Analysis on Attack Schedules in Wireless Networked Control Systems based on Channel Hopping

In this paper, we investigate the security issue in wireless networked control systems, where the sensor uses the channel hopping scheme to transmit the measurement data to the controller over multiple channels attacked by an energy-constraint jammer launching periodic Denial-of-Service attacks. Assuming that the jammer can select randomly several channels to attack at each attack time, there exists a tradeoff between the number of attacks, meaning the amount of time expended launching the attack, and the number of channels selected at each attack time. According to this, a problem arises in how to select the number of channels at each attack time to maximize the attack effect measured by the cost function in linear quadratic Gaussian control. By formulating this problem as an integer programming problem, an optimal attack schedule is obtained using the selection of channel number (SCN) algorithm proposed in this paper. Numerical simulations verify the effectiveness of the SCN algorithm.