Research On Data Link Control Based On SPMA Protocol

Tactical Targeting Network Technology(TTNT)has the characteristics of fast networking,strong self-repair capability,and excellent scalability.Each combat unit can flexibly exit the network and access the network.And it can support for over-the-horizon communications through the relay link interconnection technology to realize the joint networking of multiple combat units on the sea,land and air,and further improve the operational capability.The Statistical Priority-based Multiple Access(SPMA)protocol is an important communication protocol for the TTNT data link,which can distinguish the quality of service in multiple priority services.This thesis has conducted an in-depth study on the SPMA protocol,and proposes corresponding solutions for the problems of the SPMA protocol that the full load threshold cannot be dynamically adjusted,the low priority packets are overtime,and the network resources are wasted due to the timeout of forwarding service packets.The main work is summarized as follows.The battlefield environment is complex and changeable.In view of the fact that the SPMA protocol channel full load threshold cannot be dynamically adjusted with the battlefield environment changes,and the network is under continuous heavy load,a large number of low-priority packets have simultaneous timeout problems.A Statistical Priority Multiple Access Protocol with Adaptive Full Load Threshold(SPMA-AFT)is proposed.The SPMA-AFT protocol dynamically adjusts the channel full-load threshold through periodic statistics on the success rate of network packet delivery.In addition,in order to avoid a large number of timeouts for low-priority packets,a dynamic packet priority adjustment mechanism is designed according to the queuing delay of packets in the queue.In the complex and changeable channel scenario on the battlefield,to achieve the network load stability,a packet generation decision mechanism is designed so that the system can effectively control the rate of packet access channels.The simulation results show that the protocol can effectively improve the network system throughput and the success rate of packet initial transmission,reduce the average end-to-end delay of packets,and can ensure the transmission of low-priority services without reducing the quality of high-priority services rate.In the scenario where the heavy network load leads to a large backlog of service queues,to address the problem of more network resource waste caused by the loss of forwarding service packets,Improved SPMA Equivalent Priority Packet Scheduling Protocol(SPMA-EPS)is proposed.The protocol first designes the same priority packet scheduling algorithm.When a new packet arrives at the node,the scheduling factor is calculated by the remaining survival time of the packet and the packet size,and the packet is inserted into the corresponding position in the queue according to the size of the scheduling factor,which reduces the problem of timeout of forwarding service packets.In addition,when the buffer queue space is insufficient,by preferentially discarding its own service packets in the queue,the buffer queue space is released,reducing the loss of forwarding service packets.Finally,simulations verify that the SPMA-EPS protocol improves the performance of the SPMA protocol system in multi-hop networks to a certain extent.