Research On Opportunistic Routing Protocols For Wireless Sensor Networks

Wireless Sensor Networks(WSNs),with their easy-to-deploy sensor nodes,undertake a large number of data collection and transmission tasks in different Internet of Things(IoT)scenarios.Due to the limited energy of sensor nodes,duty-cycling(DC)technology needs to be used in WSNs to perform work/sleep scheduling of nodes.In the application of DC,the opportunistic routing protocol provides an effective solution to the problem of network transmission delay and energy consumption.This thesis focuses on the opportunistic routing protocols in duty cycle wireless sensor networks,and the following two aspects of research are carried out:Firstly,an opportunistic routing protocol based on dynamic candidate node set design is proposed for asynchronous duty cycle WSNs in nonenergy-concentrated scenarios.The protocol deduces the inverse relationship between node duty cycle and forwarding angle,thereby determining the forwarding angle of nodes with different duty cycles and their candidate node sets.For a node in the candidate node set,the forwarding priority of the node is determined according to the remaining energy of the node and the distance between the node and the sink node,and the wake-up node with the highest priority is selected as the forwarding node.When no node in the set wakes up,the protocol will increase the forwarding angle of the sending node,further expand the set of candidate nodes,and reduce the waiting delay of the sending node.The simulation results show that the proposed protocol reduces the network transmission delay and redundant data overhead compared with the traditional routing protocols based only on node communication distance and fixed forwarding angle.Secondly,an opportunistic routing protocol that combines dynamic duty cycle and power control is proposed for asynchronous duty cycle WSNs in energy-harvesting scenarios.The protocol proposes a dynamic adjustment method of the node’s duty cycle and transmit power.Then,on the basis of the candidate node set established based on the geometric distance,the probability of successful packet transmission between the sending node and the candidate node is calculated according to the sending power of the sending node,and the candidate nodes whose probability is greater than the given threshold are reserved to form a new candidate node set.For the nodes in the new set,a dynamic transmission cost is designed to establish the forwarding priority of the node.The lower the cost,the higher the priority of the node,and the wake-up node with the highest priority is selected as the forwarding node.Simulation results show that the proposed protocol has lower end-to-end delay and better energy balance compared with protocols based on power control.To sum up,the two opportunistic routing protocols proposed in this thesis have good advantages in data transmission delay,redundant data overhead and energy balance,and play a certain technical support role for the application of opportunistic routing protocols in WSNs.