Research On Key Technologies Of Invulnerability Of Industrial Wireless Sensor Networks

As the distributed network system consisted by lots of sensor nodes,wireless sensor networks are capable of sampling and delivering different kinds of environmental data and target information.But in industrial scenarios,due to the internal impacts of the networks(e.g.,large-scale deployment,heterogeneous structure,delivery delay,directional transmission)and external environmental interference,the long-term reliable operation of industrial wireless sensor networks cannot be ensured.Network invulnerability has become the major technical bottleneck for wider application of industrial wireless sensor networks.To tackle with this issue,in this dissertation we divided the task of invulnerability optimization into three phases according to the process of network building:(1)the first phase is network initialization phase in which the parameters of topology and capacity would be optimized.The goal of this stage is to enhance the network invulnerability against random failures and cascading failures;(2)the second phase is running stage,which is to ensure reliable transmission through routing-selection optimization;(3)the third phase is maintenance stage of which purpose is to solve the later maintenance issues brought by the lack of failure information.To achieve this,we introduced mechanisms of fault detection and fault diagnosis into this stage.The main research works are as follows:1)A clustering topology evolving mechanism of industrial wireless sensor networks is provided.To tackle with the topology invulnerability issue of wireless sensor networks in complicated industrial environments,we designed a clustering scale-free local-world evolving model to create a highly error-tolerant network topology and proved the degree distribution of the proposed model consistent with the power-law distribution.Given the property of directional data transmission,we built directional betweeness network structure entropy to evaluate the balance level of network loads.On this basis,we proposed a deployment scheme of long links based on the small-world theory,of which purpose is to solve the issue of energy hole caused by heterogeneity of degree distribution in scale-free topology.2)Oriented to cascading failures,a capacity-optimization scheme of industrial wireless sensor networks is proposed.According to the cascading failures caused by traffic blasts in industrial wireless sensor networks,we firstly analyzed the genuine changing discipline of traffic loads in clustering network and built a clustering cascading model by introducing the concepts of sensing loads and relaying loads.And then,we researched the invulnerability performance of clustering scale-free network and clustering random network against cascading failures.To prevent cascading failures,we proposed two schemes: capacity selection scheme and capacity distribution scheme based on capacity-extending method.3)An error-tolerant routing algorithm of industrial wireless sensor networks is designed.Given the impacts of complex environmental factors(e.g.,humidity and temperature)on network routing performance,we proposed a disjointed multi-path routing algorithm based on potential field.In this algorithm,the industrial wireless sensor networks are abstracted as an artificial potential field which is influenced by environmental field,energy field and depth field.By building weight-adjustable target field,the routing invulnerability can be improved significantly by making disjointed multipaths avoid crossing dangerous areas.And at the meanwhile,the routing can also meet the requirements of low energy-consuming level and low delivery delay.4)Fault detection and diagonosis methods are proposed in this dissertation.According to the common fault types of wireless sensor networks in industrial scenarios,we proposed a distributed fault detection algorithm based on the tendency-similarity characteristics of data sampling presented by adjacent sensor nodes.The most evident advantage of this algorithm is removing the effects of triggering moment on detection accuracy.On this basis,we presented a fault diagnosis algorithm based on artificial immune system.Through a series of procedures(i.e.,classification of antigens,training of antibodies library,antibody-antigen matching and updating of antibodies),network fault types can be identified accurately.5)We built a simulation platform and a practical system to validate the performance of proposed theories and methods.Given the current situation of lack of invulnerability simulation platforms,with considering of features(e.g.,network performance is strongly affected by environmental factors and invulnerability behaviors are event-driven),we designed a simulation platform for invulnerability of industrial wireless sensor networks by introducing environment component and event creator.And then,we built a practical industrial wireless sensor network system to test the actual performance of proposed theories and methods in a stereoscopic warehouse.The test results show that the proposed theories and methods are able to enhance the invulnerability performance of industrial wireless sensor networks effectively.In summary,this dissertation researched the related theories and methods of network invulnerability,of which purpose is to solve the invulnerability issues in industrial wireless sensor networks.Through simulations and practical tests,the performance of proposed theories and methods are verified,which can provide theoretical and practical support for constructing highly invulnerable industrial wireless sensor networks.