Research Of Topology Control Methods For Wireless Sensor Networks Based On Fuzzy Control

WSN(wireless sensor networks)have a wide range of applications in the fields of environmental monitoring,smart home,national defense and military because of the characteristics of low cost,low power consumption,distributed structure and self-organization.However,the limited energy resources of nodes make the research of WSN face great challenges.How to reduce the energy consumption of nodes and prolong the network lifecycle have been the core content of the research of WSN.A lot of research shows that topology control method is an efficient energy-saving technology of WSN.The traditional WSN topology control methods usually use clustering or power control methods to optimize the topology structure.There are problems like "hot spot",unequal energy consumption,early death of nodes and easy to be disturbed by environment.Therefore,fuzzy control is applied in this paper to optimize the initial topology of the network,reduce the energy consumption and prolong the life cycle of the network.The specific research contents include:(1)For "hot spot" problem in clustering method,a new algorithm FUCT(Fuzzy controller based Unequal Clustering method for WSN Topology control)is proposed.The control system uses the Mamdani type fuzzy controller.The input variables are node's "Residual energy","Node centrality" and "Distance to sink node".Through fuzzy inference,the output variable is the probability that the node is elected as the cluster head;In the same way,input node's "Residual energy","Node degree","Distance to sink node " into the fuzzy controller,the system outputs competition radius of this node.This design of controller can adjust the scale of clusters with different location in the network and effectively reduce the network energy consumption and solve the "hot spot" issue.Cluster maintenance is done by on-demand reconstruction,which saves a lot of energy compared with traditional on-wheel reconfiguration method.The simulation results show that the FUCT algorithm performs better than DUCF(Distributed Unequal Clustering using Fuzzy Logic)?EAUCF(Fuzzy Energy-aware Unequal Clustering Algorithm)?LEACH(Low Energy Adaptive Clustering Hierarchy)in terms of node energy consumption,network packet transmission and network lifecycle.(2)For the problem that power control method is easy to be disturbed by the environment,a topology control algorithm SAFPC(Self Adaptive Fuzzy controller basedon Power Control method for wireless sensor networks)is proposed.In this algorithm,the model of two level fuzzy controller with ‘input-output-feedback' mechanism is designed,whose main controller was responsible for the node transmission power adjustment,and auxiliary controller was responsible for the desired node degree adjustment,so as to adjust the transmission power adaptively according to the residual energy of the node.The main and auxiliary fuzzy controller are both Mamdani type.The fuzzification,fuzzy rule and defuzzification process of these two controllers are introduced in detail.The simulation results show that the performance of SAFPC algorithm in the network convergence time,average energy consumption and network lifecycle is better than the fuzzy control transmission power algorithm FCTP(Fuzzy Controller for Transmission Power).(3)For the problem that common adaptive fuzzy control method has complicated parameter adjustment,a wireless sensor network topology control algorithm AFNTC(Adaptive Fuzzy Neural Topology Control algorithm for wireless sensor networks)is designed.In this algorithm,the parameters of the fuzzy controller are trained by artificial neural network,and the communication range of nodes is constantly adjusted to control the transmission power of nodes by feedback and loop,thus the actual energy consumption of the node is close to the expected value and the lifecycle of the network is extended.The simulation results show that the AFNTC algorithm can achieve the goal of nodes' energy consumption controlled.Compared with the SAFPC and LMA(Local Mean of Neighbors Algorithm)algorithm,in AFNTC,node has a lower and more stable average energy consumption.In this paper,fuzzy control and other intelligent control methods are used to optimize the WSN topology and solve the "hot spot" problem in the traditional clustering topology control method and the uncertainty caused by the environmental interference in the power control method.It verifies the effectiveness of the proposed algorithms and provides reference for the development of topology control technology in WSN.