Industrial wireless sensor and actuator networks in industry 4.0: Exploring requirements,protocols, and challenges—A MAC survey

The vision to connect everyday physical objects to the Internet promises to create the Internet of Things (IoT), which is expected to integrate the diverse technologies such as sensors, actuators, radio frequency identification, communication technologies, and Internet protocols. Thus, IoT promises to transfer traditional industry to advance digital industry known as the Industry 4.0. At the core of the Industry 4.0 are the wireless sensor networks (WSNs) and wireless sensor and actuator networks (WSANs) that led to the development of industrial wireless sensor networks (IWSNs) and industrial wireless sensor and actuator networks (IWSANs). These networks play a central role of connecting machines, parts, products, and humans and create a diverse set of new applications to support intelligent and autonomous decision making. The IWSAN is a promising technology for numerous industrial applications because of their several potential benefits such as simple deployment, low cost, less complexity, and mobility support. However, despite such benefits, they impose several unique challenges at different layers of the protocol stack when deploying them for various monitoring and control applications in the Industry 4.0. In this article, we explore IWSAN, its applications, requirements, challenges, and solutions in the context of industrial control applications. Our main focus is on the medium access control (MAC) layer that can be exploited to satisfy such requirements. Our discussion presents extensive background study of the MAC schemes and it reviews the MAC protocols of the existing wireless standards and technologies. A number of application‐specific MAC protocols developed to support industrial applications, which are not part of these standards, are also elaborated. We rationalize to what extent the existing standards and protocols help in solving such requirements as laid down by the Industry 4.0. In the end, we emphasize on existing challenges and present important future directions.     

An energy efficient and QoS aware routing protocol for wireless sensor and actuator networks

Wireless sensor and actuator networks are composed of sensor and actuator nodes interconnected via wireless links. The actuators are responsible for taking prompt decisions and react accordingly to the data gathered by sensor nodes. In order to ensure efficient actions in such networks, we propose a new routing protocol that provides QoS in terms of delay and energy consumption. The network is organized in clusters supervised by CHs (Cluster-Heads), elected according to important metrics, namely the energy capability, the riches of connectivity, which is used to select the CH with high node density, and the accessibility degree regarding all the actuators. The latter metric is the distance in number of hops of sensor nodes relative to the actuator nodes. This metric enhances more the network reliability by reducing the communication delay when alerting the actuator nodes, and hence, reducing the energy consumption. To reach efficiently the actuator nodes, we design a delay and energy sensitive routing protocol based on-demand routing approach. Our protocol incurs less delay and is energy efficient. We perform an evaluation of our approach through simulations. The obtained results show out performance of our approach while providing effective gain in terms of communication delay and energy consumption.     

The design space of wireless sensor networks

In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics. As a consequence, it is becoming increasingly difficult to discuss typical requirements regarding hardware issues and software support. This is particularly problematic in a multidisciplinary research area such as wireless sensor networks, where close collaboration between users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. In this article we discuss the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions. We justify our view by demonstrating that specific existing applications occupy different points in the design space.     

Battery-dynamics driven tdma mac protocols for wireless body-area monitoring networks in healthcare applications

We propose the cross-layer based battery-aware time division multiple access (TDMA) medium access control (MAC) protocols for wireless body-area monitoring networks in wireless healthcare applications. By taking into account the joint effect of electrochemical properties of the battery, time-varying wireless fading channels, and packet queuing characteristics, our proposed schemes are designed to prolong the battery lifespan of the wireless sensor nodes while guaranteeing the reliable and timely message delivery, which is critically important for the patient monitoring networks. In addition, we develop a Markov chain model to analyze the performance of our proposed schemes. Both the obtained analytical and simulation results show that our proposed schemes can significantly increase the battery lifespan of sensor nodes while satisfying the reliability and delay-bound quality of service (QoS) requirements for wireless body-area monitoring networks. Furthermore, the case study of the electrocardiogram (ECG) monitoring application shows that besides meeting the delay requirements, our proposed schemes outperform the IEEE 802.15.4 and Bluetooth protocols in terms of battery lifespan.     

