Research On Timeliness Of Multi-source And Multi-priority Wireless Sensor Network

The rapid development of wireless sensor networks has spawned a large number of applications with high delay requirements.For example,in the application of automatic driving,the vehicle shall timely monitor the information of surrounding vehicles and obstacles to provide a guarantee for the safety situation of the vehicle;In telemedicine applications,real-time communication can guarantee the life and health of patients;In the agricultural greenhouse environment monitoring,the humidity,temperature,and light in the greenhouse should be monitored in real-time to provide a better environment for the growth of crops.The above applications put forward high requirements for the timeliness of the information.Traditional metrics(such as latency and throughput)are not enough to accurately measure the freshness of information,and the introduction of the age of information(Ao I)makes up for this deficiency.In addition,different application scenarios have different requirements for information.Therefore,different information should be prioritized according to different application scenarios,and the information with higher priority should be transmitted first.Based on this,this paper studies the timeliness of multi-source and multi-priority wireless sensor networks through model construction and optimization,numerical,analysis and theoretical simulation.The innovative work of this paper is mainly reflected in the following aspects:1.Research on the timeliness of multi-priority multi-stream transmission based on Geom/Geom/1/N queuing model.Firstly,the multi-source wireless sensor networks are modeled,and the sample path of age of information in discrete time is analyzed,then the expression of the average age of information of the source in this model is obtained.The threshold age of information of the source is calculated,and a packet discarding strategy is proposed based on the threshold age of information,that is,when the peak information age(PAo I)of the packet is greater than the threshold information age,the packet will be discarded.Finally,it is verified by simulation that the system has better timeliness under the discarding strategy,and the influence of parameters such as source power and communication distance on the system timeliness is analyzed.2.Research on the timeliness of multi-priority multi-stream transmission based on time division multiple access(TDMA).TDMA protocol has high data transmission reliability.In order to improve the timeliness of highly important sources,allocate the number of time slots for the source based on the priority weight.In order to calculate the expectation of the joint distribution of the arrival time interval and the packet waiting time,the corresponding auxiliary function is constructed,and the closed expression of the average age of information under the model is derived.Finally,the theoretical results are verified by Monte Carlo simulation.3.Research on timeliness of multi-source sensor networks based on non-homologous preemption.In order to analyze the timeliness of a multi-source sensor network under continuous time,two kinds of last come first served(LCFS)with non-homologous preemption strategies,namely last come first served with non-homologous preemption only in service(LCFSNS)and last come first served with non-homologous preemption only in waiting(LCFS-NW),are proposed.The multi-source transmission system model is constructed by using the stochastic hybrid systems(SHS)method combined with the Markov process theory,and the expression of the age of information under the two strategies is derived,and the timeliness of the system under different strategies is compared.