Opportunistic Wireless Control Over State-Dependent Fading Channels

The heterogeneous system consisting of the wireless control system (WCS) and mobile agent system (MAS) is ubiquitous in Industrial Internet of Things (IIoT) systems. Within this system, the positions of mobile agents may lead to shadow fading on the wireless channel that the WCS is controlled over and can significantly compromise the WCS's performance. This paper focuses on the controller design for the MAS to ensure the performance of WCS in the presence of WCS and MAS coupling. Firstly, the constrained finite field network (FFN) with profile-dependent switching topology is adopted to proceed the operational control for the MAS. By virtue of the algebraic state space representation (ASSR) method, an equivalent form is obtained for the WCS and MAS coupling. A necessary and sufficient condition in terms of constrained set stabilization is then established to ensure the Lyapunov-like performance with expected decay rate. Finally, a graphical method together with the breath-first searching is provided to design state feedback controllers for the MAS. With this method, it is easy to check the constrained set stabilization of MAS and to ensure the performance requirements of WCS in the presence of WCS and MAS coupling. The study of an illustrative example shows the effectiveness of the proposed method

Ultra reliable low latency communication in MTC network

Abstract. Internet of things is in progress to build the smart society, and wireless networks are critical enablers for many of its use cases. In this thesis, we present some of the vital concept of diversity and multi-connectivity to achieve ultra-reliability and low latency for machine type wireless communication networks. Diversity is one of the critical factors to deal with fading channel impairments, which in term is a crucial factor to achieve targeted outage probabilities and try to reach out such requirement of five 9’s as defined by some standardization bodies. We evaluate an interference-limited network composed of multiple remote radio heads connected to the user equipment. Some of those links are allowed to cooperate, thus reducing interference, or to perform more elaborated strategies such as selection combining or maximal ratio combining. Therefore, we derive their respective closed-form analytical solutions for respective outage probabilities. We provide extensive numerical analysis and discuss the gains of cooperation and multi-connectivity enabled to be a centralized radio access network

Control Aware Radio Resource Allocation in Low Latency Wireless Control Systems

We consider the problem of allocating radio resources over wireless communication links to control a series of independent wireless control systems. Low-latency transmissions are necessary in enabling time-sensitive control systems to operate over wireless links with high reliability. Achieving fast data rates over wireless links thus comes at the cost of reliability in the form of high packet error rates compared to wired links due to channel noise and interference. However, the effect of the communication link errors on the control system performance depends dynamically on the control system state. We propose a novel control-communication co-design approach to the low-latency resource allocation problem. We incorporate control and channel state information to make scheduling decisions over time on frequency, bandwidth and data rates across the next-generation Wi-Fi based wireless communication links that close the control loops. Control systems that are closer to instability or further from a desired range in a given control cycle are given higher packet delivery rate targets to meet. Rather than a simple priority ranking, we derive precise packet error rate targets for each system needed to satisfy stability targets and make scheduling decisions to meet such targets while reducing total transmission time. The resulting Control-Aware Low Latency Scheduling (CALLS) method is tested in numerous simulation experiments that demonstrate its effectiveness in meeting control-based goals under tight latency constraints relative to control-agnostic scheduling

A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks

In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs

Active Fault-Tolerance in Wireless Networked Control Systems

In a Wireless Networked Control System (WNCS), several nodes or components of the system may communicate over the common network that connects them together. Thus, there may be communication taking place between the sensors and the controller nodes, among the controllers themselves, among the sensors themselves, among the actuator themselves, and between the controller and the actuator nodes. The purpose of this communication is to improve the performance of the control system. The performance may be a measurable quantity defined in terms of a performance criterion, as in the case of optimal control or estimation, or it may be a qualitative measure described as a desired behaviour. Each node of the WNCS may act as a decision maker, making control as well as communication decisions. The presence of a network brings in constraints in the design of the control system, as information between the various decision makers must be exchanged according to the rules and dynamics of the network. Our goal is to quantify some of these constraints, and design the control system together with the communication system so as both do their best given the constraints. This work in no way attempts to suggest the best way to design a communication network that suits the needs of a particular control system, but some of the results obtained here may be used in conjunction with other results in forming an understanding as to how to proceed in the design of such systems in the future. The work proposes a novel real-time communication protocol based on the Time Division Multiple Access (TDMA) strategy, which has built-in tolerance against the network-induced effects like lost packets, assuring a highly deterministic and reliable behaviour of the overall networked control system, thus allowing the use of classical control design methods with WNCS. Determinism in the transmission times, for sending and for receiving, is assured by a communication schedule that is dynamically updated based on the conditions of the network and the propagation environment. An advanced experimentation platform has been developed, called WiNC, which demonstrates the efficiency of the protocol with two well-known laboratory benchmarks that have very different dynamics, namely the three-tank system and the inverted pendulum system. Wireless nodes belonging to both systems are coordinated and synchronized by a master node, namely the controller node. The WiNC platform uses only open source software and general-purpose (commercial, off-the shelf) hardware, thus making it with a minimal investment (low cost) a flexible and easily extendable research platform for WNCS. And considering the general trend towards the adoption of Linux as a real-time operating system for embedded system in automation, the developed concepts and algorithms can be ported with minimum effort to the industrial embedded devices which already run Linux

Real-Time Sensor Networks and Systems for the Industrial IoT

The Industrial Internet of Things (Industrial IoT—IIoT) has emerged as the core construct behind the various cyber-physical systems constituting a principal dimension of the fourth Industrial Revolution. While initially born as the concept behind specific industrial applications of generic IoT technologies, for the optimization of operational efficiency in automation and control, it quickly enabled the achievement of the total convergence of Operational (OT) and Information Technologies (IT). The IIoT has now surpassed the traditional borders of automation and control functions in the process and manufacturing industry, shifting towards a wider domain of functions and industries, embraced under the dominant global initiatives and architectural frameworks of Industry 4.0 (or Industrie 4.0) in Germany, Industrial Internet in the US, Society 5.0 in Japan, and Made-in-China 2025 in China. As real-time embedded systems are quickly achieving ubiquity in everyday life and in industrial environments, and many processes already depend on real-time cyber-physical systems and embedded sensors, the integration of IoT with cognitive computing and real-time data exchange is essential for real-time analytics and realization of digital twins in smart environments and services under the various frameworks’ provisions. In this context, real-time sensor networks and systems for the Industrial IoT encompass multiple technologies and raise significant design, optimization, integration and exploitation challenges. The ten articles in this Special Issue describe advances in real-time sensor networks and systems that are significant enablers of the Industrial IoT paradigm. In the relevant landscape, the domain of wireless networking technologies is centrally positioned, as expected