基于云计算的矿井无线传感网络火情远程监控系统

针对矿井实际需求情况,提出了一种基于云计算的无线传感网络火情远程监控系统,此系统包括通讯基站、无线传感器网络和云计算平台,其中,无线传感器网络通过通讯基站与云计算平台相连接。它包括用于采集煤矿安全数据的无线传感器、执行器和用于传输煤矿安全数据的无线网关。该系统具备低成本、自组织、低功耗、信息交互方便的特点,具有很好的应用前景。     

基于P2P的无线传感器网络应用架构研究

通过基础网络互联多个传感器网络，为用户提供大规模、大范围、多样化的信息服务成为未来无线传感器网络的应用模式之一。据此，提出了一种基于P2P（Peer-to—Peer）技术的无线传感器网络应用架构。采用P2P技术，解决了大数据量的通信瓶颈，传感器网络亦可自由加入、变更或退出，方便部署，网络可扩展性好．同时屏蔽底层网络差异及多种接入方式．为用户提供多个访问入口。     

IEEE802.15.4标准的无线传感器网络自组网方案

无线传感器网络需要低功耗短距离的无线通信技术,IEEE 802.15.4标准就是针对低速无线个人区域网络的无线通信标准,把低功耗、低成本作为设计的主要目标,由于IEEE 802.15.4标准定义的LR-WPAN网和无线传感器网络存在很多相似之处.所以把它作为无线传感器的无线通信平台.在分析LR-WPAN网的网络拓扑及形成过程的基础上,实现无线传感器网络的自组网方案.     

ATLeS-SN

As wireless sensor network platforms become increasingly more complex to design and optimize due to the multitude of interdependent parameters that must be considered, computer simulations have emerged as the primary solution to feasibly analyze the long-term effects of design changes within a deployed system. Although several successful wireless sensor network simulators have already been developed, to our knowledge, none provide the modularity necessary to model sensor nodes and/or environmental components at differing levels of abstraction. In this paper, we present the Arizona Transaction-Level Simulator for Sensor Networks (ATLeS-SN), which by virtue of its implementation language—SystemC—allows application developers to easily specify interchangeable component models in order to achieve the desired simulation correctness, performance, and scalability. We provide an overview of our proposed simulation framework and highlight its benefits using a sound ranging application.     

Optimal tracking interval for predictive tracking in wireless sensor network

An important application of wireless sensor networks is tracking moving objects. Prediction-based techniques have been proposed to reduce the power consumption in wireless sensor networks by limiting the sensor active time. This paper proposes a quantitative method to optimize the power efficiency by analyzing the effect of prediction on the energy consumption in such networks. To our best knowledge, our efforts are the first attempt made to calculate the optimal tracking interval for a given predictive tracking algorithm. Based on this method, the lifetime and power efficiency of a sensor network can be effectively improved.     

A novel energy‐aware routing mechanism for SDN‐enabled WSAN

Energy consumption is one of the most important design constraints when building a wireless sensor and actuator network since each device in the network has a limited battery capacity, and prolonging the lifetime of the network depends on saving energy. Overcoming this challenge requires a smart and reconfigurable network energy management strategy. The Software‐Defined Networking (SDN) paradigm aims at building a flexible and dynamic network structure, especially in wireless sensor networks. In this study, we propose an SDN‐enabled wireless sensor and actuator network architecture that has a new routing discovery mechanism. To build a flexible and energy‐efficient network structure, a new routing decision approach that uses a fuzzy‐based Dijkstra's algorithm is developed in the study. The proposed architecture can change the existing path during data transmission, which is the key property of our model and is achieved through the adoption of the SDN approach. All the components and algorithms of the proposed system are modeled and simulated using the Riverbed Modeler software for more realistic performance evaluation. The results indicate that the proposed SDN‐enabled structure with fuzzy‐based Dijkstra's algorithm outperforms the one using the regular Dijkstra's and the ZigBee‐based counterpart, in terms of the energy consumption ratio, and the proposed architecture can provide an effective cluster routing while prolonging the network lifetime.     

