Research On MAC Layer Mechanism Of Tactical Data Link

In the battlefield,the tactical data link is usually used to quickly and safely transmit various combat information between the command platform and the weapon platform.The advantage of the tactical data link is closely connecting the combat forces,weapon systems and command centers in space to complete the information Sharing,which can help the decision maker to make decisions quickly and enhance the cooperative combat capabilities of various arms.Among them,Tactical Targeting Network Technology(TTNT)is currently the most advanced tactical data link of the US military.It has the characteristics of high bandwidth,low latency,flexible entry and exit,and can adapt to joint operations between multiple combat platforms.In this era of high-modern warfare where discovery is destroying,TTNT data link is playing an increasing role and has become a key factor affecting the victory or defeat of a war.The MAC layer of the TTNT data link uses Statistical Priority-based Multiple Access(SPMA),It can better achieve different priority services access to the network.There are two main problems in the existing TTNT data link: 1)The Automatic Repeat re Quest(ARQ)retransmission mechanism of the MAC layer does not distinguish service types during the retransmission process,which causes some time-sensitive services to fail to reach the receiving end after multiple retransmissions,which increases the delay of the entire network and wastes some channel resources.2)There may be different packet lengths in the same priority data packet in the SPMA protocol.When the channel load is greater than a priority threshold threshold,the priority is used as the control unit to back off all low priority packets,which may cause backoff excessive and waste some channel resources.Considering the above problems,this article studies the MAC layer of the tactical data link TTNT.The main work is as follows:First,this thesis proposes a dynamic adjustment method for ARQ retransmission.In the first the application layer service information type is introduced to the traditional automatic retransmission mechanism ARQ at the data link layer,and the number of retransmissions is dynamically adjusted according to different service types to increase the transmission time of the next data frame and reduce the transmission delay of the entire data packet.Ensure that the time-sensitive services received by the receiving end will not become invalid.NS3 simulation software is used to simulate and analyze the TTNT data link.Finally,the effectiveness of the method is verified by measuring and analyzing parameters such as system throughput,system delay,data transmission success rate and delay jitter before and after optimization.Second,this thesis proposes a Multi-priority Double Threshold Access Control Protocol(MDAC).Firstly,the MDAC protocol reflects the current channel load status through the traffic statistics of the MAC layer.While ensuring that different service types have different threshold thresholds,it also adds a judgment threshold with data packets as the control unit.When the channel conditions allow,some low-priority data packets can be sent across the priority threshold to improve channel resource utilization.NS3 simulation software is used to compare the MDAC protocol proposed in this thesis with improved FSPMA protocol and TSMP protocol of SPMA protocol.Finally,the advantages of MDAC protocol are analyzed from data transmission success rate,system throughput,system average delay,channel utilization and delay jitter.