IET Wireless Sensor Systems
Print ISSN
2043-6386
Online ISSN 2043-6394
Online ISSN 2043-6394
IET Wireless Sensor Systems is aimed at the growing field of wireless sensor networks and distributed systems, which has been expanding rapidly in recent years and is evolving into a multi-billion dollar industry.
The Journal has been launched to give a platform to researchers and academics in the field and is intended to cover the research, engineering, technological developments, innovative deployment of distributed sensor and actuator systems.
Latest content
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Sensor selection for improving accuracy of target localisation in wireless visual sensor networks
- Author(s): W. Li; W. Zhang
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p.
293
–301
(9)
Considering target localisation without prior knowledge of the target is one of the critical areas of development, in this study, the authors propose a new sensor selection solution that improves the accuracy of target localisation without prior knowledge of the target in wireless visual sensor networks. The proposed solution exploits the properties of the overlap region of the target in images: (i) the more overlap grade, the more cameras project images of the target in the same direction; (ii) the greater overlap area, the higher possibility that the target is located in the region. The authors formulate the sensor selection problem as one of maximising the utility of multiplying the overlap grade by the overlap area gained from a set of sensors. Simulation results show the effectiveness of this approach of sensor selection in terms of improving the accuracy of target localisation.
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Non-uniform distribution of multi-hop sensor networks: performance improvement and energy hole mitigation
- Author(s): A. Mahani; A. Kargar; Y.S. Kavian; H.F. Rashvand
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p.
302
–308
(7)
The authors consider that packet forwarding strategies drastically affect the traffic patterns in multi-hop wireless networks such as wireless sensor networks (WSN). The converge-cast nature of the WSN traffic pattern is an imbalanced pattern, which leads to many issues including: 1- energy holes 2- high delay 3- traffic blockage. In this study, the effects of the node's density on the total delay, throughput and consumed energy of a WSN is considered. Here the authors demonstrate that under a non-uniform distribution method the WSN encounters much lesser energy holes and prolongs the network life cycle. So Zipf distribution is used and the performance metrics and lifetime of a WSN for uniform and Zipf distribution are compared. The simulation results show that a WSN with Zipf distribution works more energy efficient than a uniform density network. Also the Zipf distribution with different characterising exponent reports a trade-off between network lifetime and end-to-end delay.
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Tracking objects using hexagons in sensor networks
- Author(s): S.-H. Wang; R.-S. Chang; S.-L. Tsai
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p.
309
–317
(9)
The authors propose a communication scheme for collaboration groups to track objects in a sensor network. Inside a group, sensors are clustered dynamically to help group communication. Each cluster is a geographical hexagon area. Since tracking objects does not necessarily need all sensors to be running, the authors propose a local communication protocol to deal with object tracking. The authors design a data transmission route for the sensors communication. Using the hexagonal clustering idea, the authors can save power in collaboration groups for tracking objects. However, the cluster area affects the energy usage in object tracking. The authors optimise the size of cluster area to minimise energy consumption and show related analysis about finding the optimal hexagonal edge. In addition, the authors use dynamic clustering to handle the ping-pong effect resulting from targets shifting between different clusters. The simulation results show better performance than other communication schemes.
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Topology-controlled adaptive clustering for uniformity and increased lifetime in wireless sensor networks
- Author(s): D.P. Dahnil; Y.P. Singh; C.K. Ho
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p.
318
–327
(10)
Owing to the dynamic nature of sensor network applications the adoption of adaptive cluster-based topologies has many untapped desirable benefits for the wireless sensor networks. In this study, the authors explore such possibility and present an adaptive clustering algorithm to increase the network's lifetime while maintaining the required network connectivity. The proposed scheme features capability of cluster heads to adjust their power level to achieve optimal degree and maintain this value throughout the network operation. Under the proposed method a topology control allows an optimal degree, which results in a better distributed sensors and well-balanced clustering system enhancing networks' lifetime. The simulation results show that the proposed clustering algorithm maintains the required degree for inter-cluster connectivity on many more rounds compared with hybrid energy-efficient distributed clustering (HEED), energy-efficient clustering scheme (EECS), low-energy adaptive clustering hierarchy (LEACH) and energy-based LEACH.
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Hop-based approach for holes and boundary detection in wireless sensor networks
- Author(s): I.M. Khan; N. Jabeur; S. Zeadally
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p.
328
–337
(10)
In wireless sensor networks (WSNs), sensors are frequently prone to failure because of their limited batteries lifetime and external spatio-temporal events. Consequently, coverage and communication holes may appear preventing reliable and durable routing pathways. To efficiently deal with the effects of holes and prevent their expansions, it is unavoidable for any solution to detect their boundaries. This issue had been addressed by several works, many of which are based on topological approaches where sensor nodes’ connectivity is used. The authors propose a topological approach for the detection of the boundaries of holes. The approach also allows for the detection of the boundaries of the sensor network which is an important concern when sensors are deployed randomly in harsh, remote areas. The approach is based on the identification and the checking of the connectivity of the x-hop neighbours surrounding every node. The results of our simulations conducted on randomly and uniformly deployed WSNs demonstrate high accuracy and reduced requirements in terms of network connectivity degree and communication overhead compared to other existing approaches.
