Research On Beacon Mechanism Of Neighbor Discovery In Low Duty Cycle Wireless Sensor Networks

Wireless sensor network(WSN)is a self-organizing network composed of sensor nodes,which can monitor,collect and transmit environmental information,and mutual discovery among neighboring nodes is the premise of completing the networking.Since wireless sensor network is an energy-limited network,nodes often work in duty cycle mode in order to extend the working cycle of the whole network as much as possible.However,at this time,the nodes are in the state of off radio during most of the working time,so it is difficult to realize mutual discovery among nodes.Neighbor nodes discover each other through sending and receiving beacons.Therefore,neighbor discovery beacons mechanism mainly studies the beacons interaction mechanism with high performance and universality to realize the fast networking between sensor nodes.The current beacon mechanisms of neighbor discovery have some problems.First,in the theoretical analysis,the beacon sending process is often taken as a whole for modeling analysis,which is greatly deviated from the actual situation.Secondly,most of the current beacon mechanisms are based on the transceiver unseparated mode,and the transmission and reception of the beacon are all completed in a slot,which has high requirements on the slot size.In addition,the performance of the existing beacon mechanism in terms of detection probability and beacon conflict needs to be improved,especially in the case of small slot size.To solve the above problems,this paper first defines a detailed slot model which is closer to the actual working situation of nodes,and proposes a beacon mechanism based on the transceiver separation mode.Then the performance of the proposed beacon mechanism under random retreat is explored.Finally,an optimal slot model is constructed according to the relationship between the discovery latency and the slot size under different beacon mechanisms.Based on this model,the optimal slots under different beacon mechanisms are analyzed.The specific work contents of this paper are as follows:Firstly,a typical beacon mechanism and a deterministic neighbor discovery protocol are implemented on the Telos B node,and a precise slot model is defined according to the working principle of the node,which can be used to analyze the working condition of the node more accurately.In addition,a transceiver separation beacon mechanism based on ACK is proposed,and the theoretical discovery probability and other performance of the mechanism are analyzed.Experimental results show that the proposed mechanism can improve the discovery probability and reduce the discovery latency.Then,the persistent conflict between nodes is analyzed,and the working principle and discovery performance of the proposed beacon mechanism under random retreat are discussed.The experiment results show that the random retreat mechanism can alleviate the persistent conflict and reduce the maximum discovery latency between neighbor nodes.Finally,the programming implementation of different beacon mechanisms under different slot sizes is completed on the Telos B node,and an optimal slot model is constructed according to the relationship between latency and slot sizes under different beacon mechanisms,which can be used to predict the optimal slot.Experimental results show that the optimal slot sizes under different beacon mechanisms can be roughly determined based on this model.