Recently, public attention is thoroughly aroused as to the security threats of Cyber-Physical Systems (CPS), which can seriously disrupt the system operation. In order to analyze the impact of potential cyber-attacks, one needs to investigate the attack scheduling strategy from the attacker's perspective. In this paper, we investigate the optimal attack schedules to degrade the system performance through multiple interactive channels against remote state estimation, which is different from the studies through multiple independent channels. Specifically, a channel is affected when the attacker launches an attack on another one, causing two different loss rates of the data package. Based on this, we represent the estimation error covariance of the remote estimator. Then we give the optimal jamming attack schedule theoretically. Finally, the effectiveness of the theoretical results is shown by numerical simulations.INDEX TERMS Cyber-physical systems, jamming attack schedule, interactive channels, remote state estimation.
I. INTRODUCTION
Cyber-Physical Systems are agents with integrated control, communication, computation. CPS have a wide application in many areas, such as aerospace, chemical processes, manufacturing, civil infrastructure, energy, intelligent transportation and battle field [1]-[3], [5], [10], [23]. The emergence of cyber-attacks has made wireless CPS more and more vulnerable. Take a very famous example, in June 2010 ''Stuxnet'' attacked an Iranian nuclear facility at Natanz, which damaged 60 persent hosts [4]-[6]. It is the first time that physical devices have been damaged by malicious computer programs.Based on the attacker's model knowledge, disclosure and disruption resources, cyber-attacks can be categorized into Denial-of-Service (DoS) attack, replay attack, false data injection attack, zero dynamics attack, covert attack and eavesdropping attack [7], [10]. Common malicious attacks are DoS attack [8], replay attack [9] and false data injection attack [7]. DoS attack aims to cause random loss of transmitted data by jamming the wireless communication channels to block the exchange of information between the system components, which is the most reachable attack [11]-[13]. Such attack can ignore protocols normally used and continu-The associate editor coordinating the review of this manuscript and approving it for publication was Parul Garg.