Research On Multiple Access Technology Of High Load Satellite Network

Due to its wide coverage and small geographical impact,the LEO satellite network has attracted worldwide attention.In the past few decades,the LEO satellite network has developed rapidly,the number of users is increasing,and the load on the LEO satellite network is also increasing rapidly.Compared to Wireless Local Area Network of the ground,the LEO satellite network transmission delay is longer,most of the business is of the burst type and the length of the packet is differ.The existing demand multiple access have the problem of long transmission delay when transfer short packets of burst type,and although random multiple access technologies can ensure the timely delivery of sudden business group,but if the network load is high,serious packet conflict,successful probability will be low,at this point,the packets were forced to retransmission,transmission delay will increase sharply.Therefore,how to design a new type of multi access technology for the high load scenario becomes an important problem to be solved for the LEO satellite network.In view of the above problems,this paper makes the following research:Random multiple access technology can be well applied to low-orbit satellite network scenarios with long delay and more burst type data packets.In order to solve the problem of serious packet conflict and low system performance when the network load is high,this paper proposes hybrid dynamic partition multiple access technology(HDPMA),which introduces fixed multiple access technology on the basis of preserving random multiple access technology.A TDMA frame is divided into a random access area and a fixed access area,the fixed access area transmits the long data packet,and the random access area transmits the short data packet in the way of competing to solve the diversity time slot ALOHA(CRDSA).In order to ensure that random access area and fixed access area are separated from each other without interpenetration,a resource allocation strategy for fixed access area is proposed.A maximum threshold is set in the fixed access area to ensure the fairness of users in the random access area,and a flow control mechanism is introduced when the load is high.Simulation results show that this method can not only ensure the efficient and stable transmission of long packet,but also reduce the probability of short packet packet collision.When the load is high,the system can still achieve high throughput performance and delay performance.In order to distinguish the length and type of data packets sent by users,the sending end and the receiving end often need to conduct frequent signaling interaction.In the satellite network with long delay,such round-trip signaling interaction will bring about great transmission delay.In order to solve this problem,in HDPMA,each packet sent by the sending side contains an identity bit indicating the length of the packet.This piggy-back identification method will not introduce additional transmission delay in the original random multiple access mechanism,so as to ensure that the average transmission delay of the packet is maintained at a low level.In order to verify the feasibility of proposed HDPMA in the actual scene,this paper designs the platform based on hybrid dynamic division multiple access technology demonstration project,the plan by the side of the ARM software and hardware programmable logic side of two parts,including many of the software and hardware modules,such as the choice of time slot,time slot allocation,interference elimination and other modules,and gives the applicable to HDPMA multiple access technology of the new frame format design.Finally,the demonstration platform is implemented by FPGA development board ZC706,which verifies the feasibility of the hybrid dynamic partition multiple access technology proposed in this paper.