Consecutive Wake-up Schedule Schemes For Wireless Sensor Network Of Low Duty Cycle

Wireless sensor network is a distributed network composed of multiple wireless sensor nodes with sensing information,processing data and communication capabilities.It is widely used in military work,health care,smart home and environmental monitoring.In a network with sparse events,due to the low probability of events,nodes often adopt low duty cycle mode to reduce energy consumption,however,at this time,the data transmission process in the network may not be carried out because the receiving node is in a sleep state.After multi-hop routing in the network,the accumulated sleep delay can have a significant impact on the real-time data collection.Recently,some researchers have proposed an optimization scheme based on the monitoring and forwarding of ACK information,that is,if the receiver’s next hop node listens to the receiver’s return to the sender’s Rack,Rack means that the receiver can receive data,the receiver’s next hop node will dynamically change the node’s wake-up schedule and delay going to sleep,which can eliminate sleep delays to some extent.However,this improvement still has limitations and only implements piped transfer between 3 nodes.The main contributions of this thesis include the following two points:(1)This thesis proposes a basic consecutive wake-up schedule(BCWS)scheme.This scheme mainly adds a time slot after the time slot when the receiver returns the Rack message,so that the next hop node of the receiver can continue to deliver the message that the packet will arrive to the downstream node after successfully listening to the Rack,so as to realize the mechanism that the nodes on the whole route can have the opportunity to perceive the arrival of data in advance.The premise for the B-CWS scheme to take effect is that the next hop node of the receiver can successfully listen to the Rack.In the network environment with low duty cycle,the probability of the scheme taking effect is limited,so the optimization range of transmission delay is limited.(2)To address the limitations of B-CWS,we propose a consecutive wake-up schedule scheme based on segmented data transmission(S-CWS).On the basis of B-CWS,by segmenting the packet transmission process,the current receiver uses the time slot between segments to notify the next hop node,so as to increase the probability that the next hop node perceives that a packet is about to arrive,dynamically change the wake-up schedule,and delay entering the sleep state,so as to further reduce the sleep delay in the transmission process.We performed a theoretical analysis in a linear network and found that the strategy proposed in this thesis can effectively improve the network performance.In the case of event-sparse planar networks,there are fewer cases of multiple routing paths interfering with each other due to the relatively small amount of data generated by the nodes.Thus,in most cases,the strategy proposed in this thesis can operate effectively in flat networks with sparse events.The effectiveness of the proposed CWS series scheme is demonstrated by theoretical calculations and extensive experimental results and compared with previous studies,the B-CWS and S-CWS schemes can achieve 27.4% and 47.9% delay reduction,respectively.