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This study investigates the distributed fusion estimation problem for multi‐sensor non‐linear networked systems with random access protocol (RAP) and cyber attacks. For each sensor, the RAP is applied to determine which channel can enter the communication networks at each transmission instant. The process of transmitting measurements to a corresponding local estimator (LE) via the wireless network may be attacked by a vicious attacker. Hence, a detector based on cross‐correlation of the causal sequence is proposed in the LE. Moreover, a distributed fusion estimation algorithm based on a sequential covariance intersection fusion technique is designed utilising local estimations calculated by modified unscented Kalman filter. A sufficient condition is obtained to guarantee the boundedness of fusion estimation error. Finally, a numerical simulation is given to demonstrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

Resilient dynamic event‐triggered control design problem is concerned for frequency stabilisation of multi‐area power systems with renewable energy penetration under transmission delay and denial‐of‐service (DoS) attacks. The main works are presented as followings: (1) A novel state‐space model is established to describe multi‐area power systems with solar and wind generation disturbance under load frequency control and virtual inertia control (LFC‐VIC). (2) The influence of DoS attacks is considered and first modelled by model‐based average dwell time (MDADT). A criterion of preserving desired exponential H∞ performance is obtained about the required lower bound of average dwell time (ADT) of sleep intervals, namely τF>ln⁡λ0/α1 and the tolerable upper bound of ADT of attack intervals, namely τD<−(ln⁡λ1+(α0+α1)dM)/α0. (3) To reduce communication load, a dynamic event‐triggered mechanism (DETM) is proposed and designed jointly with resilient LFC‐VIC scheme by using piecewise Lyapunov–Krasovskii functional method and LMIs technique. (4) To defence DoS attacks actively, based on the resulting MDADT criterion, a dynamic prediction strategy is proposed to compensate the packet drops with unknown bound subjected to attack strategy. Finally, a numerical example for a two‐area power system is carried out to verify the designed resilient LFC‐VIC scheme and the DETM. [ABSTRACT FROM AUTHOR]

Despite the importance of cyber‐security for networked control systems, no suitable cryptosystem exists for networked control systems that guarantees stability and has low computational complexity. This study proposes a novel dynamic ElGamal cryptosystem for encrypted control systems. The proposed cryptosystem is a multiplicative homomorphic cryptosystem, and it updates key pairs and ciphertexts by simple updating rules with modulo operations at every sampling period. Furthermore, the authors modify the proposed cryptosystem by using a dynamic encoder and decoder so that the asymptotic stability of the encrypted control systems is guaranteed. Numerical simulations demonstrate that the encrypted controller with the proposed cryptosystem achieves asymptotic stability while randomly updating key pairs and ciphertexts. The feasibility of the proposed encrypted control system is evaluated through regulation control with a positioning table testbed. The processing time of the proposed encrypted control system is on the order of milliseconds, indicating that the system achieves real‐time control. [ABSTRACT FROM AUTHOR]

Wireless Communication technologies are growing rapidly to meet increasing demands of users. This creates overhead in existing wireless systems. This manifests in the continuous development of wireless systems to keep pace with the increasing capacity demand. Increase in the number of users increases congestion in cellular bands, hence Extremely High Frequency (EHF) bands such as mmWave are attracting growing attention for use in cellular networks. Millimeter Wave (mmWave) bands can support multi‐Gigabit rates for large bandwidth applications in Next generation networks. These bands have certain limitations like, these cannot travel long distances and cannot penetrate buildings and other objects. These limitations can be advantageously exploited to provide more secure communication and permit high‐frequency reuse. This will facilitate efficient spectrum utilization and support design of densely packed networks. This paper reviews the propagation characteristics of mmWaves and effect of external factors like atmospheric gases, rain, foliage, and diffraction. Our main focus will be to study the effect of these factors on the propagation of mmWave frequencies to be used for 5G cellular networks. We evaluate the losses due to atmospheric gases, rain and foliage at 28, 30 and 60 GHz frequencies which are supposed to be used in 5G cellular networks. [ABSTRACT FROM AUTHOR]

This study presents a robust defence strategy in reaction to destabilising cyber‐physical attacks launched against linear time invariant systems and its application to power systems. The proposed protection scheme aims at making the dynamics of a selected subsystem decoupled from the dynamics of the subsystem targeted by the attack. The standard decoupling methods are made robust, in spite of poor information about plant parameters and lack of state measurement, with the aid of an extended observer. In this way, it is possible to keep the protected dynamics arbitrarily close to the one of a suitably chosen stable system, so long as the dynamics being targeted by the attack remain within the prescribed bounds. The proposed defence strategy is presented in the context of modern power systems, wherein generators and transmission networks are operated by different players and shown to be effective using the Western System Coordinating Council 9‐bus test power network. [ABSTRACT FROM AUTHOR]

This study considers a model that a centralised sensor network is attacked by an invader, who launches the denial‐of‐service (DoS) attack on the network. To understand the behaviour of the invader and propose necessary protection accordingly, the authors study how the invader optimises his attack. In the model, the sensors take a measurement of a process and send the measurements to a remote estimator for state estimation. The invader intends to block the communication channels from the sensors to the estimator by the DoS attack in order to degrade the estimation performance. Constrained by a power budget, the invader needs to decide which sensors and at which time instances to attack, with the target that the estimation performance is mostly deteriorated. In this study, two scenarios that the system has a single sensor and has multiple sensors are investigated, respectively. For the system with a single sensor, the analytical result of the optimal attack schedules is given. For the system with multiple sensors, numerical methods are proposed, where the problem is relaxed and transformed into a convex optimisation problem which can be solved by efficient numerical algorithms. [ABSTRACT FROM AUTHOR]