Research Of Task Scheduling Strategy In Wireless Rechargeable Sensor Networks Based On Information Freshness

Wireless Sensor Networks(WSN)is a network information system that combines distributed information collection,transmission and information processing technologies,and is known as the milestone of the fourth industrial technology revolution after personal computers,computer networks and wireless communications.However,the limited energy brings many problems to WSNs,such as poor network stability,short service life,limited application scope,and low quality of service,which seriously limits the promotion and use of WSNs.In order to solve the problem of limited node range,Wireless Rechargeable Sensor Networks(WRSN)came into being,offering unlimited possibilities for the development of WSNs.The increasing demand for real-time information in WRSNs,where outdated information loses its value,makes it critical to keep the information fresh,making the problem of information freshness in WRSNs an important issue that needs to be addressed urgently.Traditional network performance metrics,such as throughput and latency,can no longer effectively describe the freshness of information in the system.For this reason,some scholars have proposed to use Age of Information(Ao I,Age of Information)to portray the freshness of information in the network.In this paper,we investigate the node work scheduling strategy in WRSN based on the average Ao I minimization problem of WRSN.The specific work in this paper is as follows:First,considering the real-time requirements of WRSN for receiving information in practical applications and the energy limitation of nodes in the network,a WRSN model with nodes equipped with a single finite capacity rechargeable battery is constructed,and the nodes’ average Ao I is investigated with respect to the charging strategies of nodes and the working parameters.Stochastic Hybrid Systems(SHS)method is used to analyze the average Ao I of the nodes under different charging strategies,and the effects of system operating parameters such as packet arrival rate and node service rate on the average Ao I of the nodes are explored.Based on the results of this theoretical study,the relationship between battery energy threshold,charging strategy and node average Ao I is simulated and analyzed;the Ao I performance of the full charging strategy and partial charging strategy is compared,and it is proved that the full charging strategy can effectively reduce the node average Ao I,and it is the optimal charging strategy in the single-battery wireless sensor network model.Second,since the current is directional and always flows from high potential to low potential,this means that a single rechargeable battery at a node cannot be discharged while being charged.In order to ensure that the nodes can complete the sensing task properly while further reducing the average Ao I,this paper improves the single-battery WRSN system model,proposes a WRSN model where each node is equipped with dual finite capacity rechargeable batteries,and investigates the problem of minimizing the average Ao I of the system when the nodes can work in rotation with dual batteries.To solve this problem,the virtual queue plus penalty drift theory in Lyapunov optimization is introduced,and the optimization problem is solved at each time slot by transforming the optimization problem into the form of drift plus penalty at each time slot using the exhaustive search method,and finally the node work scheduling algorithm based on Lyapunov optimization theory is obtained.The simulation verifies the effectiveness of the proposed WRSN model for dual finite capacity rechargeable batteries and the proposed node work scheduling algorithm based on Lyapunov optimization.