Design And Implementation Of Medium Access Control Protocol For Low Orbit Inter-satellite Network

With the rapid development of space information network technology,satellite communication technology has played a pivotal role in space information network,such as navigation and positioning,emergency rescue,ground observation and mobile communication and so on.Collaborating to complete complex space missions through the networking of multiple small satellites has become the development direction of future integrated space information network.The premise of inter-satellite network is that information and data can be interconnected between small satellites.However,the existing small satellite networks have the following characteristics:diverse access points and network nodes,large transmission rates of inter-satellite links,dynamic changes in network topology,and large propagation delays due to long-distance communications.Those characteristics require the inter-satellite network to have a high degree of adaptability and reliability.As a key technology in inter-satellite network system,the MAC protocol can ensure the correct transmission of data and the quality of communication.Besides,MAC protocol can avoid the waste of valuable channel resources,which is important for improving the inter-satellite network performance and meeting the needs of different communication services.Therefore,designing an access protocol that is compatible with the inter-satellite network communication scenario is of great significance for building a space information network.According to the characteristics of the inter-satellite communication scenario in the Master-Slave mode,this paper studies a MAC protocol suitable for inter-satellite network with the dynamic change of network topology and long-distance communication.The main contents are:(1)For the dynamically changes of traffic load,a dynamic time slot allocation scheme based on CSMA/CA and TDMA multiple access protocol is proposed,the simulation verifies the effective of the proposed scheme;(2)For the characteristics of large propagation delay caused by the long-distance communication between satellites,an improved MAC protocol for inter-satellite network based on the IEEE 802.11 ad standard protocol is proposed,and the software and hardware collaborative design is conducted based on Xilinx ZYNQ 7000 series development boards;(3)A physical platform based on the proposed inter-satellite network MAC protocol software and hardware collaborative design is established,the basic transmission functions of data frame and beacon frame are implemented.According to the simulation results,the dynamic time slot allocation scheme for hybrid multiple access protocol proposed in this paper can improve the system throughput,reduce the average delay and raise the channel utilization.According to the function verification of the physical platform for protocol stack,the inter-satellite network MAC protocol designed in this paper can effectively realize the data transmission function,which has a positive effect on the future inter-satellite network physical research.