Self-propagating mal-packets in wireless sensor networks: Dynamics and defense implications

Self-propagating mal-packets have become an emergent threat against information confidentiality, integrity, and service availability in wireless sensor networks. While playing an important role for people to interact with surrounding environment, wireless sensor networks suffer from growing security concerns posed by mal-packets because of sensor networks’ low physical security, lack of resilience and robustness of underlying operating systems, and the ever-increasing complexity of deployed applications.In this paper, we study the propagation of mal-packets in 802.15.4 based wireless sensor networks. Based on our proposed mal-packet self-propagation models, we use TOSSIM, a simulator for wireless sensor networks, to study their propagation dynamics. We also present a study of the feasibility of mal-packet defense in sensor networks. Specifically, we apply random graph theory and percolation theory to investigate the immunization of highly-connected nodes, i.e., nodes with high degrees of connectivity. Our goal is to partition the network into as many separate pieces as possible, thus preventing or slowing down the mal-packet propagation. We study the percolation thresholds of different network densities and the effectiveness of immunization in terms of connection ratio, remaining link ratio, and distribution of component sizes. We also present an analysis of the distribution of component sizes.     

Secure encrypted-data aggregation for wireless sensor networks

This paper proposes a secure encrypted-data aggregation scheme for wireless sensor networks. Our design for data aggregation eliminates redundant sensor readings without using encryption and maintains data secrecy and privacy during transmission. Conventional aggregation functions operate when readings are received in plaintext. If readings are encrypted, aggregation requires decryption creating extra overhead and key management issues. In contrast to conventional schemes, our proposed scheme provides security and privacy, and duplicate instances of original readings will be aggregated into a single packet. Our scheme is resilient to known-plaintext attacks, chosen-plaintext attacks, ciphertext-only attacks and man-in-the-middle attacks. Our experiments show that our proposed aggregation method significantly reduces communication overhead and can be practically implemented in on-the-shelf sensor platforms.     

基于无线传感网络的小世界演化研究

提高无线传感网络的传输效率、节约整个网络的能量消耗是我们研究无线传感网络的重要内容。通常都是通过改变网络的拓扑结构来实现效率的提高,本文给出了一种新的思路去节约能耗。本文讨论了权重与与无线传感网传输效率的关系,将有权的无线传感网络链路上的权值进行随机的分配,我们发现将权重随机分配后网络的传输效率得到了提高并且随着权重分布概率的增大网络的传输效率不断增大。这为我们研究权重对无线传感网络的影响提供了基础。     

基于无线感知反应网络的智能家庭系统

Wireless sensor-actuator networks can bring flexibility to smart home. We design and develop a smart home prototype using wireless sensor-actuator network technology to realize environmental sensing and the control of electric appliances. The basic motivation of our solution is to utilize the collaboration among a mass of low-cost sensor nodes and actuator nodes to make life convenient. To achieve it, we design a novel system architecture with assembled component modules. In particular, we address some key technical challenges: 1) Field-Programmable Gate Array (FPGA) Implementation of Adaptive Differential Pulse Code Modulation (ADPCM) for audio data; 2) FPGA Implementation of Lempel Ziv Storer Szymanski (LZSS) for bulk data; 3) combination of complex control logic. Finally, a set of experiments are presented to evaluate the performance of our solution.     

基于特征根优化的无线网络控制系统故障检测滤波器设计

为提高无线传感器执行器网络(WSANs)的可靠性,本文提出了一种面向WSANs的故障检测滤波器的优化设计方法.针对无线网络固有的较大的数据包传输延迟,本文将该传输延迟对网络控制系统的影响建模为一种外部噪音,创造性地提出了基于特征根分解和扰动频率估计的优化算法,以滤除网络传输延迟导致的噪音.该方法只需在有限个频率点对目标函数进行优化,且避免了马尔科夫转移矩阵难以获得的难题.最后,通过MATLAB/NS2的混合仿真验证了该设计的有效性.     

