A Novel Dual Separate Paths (DSP) Algorithm Providing Fault-Tolerant Communication for Wireless Sensor Networks

Nguyen Tien, Semog Kim, Jong Rhee, Sang Park
2017 Sensors  
Fault tolerance has long been a major concern for sensor communications in fault-tolerant cyber physical systems (CPSs). Network failure problems often occur in wireless sensor networks (WSNs) due to various factors such as the insufficient power of sensor nodes, the dislocation of sensor nodes, the unstable state of wireless links, and unpredictable environmental interference. Fault tolerance is thus one of the key requirements for data communications in WSN applications. This paper proposes a
more » ... novel path redundancy-based algorithm, called dual separate paths (DSP), that provides fault-tolerant communication with the improvement of the network traffic performance for WSN applications, such as fault-tolerant CPSs. The proposed DSP algorithm establishes two separate paths between a source and a destination in a network based on the network topology information. These paths are node-disjoint paths and have optimal path distances. Unicast frames are delivered from the source to the destination in the network through the dual paths, providing fault-tolerant communication and reducing redundant unicast traffic for the network. The DSP algorithm can be applied to wired and wireless networks, such as WSNs, to provide seamless fault-tolerant communication for mission-critical and life-critical applications such as fault-tolerant CPSs. The analyzed and simulated results show that the DSP-based approach not only provides fault-tolerant communication, but also improves network traffic performance. For the case study in this paper, when the DSP algorithm was applied to high-availability seamless redundancy (HSR) networks, the proposed DSP-based approach reduced the network traffic by 80% to 88% compared with the standard HSR protocol, thus improving network traffic performance. 2 of 21 other and interact with the physical world via sensors [3] . CPS is a rapidly emerging field which is expected to affect all aspects of life in the near future [4]; the applications of CPS include automotive systems, smart space, healthcare, military systems, emergency real-time systems, environmental monitoring and control, smart transportation, traffic control and safety, power generation and distribution, aircraft, instrumentation, water management systems, trains, physical security, asset management, and distributed robotics [5, 6] . WSN technology is used in the development of CPSs for real-time decision-making systems in the aforementioned applications [6] . CPS is increasingly used in life-critical applications, where the probability of failure must be kept below very low levels. Seamless fault-tolerant communication is therefore one of the key requirements for life-critical and mission-critical applications, and fault-tolerance has long been one of the major concerns for communications for sensors in CPS [7] . Fault-tolerance in a WSN ensures that the WSN is available for use without any interruption when any link or node failure occurs in the network. Therefore, fault-tolerance improves the availability, reliability, and dependability of the WSN [8]. Several techniques have been proposed to provide fault-tolerance in WSNs; these techniques can be classified into three categories, including redundancy-based techniques, clustering-based techniques, and deployment-based techniques [9]. Redundancy-based techniques provide fault-tolerance based on redundancy mechanisms such as path redundancy, node redundancy, and time redundancy. Clustering-based techniques use clustering mechanisms to provide fault-tolerance for WSNs. Clustering mechanisms divide a WSN into several disjointed or overlapping clusters. Each cluster elects one node as a representative of the cluster, called a cluster head. Clustering is an effective way to reduce energy consumption in WSNs. Finally, deployment-based techniques focus on the deployment of sensor nodes in WSNs to lead to effective design goals. There are several ways to deploy sensor nodes (SNs) in WSNs, including the pre-deployment of sensor nodes, the deployment of sensor nodes during use, and the post-deployment of nodes [8] . Several fault-tolerant techniques are described in Section 2. In this paper, we propose a novel path redundancy-based algorithm, called the dual separate paths (DSP) algorithm, for providing fault-tolerant communication and improving network traffic performance in WSNs, as well as in other networks. The main idea of DSP is to find dual paths between a source node and a destination node in a network. The dual paths are node-disjoint paths with an optimal path distance. The dual paths are used to forward unicast frames from the source to the destination, resulting in seamless communication over the network. The proposed DSP algorithm can be applied to wired and wireless networks, such as high-availability seamless redundancy (HSR) networks and WSNs, to provide fault-tolerant communication with improved network traffic performance for applications that require high availability, such as fault-tolerant CPSs and substation automation systems. We perform a case study to analyze and evaluate the performance of the DSP-based approach, which applies the DSP algorithm to HSR networks. The motivation of this case study is to demonstrate that the DSP-based approach not only provides fault-tolerant communication, but also improves the network traffic performance for wired and wireless networks. In the case study, the DSP-based approach establishes dual paths between source and destination QuadBox pairs in an HSR network. The DSP-based approach then uses the dual paths to forward unicast frames from the source to the destination, instead of doubling and flooding the frames over the whole network, as is done using the standard HSR protocol. Therefore, the DSP approach not only provides seamless redundancy, but also significantly reduces redundant unicast traffic in HSR networks, thus improving the network performance. The remainder of this paper is organized as follows. We describe related works in Section 2. In Section 3, we describe the DSP algorithm in more detail. Then, in Section 4, we introduce the case study, in which the DSP algorithm is applied to HSR networks to provide fault-tolerant communication as well as reducing redundant unicast traffic in the networks. We analyze and evaluate the performance of the proposed DSP-based approach in Section 5, while in Section 6, we describe several simulations
doi:10.3390/s17081699 pmid:28757544 pmcid:PMC5579733 fatcat:cjy3lxupr5fnnjkwys2jqj7fqy