| With the rapid development of wireless communication,more and more communication systems produce multi priority traffic.Different priority traffic has different requirements on delay and loss rate.In tactical target network technology(ttnt)system,traffic multi priority is achieved by statistical priority multiple access(SPMA)protocol,which is located in the data link layer and plays a very important role in the data link.As a new multiple access protocol,SPMA protocol needs to support multiple different types of services to provide lower delay and higher transmission success rate for high priority burst packets.In this paper,the key technology of statistical priority multiple access(SPMA)is deeply studied.Firstly,the key performance index of physical layer is analyzed based on coded Aloha,and the relationship between channel load rate and packet delivery rate is obtained,and the setting method of priority threshold is analyzed.Then,the simulation model verifies the effectiveness of the backoff algorithm in SPMA protocol and the differentiated transmission performance guarantee for different priority services.The specific work includes:(1)This paper studies the multiple access technology and multiple access protocol of tactical data link.By analyzing and comparing the principles and performance characteristics of several common multiple access protocols,SPMA protocol is introduced,and the operation mechanism of SPMA protocol is deeply studied.(2)The physical layer of the system is analyzed and designed based on coded Aloha.Firstly,the theoretical derivation and analysis of the burst delivery rate are carried out,and the correction method of the burst delivery rate is proposed,and the simulation is carried out under two different conflict schemes and different nodes.On the basis of burst delivery rate,this paper proposes a correction method of packet delivery rate,and carries out simulation verification under two different conflict schemes and different nodes.Then the channel load rate is evaluated and the principle of setting priority threshold is analyzed.Finally,under the condition that the highest level packet delivery rate is 99%,the dichotomy method is used to get the channel load rate,that is,the highest level threshold value.Combined with the evaluation error of channel load rate and the theoretical analysis of each threshold setting,other priority thresholds are obtained,which lays the foundation for the research of backoff algorithm.(3)This paper further analyzes the backoff algorithm in SPMA protocol,builds a simulation model on Visual Studio 2017 and MATLAB software platform to verify the effectiveness of the backoff algorithm in SPMA protocol,and verifies the guarantee of differential transmission performance of different priority services from the perspective of packet delivery rate,system throughput and end-to-end delay. |
