Wireless Sensor And Actuator Networks Applications Research Articles

SANSync: An Accurate Time Synchronization Protocol for Wireless Sensor and Actuator Networks

Wireless sensor and actuator networks (WSANs) consists of a large number of sensors and a relatively small number of actuators connected through wireless links. In the WSANs applications, sensors detect the events in their environment and inform actuators. The actuators cooperate together and respond quickly to events. To coordinate their operations, a common time reference to all nodes in the network is a critical need. In this paper, we propose an accurate time synchronization protocol for WSANs, namely Sensor and Actuator Networks Synchronization Protocol (SANSync), which allows the clocks of all sensors and actuators in the network to be synchronized with a reference clock. SANSync is based on clustering; it takes advantage of the large transmission capacity of actuators to increase the accuracy of time synchronization. The simulation results show that the proposed protocol increases significantly the accuracy of time synchronization compared to FTSP and FCSA protocols.

Reanalyzing a simplified Markov model for the low-density P2P wireless sensor and actuator networks

Wireless sensor and actuator networks (WSAN) are an important part of the emerging Industrial Internet of Things concept. Providing a computationally simple but relatively accurate analytical quality of service (QoS) model for the wireless communications technology is an essential step in developing distributed adaptive network protocols which try to satisfy the stringent industrial QoS requirements. In this paper, a novel Markov chain analysis and delay model has been proposed for the IEEE802.11-based WSANs applications which improves the accuracy while maintaining simplicity and considering the implicit industrial characteristics. Simulation results prove its superior performance compared with similar works.

A compositional approach for modeling and timing analysis of wireless sensor and actuator networks

Wireless sensor and actuator networks (WSAN) are created through the integration of multiple nodes which acquire data and perform reaction based on them. In a general overview, sensor nodes of WSANs are responsible for data acquisition and sending them to a central node. The central node stores all the received data and performs reactions. Timing verification of WSAN applications to ensure schedulability of tasks is a challenge, and is generally performed by worst-case analysis. This process is error-prone and inherently conservative. On the other hand, using model checking for analyzing WSAN applications results in state space explosion even for middle-sized configurations. The reason is the necessity of considering the interleaving of the large number of sensors in WSANs. In this paper, we show how to build an actor-based model of WSAN applications, starting from sensor node-level and moving towards the full system, and we show how this compositional modeling improves analysability and modifiability. Realtime extension of actor model is appropriate for modeling WSAN applications where we have many concurrent and asynchronous processes, and interdependent realtime deadlines. We demonstrate the approach using a case study of a distributed realtime data acquisition system for high-frequency sensing, where Timed Rebeca is used for modeling. We use model checking to check the intra/inter-sensor node schedulability.

A Kautz-Based Wireless Sensor and Actuator Network for Real-Time, Fault-Tolerant and Energy-Efficient Transmission

Wireless sensor and actuator networks (WSANs) are composed of sensors and actuators to perform distributed sensing and actuating tasks. Most WSAN applications (e.g., fire detection) demand that actuators rapidly respond to observed events. Therefore, real-time (i.e., fast) and fault-tolerant transmission is a critical requirement in WSANs to enable sensed data to reach actuators reliably and quickly. Due to limited power resources, energy-efficiency is another crucial requirement. Such requirements become formidably challenging in large-scale WSANs. However, existing WSANs fall short in meeting these requirements. To this end, we first theoretically study the Kautz graph for its applicability in WSANs to meet these requirements. We then propose a Kautz-based REal-time, Fault-tolerant and EneRgy-efficient WSAN (REFER). REFER embeds Kautz graphs into the physical topology of a WSAN for real-time communication and connects the Kautz graphs using distributed hash table (DHT) for high scalability. We also theoretically study routing paths in the Kautz graph, based on which we develop an efficient fault-tolerant routing protocol. It enables a relay node to quickly and efficiently identify the next shortest path from itself to the destination based only on node IDs upon routing failure, rather than relying on retransmission from the source. REFER is advantageous over previous Kautz graph based works in that it does not need an energy-consuming protocol to find the next shortest path and it preserves the consistency between the overlay and physical topology. We further improve routing in REFER by multi-path based routing and energy-efficient multicasting within and between Kautz graph cells, respectively. Extensive experimental results demonstrate the superior performance of REFER in comparison with existing WSAN systems in terms of real-time communication, energy-efficiency, fault-tolerance and scalability.

An approach based on the domain perspective to develop WSAN applications

As wireless sensor and actuator networks (WSANs) can be used in many different domains, WSAN applications have to be built from two viewpoints: domain and network. These different viewpoints create a gap between the abstractions handled by the application developers, namely the domain and network experts. Furthermore, there is a coupling between the application logic and the underlying sensor platform, which results in platform-dependent projects and source codes difficult to maintain, modify, and reuse. Consequently, the process of developing an application becomes cumbersome. In this paper, we propose a model-driven architecture (MDA) approach for WSAN application development. Our approach aims to facilitate the task of the developers by: (1) enabling application design through high abstraction level models; (2) providing a specific methodology for developing WSAN applications; and (3) offering an MDA infrastructure composed of PIM, PSM, and transformation programs to support this process. Our approach allows the direct contribution of domain experts in the development of WSAN applications, without requiring specific knowledge of programming WSAN platforms. In addition, it allows network experts to focus on the specific characteristics of their area of expertise without the need of knowing each specific application domain.

A State-Machine Model for Reliability Eliciting over Wireless Sensor and Actuator Networks

Advances in communications and embedded systems have led to the proliferation of wireless sensor and actuator networks (WSANs) in a wide variety of application domains. One important key of many such WSAN applications is the needed to meet non-functional requirements (e.g., lifetime, reliability, time guarantees) as well as functional ones (e.g. monitoring, actuation). Some application domains even require that sensor nodes be deployed in harsh environments (e.g., refineries), where they can fail due to communication interference, power problems or other issues. Unfortunately, the node failures can be catastrophic for critical or safety related systems. State machines can offer a promising approach to separate the two concerns – functional and non-functional – bringing forth reliability exception conditions handling, by means of fault handling states. We develop an approach that allows users to define and program typical applications using their platform language, but also adds state machine logic to design, view and handle explicitly other concerns such as reliability. The experimental section shows a working deployment of this concept in an industrial refinery setting

Simulated annealing for optimisation with wireless sensor and actuator networks

In wireless sensor and actuator networks (WSANs), because of unreliable transmission of sensory measurements and controller commands by wireless multi-hop, the controller's view of the system status is obscure and intermittent, resulting in infeasibility of direct analytical optimisation methods for WSAN applications. A simulated annealing based method is proposed, which features in stochastic trials and selective accepting. It is shown by simulations that the method is powerful in terms of satisfying user requirements.