RADIOELECTRONIC AND COMPUTER SYSTEMS

The Markov availability model of a physical security system is investigated. The actuality of research caused by the need to protect the physical security systems not only from physical failures, but also from cyber-attackers. When constructing the model, it is assumed that the properties of stationary, ordinariness and absence of aftereffects of event flows in the system, the low probability of failure of the software component and cloud services. It also takes into account the fact that acts of vandalism occur on objects of the first zone that are outside the perimeter. The typical algorithm of construction of the Markov model based on determination of sets of states and mechanisms of interaction is used. The evaluation of the functioning of the multi-zone system was carried out taking into account three degrees of degradation from the normal state to the states of simultaneous failure of all three zones. The top state of S1 corresponds to the normal state of the system without failures. The states S2, S3, S4 correspond to the states of the first level of degradation of the system, in which hardware failure occurred in one of the zones. The states S5, S6, S7 correspond to the states of the second level of degradation of the system, in which there were hardware failures in two zones. Condition S8 corresponds to the state of complete failure of all three zones of the system. To evaluate the availability functions, the Markov model was calculated and investigated for different sets of input data. The following parameters were chosen: hardware failure rate due to unintentional physical and design defects; the intensity of recovery of hardware after failure and the degree of "aggression" of the attackers, which depends on external factors. The results of the simulation conclude that the parameters of failure rates and recovery are affected by the availability values of the different degradation levels and the relationship between them. It is determined that with increasing input parameters - the failure rate of hardware and the coefficient of "aggression" of intruders, the stationary availability coefficients of all levels of degradation decrease.

physical security system; availability indicators; Markov model; degradation levels; multi-zone architecture

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