Performance Analysis Of The Statistical Priority-based Multiple Access

Tactical data link is a data communication system used in battlefield environment.Statistical Priority-based Multiple Access(SPMA)is the MAC protocol used for Tactical Targeting Network Technology(TTNT),the next generation of Data Link System of the US Army.As a new MAC protocol on testing and to be used in the near future,SPMA is required to support for multiple different Classes of Services(COS),provide a much lower latency for packets with high priority and an extremely high first transmission success rate for all packets sent out.And the flow control mechanism used in SPMA could increase the stability of the communication system while improving the channel utilization.All these properties make SPMA a much better protocol for Aeronautical Ad-hoc Network(AANET)than others.The main works and highlights of this thesis are the following:Firstly,in this thesis we analyzed all existing media access control protocols used for AANET.We compared SPMA with all other MAC protocols and proved that SPMA is much better than others.We propose a simple but accurate analytical model to compute the Slot Transmission Probability(STP)with the assumption of saturated input.With the STP and M/G/1 priority queue theory,we get the mean delay,packet loss rate,throughput and other properties of the system.Secondly,a system simulation platform was build according to related patents to analyse the properties of SPMA.The accuracy of the analytical model we proposed is proved by simulations implemented.All results show that SPMA can guarantee the timeliness and reliability of the highest priority and maintain the stability of the system throughput.The transport delay of the packets with the highest priority is no more than 2 milliseconds and the success rate of first transportation is higher than 99 percent.The excellent characteristics meet the trend of future development of data link.Thirdly,the performance of SPMA and CSMA/CA are compared in this paper,and the simulation results show that SPMA protocol is more suitable for the system with a large scale and a harsh demand for system delay.Fourthly,we proposed an algorithm to solve the problem of that SPMA protocol could not perfectly deal with the situation of unbalanced traffic load.The algorithm is named as Dynamic Threshold Setting(DTS).We simulated the performance differences between DTS and fixed threshold setting.The results show that DTS could improve channel utilization and the fairness of the system.