Performance evaluation of IEEE 802.15.4 sensor networks in industrial applications

Wireless sensor networks have been widely applied in industrial applications especially since the release of IEEE 802.15.4 standard. By participating in an automobile project in which an IEEE 802.15.4 based sensor and actuator network is deployed to measure and control the vibrations of an automotive system, we need to study many metrics of IEEE 802.15.4 sensor networks (e.g., packet delivery rate, latency, and energy consumption) under various sampling rates. In order to provide detailed modeling of hardware and software as well as network behaviors on each sensor node, we conduct plenty of experiments on a SystemC‐based wireless sensor networks simulator IDEA1, which supports the hardware and software co‐simulation of sensor nodes with certain flexibility of abstraction level. Compared with the existing works on performance evaluation of IEEE 802.15.4 protocols, the main contributions of this paper are the comprehensive studies of both beacon‐enabled and nonbeacon‐enabled modes under various parameter settings and the beacon tracking synchronization mechanism in the IEEE 802.15.4 standard, which is ignored in most previous works. Additionally, the in‐depth analysis of simulation results enables us to find the best parameter configurations to different traffic loads and application requirements, which can be used as general experiences for other applications.Copyright © 2014 John Wiley & Sons, Ltd.     

FPGA Implementation and Energy Cost Analysis of Two Light-Weight Involutional Block Ciphers Targeted to Wireless Sensor Networks

In this paper, we investigate the energy cost of the FPGA implementation of two cryptographic algorithms targeted to wireless sensor networks (WSNs). Recent trends have seen the emergence of WSNs using sensor nodes based on reconfigurable hardware, such as a field-programmable gate arrays (FPGAs), thereby providing flexible functionality with higher performance than classical microcontroller based sensor nodes. In our study, we investigate the hardware implementation of involutional block ciphers since the characteristics of involution enables performing encryption and decryption using the same circuit. This characteristic is particularly appropriate for a wireless sensor node which requires the function of both encryption and decryption. Further, in order to consider the suitability of a cipher for application to a wireless sensor node, which is an energy constrained device, it is most critical to consider the cost of encryption in terms of energy consumption. Hence, we choose two involutional block ciphers, KHAZAD and BSPN, and analyze their energy efficiency for FPGA implementation.     

IRS: application reconfiguration scheme for wireless sensor networks

Application reconfiguration is essential to achieving flexibility and adaptability of wireless sensor networks (WSNs) used in environment monitoring. In this paper, we present an integrated reconfiguration scheme (IRS) for implementing environment adaptive application reconfiguration (EAAR) in WSNs. In our scheme, application reconfiguration is implemented with the push‐based paradigm for densely distributed nodes and the cluster‐based hybrid reconfiguration (CHR) paradigm for sparsely distributed nodes. We demonstrate the energy‐efficiency and scalability of our scheme by analyzing the energy consumption based on a randomly deployed sensor network. Moreover, we derive the density threshold of reconfiguration nodes (RNs) for determining if the nodes are densely or sparsely distributed, and choose the mode of operation for IRS. We use extensive simulation experiments to demonstrate the effectiveness of our scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

Technologies for highly miniaturized autonomous sensor networks

Recent results of the autonomous sensor research program HUMAN++ will be summarized in this paper. The research program aims to achieve highly miniaturized and (nearly) autonomous sensor systems that assist our health and comfort. Although the application examples are dedicated to human monitoring/assistance, the necessary technology development for this program is generic and can serve many wireless sensor applications. This multi-disciplinary program combines research on wireless ultra-low-power communications, research on 2D/3D integration and packaging platforms, energy scavenging techniques, as well as low-power and ultra-low-power sensor circuit design. An example sensor system is the wearable wireless EEG system.     

An Epidemic Theoretic Framework for Vulnerability Analysis of Broadcast Protocols in Wireless Sensor Networks

While multi-hop broadcast protocols, such as Trickle, Deluge and MNP, have gained tremendous popularity as a means for fast and convenient propagation of data/code in large scale wireless sensor networks, they can, unfortunately, serve as potential platforms for virus spreading if the security is breached. To understand the vulnerability of such protocols and design defense mechanisms against piggy-backed virus attacks, it is critical to investigate the propagation process of these protocols in terms of their speed and reachability. In this paper, we propose a general framework based on the principles of epidemic theory, for vulnerability analysis of current broadcast protocols in wireless sensor networks. In particular, we develop a common mathematical model for the propagation that incorporates important parameters derived from the communication patterns of the protocol under test. Based on this model, we analyze the propagation rate and the extent of spread of a malware over typical broadcast protocols proposed in the literature. The overall result is an approximate but convenient tool to characterize a broadcast protocol in terms of its vulnerability to malware propagation. We have also performed extensive simulations which have validated our model.