Research On The Topological Evolution Of Wireless Sensor Networks Based On The Scale-free Theory

Wireless sensor networks(WSN)are deployed in areas with inaccessible and harsh environments.They often face problems of node failure and poor network intrusion,which greatly shortens the network life cycle and seriously affects the normal use of the network,tasks cannot be completed on time.Therefore,the energy consumption and damage resistance of the network is a key issue to be considered when designing the WSN topology.The node degree distribution in a scale-free network is not uniform but has power-law characteristics.Therefore,nodes have good invulnerability to random strike and can meet the requirements of WSN topology design.At present,most scale-free network models are based on the Barabási-Albert(BA)model for extended evolution,but the unity and growth model of the BA model's preferred connection is quite different from the actual network,which has certain limitations.Therefore,based on the existing scale-free model,combined with the dynamic requirements of WSN,this thesis designs a network model with energy optimization and invulnerability.The main research contents of this thesis are as follows:1.Aiming at the problem of node failure that often occurs in WSN,a weighted scale-free topology evolution model Poisson growth weighted scale-free topology evolution model(PWSM)based on Poisson growth is proposed.This model introduces the dynamic weights into the topology evolution of the network based on the weighted network model proposed by Alain Barrat et al.(BBV for short).At the same time,in the priority connection mechanism,not only the factor of the node degree in the classical scale-free BA model is considered,but also the locality of the node and the residual energy of the node.Considered comprehensively,a new edge weight expression is defined.Through theoretical deduction,it is proved that the topological point weight,edge weight and nodal degree generated by the evolution of this model obey the power law distribution and have scale-free characteristics.The simulation results show that the network topology can balance network energy consumption and has high transmission efficiency and connectivity.2.Aiming at the vulnerability of WSN to deliberate attacks in practical applications,a scale-free topology evolution model with controllable power law controllable power rate scale-free topology evolution model(CRSM)is proposed.This CRSM model firstly realizes the distribution of cluster heads with the help of the Hybrid Energy Efficient Distribute(HEED)clustering algorithm.Then,when constructing the inter-cluster topology,the node degree,the residual energy of the cluster head node and the distance between nodes are considered,so that the cluster head nodes with large residual energy have higher connection probability.Finally,the topology evolution between cluster heads is carried out by combining scale-free networks with random walks.The theoretical derivation shows that the network topological degree distribution generated by the model obeys the power law distribution,and the power law index is adjustable within a certain range due to the introduction of the adjustment parameters.3.In order to make the evolved topology have good self-healing,reconfigurability and adjustability,a scale-free topology evolution model with link compensation mechanism link compensation mechanism in scale-free topology evolution model(LCSM)is proposed based on CRSM.This model adds link deletion according to the actual characteristics of the WSN change.For nodes with low energy,large distance nodes and their corresponding links are also deleted,which can reduce network energy consumption and the cost of joining links for failed links and nodes.Thus,the compensation mechanism can extend the life of the network.The simulation results show that the network topology evolved by the above two models has high robustness under random and deliberate attacks,which can meet the robustness requirements of WSN in harsh environments.