Research On The Multiple Access Technology In Lunar MANETs With QoS Guarantees For Multiple Services

The efficient and reliable communication on the lunar surface lays a solid foundation for the successful completion of moon exploration missions.There exist great differences in Qo S(Quality of Service)for lunar communication flows due to the various requirements of the exploration mission.Especially for transmission tasks such as vital signs information of astronaut and controlling information,the lunar communication network(LCN)must first supply extremely ultra-low latency and extremely reliable information transmission for this type of special services.To support multi-user shared access and improve service transmission efficiency and reliability,multiple access protocols have become its core technology,which is also the cornerstone of constructing an efficient and reliable LCN.Based on the characteristics of lunar communication flows,a statistical priority-based multiple access with dynamic threshold(SPMA-DT)protocol that aims at low latency and high reliability is proposed in this thesis.SPMA-DT firstly designs a dynamic threshold adjustment approach based on the successful transmission probability of frames(DTASTPF),which reflects the real-time network load by the STPF.Besides,DTA-STPF can dynamically adjust the threshold of each priority through the comparison of the current STPF with the STPF of the highest priority flow,which can avoid access interference of other services and concentratively supply the high reliable transmission for the highest priority flow.Furthermore,a new access approach based on SPMA-DT combined with the NonOrthogonal Multiple-Access(NOMA)is proposed to break through the orthogonality of resource usage by introducing the dimension of power domain.Moreover,the communication nodes can successfully separate and receive conflicting data on the same temporal-frequency resource through the power difference of received signals and serial interference cancellation technology,which greatly cultivate the network throughput though the cost of the computational complexity increases.In order to verify the performance of the protocol in terms of delay and reliability,SPMADT protocol is evaluated under different network load and flows intensity by computer simulation in this thesis.The simulation results show that SPMA-DT can implement firm guarantees for ultra-low access delay of 1ms and high reliability of 99% for the highest priority flow.In addition,SPMA-DT can further improve the network throughput by more than 70% through combining with NOMA,effectively supporting the access of other kinds of flows.