Research On Dynamic Bandwidth Allocation Strategy For Cyber-Physical Systems Under Denial-of-Service Attacks

The Cyber-Physical System(CPS)can be characterized as a complex networked control system,which highly integrates physical resources in the real world with information resources in the cyber space.It has become the preferred architecture for many large-scale complex control systems.Sharing the open network with limited bandwidth brings convenience to the control system,and it also makes CPS face more security issues.The Denial-of-Service(DoS)attack is the most common type of network attacks.It affects the real-time performance of data transmission by occupying the limited network resources of the control or sensing channels,which brings great challenges to the security of CPS.This thesis studies the dynamic allocation of CPS network resources under DoS attacks.The specific contents are as follows:First of all,the model establishment of CPS under DoS attacks is considered.The network model of CPS and the attack modes of time-constrained DoS attacks are described and illustrated respectively.The constraints conditions of DoS attack are given from the two aspects: attack frequency and attack duration.By analyzing the impact of DoS attacks on CPS,a sufficient condition for ensuring the stability of the input state of the system under the DoS attack constraints is given.The definition and characteristics of the event-triggered communication strategy and the impact of network bandwidth limitations on CPS are described in detail,and the problems and subsequent developments are explained.Secondly,according to the characteristics of each subsystem,the unique initial sampling period is selected.The uniqueness of each subsystem's bandwidth requirements and the discrete event-triggered communication strategy which has the advantage of reducing the network communication are considered.A hybrid communication strategy based on dynamic bandwidth allocation and discrete event-triggered is proposed.On this basis,considering the total network bandwidth of CPS,this thesis actively adapts to the sharp changes in bandwidth requirements of each subsystem caused by DoS attacks through the proposed hybrid communication strategy,and realizes the confrontation of DoS attacks from the perspective of bandwidth dynamic allocation.A simulation example is given to demonstrate the effectiveness of the proposed hybrid communication strategy.At last,according to the uniqueness of bandwidth requirements of each subsystem under DoS attacks,the subsystems of CPS are classified,and a dynamic bandwidth allocation strategy is proposed to deal with the impact of DoS attacks on the system.Based on the proposed dynamic bandwidth allocation scheme,the system performance is analyzed,and the stability of the CPS is proved.The feasibility and effectiveness of the proposed design in this chapter are verified by simulation examples.