity-1 protocol operation,status display and performance evaluation.Finally,the designed system is tested on a softwave and hardwave platform,which verifies the feasibility and correctness of the Proximitity-1 Space Link Protocol. |
