Research On Satellite Resource Scheduling Mechanism Based On MF-TDMA

With the rapid development of satellite communications,VSAT satellite communication system has got more and more attention.By utilizing MF-TDMA,it has features of high-speed transmission,networking flexibility,good scalability and so on,which leads to its wide application in broadcast,weather monitoring,earthquake monitoring,military communications and other fields.However,due to the increasing demand for multi-user and multi-service in modern communication,efficient resource scheduling has aroused general interest in the current research.In VSAT system,the user can only transmit data or receive data at the same time due to working at the half-duplex mode,so that there are many communication links in the network and it's necessary to schedule them.The current MF-TDMA is mainly for the uplink of satellite system such as DVB-RCS.The scheduling scheme based on that cannot be used for VSAT system because there is no such a problem of conflict between transmitting and receiving of the user in the uplink.In the link scheduling,the transmission and reception of the users need to be assigned simultaneously.But the main research is focused on the single carrier TDMA mechanism,which cannot solve the problem of time slot conflict under multi-carrier in MF-TDMA.Therefore,this paper mainly studies the effective scheduling of MFTDMA link resources,which is improved from frame structure design and link scheduling algorithm respectively.The improved schemes can reduce the conflict and improve the network performance on the basis of VSAT system.Firstly,this paper studies the optimal design of MF-TDMA frame structure.It analyzes the parameters of MAC header and guard time in VSAT system frame structure.Then,the influence of the request slot,the number of timeslots and the length of the slot is analyzed theoretically.Finally,the relation of both the resource utilization rate and the time delay to the relevant parameters is shown with the simulation,and the optimal design of the frame structure is realized.Secondly,aiming at the link scheduling of MF-TDMA,this paper proposes an algorithm called Max Weight Link Schedule(MWLS).The algorithm abstracts the resource scheduling model into the link assignment model in the directed graph.By analyzing the influence of each scheduling principle on the link allocation,the mathematical model with the multiconstraint condition is solved,and the scheduling strategy is proposed to minimize the conflict.Then,compared with the sequential link scheduling,random link scheduling,interference priority link scheduling,the simulation results show that MWLS can effectively improve the utilization rate of network resources and reduce the generation of time debris.Meantime,it reduces the traffic rejection rate and the packet loss rate,which is more conducive to the transmission of satellite IP services.In this paper,the proposed resource scheduling scheme can adapt to the VSAT satellite communication system better than the existing optimization scheme,and it has more practical significance on the corresponding research of MF-TDMA.