Pouria Zand

Wireless Industrial Monitoring and Control Networks: The Journey So Far and the Road Ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks.

Implementation of WirelessHART in NS-2 simulator

One of the first standards in the wireless sensor networks domain, WirelessHART, was introduced to address industrial process automation and control requirements. The standard can be used as a reference point to evaluate other wireless protocols in the domain of industrial monitoring and control. This makes it worthwhile to set up a reliable WirelessHART simulator to achieve that reference point in a relatively easy way. This paper explains our implementation of WirelessHART in the NS-2 simulator. According to our knowledge, this is the first implementation that supports the WirelessHART network manager as well as the whole stack of the WirelessHART standard. We evaluated the performance of our implementation in terms of delay and communication load in the network. This implementation offers an alternative to expensive testbeds for testing WirelessHART.

D-MSR: a distributed network management scheme for real-time monitoring and process control applications in wireless industrial automation.

Current wireless technologies for industrial applications, such as WirelessHART and ISA100.11a, use a centralized management approach where a central network manager handles the requirements of the static network. However, such a centralized approach has several drawbacks. For example, it cannot cope with dynamicity/disturbance in large-scale networks in a real-time manner and it incurs a high communication overhead and latency for exchanging management traffic. In this paper, we therefore propose a distributed network management scheme, D-MSR. It enables the network devices to join the network, schedule their communications, establish end-to-end connections by reserving the communication resources for addressing real-time requirements, and cope with network dynamicity (e.g., node/edge failures) in a distributed manner. According to our knowledge, this is the first distributed management scheme based on IEEE 802.15.4e standard, which guides the nodes in different phases from joining until publishing their sensor data in the network. We demonstrate via simulation that D-MSR can address real-time and reliable communication as well as the high throughput requirements of industrial automation wireless networks, while also achieving higher efficiency in network management than WirelessHART, in terms of delay and overhead.

A distributed scheduling algorithm for real-time (D-SAR) industrial wireless sensor and actuator networks

Current wireless standards and protocols for industrial applications, such as WirelessHART and ISA100.11a, typically use centralized network management for communication scheduling and route establishment. However, due to their centralized nature, these protocols have difficulty coping with dynamic large-scale networks. To address this problem, we propose D-SAR, a distributed resource reservation algorithm that allows source nodes to meet the Quality-of-Service requirements for peer-to-peer communication. D-SAR uses concepts derived from circuit switching and Asynchronous Transfer Mode (ATM) networks and applies them to wireless sensor and actuator networks. Simulations show that latency in connection setup is 93% less in D-SAR compared to WirelessHART and that 89% fewer messages are sent during connection setup in case the distance from source to destination is 12 hops.

Simulation & analysis of WirelessHART nodes for real-time actuator application

WirelessHART protocol was specifically designed for real-time communication in the wireless sensor networks domain for industrial process automation requirements. Whereas the major purpose of WirelessHART is the read-out of sensors with moderate real-time requirements, an increasing demand for integration of actuator applications can be observed. Therefore, it must be verified that the WirelessHART protocol gives sufficient support to real-time industry requirements. As a result, the delay of especially burst and command messages from actuator and sensor nodes to the gateway and vice versa must be analyzed. In this paper, we implemented a WirelessHART network scenario in WirelessHART simulator in NS-2 , simulated and analyzed its time characteristics under ideal and noisy conditions. We evaluated the performance of the implementation in order to verify whether the requirements of industrial process and control can be met. This implementation offers an early alternative to expensive test beds for WirelessHART in real-time actuator applications.

Efficient I/O joining and reliable data publication in energy harvested ISA100.11a network

Energy harvesting technologies have brought a paradigm shift in the industrial automation sector by procreating self-powered wireless input/output (I/O) devices. Unfortunately, current wireless technologies for industrial applications, such as ISA100.11a and WirelessHART, are yet far from supporting harvester powered I/O devices. Although several works have been conducted to address the requirements of energy harvested I/O devices, most of those have focused on minimizing the I/O energy consumption during the steady-state phase of the network. However, a very important aspect, the energy consumption during network joining that consumes a significant amount of energy, is overlooked in these works. In this paper, we therefore analyze the I/O energy consumption in ISA100.11a network during the joining phase in addition to that in normal operation to better understand the challenges of energy harvesting communications. Then, we propose an energy efficient network joining scheme to support harvester powered I/O devices in ISA100.11a network. The proposed scheme significantly reduces the joining delay when compared with the traditional ISA100.11a joining scheme. We also propose a reliable data transmission scheme for energy harvested I/O devices by utilizing spatial diversity that can outperform ISA100.11a data publication through significant improvement in packet reception.

D-MHR: A distributed management scheme for hybrid networks to provide real-time industrial wireless automation

Current wireless technologies for industrial application, such as WirelessHART and ISA100.11a, use a centralized management approach which makes it difficult and costly for harvester-powered I/O devices to re-join the network in case of power failure. The communication overhead and delay to cope with the dynamic environment of a large-scale industrial network are also very high for an I/O device. In this paper, we therefore propose a distributed management scheme named D-MHR, which can address the requirements of energy constrained I/O devices. In D-MHR, the routers can dynamically reserve communication resources and manage the I/O devices in the local star sub-networks. We demonstrate that D-MHR achieves higher network management efficiency compared to IS100.11a standard, without compromising the latency and reliability requirements of industrial wireless networks.

A distributed management scheme for supporting energy-harvested I/O devices

Current wireless technologies for industrial application, such as WirelessHART and ISA100.11a, are not designed to support harvester-powered input/output (I/O) devices, where energy availability varies in a non-deterministic manner. The centralized management approach of these standards makes it difficult and costly for harvester-powered I/O devices (sensor/actuators) to re-join in the network in case of power failure. The communication overhead and delay to cope with the dynamic environment of a large-scale industrial network are also very high for an I/O device. In this paper, we therefore propose a Distributed Management scheme for Hybrid networks to provide Real-time communication (D-MHR) based on the IEEE 802.15.4e and Routing Protocol for Low power and Lossy Networks (RPL) standards, which can address the requirements of energy constrained I/O devices. In D-MHR, the routers can dynamically reserve communication resources and manage the I/O devices in the local star sub-networks. We demonstrate that D-MHR achieves higher network management efficiency compared to IS100.11a standard, without compromising the latency and reliability requirements of industrial wireless networks.