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Recursive clock skew estimation for wireless sensor networks using reference broadcasts
- Author(s): H. Yiğitler; A. Mahmood; R. Virrankoski; R. Jäntti
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p.
338
–350
(13)
Reference broadcast-based time synchronisation protocols are appreciated by the wireless sensor network community for their low-power demands. The underlying time relation characteristics of the broadcast-based time synchronisation schemes are prone to the effects resulting from the time record correlations. The recursive equivalents of the existing time synchronisation methods have large clock skew estimation error variance since these methods ignore the effect of correlation. In this study, the authors propose a novel recursive clock synchronisation algorithm based on a time relation model that reflects the effect of correlation. The authors utilise the maximum likelihood estimator to reach an asymptotically consistent and efficient clock skew estimator. The authors theoretically evaluate the performance of the developed estimator and compare it with the existing ones. Of the methods studied, the proposed estimator achieved the smallest estimation error variance. Experimental validation suggests an accuracy of less than one tick at synchronisation instants for a 6 h experiment.
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Two-tiered wireless sensor networks – base station optimal positioning case study
- Author(s): R.K. Tripathi; Y.N. Singh; N.K. Verma
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p.
351
–360
(10)
In this study, the question of ‘Where should the base station be placed in a two-tiered wireless sensor network (WSN) field?’ has been investigated. The objective is to minimise the overall energy consumption in a WSN. A heuristic algorithm has been proposed to find such a base station location. Considering some nodes to be far enough to use a different path loss model for their signals to the base station, our proposed algorithm considers two categories of nodes and hence two different path loss models based on their distance from the base station. The results show that the new algorithm provides a better base station location than the earlier methods. The overall energy consumption is quite close to the optimal solution.
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Scheme for preventing low-level denial-of-service attacks on wireless sensor network-based home automation systems
- Author(s): K. Gill; S.-H. Yang; W. Wang
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p.
361
–368
(8)
Remote access to home automation systems (HASs) through the Internet creates the potential for malicious users from across the Internet to attack the HASs. One such threat is that of a denial-of-service (DoS) attack that may disrupt communications or block remote access to the HASs. Existing approaches for DoS defence are generic and are not capable of filtering out all attack traffic, so a small amount of attack traffic reaches an HAS. This small level of attack traffic poses a significant threat to the HAS that are increasingly comprised of resource-limited wireless sensor networks (WSNs). This study proposes implements and evaluates a novel defence strategy designed to work alongside existing approaches for DoS defence to overcome the aforementioned shortcomings. The proposed defence strategy consists of three entities, the virtual home, remote home server and DoS defence server. The experimental results show that the proposed strategy can filter low-level attack traffic and thereby protect low-resource networks, such as WSN-based HASs.
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Spreading-factor based addressing-tree protocol for ad-hoc wireless sensor networks
- Author(s): S. Saxena; S. Mishra; A.K. Sharma; D.S. Chauhan
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p.
369
–376
(8)
Tree-routing (TR) is a fundamental protocol most suited for a tree-like sensor network. Here, a sensor node deployed as leaf node senses the environmental phenomenon and forwards it to the sink node positioned as the root node by following a fixed parent–child path. This strategy prevents the network from flooding path search messages and saves bandwidth. The enhanced-tree-routing (ETR) protocol is an improvement to the TR protocol that uses a structured node address assignment scheme and considers neighbouring tables stored at each sensor node to find the shortest path to the sink. This requires minimum computation energy, storage and provides energy-efficient routing. In this paper the authors have proposed a spreading factor-based addressing (SFBA-tree) approach based on a non-blocking orthogonal vector spreading factor addressing technique, for the TR protocol and usage of movable sinks to eliminate excessive multi-hopping caused by the ETR protocol while discovering the shortest paths. Also, the authors have shown an SFBA-tree implementation to the ZigBee networks to prevent storage space and computation. The simulation result shows that the new scheme provides energy-efficient addressing and communication in a moderate size tree network.
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Improving transmission reliability of low-power medium access control protocols using average diversity combining
- Author(s): M. Ghamari; B.M. Heravi; U. Roedig; B. Honary; C.A. Pickering
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p.
377
–384
(8)
Embedded computer systems equipped with wireless communication transceivers are nowadays used in a vast number of application scenarios. Energy consumption is important in many of these scenarios, as systems are battery operated and long maintenance-free operation is required. To achieve this goal, embedded systems employ low-power communication transceivers and protocols. However, currently used protocols cannot operate efficiently when communication channels are highly erroneous. In this study, we show how average diversity combining (ADC) can be used in state-of-the-art low-power communication protocols. This novel approach improves transmission reliability and in consequence energy consumption and transmission latency in the presence of erroneous channels. Using a testbed, we show that highly erroneous channels are indeed a common occurrence in situations, where low-power systems are used and we demonstrate that ADC improves low-power communication dramatically.
