Research On Key Technology Of Heterogeneous Entity Communication In Cyber-Physical Systems

The past years have been witnessed a rapid development of information technology,which brings us convenience and promotes our lifestyle.As various technologies begin to mature,it is possible to solve more problems by integration of different technologies.The requirement sparks the birth of Cyber-Physical Systems(CPS).CPS are a kind of emerging large-scale and networked systems.By the integration of computing technology,communication technology,control technology in a collaborative and autonomous manner,the cyber space and the physical space are deeply coupled and interacted.The goal–the physical world is controlled by the cyber world in a real-time,trusted and efficient manner-is finally achieved.CPS is attracting extensive attention from both academia and industry since its birth.It is considered as the driving force of Industry 4.0.Communication network is the bridge between the physical space and the cyber space.It promotes the scalability and expands the scale of CPS.It is also provided to support distributed real-time computing and cooperative control.By connecting different computing units and physical units spatially scattered,remote monitoring comes into reality.There are new challenges associated with communication in CPS.The goals of applications require deterministic behaviors.Communication network should provide real-time and reliable data delivery.However,network protocols induce non-deterministic delays.Dynamical environments and heterogeneous networks lead to unpredictable communication performance.These factors impose uncertainties on computing and control.Therefore,it is valuable and necessary to research the key technologies of communication in CPS.By modeling the CPS network,the mutual effects of communication,computing and control can be described.Then the timing behaviors of communication under different scenarios can be analyzed.Meanwhile,in order to avoid the deterioration of control performance due to unpredictable communication performance and guarantee real-time data transmission,it is also meaningful to optimize the resource allocation and provide delay-aware communication services.Specifically,the main contributions of the thesis can be concluded as follows:1.Network characteristics and its modeling method in Cyber-physical systems.The thesis discusses network characteristics in CPS,such as real-time,high reliability,heterogeneous networking,dynamical topology,deeply interaction with environments.The effects of characteristics on communication performance are analyzed.Then the technical challenges of modeling CPS network are discussed.The way to choose model parameters and how the parameters affect model performance are concluded.Then CPS network model is presented.The presented model is instantiated through a typical scenario.The model parameters are also checked.2.The analyzing method of communication performance impaired by physical factors.Noise widely exists in communication systems.The thesis investigates the noise problem in CPS.It can be found that the common used model,i.e.,Middleton Class A noise model,cannot well describe the noise features.Therefore,the thesis presents extended Bernoulli-Gauss model to represent the impulse noise.The presented model describes the relationships between the model parameters and the noise.It also quantitatively analyzes the impacts of the physical impairments on communication performance.Then the analyzing method is used in Controller Area Network(CAN),which is a typical networking protocol in industrial scenarios.Meanwhile,the thesis also analyzes the effects of other physical factors on CAN,such as temperature,impedance.3.The delay-aware schedule method for distributed information fusion.The thesis investigates the allocation problem of communication resource in large-scale and heterogeneous network.As the real-time traffic and the non-real-time traffic coexist,in order to provide real-time data delivery,the proposed schedule method takes both the timing constraints and the historical transmission statistics into consideration.Its distributed greedy implementation is proposed.Simulation results show the proposed policy achieves good real-time satisfaction and avoids the notorious problem of link starvation.4.Heterogeneous delay guaranteed method based on non-cooperative game.In the context of heterogeneous nodes and all real-time traffic,the transmission faces a fiercer competition.The thesis combines the distributed scheduling algorithm with game theory.A non-cooperative game framework is proposed to describe the interactions among multiple links.Without message passing,the goal of real-time communication with heterogeneous delay constraints and link schedule is achieved.By theoretical analysis,the proposed one-shot strategy can guide all the nodes to play the best response and achieve the Nash equilibrium point.Simulation results shows good real-time performance and scalability under different scenarios.Finally,the thesis concludes above researches.Further research issues and directions that are valuable are also discussed.